The Next
Generation
City Wireless
Evaluation
Nov. 14, 2008
City of Pittsburgh
Wi-MAN
Jamil Masarweh, Suk Un Han,
Myung Soo Shim, Ning Tantai,
Sin-Young Park
Table of Contents
1. Executive Summary ........................................................................................................................5
2. Technology Description and Analysis ..............................................................................................7
2.1 Wi-Fi .................................................................................................................................................... 7
2.1.1 Introduction ................................................................................................................................. 7
2.1.2 Analysis 2.1.2.1 Technical Description (802.11a\b\g\n) ............................................................. 8
2.1.2.1.1 802.11-1997 (802.11 legacy) ............................................................................................ 8
2.1.2.1.2 802.11a............................................................................................................................. 8
2.1.2.1.3 802.11b ............................................................................................................................ 8
2.1.2.1.4 802.11g............................................................................................................................. 9
2.1.2.1.5 802.11-2007 ................................................................................................................... 10
2.1.2.1.6 802.11n .......................................................................................................................... 10
2.1.3 Deployment Strategy ................................................................................................................. 13
2.1.4 Table Summary .......................................................................................................................... 15
2.2 WiMAX .............................................................................................................................................. 17
2.2.1 Introduction ............................................................................................................................... 17
2.2.2 Analysis ...................................................................................................................................... 18
2.2.2.1 Technical Description .............................................................................................................. 18
2.2.2.1.1 fixed WiMAX................................................................................................................... 18
2.2.2.1.2 mobile WiMAX ............................................................................................................... 19
2.2.3 Deployment Strategy ................................................................................................................. 19
2.2.4 Table Summary .......................................................................................................................... 20
2.3 3G ...................................................................................................................................................... 21
2.3.1 Introduction ............................................................................................................................... 21
2.3.2 Analysis ...................................................................................................................................... 22
2.3.1.1 Technical Description .............................................................................................................. 22
2.3.1.1.1 3GPP ............................................................................................................................... 22
2.3.1.1.2 3GPP2 ............................................................................................................................. 23
2
2.3.1.1.3 WCDMA and HSPA family .............................................................................................. 24
2.3.1.1.4 UMTS-TDD family ........................................................................................................... 24
2.3.1.1.5 3GPP Long Term Evolution ............................................................................................. 25
2.3.1.1.6 CDMA ............................................................................................................................. 27
2.3.1.1.7 EVDO .............................................................................................................................. 27
2.3.1.1.8 UMB................................................................................................................................ 28
2.3.1.1.9 Conclusion ...................................................................................................................... 29
2.3.2 City Deployment ........................................................................................................................ 29
2.2.1.3 Table Summary ....................................................................................................................... 30
2.4 Comparison of Technologies ............................................................................................................. 33
2.4.1 Comparison between WiMAX and Wi-Fi ................................................................................... 33
2.4.2 3G VS WiMAX ............................................................................................................................. 34
2.4.3 Conclusion: Setting the Expectation: ......................................................................................... 37
Summary of Municipal Wi-Fi projects overview and results. ..................................................... 37
The case of Boston: ..................................................................................................................... 38
The Case of San Francisco: .......................................................................................................... 38
The Case of Philadelphia: ............................................................................................................ 38
3. Network Solution for Pittsburgh ................................................................................................... 39
3.1 Desired Goals for the City ................................................................................................................. 39
3.1.1 WiMAN needs to Target Three Major Markets ......................................................................... 39
3.1.2 Goals of Pittsburgh within the Flow........................................................................................... 40
3.2 Pittsburgh Demographic Information ............................................................................................... 40
3.2.1 Daytime Population Change ...................................................................................................... 42
3.3 Choice of Technology: mobile WiMAX.............................................................................................. 43
3.4 Network Deployment Process .......................................................................................................... 44
3.4.1 Network Architecture Concept .................................................................................................. 44
3.4.2 WiMAX Network Diagram Samples: .......................................................................................... 45
3.4.3 Deployment Plan ........................................................................................................................ 47
3.5 Adoption Plan.................................................................................................................................... 47
3.5.1 Current WiMAX Subscription Rate ............................................................................................. 47
3.5.1.1 WiMAX in Scottsburg, IN ..................................................................................................... 47
3
3.5.1.2 WiMAX in Baltimore, MD by XOHM ................................................................................... 48
3.5.2 Current 3G Data Plan ................................................................................................................. 48
3.5.2.1 AT&T.................................................................................................................................... 48
3.5.2.2 Verizon ................................................................................................................................ 49
3.5.3 Current City-Owned Wi-Fi Downtown Pittsburgh Data Plan ..................................................... 50
3.5.4 Current WiMAX Device .............................................................................................................. 50
3.5.5 Solutions for Current Laptop & Mobile Devices ........................................................................ 51
3.5.6 Data Plan Recommendation ...................................................................................................... 52
4. Cost analysis and cost estimative ranges. ...................................................................................... 53
4.1 The Capital Expenditure - CAPEX ...................................................................................................... 53
CAPEX .......................................................................................................................................... 56
Reference 2. ................................................................................................................................ 56
4.2 Revenue Estimation .......................................................................................................................... 59
4
1. Executive Summary
The need of better standards and services in municipal areas are making cities investigate more and
more in the deployment of technological projects and in the research of new concepts, for the
advancements and rising of these standards. The Wireless technology for instance has enabled cities
throughout the United States to achieve new standards, perform tasks that where overly impractical
and routine in new ways. Seeing a city nowadays as livable, attractive to the public or business alike is
the preoccupation of many city leaders that are finding technology to be the solution for most of these
points. Deploying a Wireless Municipal Area Network, Wi-MAN, has been the trend for many cities over
the past 5 years to solve these concerns. A number of 406 US cities have been estimated to have
deployed or started or planned to have a municipal Wi-MAN from 2003 to 2008.
All these cities have started with enthusiasm and then had to face many of the hard realities that the
technology has presented. The case by case study (in section 3), of each Wi-MAN projects reveals some
issue patterns, like the sustainability of the project itself, the business models used, and the specific
technology used. One overwhelming pattern was that many projects have set wrong expectations of the
technology. Thus, Municipal wireless has received a bad name after aborted attempts to launch citywide Wi-Fi services.
In this report we have examined the different technologies that can be used in a Wireless Municipal
Area Network, from Wi-Fi, (Wireless Fidelity, also known as the 802.11 standard), mobile WiMAX
(Worldwide Interoperability for Microwave Access, known as the 802.16e standard) and 3G (third
generation of mobile phone standards). In the first part, each technology is described and analyzed. A
comparison was then made, to give an idea in one view, of how each of them is unique and differ from
the other. The requirement of the City of Pittsburgh, for adopting a WiMAN , for the public services, and
the benefit of the citizens, business and the city itself, cannot be fulfilled with a technology that cannot
be easily adopted, relatively cheap, and compares to current market offers for similar products.
After many case studies of each technology in different cities, mobile WiMAX has been selected to be
the technology of choice for being an efficient and reliable WiMAN. No comparison could be better than
real project lessons from both Wi-Fi WIMAN and WiMAX WiMAN projects. In fact mobile WiMAX
WIMAN, has been implemented in pilot cities, with very encouraging results, where Wi-Fi project have
failed even before a benefit was made from the deploying City. In the research for real projects in the
USA, not a single city used 3G as WIMAN solution. 3G remains of the domain mobile phone and has a
limited or costly adoption in other application.
The comparison of technologies, along with the real projects analysis from the internet, have all favored
the selection of WIMAX. The latter, in fact embraces the best of both technologies combined, (Wi-Fi and
3G).
5
Understanding the demographic of Pittsburgh is essential to draft the solution. A WIMAN project has
key factors that need to be considered, such city size, density and daytime population. In the third part
of this document, these factors are illustrated in order to draft a sustainable solution of the City. A
sample network diagram is also used to give the reader an idea of the topology of a WiMAX network to
be deployed. WiMAX not only is going a step beyond, in its specific characteristic, over other
technologies, but it’s network design - the mesh topology- is essential to the success of a WIMAN. Other
important factors such the estimated cost of user subscription to a Wireless broadband are also
illustrated.
To estimate the Costs associated with such a project, the successful deployments in big cities like
Chicago and medium sized cities like Baltimore and Boston have been analyzed in the fourth part of this
document. Different costing approaches have been taken in consideration in order to have nearaccurate and realistic costs. Essential data have been gathered from the other mentioned cities and
proportional and linear calculations have been used to estimate cost between 16 and 20 Million USD for
the deployment of the mobile WiMAX network.
The final section of this document illustrates the estimated revenues for the City from such a project.
6
2. Technology Description and Analysis
2.1 Wi-Fi
2.1.1 Introduction1
The 802.11 family includes over-the-air modulation techniques that use the same basic protocol. The
most popular are those defined by the 802.11b and 802.11g protocols, and are amendments to the
original standard. 802.11-1997 was the first wireless networking standard, but 802.11b was the first
widely accepted one, followed by 802.11g and 802.11n. Security was originally purposefully weak due to
export requirements of some governments, and was later enhanced via the 802.11i amendment after
governmental and legislative changes. 802.11n is a new multi-streaming modulation technique that is
still under draft development, but products based on its proprietary pre-draft versions are being sold.
Other standards in the family are service amendments and extensions or corrections to previous
specifications.
802.11b and 802.11g use the 2.4 GHz ISM band, operating in the United States under Part 15 of the US
Federal Communications Commission Rules and Regulations. Because of this choice of frequency band,
802.11b and g equipment may occasionally suffer interference from microwave ovens and cordless
telephones. Bluetooth devices, while operating in the same band, in theory do not interfere with
802.11b/g because they use a frequency hopping spread spectrum signaling method (FHSS) while
802.11b/g uses a direct sequence spread spectrum signaling method (DSSS). 802.11a uses the 5 GHz UNII band, which offers 8 non-overlapping channels rather than the 3 offered in the 2.4GHz ISM
frequency band.
The segment of the radio frequency spectrum used varies between countries. In the US, 802.11a and
802.11g devices may be operated without a license, as allowed in Part 15 of the FCC Rules and
Regulations. Frequencies used by channels one through six (802.11b) falls within the 2.4 GHz amateur
radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC
Rules and Regulations, allowing increased power output but not commercial content or encryption.
1
http://en.wikipedia.org/wiki/802.11
7
2.1.2 Analysis
2.1.2.1 Technical Description (802.11a\b\g\n)
2.1.2.1.1 802.11-1997 (802.11 legacy)
The original version of the standard IEEE 802.11, released in 1997 and clarified in 1999, specified two
raw net bit rates of 1 or 2 megabits per second (Mbit/s), plus forward error correction code, to be
transmitted in Industrial Scientific Medical frequency band at 2.4 GHz.
Legacy 802.11 was rapidly supplemented (and popularized) by 802.11b.
2.1.2.1.2 802.11a
Release date
Op. Frequency
Net bit rate
(Type)
Net bit rate
(Max)
Gross bit rate
(Max)
Range
(Indoor)
October
1999
5 GHz
23 Mbit/s
54 Mbit/s
72 Mbit/s
~35 m
The 802.11a standard uses the same data link layer protocol and frame format as the original standard,
but an OFDM based air interface (physical layer). It operates in the 5 GHz band with a maximum net
data rate of 54 Mbit/s, plus error correction code, which yields realistic net achievable throughput in the
mid-20 Mbit/s
Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively un-used 5 GHz
band gives 802.11a a significant advantage. However, this high carrier frequency also brings a
disadvantage: The effective overall range of 802.11a is less than that of 802.11b/g; 802.11a signals
cannot penetrate as far as those for 802.11b because they are absorbed more readily by walls and other
solid objects in their path.
2.1.2.1.3 802.11b
Release date
Frequency band
Data rate (typical)
Data rate (maximum)
Range (indoor)
October 1999
2.4 GHz
4.5 Mbit/s
11 Mbit/s
~38 m
8
802.11b has a maximum raw data rate of 11 Mbit/s and uses the same media access method defined in
the original standard. 802.11b products appeared on the market in early 2000, since 802.11b is a direct
extension of the modulation technique defined in the original standard. The dramatic increase in
throughput of 802.11b (compared to the original standard) along with simultaneous substantial price
reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.
802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices
operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and
cordless telephones.
2.1.2.1.4 802.11g
IEEE 802.11g-2003 or 802.11g is an amendment to the IEEE 802.11 specification that extended
throughput to up to 54 Mbit/s using the same 2.4 GHz band as 802.11b. This specification under the
marketing name of Wi-Fi has been implemented all over the world. The 802.11g protocol is now Clause
19 of the published IEEE 802.11-2007 standard.
802.11g was the third modulation standard for Wireless LAN. It works in the 2.4 GHz band (like 802.11b)
but operates at a maximum raw data rate of 54 Mbit/s, or about 19 Mbit/s net throughputs (identical to
802.11a core, except for some additional legacy overhead for backward compatibility). 802.11g
hardware is fully backwards compatible with 802.11b hardware. Details of making b and g work well
together occupied much of the lingering technical process. In an 11g network, however, the presence of
a legacy 802.11b participant will significantly reduce the speed of the overall 802.11g network.
The modulation scheme used in 802.11g is orthogonal frequency-division multiplexing (OFDM) copied
from 802.11a with data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbit/s, and reverts to CCK (like the
802.11b standard) for 5.5 and 11 Mbit/s and DBPSK/DQPSK+DSSS for 1 and 2 Mbit/s. Even though
802.11g operates in the same frequency band as 802.11b, it can achieve higher data rates because of its
heritage to 802.11a.
The then-proposed 802.11g standard was rapidly adopted by consumers starting in January 2003, well
before ratification, due to the desire for higher speeds, and reductions in manufacturing costs. By
summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in
a single mobile adapter card or access point.
Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already
crowded 2.4 GHz range. Devices operating in this range include: microwave ovens, Bluetooth devices,
baby monitors and (in the USA) digital cordless telephones which can lead to interference issues.
Additionally the success of the standard has caused usage/density problems related to crowding in
9
urban areas. This crowding can cause a dissatisfied user experience as the number of non-overlapping
usable channels is only 3 in FCC nations or 4 in European nations.2
Release
date
Op.
Frequency
Net bit rate
(Type)
Net bit rate
(Max)
Gross bit rate
(Max)
Range
(Indoor)
June 2003
2.4 GHz
19 Mbit/s
54 Mbit/s
72 Mbit/s
~38 m
In June 2003, a third modulation standard was ratified: 802.11g. This works in the 2.4 GHz band (like
802.11b), but uses the same OFDM based transmission scheme as 802.11a. It operates at a maximum
physical layer bit rate of 54 Mbit/s exclusive of forward error correction codes, or about 19 Mbit/s
average throughout. 802.11g hardware is fully backwards compatible with 802.11b hardware.
The then-proposed 802.11g standard was rapidly adopted by consumers starting in January 2003, well
before ratification, due to the desire for higher speeds, and reductions in manufacturing costs. By
summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in
a single mobile adapter card or access point. Details of making b and g work well together occupied
much of the lingering technical process; in an 802.11g network, however, activity by a 802.11b
participant will reduce the speed of the overall 802.11g network.
Like 802.11b, 802.11g devices suffer interference from other products operating in the 2.4 GHz band.
Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and
cordless telephones.
2.1.2.1.5 802.11-2007
In 2003, task group TGma was authorized to "roll up" many of the amendments to the 1999 version of
the 802.11 standard. REVma or 802.11ma, as it was called, created a single document that merged 8
amendments (802.11a,b,d,e,g,h,i,j) with the base standard. Upon approval on March 08, 2007,
802.11REVma was renamed to the current standard IEEE 802.11-2007. This is the single most modern
802.11 document available that contains cumulative changes from multiple sub-letter task groups.
2.1.2.1.6 802.11n
IEEE 802.11n is a proposed amendment to the IEEE 802.11-2007 wireless networking standard to
significantly improve network throughput over previous standards, such as 802.11b and 802.11g, with a
significant increase in the maximum raw (PHY) data rate from 54 Mbit/s to a maximum of 600 Mbit/s.
The current state of the art supports a PHY rate of 300 Mbit/s, with the use of 2 spatial streams at a
channel width of 40 MHz. Depending on the environment, this may translate into a user throughput
(TCP/IP) of 100 Mbit/s.
2
http://en.wikipedia.org/wiki/802.11g
10
802.11n is expected to be finalized in November 2009, although many "Draft N" products are already
available.
IEEE 802.11n builds on previous 802.11 standards by adding multiple-input multiple-output (MIMO) and
Channel-bonding/40 MHz operation to the physical (PHY) layer, and frame aggregation to the MAC
layer.
MIMO uses multiple transmitter and receiver antennas to improve the system performance. MIMO is a
technology which uses multiple antennas to coherently resolve more information than possible using a
single antenna. Two important benefits it provides to 802.11n are antenna diversity and spatial
multiplexing.
MIMO technology relies on multipath signals. Multipath signals are the reflected signals arriving at the
receiver some time after the line of sight (LOS) signal transmission has been received. In a non-MIMO
based 802.11a/b/g network, multipath signals were perceived as interference degrading a receiver's
ability to recover the message information in the signal. MIMO uses the multipath signal's diversity to
increase a receiver's ability to recover the message information from the signal.
Another ability MIMO technology provides is Spatial Division Multiplexing (SDM). SDM spatially
multiplexes multiple independent data streams, transferred simultaneously within one spectral channel
of bandwidth. MIMO SDM can significantly increase data throughput as the number of resolved spatial
data streams is increased. Each spatial stream requires a discrete antenna at both the transmitter and
the receiver. In addition, MIMO technology requires a separate radio frequency chain and analog-todigital converter for each MIMO antenna which translates to higher implementation costs compared to
non-MIMO systems.
Channel Bonding, also known as 40 MHz, is a second technology incorporated into 802.11n which can
simultaneously use two separate non-overlapping channels to transmit data. Channel bonding increases
the amount of data that can be transmitted. 40 MHz mode of operation uses 2 adjacent 20 MHz bands.
This allows direct doubling of the PHY data rate from a single 20 MHz channel.
Coupling MIMO architecture with wider bandwidth channels offers the opportunity of creating very
powerful yet cost-effective approaches for increasing the physical transfer rate.
Aggregation is a process of packing multiple MSDUs or MPDUs together to reduce the overheads and
average them over multiple frames, thus increasing the user level data rate. A-MPDU aggregation
requires the use of Block Acknowledgement or BlockAck, which was introduced in 802.11e and has been
optimized in 802.11n.
Backward compatibility
When 802.11g was released to share the band with existing 802.11b devices, it provided ways of
ensuring coexistence between the legacy and the new devices. 802.11n extends the coexistence
11
management to protect its transmissions from legacy devices, which include 802.11g, 802.11b and
802.11a. There are MAC and PHY level protection mechanisms as listed below:
1. PHY level protection: Mixed Mode Format protection (also known as L-SIG TXOP Protection): In
mixed mode, each 802.11n transmission is always embedded in an 802.11a or 802.11g
transmission. For 20 MHz transmissions, this embedding takes care of the protection with
802.11a and 802.11g. However, 802.11b devices still need CTS protection.
2. PHY level protection: Transmissions using a 40 MHz channel in the presence of 802.11a or
802.11g clients require using CTS protection on both 20 MHz halves of the 40 MHz channel,
to prevent interference with legacy devices.
3. MAC level protection: An RTS/CTS frame exchange or CTS frame transmission at legacy rates can
be used to protect subsequent 11n transmission.
Even with protection, large discrepancies can exist between the throughputs an 802.11n device can
achieve in a greenfield network, compared to a mixed-mode network, when legacy devices are present.
This is an extension of the 802.11b/802.11g coexistence problem.
Wi-Fi Alliance
As of mid-2007, the Wi-Fi Alliance has started certifying products based on IEEE 802.11n Draft 2.0. This
certification program established a set of features and a level of interoperability across vendors
supporting those features, thus providing one definition of 'draft n'. The Baseline certification covers
both 20 MHz and 40 MHz wide channels, and up to two spatial streams, for maximum throughputs of
144.4 Mbit/s for 20 MHz and 300 Mbit/s for 40 MHz (with Short Guard interval). A number of vendors in
both the consumer and enterprise spaces have built products that have achieved this certification. The
Wi-Fi Alliance certification program subsumed the previous industry consortium efforts to define
802.11n, such as the now dormant Enhanced Wireless Consortium (EWC). The Wi-Fi Alliance is
investigating further work on certification of additional features of 802.11n not covered by the Baseline
certification, including higher numbers of spatial streams (3 or 4), Greenfield Format, PSMP, Implicit &
Explicit Beamforming and Space-Time Block Coding.
802.11n is a proposed amendment which improves upon the previous 802.11 standards by adding
multiple-input multiple-output (MIMO) and many other newer features. The TGn workgroup is not
expected to finalize the amendment until December 2009. Enterprises, however, have already begun
migrating to 802.11n networks based on Draft 2 of the 802.11n proposal. A common strategy for most
companies is to utilize 802.11n to support existing 802.11b and 802.11g client devices and then migrate
client devices to 802.11n as they become available.
Release date
Op. Frequency
Data rate (Type)
12
Data rate (Max)
Range (Indoor)
Pending
5 GHz and/or 2.4 GHz
74 Mbit/s
300 Mbit/s (2 streams)
~70 m
2.1.3 Deployment Strategy
To achieve maximum throughput a pure 802.11n 5 GHz network is recommended. The 5 GHz band has
substantial capacity due to many non-overlapping radio channels and less radio interference as
compared to the 2.4 GHz band. An 802.11n-only network may be impractical for many users because
the existing computer stock is predominantly 802.11b/g only. Replacement of incompatible Wi-Fi cards
or of entire laptop stock is necessary for older computers to operate on the network. Consequently, it
may be more practical in the short term to operate a mixed 802.11b/g/n network until 802.11n
hardware becomes more prevalent. In a mixed-mode system, it’s generally best to utilize a dual-radio
access point and place the 802.11b/g traffic on the 2.4 GHz radio and the 802.11n traffic on the 5 GHz
radio.
Pittsburgh Goes Live With Downtown Tropos Metro-Scale Wi-Fi Mesh Network; Residents, Workers and
Visitors Get Free and Low Cost Wi-Fi Access Services and Wi-Fi Community Services Based on Tropos
Networks' MetroMesh System.
Pittsburgh -- Tropos Networks, the market leader for metro-scale, Wi-Fi mesh network systems, today
announced that Pittsburgh has gone live with its Downtown Wi-Fi Network using the Tropos MetroMesh
municipal Wi-Fi infrastructure, the most widely deployed Wi-Fi mesh technology in the world.
The initiative of the Pittsburgh Downtown Partnership (PDP) in conjunction with the city of Pittsburgh,
the network is operated by US Wireless Online and today provides free and fee-based packages for
outdoor access in the Central Business District/Golden Triangle, and the growing areas of North Shore
and Lower Hill District.
"Our goal is to bring cutting-edge amenities to Downtown Pittsburgh to continue to enhance and enrich
the experience of workers, residents and visitors to the area. Wi-Fi Downtown Pittsburgh creates a
valuable community resource for connecting people while outdoors," said Michael M. Edwards,
president and CEO of the PDP. "The attractive economics of the Tropos solution has allowed us, in
partnership with US Wireless Online, to establish a network quickly and economically. Plus the Tropos
technology gives us the flexibility and capability to deal with the environmental challenges presented by
the hilly terrain of the area."
"The response and the feedback to date have been overwhelmingly positive for this downtown
Pittsburgh service. Working with Tropos Networks' state-of-the-art metro-scale Wi-Fi infrastructure, we
were able to quickly and cost-effectively deploy the network over the downtown area and offer the free
and low cost services to the community," said Timothy J. Pisula, executive vice president and CTO of US
Wireless Online, one of the nation's largest wireless Internet broadband network operators, and
13
provider of similar municipal Wi-Fi networks using Tropos MetroMesh systems in Baton Rouge and
other cities.
In addition to the downtown, Wi-Fi Downtown Pittsburgh is also providing municipal benefits, including
four secured mobile command units now up and running for the City of Pittsburgh public safety use. In
the next couple of months, it will address digital divide issues by providing complimentary connections
in partnership with Wireless Neighborhoods, an alliance of community and faith organizations
committed to support children's education, promote economic development and address other social
barriers.
"While our Tropos MetroMesh Wi-Fi systems are deployed in many major cities throughout the world,
this Wi-Fi network covering downtown Pittsburgh is particularly gratifying for me," said Bert Williams,
Pittsburgh native and acting vice president of marketing for Tropos Networks. "I'm proud to work for a
company that is providing a real economic and social benefit to my hometown as well as other
communities."
The Pittsburgh network uses more than 55 Tropos Networks' 5210 MetroMesh Wi-Fi routers on light
poles throughout the downtown, enabling reliable wireless data connectivity between users and the
Internet. Deployed in more than 300 customer sites worldwide, Tropos MetroMesh routers quickly and
economically use the intelligent Tropos Predictive Wireless Routing Protocol (PWRP(TM)) to provide
pervasive coverage over metro areas. PWRP forms a wireless mesh, dynamically routing traffic along the
highest throughput path to a wired gateway. This intelligent routing negates effects of radio frequency
(RF) interference, wired backhaul failure and mesh router failure.
Tropos(R) Networks is the market leader in delivering metro-scale Wi-Fi mesh network systems. Our
systems have been selected to unwire more major league cities than all competitors combined and are
installed in 30 countries. The patented Tropos MetroMesh(TM) architecture delivers the ultimate
scalability, high capacity at low cost and great user experience demanded by carriers, municipalities and
network users. Our unique expertise includes high-performance mesh software development, mesh RF
engineering, metro-scale network planning, deployment and optimization, and navigating the municipal
approval process.
Tropos is a registered trademark of Tropos Networks, Inc. Tropos Networks, MetroMesh, PWRP, AMCE
and Metro-Scale Mesh Networking Defined are trademarks of Tropos Networks, Inc. All other brand or
product names are trademarks or registered trademarks of their respective holder(s).3
3
http://findarticles.com/p/articles/mi_m0EIN/is_2006_Sept_13/ai_n26984352
14
2.1.4 Table Summary
Parameter
802.11a
802.11b
802.11g
802.11n4
802.11y
Standard
802.11a(1999)
802.11b(1999)
802.11g(2003)
Exp.Nov2009
2008
Uplink Data Rate
54Mbps
11Mbps
54Mbps
200Mbps
23Mbps
Downlink Data
Rate
latency
Mobility
Hand Off
54Mbps
11Mbps
54Mbps
200Mbps
23Mbps
none
No
No
none
no
no
3.5ms
no
no
3.5ms
no
Yes
none
no
yes
Coverage indoor
35m
38m
38m
70m
50m
140m
140m
250m
5000m
Coverage outdoor 120m
The best new 802.11n wireless routers deliver strong performance, coverage, and compatibility--but
picking the right one for your network is more complicated than ever.
What a difference a couple of years make. In our first roundup of draft-802.11n Wi-Fi routers ", we
found so many problems, we couldn't recommend any of them: Firmware was buggy, interoperability
between vendors was hit-and-miss, and performance was not as good as that of some enhanced,
earlier-generation 802.11g routers.
And the Wi-Fi certified products are worthy updates. With link rates--the nominal connection speeds, as
opposed to real-world throughput--of up to 300 megabits per second (compared with 54 mbps for
standard 802.11g) and extended range (thanks to multiple smart antennas), 802.11n Wi-Fi is the first
Wi-Fi technology that can rival wired 100-mbps Ethernet in performance. Upgrading your home router
to 802.11n is thus one of the quickest and easiest ways to improve your network.
But choosing a particular 802.11n router has become more complicated than ever because the standard
covers a lot of ground that lets vendors issue a dizzying array of product options, with literally dozens of
models ranging in price from $50 to $250. D-Link alone has six 802.11n routers.
The 802.11n variant of Wi-Fi achieves its high through put (typically four times that of 802.11g) in two
ways. First, it uses MIMO (multiple input, multiple output) antenna technology to transmit more data at
a time. Intelligent antennas combine streams of data arriving at different times from multi??path signals
bouncing off walls, floors, and ceilings. Entry-level routers typically have two receiving and transmitting
antennas; midrange and high-end models have three of each.
4
http://en.wikipedia.org/wiki/802.11n
15
Second, draft-n uses channel bonding: Instead of the 20-MHz-wide channels found in previous Wi-Fi
standards, 802.11n can use 40-MHz-wide channels, which in theory should double their data-carrying
capacity.
Pre-802.11n Products
Even before there was a draft of the 802.11n standard that had reached any degree of consensus in the
802.11 Working Group, there were many products available that claimed to be "pre-n." These products
were based on one or another of the many proposals that were made to the 802.11 Working Group.
Most of these products were not compatible or interoperable between different vendors.
802.11n Technology
The goal of the work on 802.11n is to dramatically increase the effective throughput of 802.11 devices,
not to simply build a radio capable of higher bit rates. The difference between these goals is like the
difference between the mileage you achieve with your own, personal driving habits and the EPA-rated
mileage for your model of car. To increase the effective throughput of an 802.11 device requires more
than providing a higher bit rate. There are aspects of the 802.11 standard that are "overhead" for the
802.11 protocol. Many of these overhead aspects can't be reduced or eliminated. The effect is that,
without using other methods, there is an absolute upper bound on the effective throughput.
802.11n is much more than just a new radio for 802.11. In addition to providing higher bit rates (as was
done in 802.11a, b, and g), 802.11n makes dramatic changes to the basic frame format that is used by
802.11 devices to communicate with each other. This section will describe the changes incorporated in
802.11n, including MIMO, radio enhancements, and MAC enhancements.
Multiple-input multiple-output (MIMO) is the heart of 802.11n. This technical discussion of MIMO
provides a basis for understanding how 802.11n can reach data rates of 600 Mbps.
To understand the improvement brought by MIMO technology, it is important to understand some of
the basics that determine how well a traditional radio operates. In a traditional, single-input singleoutput radio, the amount of information that can be carried by a received radio signal depends on the
amount by which the received signal strength exceeds the noise at the receiver, called the signal-tonoise ratio, or SNR. SNR is typically expressed in decibels (dB). The greater the SNR, the more
information that can be carried on the signal and be recovered by the receiver.
To understand this situation, imagine the analogy of your eye as the receiver. Is your eye able to detect
whether a table lamp is on or off in the house next door? In this analogy, ambient light is the noise. At
night, detecting that the lamp is on or off is quite easy. However, in full daylight, it is much more difficult
to make the same determination, because the ambient light is much brighter, and the tiny amount of
additional light from the lamp can be undetectable.
Light, like a radio wave, disperses uniformly from its source. The farther the receiver is from the source,
the less power is received from the source. In fact, the amount of power received decreases more
16
rapidly than the square of the distance from the source. Noise, unfortunately, is often constant in the
environment, due to both natural and man-made causes.
So, returning to the table lamp example, when it is too bright to determine if the lamp next door is on or
off, it might be possible to make that determination from just outside the neighbor's window.
Alternatively, it might be possible to make the determination if the neighbor changed the 40 watt bulb
for a 150 watt bulb. In both cases, the SNR increases-in the first case, because the distance to the source
is reduced, and in the second case, because the power of the transmitter is increased.
Once the minimum SNR is achieved to allow information to be exchanged at the desired rate, any
additional SNR is like money in the bank. That additional SNR can be spent on increasing the information
rate, increasing the distance, or a little bit of both. However, you can't spend the same dB more than
once, just as you can't spend the same dollar more than once (at least not without encountering some
unpleasant consequences).
All this is background to understand the improvements that MIMO technology brings to 802.11.
In addition to MIMO technology, 802.11n makes a number of additional changes to the radio to increase
the effective throughput of the WLAN. The most important of these changes are increased channel size,
higher modulation rates, and reduced overhead. This section will describe each of these changes and
the effect they have on WLAN throughput.
2.2 WiMAX
2.2.1 Introduction
WiMAX is the acronym for
“Worldwide Interoperability for
Microwave Access”. It is a
telecommunications technology
that provides for the wireless
transmission of data using a variety
of transmission modes, from pointto-point links to full mobile
cellular-type access. The
technology provides up to 70
Mb/sec symmetric broadband
speed without the need for cables.
The technology is based on the
17
IEEE 802.16 standard (also called Wireless MAN). The name "WiMAX" was created by the WiMAX
Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. 5
2.2.2 Analysis
2.2.2.1 Technical Description
WiMAX is an effective metropolitan area access technique with many favorable features like flexibility,
cost efficiency and fast networking, which not only provides wireless access, but also serves to expand
the access to wired network.
The coverage area of WiMAX is around 30 to 50 kilometer. I can provide high 100Mbps data rates in 20
MHz bandwidth.
WiMAX is based on IEEE 802.16 Standard. In standard 802. 16d three different kinds of physical layer
technologies are defined which are single carrier applied in the 10-66GHz fixed wireless access system,
OFDMA 256 points is used in 2-11 GHz Fixed wireless access and OFDMA 2048 points which is the
frequency up to 11 GHz(IEE 802.16d/WiMAX) for scenarios requiring long distance links between
operator point of presence (POP) and Wireless Local Network(WLAN) Area cells.
WiMAX inter works with existing and emerging technologies both wired and wireless. WiMAX also
supports Voice over IP(VO IP). WiMAX can serve as a backbone for Wireless hotspots for connecting to
the internet.
WiMAX solve the problem of “Last mile access”. The frequency 2.5. & 3.5 GHz require a license while
5.86 GHz is unlicensed band. WiMAX offers true broadband connections that support multiple usage
scenario including fixed, portable and mobile access using the same network infrastructure. Mobile
WiMAX is based on IEEEE 802.16e-2005 standards and operates in the frequency of 2.3 GHz, 2.5 GHz,
3.3 GHz, and 3.4-3.8 GHz spectrum bands.
WiMAX which is Orthogonal Frequency Division Multiple Access (OFDMA) having a performance edge in
delivering IP data services compared to 3G technologies. The main advantages of WiMAX when
compared to other access network technologies are the longer range and more sophisticated support of
Quality of Service.
2.2.2.1.1 fixed WiMAX
802.16-2004 is often called 802.16d, since that was the working party that developed the standard. It is
also frequently referred to as "fixed WiMAX" since it has no support for mobility. 6
5
http://www.iburst.co.za/default.aspx?link=wimax_faqs
18
2.2.2.1.2 mobile WiMAX
802.16e-2005 is an amendment to 802.16-2004 and is often referred to in shortened form as 802.16e. It
introduced support for mobility, amongst other things and is therefore also known as "mobile WiMAX".
WiMAX Strength
1.
2.
3.
4.
5.
High-speed data and Internet connectivity7
Wireless rather than wired access, so it would be a lot less expensive than cable or DSL
and much easier to extend to suburban and rural areas 8
Broad coverage like the cell phone network instead of small Wi-Fi hotspots
A wireless alternative to cable and DSL offerings9
An assured Quality of Service10
2.2.3 Deployment Strategy
The largest mobile WiMAX network, based on the IEEE 802.16e-2005 standard is 145,000 subscribers for
KT in South Korea and 10,000 subscribers for Wateen in Pakistan.11
South Korea’s WiBro service runs at 2.3GHz while Wateen’s service uses 3.5GHz. Intel is uncommitted to
the 2.3GHz and 3.5GHz bands with is Echo Peak. Echo Peak is tuned specifically to 2.5GHz to 2.7GHz
operation, limiting the markets where it can be applied.
Countries with existing 2.5GHz operators offering WiMAX besides the United States includes: Brazil,
India, Ireland, Japan, Mexico, Morocco, Peru, Russia, Singapore, Taiwan, Thailand and Venezuela. Those
markets will eventually grow the business case for Intel module, but they are not a consideration for
accelerating Echo Peak’s availability.
Recently, Baltimore will become the first U.S. city with a WiMAX network. Intel said it will be hosting a
launch event throughout the Bond Street Wharf Park in Baltimore on October 8.
The never-ending story of the rollout of WiMAX in the U.S. is seeing some light. Originally scheduled for
a late 2007 introduction, XOHM delayed WiMAX mostly because of its financial troubles. A group of
companies created a new foundation for WiMAX in May and XOHM noted in July that it would introduce
WiMAX in September. Now we know it will be October, but the good news is clearly the wireless
broadband technology, often described as 4G, is finally here.
http://en.wikipedia.org/wiki/Wimax
http://computer.howstuffworks.com/wimax.htm
8 http://computer.howstuffworks.com/wimax.htm
9 http://www.iburst.co.za/default.aspx?link=wimax_faqs
10 http://www.iburst.co.za/default.aspx?link=wimax_faqs
11 http://www.multipulse.com/include/wifi-and-wimax-case-study.pdf
6
7
19
“Select” U.S. cities, including Chicago and Washington, D.C., are expected to receive WiMAX service
later this year, with the majority following in 2009 and 2010, XOHM said.12
2.2.4 Table Summary
Parameter
Bandwidth
Standards
Published
Downlink rate
Uplink rate
Modulation
Multiplexing
Fixed WiMAX
up to 20 MHz13
1.25 to 28 MHz14
IEEE 802.16-2004
December 200116
Handles uplink and downlink
BPSK, QPSK, 16QAM, 64QAM20
Time Division Multiple (TDM)22
Duplexing
Time Division Duplex(TDD),
Frequency Division Duplex(FDD)24
Frequency
3.5 MHz, 5 MHz, 7 MHz and 10
MHz26
Fixed station access can extend up
to 30 miles (50 km) while mobile
stations range from 3 - 10 miles (5 15 km).28
Coverage
12
Mobile WiMAX
1.25 MHz, 5 MHz, 10 MHz or 20
MHz15
IEEE 802.16e-2005
December 200517
70 Mbit/s18
70 Mbit/s19
QPSK, 16 QAM, 64 QAM21
Orthogonal Frequency Division
Multiple Access (OFDMA)23
Time Division Duplex(TDD),
Frequency Division Duplex
(FDD optional)25
5 MHz, 8.75 MHz and 10 MHz27
1-3miles29
In urban environments, cell
ranges rapidly shrink from 1 to
1.5km (pure outdoor coverage) to
an average of 400-500m to
achieve just basic indoor
coverage. 30
http://www.tgdaily.com/content/view/39445/103/
13
http://www.sramanamitra.com/2007/12/10/fixed-wimax-last-mile-broadband
14 http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&ckey=511223&nid=-34704.536895062.00&id=511223
15 http://en.wikipedia.org/wiki/Mobile_WiMAX#Mobile_WiMAX
16 http://www.iaria.org/conferences2008/filesCTRQ08/CTRQ_2008_WiMAX_tutorial_EB-v1.3.pdf
17 http://en.wikipedia.org/wiki/Mobile_WiMAX#Mobile_WiMAX
18 http://en.wikipedia.org/wiki/Mobile_WiMAX#Mobile_WiMAX
19 http://en.wikipedia.org/wiki/Mobile_WiMAX#Mobile_WiMAX
20 http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&ckey=511223&nid=-34704.536895062.00&id=511223
21
http://www.home.agilent.com/agilent/product.jspx?nid=-34704.536905728.00&cc=US&lc=eng
22
http://hsn.cse.nsysu.edu.tw/papers/download/Fixed_WiMAX_Field_Trial_Measurements_and_Analyses-slides.ppt
23 http://www.alvarion-usa.com/upload/contents/291/Comparing_WiMAX_vs_3G_White_Paper.pdf
24 http://www.pori.tut.fi/infohakemisto/di/kurssimateriaalit/laajakaistaverkot/Wimax%20-%20Wireless%20Broadband.ppt
25 http://www.alvarion-usa.com/upload/contents/291/Comparing_WiMAX_vs_3G_White_Paper.pdf
26
http://en.wikipedia.org/wiki/Wimax
27 http://en.wikipedia.org/wiki/Wimax
28 http://www.intel.com/support/wireless/wmax/5350_5150/sb/CS-028905.htm
29 http://searchmobilecomputing.techtarget.com/searchMobileComputing/downloads/Finneran.pdf
30
http://www.wimaxforum.org/documents/downloads/senzafili_indoorcoveragesurvey_updated.pdf
20
Latency
Mobility
Capability
less than 10ms (milliseconds)31
Not applicable
Hand-over
Handoff
less than 50 ms32
Up to 120 km/ph33
OFDMA 2K-FFT, 512-FFT and 128FFT34
Network-optimized hard
handoff(HHO)35
2.3 3G
2.3.1 Introduction36
3G refers to the third generation of developments in wireless technology, especially mobile
communications. The third generation, as its name suggests, follows the first generation (1G) and
second generation (2G) in wireless communications.



1G
The 1G period began in the late 1970s and lasted through the 1980s. These systems featured
the first true mobile phone systems, known at first as "cellular mobile radio telephone." These
networks used analog voice signaling, and were little more sophisticated than the repeater
networks used by amateur radio operators.
2G
The 2G phase began in the 1990s and much of this technology is still in use. The 2G cell phone
features digital voice encoding. Examples include CDMA and GSM. Since its inception, 2G
technology has steadily improved, with increased bandwidth, packet routing, and the
introduction of multimedia.
3G
3G includes capabilities and features such as:
Enhanced multimedia (voice, data, video, and remote control).
Usability on all popular modes (cellular telephone, e-mail, paging, fax, videoconferencing, and
Web browsing).
Broad bandwidth and high speed (upwards of 2 Mbps).
Roaming capability throughout Europe, Japan, and North America.
While 3G is generally considered applicable mainly to mobile wireless, it is also relevant to fixed wireless
and portable wireless. A 3G system should be operational from any location on, or over, the earth's
31
http://www.wimax.com/education/wimax
http://www.tutorialspoint.com/wimax/wimax_mobility_support.htm
33 http://www.tutorialspoint.com/wimax/wimax_mobility_support.htm
34 http://www.wimax.com/education/faq/faq45/?searchterm=mobilewimaxCapability
35
http://www.alvarion-usa.com/upload/contents/291/Comparing_WiMAX_vs_3G_White_Paper.pdf
36 http://searchtelecom.techtarget.com/sDefinition/0,,sid103_gci214486,00.html
32
21
surface, including use in homes, businesses, government offices, medical establishments, the military,
personal and commercial land vehicles, private and commercial watercraft and marine craft, private and
commercial aircraft (except where passenger use restrictions apply), portable (pedestrians, hikers,
cyclists, campers), and space stations and spacecraft.
3G offers the potential to keep people connected at all times and in all places. Researchers, engineers,
and marketers are faced with the challenge of accurately predicting how much technology consumers
will actually be willing to pay for. Another challenge faced by 3G services is competition from other highspeed wireless technologies, especially mobile WiMAX, and ability to roam between different kinds of
wireless networks.
The status of mobile wireless communications, as of July 2007, is a mix of 2nd and 3rd generation
technologies.
2.3.2 Analysis
2.3.1.1 Technical Description
2.3.1.1.1 3GPP37
There are two different kinds of standards here. One is called 3GPP; the other is 3GPP2.
The 3rd Generation Partnership Project (3GPP) is a collaboration between groups of
telecommunications associations, to make a globally applicable third generation (3G) mobile phone
system specification within the scope of the International Mobile Telecommunications-2000 project of
the International Telecommunication Union (ITU). 3GPP specifications are based on evolved Global
System for Mobile Communications (GSM) specifications. 3GPP standardization encompasses Radio,
Core Network and Service architecture.
3GPP should not be confused with 3rd Generation Partnership Project 2 (3GPP2), which specifies
standards for another 3G technology based on IS-95 (CDMA), commonly known as CDMA2000.
Standard
3GPP standards are structured as Releases. Discussion of 3GPP thus frequently refers to the functionality
in one release or another.
Version
Released
Release 98
1998
37
Info
This and earlier releases specify pre-3G GSM networks
http://en.wikipedia.org/wiki/3GPP
22
Release 99
2000 Q1
Specified the first UMTS 3G networks, incorporating a CDMA air interface
Release 4
2001 Q2
Originally called the Release 2000 - added features including an all-IP Core
Network
Release 5
2002 Q1
Introduced IMS and HSDPA
Release 6
2004 Q4
Integrated operation with Wireless LAN networks and adds HSUPA, MBMS,
enhancements to IMS such as Push to Talk over Cellular (PoC), GAN[7]
Release 7
2007 Q4
Focuses on decreasing latency, improvements to QoS and real-time
applications such as VoIP.[8] This specification will also focus on HSPA+
(High Speed Packet Access Evolution), SIM high-speed protocol and
contactless front-end interface (Near Field Communication enabling
operators to deliver contactless services like Mobile Payments), EDGE
Evolution.
Release 8
and
onwards
In progress
(expected
2009)
LTE, All-IP Network (SAE). Release 8 constitutes a refactoring of UMTS as
an entirely IP based fourth-generation network.
Each release incorporates hundreds of individual standards documents, each of which may have been
through many revisions. Current 3GPP standards incorporate the latest revision of the GSM standards.
3GPP's plans for the future beyond Release 7 are in the development under the title Long Term
Evolution ("LTE").
2.3.1.1.2 3GPP238
The 3rd Generation Partnership Project 2 (3GPP2) is a collaboration between telecommunications
associations to make a globally applicable third generation (3G) mobile phone system specification
within the scope of the ITU's IMT-2000 project. In practice, 3GPP2 is the standardization group for
CDMA2000, the set of 3G standards based on earlier 2G CDMA technology.
38
http://en.wikipedia.org/wiki/3rd_Generation_Partnership_Project_2
23
2.3.1.1.3 WCDMA and HSPA family
With the evolvement of these releases, different versions of 3G come up, from WCDMA in 2000 to 3G
Long Term Evolution, which is recognized as 4G or pre-4G, in 2008.
WCDMA or UMTS is the most widely used among 3GPP. Though it is the earliest version of 3G, it is
mature in commercial use. From technical perspective, its downlink and uplink data rate are 384 kbps
and 128 kbps. It is not high compared to a later 3GPP version called HSDPA, the downlink data rate is as
high as 3.6mbps. There’s an another main factor- latency, a synonym for delay, which is an expression of
how much time it takes for a packet of data to get from one designated point to another. In some
usages (for example, AT&T), latency is measured by sending a packet that is returned to the sender and
the round-trip time is considered the latency.39 It is a critical factor in mobile service, because it directly
influences the quality of service. The latency of WCDMA is about 150ms,40 while that of HSDPA is 6585ms.41 It is a significant improvement for HSDPA. Actually, almost all the factors to evaluate a wireless
technology of HSPDA are much better than that of WCDMA. You can find the detailed comparison in
technical summary table.
HSUPA is High Speed Uplink Pocket Access. The specifications of HSUPA are included in 3GPP release 6.
The technical purpose of the Enhanced Uplink feature is to improve the performance of uplink dedicated
transport channels, i.e. to increase capacity and throughput and reduce delay.42 The downlink and
uplink data rate of HSUPA are both higher than that of HSDPA. They are 14.1 Mbps43 and 5.7 Mbps44.
The latency is 50ms. HSPA+, also known as evolved HSPA, provides HSPA data rates up to 42 Mbps on
the downlink and 22 Mbps on the uplink with MIMO technologies and higher order modulation. It is
defined in 3GPP Release 7.45 HSPA family is a collection of mobile telephony protocols that extend and
improve the performance of existing UMTS protocols. It is compatible with UMTS.
2.3.1.1.4 UMTS-TDD family
However, UMTS-TDD family is not directly compatible with UMTS. UMTS-TDD is a mobile data network
standard built upon the UMTS 3G cellular mobile phone standard, using a TD-CDMA, TD-SCDMA, or
other 3GPP-approved, air interface that uses Time Division Duplexing to duplex spectrum between the
up-link and down-link. While a full implementation of UMTS, it is mainly used to provide Internet access
in circumstances similar to those where WiMAX might be used. TD-CDMA is the primary air interface
used by UMTS-TDD. TD-CDMA is closely related to W-CDMA, and provides the same types of channels
where possible. W-CDMA's HSDPA/HSUPA enhancements are also implemented under TD-CDMA. 46
39
http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212456,00.html
http://www.pcca.org/standards/architecture/hsdpa.pdf
41 http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=04022310
42
http://en.wikipedia.org/wiki/High-Speed_Uplink_Packet_Access
43 http://www.telegeography.com/cu/article.php?article_id=25650
44 http://wirelessfederation.com/news/category/hsupa/
45 http://en.wikipedia.org/wiki/Evolved_HSPA
46 http://en.wikipedia.org/wiki/UMTS-TDD#cite_note-1
40
24
Compared with UMTS, UMTS-TDD uses time division duplexing, allowing the up-link and down-link to
share the same spectrum. This allows the operator to more flexibly divide the usage of available
spectrum according to traffic patterns. For ordinary phone service, you would expect the up-link and
down-link to carry approximately equal amounts of data (because every phone call needs a voice
transmission in either direction), but Internet-oriented traffic is more frequently one-way. For example,
when browsing a website, the user will send commands, which are short, to the server, but the server
will send whole files, that are generally larger than those commands, in response.
UMTS-TDD tends to be allocated frequency intended for mobile/wireless Internet services rather than
used on existing cellular frequencies. This is, in part, because TDD duplexing is not normally allowed on
cellular, PCS/PCN, and 3G frequencies. TDD technologies open up the usage of left-over unpaired
spectrum.
2.3.1.1.5 3GPP Long Term Evolution47
3GPP Long Term Evolution (LTE) describes the latest standardization work by 3rd Generation Partnership
Project (3GPP) in the mobile network technology tree. It defines a set of high level requirements (new
high-speed Radio Access method) for mobile communications systems to compete with other latest
cellular broadband technologies, particularly WiMAX.
Unlike other latest deployed technologies such as HSPA, LTE is accommodated within a new Packet Core
architecture called Enhanced Packet Core (EPC) network architecture. EPC is designed to deploy TCP/IP
protocols thus enabling LTE to support all IP-based services including voice, video, rich media and
messaging with end-to-end Quality of Service (QoS). The EPC network architecture also enables
improved connections and hand-over to other fixed-line and wireless access technologies while giving
an operator the ability to deliver a seamless mobility experience.
To achieve all the targets mentioned herein, LTE Physical Layer (PHY) employs advanced technologies
that are new to cellular applications. These include Orthogonal Frequency Division Multiple Access
(OFDMA) and multiple-input and multiple-output (MIMO) data transmission. Smart Antennas are also
deployed to accomplish those targets. Furthermore, the LTE PHY deploys the OFDMA for the Downlink
(DL) - that is from the Base Station (BS) to the User Equipment (UE) and Single Carrier Frequency Division
Multiple Access (SC-FDMA) for the Uplink (UL). These technologies will further minimize the LTE system
and UE complexities while allowing flexible spectrum deployment in existing or new frequency
spectrum.
Technically speaking, a fundamental objective of the 3GPP LTE project is to offer higher data speeds for
both DL and UL transmissions. In addition to that, it is obviously LTE to be characterized by reduced
packet latency while promising a superior experience in online gaming, Voice over IP (VoIP)
47
http://en.wikipedia.org/wiki/3GPP_Long_Term_Evolution
25
videoconferencing and other real-time professional services. Now that based on the feasibility study
under 3GPP, the following are the important features of LTE:

OFDMA on the DL and SC-FDMA on the UL
3GPP Release 8 specifies an all-new RAN that combines OFDMA-based modulation and multiple
access schemes for the downlink, as well as SC-FDMA for uplink. These new technologies (OFDM
schemes) are deliberately deployed to split available spectrum into thousands of extremely
narrowband carriers, such that each carrier is capable of carrying a part of signal. This is what is
known as multiple carrier transmission.
To enhance the OFDM schemes, LTE also employs other higher order modulation schemes such
as 64QAM and sophisticated Forward Error Correction (FEC) schemes such as tail biting,
convolution coding and turbo coding. Furthermore, complementary radio techniques such as
MIMO and Beam Forming with up to four antennas per station are also deliberately deployed
for further enhancement of innate spectral efficiency of OFDM schemes.
The results of these radio interface features are obvious, enabling LTE to have improved radio
performance. As such they yield the spectral efficiency up to 3 to 4 times that of HSDPA Release
6 in the LTE DL and up to 2 to 3 times that of HSUPA Release 6 in UL. Consequently,
theoretically, the DL peak data rates extend up to 300Mbit/s per 20MHz of spectrum. Similarly,
theoretical UL peak data rates can reach 75Mbit/s per 20MHz of spectrum as well as supporting
at least 200 active users per cell in 5MHz.

All-IP Packet Optimized Network Architecture
LTE has a ‘flat’, all-IP based core network with a simplified architecture, open interface and
fewer system nodes. Indeed, the all-IP based network architecture together with the new RAN
reduces network latency, improved system performance and provide interoperability with
existing 3GPP and non-3GPP technologies. Within 3GPP, all-IP based core network architecture
is now known as Evolved Packet Core (EPC). EPC is the result of standardization work within
3GPP which targeted to convert the existing System Architecture Evolution (SAE) to an all-IP
system.

Advanced Antenna Techniques
LTE is enhanced with MIMO, Spatial-Division Multiple Access (SDMA) and Beam Forming. These
are advanced radio antenna techniques which are complementary to each other. These
techniques are deployed for better air interface via enhancing the innate spectral efficiency of
OFDM schemes. Furthermore, these techniques can be used to trade-off between higher sector
capacity, higher user data rates, or higher cell-edge rates, and thus enable mobile operators to
have finer control over the end-user experience.
26
2.3.1.1.6 CDMA48
CDMA2000 is under 3GPP2, which should not be confused with 3GPP.
It is a hybrid 2.5G / 3G technology of mobile telecommunications standards that use CDMA, a multiple
access scheme for digital radio, to send voice, data, and signaling data (such as a dialed telephone
number) between mobile phones and cell sites. CDMA2000 is considered a 2.5G technology in 1xRTT
and a 3G technology in EVDO.
CDMA2000 has a relatively long technical history, and remains compatible with the older CDMA
telephony methods (such as cdmaOne) first developed by Qualcomm.
CDMA2000 is an incompatible competitor of the other major 3G standard UMTS.
CDMA2000 EV-DV (Evolution-Data/Voice), supports downlink (forward link) data rates up to 3.1Mbit/s
and uplink (reverse link) data rates of up to 1.8Mbit/s.
2.3.1.1.7 EVDO49
Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or EVDO, was designed as an
evolution of the CDMA2000 (IS-2000) standard that would support high data rates and could be
deployed alongside a wireless carrier's voice services.
EV-DO Rev B is the latest version of EVDO.
48
49
http://en.wikipedia.org/wiki/3GPP_Long_Term_Evolution
http://en.wikipedia.org/wiki/Evolution-Data_Optimized#cite_note-RevAStandard-6
27
EV-DO Rev B is a multi-carrier evolution of the Rev A specification. It maintains the capabilities of EV-DO
Rev A, and provides the following enhancements:






Higher rates per carrier (up to 4.9Mbit/s on the downlink per carrier). Typical deployments are
expected to include 2 or 3 carriers for a peak rate of 14.7Mbit/s
Higher rates by bundling multiple channels together enhance the user experience and enables
new services such as high definition video streaming.
Uses statistical multiplexing across channels to further reduce latency, enhancing the experience
for latency-sensitive(only 50 ms for latency) services such as gaming, video telephony, remote
console sessions and web browsing.
Increased talk-time and standby time
Hybrid frequency re-uses which reduces the interference from the adjacent sectors and
improves the rates that can be offered, especially to users at the edge of the cell.
Efficient support for services that have asymmetric download and upload requirements (i.e.
different data rates required in each direction) such as file transfers, web browsing, and
broadband multimedia content delivery.
2.3.1.1.8 UMB50
UMB (Ultra Mobile Broadband) is the brand name for the project within 3GPP2 to improve the
CDMA2000 mobile phone standard for next generation applications and requirements. The system is
based upon Internet (TCP/IP) networking technologies running over a next generation radio system,
with peak rates of up to 280Mbit/s. Its designers intend for the system to be more efficient and capable
of providing more services than the technologies it replaces.
The standard of UMB is published at 2007. And it will be commercial available at early 2009.
To provide compatibility with the systems it replaces, UMB supports handoffs with other technologies
including existing CDMA2000 1X and 1xEV-DO systems. However 3GPP2 added this functionality to LTE,
allowing LTE to become the single upgrade path for all wireless networks.
Features of UMB:





50
OFDMA-based air interface
Frequency Division Duplex
Scalable bandwidth between 1.25-20 MHz (OFDMA systems are especially well suited for wider
bandwidths larger than 5 MHz)
Supports mixed cell sizes, e.g., macro-cellular, micro-cellular & pico-cellular.
IP network architecture
http://en.wikipedia.org/wiki/Ultra_Mobile_Broadband#cite_note-0
28


Supports flat, centralized and mixed topologies
Significantly higher data rates & reduced latencies using FL advanced antenna techniques
o
o
o
MIMO, SDMA and Beamforming
Data speeds over 275Mbit/s downstream and over 75Mbit/s upstream
Latency is as low as 16 ms.
2.3.1.1.9 Conclusion
From technical perspective, we think LTE is the most advanced one. It adopts advanced technologies
that are new to cellular applications. It deploys MIMO for data transmission. Smart Antennas are also
deployed to accomplish those targets. Furthermore, the LTE PHY deploys the OFDMA for the Downlink
and SC-FDMA for uplink. Those new technologies greatly assist technical features. From the data we
got, the downlink data rate is theoretically as high as 300Mbsp. The latency is only 5-10ms. The
coverage is 100km. So LTE has the best technical feature among 3G technologies. But the drawback of
LTE is that it is not standardized yet. From 3GPP official website, it is probably to be done at December
2008 .51 So even the features of LTE is great, we won’t take a risk to adopt it.
We recommend HSPA among 3GPP. Since it has high download and upload speed for mobiles, relatively
low latency, and especially it is already deployed for commercial use. Furthermore, HSPA can be
implemented in both UMTS and UMTS-UDD. So instead of pick up one from UMTS or UMTS-TDD, we will
use HSPA as a delegate of 3GPP when comparing with Wi-Fi and WiMAX.
For 3GPP2, UMB is the most advanced version. But the problem is that, as what we find, there is no
carrier claim to have a plan to adopt UMB. Even those CDMA2000 carriers go for LTE. So we won’t
consider UMB.
Instead we will pick up EV-DO Rev.B for 3GPP2. It is the latest version which is now in commercial use.
The reason is mainly that its technical feature is the most advanced one in 3GPP2 except UMB.
We will discuss HSPA, LTE with other wireless technologies in the comparison section.
2.3.2 City Deployment
The first pre-commercial 3G network was launched by NTT DoCoMo in Germany branded FOMA, in May
2001 on a pre-release of W-CDMA-GA3Y technology. The first commercial launch of 3G was also by NTT
DoCoMo in Japan on October 1, 2001. The second network to go commercially live was by SK Telecom in
South Korea on the CDMA2000 1xEV-DO technology in January 2002. By May 2002 the second South
Korean 3G network was launched by KTF on EV-DO and thus the Koreans were the first to see
competition among 3G operators.
51
http://www.3gpp.org/releases
29
The first European pre-commercial network was at the Isle of Man by Manx Telecom, the operator
owned by British Telecom, and the first commercial network in Europe was opened for business by
Telenor in December 2001 with no commercial handsets and thus no paying customers. These were
both on the W-CDMA technology.
The first commercial United States 3G network was by Monet Mobile Networks, on CDMA2000 1x EVDO technology, but this network provider later shut down operations. The second 3G network operator
in the USA was Verizon Wireless in October 2003 also on CDMA2000 1x EV-DO, and this network has
grown strongly since then.
The first pre-commercial demonstration network in the southern hemisphere was built in Adelaide,
South Australia by m.Net Corporation in February 2002 using UMTS on 2100MHz. This was a
demonstration network for the 2002 IT World Congress. The first commercial 3G network was launched
by Hutchison Telecommunications branded as Three in April 2003.
In December 2007, 190 3G networks were operating in 40 countries and 154 HSDPA networks were
operating in 71 countries, according to the GMSA. In Asia, Europe, Canada and the USA,
telecommunication companies use W-CDMA technology with the support of around 100 terminal
designs to operate 3G mobile networks.
In Europe, mass market commercial 3G services were introduced starting in March 2003 by 3 (Part of
Hutchison Whampoa) in the UK and Italy. The European Union Council suggested that the 3G operators
should cover 80% of the European national populations by the end of 2005.
Roll-out of 3G networks was delayed in some countries by the enormous costs of additional spectrum
licensing fees. (See Telecoms crash.) In many countries, 3G networks do not use the same radio
frequencies as 2G, so mobile operators must build entirely new networks and license entirely new
frequencies; an exception is the United States where carriers operate 3G service in the same frequencies
as other services. The license fees in some European countries were particularly high, bolstered by
government auctions of a limited number of licenses and sealed bid auctions, and initial excitement over
3G's potential. Other delays were due to the expenses of upgrading equipment for the new systems.
By June 2007 the 200 millionth 3G subscriber had been connected. Out of 3 billion mobile phone
subscriptions worldwide this is only 6.7%. In the countries where 3G was launched first - Japan and
South Korea - over half of all subscribers use 3G. In Europe the leading country is Italy with a third of its
subscribers migrated to 3G. Other leading countries by 3G migration include UK, Austria, Australia and
Singapore at the 20% migration level. A confusing statistic is counting CDMA 2000 1x RTT customers as if
they were 3G customers. If using this oft-disputed definition, then the total 3G subscriber base would be
475 million at June 2007 and 15.8% of all subscribers worldwide.
2.2.1.3 Table Summary
The table shows technical details of different kinds of 3G technologies.
30
3G
3G pp
WCDMA
HSPA
HSDPA
UMTS-TDD
HSUPA
HSPA+
384KBP 3.6Mbps53
S52
14.1Mb
ps54
42Mbps
With
combinati
on of
MIMO
and
64QAM55
Upload
128KBP 1.2Mbps62
S61
5.7
Mbps63
Standard
3GPP
Releas
e 1999,
2000
3GPP
Release
6,
2004
11.5Mbps
(16QAMin
UPLINK) 64
3GPP
Release 7,
2007
Download
Coverage
3GPP
Release 5,
2002
1.8 km 2km
(1.12mi (1.242
les)71
miles)72
1.18km
(0.733m
iles)73
TDCDMA
42.2Mbp
s56
TDSCDMA
2Mbps57
NA
2Mbps65
75Mbps66
3GPP
Release
6,
2004
3GPP
Release
4,
2001
3GPP
Release 8,
2008
58
21 km
(13miles)
74
52
3GPP
REL.8/LTE
(Pre 4G)
(E-UTRA)
300Mbps
100 km
(62.1miles
)75
3G pp2
CDMA
20001xE
V-DO
Rev. B
4.9Mbp
s59
UMB
275Mbps
60
1.8
Mbps67
75Mbps68
cdma20
00
1xEVDO
Rev. B,
200769
UMB
standard,
200770
5-15km
(39.3miles
http://www.samstores.com/details.asp?ProdID=3156
http://www.obsessable.com/feature/cellular-data-basics-ev-do-vs-hsdpa-vs-wimax/
54 http://www.telegeography.com/cu/article.php?article_id=25650
55 http://www2.rohde-schwarz.com/file_11064/1MA121_01E.pdf
56 http://forums.wirelessadvisor.com/international-wireless-forum-including-canada-mexico/60107-japan-testing-td-cdma.html
57 http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01381872
58 http://www.umts-forum.org/component/option,com_docman/task,doc_download/gid,1904/Itemid,12/
59 http://www.alvarion-usa.com/upload/contents/291/Comparing_WiMAX_vs_3G_White_Paper.pdf
60 http://en.wikipedia.org/wiki/Ultra_Mobile_Broadband
61 http://www.samstores.com/details.asp?ProdID=3156
62 http://www.obsessable.com/feature/cellular-data-basics-ev-do-vs-hsdpa-vs-wimax/
63 http://wirelessfederation.com/news/category/hsupa/
64 http://www2.rohde-schwarz.com/file_11064/1MA121_01E.pdf
65 http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=01381872
66 http://www.umts-forum.org/component/option,com_docman/task,doc_download/gid,1904/Itemid,12/
67 http://www.cdg.org/technology/3g/evolution.asp
68 http://en.wikipedia.org/wiki/Ultra_Mobile_Broadband
69 http://www.evdoinfo.com/content/view/719/64/
70 http://www.cdg.org/technology/3g_umb.asp
71 http://www.comlab.hut.fi/studies/3275/Cellular_network_planning_and_optimization_part8.pdf
72 http://www.ursi.org/Proceedings/ProcGA05/pdf/C01.2(01660).pdf
73 https://dspace.ist.utl.pt/bitstream/2295/154215/1/FinalVersion.pdf
53
31
Mobility
120km
/h77
250km/h78 300
km/h79
NA
120
km/h80
125
km/h81
350km/h82
)76
300
km/h83
Latency
150ms
65-85ms86
50ms88
NA
NA
5-10ms89
50ms90
16ms91
Hard93
Hard94
Hard95
Soft96
Soft97
50 ms87
300
km/hr84
85
Hand off
Hard92
74
http://www.palowireless.com/3g/docs/TD-SCDMA-China.pdf
http://publish.it168.com/2007/0623/20070623068901.shtml
76http://www.airvana.com/technology/technology_evdo_rev_a.htm
77http://books.google.com/books?ct=result&id=wQxgeqd9cDcC&dq=wcdma+km%2Fh&ots=XRYHhMtbn_&pg=PA18&lpg=PA18
&sig=ACfU3U03cru0If5hjMbkRVGte-P7do1sPA&q=km%2Fh#PPA340,M1
75
78
http://www.eett.gr/export/sites/default/sites/EETT/NewsReleases/Events/Yiatzidis.pdf
http://bwrc.eecs.berkeley.edu/Presentations/Retreats/Winter_Retreat_2007/Krenik_BWRCWin2007.pdf
80 http://www.eett.gr/export/sites/default/sites/EETT/NewsReleases/Events/Yiatzidis.pdf
81 http://www.palowireless.com/3g/docs/TD-SCDMA-China.pdf
82 http://www.dspdesignline.com/howto/208808450;jsessionid=0E4LYKXWD0B2GQSNDLQCKH0CJUNN2JVN
83
http://www.springerlink.com/content/q23126286n668518/fulltext.pdf?page=1
84 http://www.3gpp2.org/Public_html/News/Release_UMBSpecification24SEP2007.pdf
85 http://www.pcca.org/standards/architecture/hsdpa.pdf
86 http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=04022310
87 http://hsupa.blogspot.com/
88
http://3g4g.blogspot.com/2008/01/comparison-hspa-vs-lte.html
89 http://mobiledevdesign.com/tutorials/lte_next_step_cellular_3g-1027/
90 http://www.cdg.org/technology/3g/evolution.asp
91 http://www.qualcomm.com/products_services/networks/umb/
92
http://www.eurasip.org/Proceedings/Ext/ISCCSP2006/defevent/papers/cr1277.pdf
93 http://www.umtsworld.com/technology/tdcdma.htm
94 http://www.umtsworld.com/technology/tdscdma.htm
95 http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/4196544/4196545/04196768.pdf?temp=x
79
96
97
http://en.wikipedia.org/wiki/Handoff#Types_of_Handoff
http://en.wikipedia.org/wiki/Handoff#Types_of_Handoff
32
2.4 Comparison of Technologies
2.4.1 Comparison between WiMAX and Wi-Fi
Comparisons and confusion between WiMAX and Wi-Fi are frequent, possibly because both
begin with the same two letters, are based upon IEEE standards beginning with "802.", and are
related to wireless connectivity and Internet access. However, the two standards are aimed at
different applications.
This table shows technical comparison of Wi-Fi and mobile WiMAX.98
Uplink Data Rate(Mbps)
Downlink Data Rate(Mbps)
Latency
Mobility
Hand off
54
54
820.11n
(Wi-Fi)
IEEE 802.11n-Exp.
Nov 2009
200
200
NO
NO
Coverage
140m
250m
Standard
802.11g
(Wi-Fi)
IEEE 802.11g-2003
802.16e
(mobile WiMAX)
IEEE 802.16e-2005
70
70
50
Up to 120 km/h
Network-optimized
hard handoff(HHO)
1-3miles
We can get some conclusion from this table, as well as what we found from other sources.99
 Mobile WiMAX has more downlink and uplink data rate than generally used Wi-Fi technology802.11g and previous version. 802.11n has the higher data rate than mobile WiMAX. It fits
future demands of the network usage.
 Mobile WiMAX supports high mobility. Even when a vehicle runs at 120 km per hour, the user
on that vehicle can enjoy wireless service. Generally, Wi-Fi network doesn’t support high
mobility. So mobility factor favors WiMAX.
 WiMAX is a long-range system, covering many 1-3 miles that typically uses licensed spectrum (al
though it is possible to use unlicensed spectrum) to deliver a point-to-point connection to the I
nternet from an ISP to an end user.
 Wi-Fi is generally a shorter range system, typically tens of yards/meters, though its range can be
extended to over a kilometer using directional antennas. Wi-Fi uses unlicensed spectrum to
provide access to a network. Typically Wi-Fi is used by an end user to access his/her own
network, which may or may not be connected to the Internet. In Pittsburgh case, if we adopt
98
99
The data in this table are from 2.1 and 2.3. The meaning of items in the table is explained in 2.1.
http://www.multipulse.com/include/wifi-and-wimax-case-study.pdf
33
Wi-Fi to cover the entire city, we will install too many hot spot which distinctly increase the
cost.
 WiMAX and Wi-Fi have quite different Quality of Service (QoS) mechanisms. WiMax uses a
mechanism based on connections between the Base Station and the user device. Each
connection is based on specific scheduling algorithms, which means that QoS parameters can
be guaranteed for each flow. Wi-Fi has introduced a QoS mechanism similar to fixed Ethernet,
where packets can receive different priorities based on their tags. This means that QoS is
relative between packets/flows, as opposed to guarantee.
 WiMAX is highly scalable from what are called "femto"-scale remote stations to multi-sector
'maxi' scale base that handle complex tasks of management and mobile handoff functions and
include MIMO-AAS smart antenna subsystems.
 802.11n is the most advanced version of Wi-Fi. From the data we got, it has some better
technical features than WiMAX. However, the standard of 802.11n is still a draft and not
finalized. So, the existing so called 802.11n devices may not fully satisfy the final standard, and
we may spend much more money than it should be to adopting 802.11n network, which is not
technically and commercially mature.
Based on the above analysis, WiMAX is more appropriate than Wi-Fi.
2.4.2 3G VS WiMAX
Enhancements for CDMA-based 3G systems, HSPA, offer 3G operators the opportunity to upgrade the
throughput performance of WCDMA networks respectively. HSDPA is available and being deployed
extensively. EVDO-Rev B and HSUPA will be available in the 2007 to 2008 time frame. The expected
availability of mobile WiMAX in 2007 will provide existing and new mobile operators an added
alternative to consider for the delivery of broadband mobile services.
The following table shows the comparison of HSPA, EVDO Rev. B and mobile WiMAX:100
HSPA
Standard
3GPP
Release 6,
2004
Uplink Data Rate(Mbps)
Downlink Data Rate(Mbps)
Latency
Mobility
Hand off
5.7
14.1
50 ms
300 km/h
Hard
CDMA 20001xEV-DO
Rev. B
cdma2000
1xEV-DO
Rev. B,
2007101
1.8
4.9
50ms
300km/h
Hard
Coverage
0.73miles
3-9miles
100
101
The data of the table is from the previous part.
http://www.evdoinfo.com/content/view/719/64/
34
802.16e
(mobile WiMAX)
IEEE 802.16e-2005
70
70
50ms
Up to 120 km/h
Network-optimized
hard handoff(HHO)
1-3miles
Based on the data we got and other sources102, we get analysis as follows:
 The data rate for WiMAX is the highest compared with two 3G technologies.
 WiMAX uses OFDMA modulation, which enables a large number of sub-carriers (up to 2
048) with low complexity.103
 As sub-carrier orthogonality is not effected in multipath environment, the OFDMA syste
ms are robust against interference so long as the delay variation is less than cyclic prefi
x.104
CDMA systems(EVDO) generally require RAKE receivers to combat multipath fading. Ho
wever, in addition to multipath, other impairments such as frequency offset, Doppler ef
fect and lack of time synchronization can cause CDMA systems to suffer from intra-cell i
nterference106.
 OFDMA Scalability is obtained by adjusting FFT size depending on available spectrum 106.
It allows adjusting the bandwidth based on available spectrum106.
 OFDMA allows allocation of different portions of the channel so that there is no (or little
) multiple access interference (MAI) between multiple users. OFDMA therefore, can sup
port higher order uplink modulations and achieve higher uplink spectral efficiency 106.
With CDMA, on the other hand, each user transmits over the entire channel. Even thou
gh it is possible to construct orthogonal spreading codes, this is rarely done due to the
uplink synchronization issues106.
 Both 1xEVDO and HSPA signals occupy entire bandwidth. It doesn’t efficiently use the ba
ndwidth 106.
Mobile WiMAX signals on the other hand only occupy a portion of the bandwidth. In br
oadband wireless channels, propagation conditions can vary over different portions of t
he spectrum in different ways for different users. Mobile WiMAX supports frequency se
lective scheduling to take full advantage of multi-user frequency diversity and improve
QoS. WiMAX makes it possible to allocate a subset of sub-carriers to mobile users base
d on relative signal strength. By allocating a subset of sub-carriers to each MS for which
the MS enjoys the strongest path gains, this multi-user diversity technique can achieve
significant capacity gains over TDMA/CDMA106.
 Mobile WiMAX, 1xEVDO and HSPA all support frequency reuse one, i.e. all cells/sectors
102
http://www.cs.umd.edu/class/spring2007/cmsc818z/EVDO,%20HSPA%20&%20WiMAX-4.ppt,
http://www.alvarion-usa.com/upload/contents/291/Comparing_WiMAX_vs_3G_White_Paper.pdf
103 http://www.cs.umd.edu/class/spring2007/cmsc818z/EVDO,%20HSPA%20&%20WiMAX-4.ppt
104 http://www.cs.umd.edu/class/spring2007/cmsc818z/EVDO,%20HSPA%20&%20WiMAX-4.ppt
35
operate on one frequency channel to maximize spectrum utilization. However, due to h
eavy interference in (common frequency) reuse ‘1’ deployment, users at the cell edge
may suffer low connection quality.
1xEVDO and HSPA address the interference issue by adjusting the loading of the netwo
rk. However, the same loading factor is applied to all users within the coverage area, le
ading to capacity loss by “over-protecting” users that are closer to the base station.
In WiMAX the sub-channel reuse pattern can be configured so that users close to the b
ase station operate on the zone with all sub-channels available. While for the edge user
s, each cell/sector operates on the zone with a fraction of all sub-channels available106.
 In CDMA-based systems, the signals occupy the entire bandwidth. Since the processing c
omplexity for smart antenna technologies scales with the channel bandwidth, supporti
ng advanced antenna technologies in broadband wireless channels poses a more signifi
cant challenge than it does with Mobile WiMAX.
Since OFDM/OFDMA converts a frequency selective wideband channel into multiple fla
t narrow band sub-carriers it is far easier to support smart antenna technologies. Mobil
e WiMAX supports a full range of smart antenna technologies to enhance performance
including Beam-forming, STC (Space Time Coding) and SM (Spatial Multiplexing). These
technologies can improve both system coverage and capacity106.
 Throughput Comparison105
105
http://www.alvarion-usa.com/upload/contents/291/Comparing_WiMAX_vs_3G_White_Paper.pdf
36
Mobile WiMAX has much better net throughput than EVDO and HSPA.
 Spectral Efficiency Comparison108
Mobile WiMAX has higher spectral efficiency than EVDO and HSPA.
Based on the analysis above, we found that Mobile WiMAX has much better technical features t
han EVDO and HSPA. So we prefer WiMAX to 3G.
2.4.3 Conclusion: Setting the Expectation:
The public demand of data on the go has been well understood by carriers like AT&T, Verizon, Sprint and
others. Most of these latter, currently offer a 3G or limited Wi-Fi spots connectivity that are
questionable technologies in terms of value for the consumer.
For instance, 3G is fast enough to pump Web pages to iPhones and other smart phones, but it can be
painfully slow feeding the bigger data appetites of laptops, whose users expect to stream music and
watch video.
With the digital advancement, customers are requiring true portability, ubiquity, easier adoptions,
mobility and- off course- richer digital experiences. The 3G and Wi-Fi technologies have been setting
some standards on some of these mentioned criteria’s, but have lacked to implement “a bit of
everything”.
Summary of Municipal Wi-Fi projects overview and results.
A detailed look at WiMAN projects in other cities shows that Wi-Fi deployments are not as revolutionary
as they sounded on paper or during pre-deployment phases. For instance, “the network build-out in
Philadelphia PA, the trailblazer among major cities embracing wireless as a vital new form of municipal
37
infrastructure, is progressing slower than expected.106” According to Esme Vos, founder of consultancy
MuniWireless.com, “415 U.S. cities and counties are now building or planning to build municipal Wi-Fi
networks, but deployments are slowing down slightly" .
The sustainability model of some technologies, like Municipal Wi-Fi, in any business model, is not able to
keep up with the promises done by the partnering companies. “Perhaps the clearest hint of trouble
ahead is that some of the companies partnering with cities on these projects, including EarthLink and
AT&T, are having second thoughts about remaining in the municipal Wi-Fi business.”i
Major US cities and American carriers still struggle with Wi-Fi. Cities project now are unlikely to be
completed at any time in 2008.
The case of Boston:
“Boston's push for citywide wireless Internet access, delayed by technical challenges and slower than
anticipated fund-raising, is no longer expected to meet the city's original goal of blanket coverage by the
end of next year, project leaders conceded.
While the signal was robust near the traffic light pole at the students' intersection, it has been spotty
elsewhere in the pilot area, where trees and buildings have interfered with the signal between the
routers and wireless users. City and OpenAirBoston officials have concluded they will need to add
another 10 to 13 routers to overcome technology limitations in the pilot district. "As other cities have
found, we need more equipment than we'd initially expected to get the coverage," Reeve, the
OpenAirBoston chief, said.107”
The Case of San Francisco:
In San Francisco, recent developments have left many observers scratching their heads over whether
that city's Wi-Fi project, announced more than a year ago, will ever get off the ground. In July, the
president of the city's Board of Supervisors revealed that he was seeking to change the terms of the
preliminary contracts awarded to EarthLink and Google108
The Case of Philadelphia:
Mayor John Street announced plans to make Philadelphia the nation’s first major “wireless city” back in
the fall of 2004, the press couldn’t get enough. “Forget cheese steaks, cream cheese, and brotherly
love,” declared The New York Times. “Philadelphia wants to be known as the city of laptops.”
Philadelphia’s goal to cover 135 square miles with a cloud of Internet connectivity was ambitious. But
the need was undeniable. High-speed Internet access was fast becoming an economic, educational, and
106
http://www.businessweek.com/technology/content/aug2007/tc20070814_929868.htm
Technology, funding gap slow Hub's Wi-Fi effort,
http://www.boston.com/business/technology/articles/2007/11/06/technology_funding_gap_slow_hubs_wifi_
effort/?page=full
107
108
http://www.businessweek.com/technology/content/aug2007/tc20070814_929868.htm
38
social necessity. Yet most of Philly’s residents were stranded on the wrong side of the digital divide,
unable to access or afford a broadband connection.109
On the technology side, Wi-Fi municipal wireless initiatives often ran into higher-than-expected
equipment costs, as the task of blanketing large urban areas with Wi-Fi coverage proved harder than
anticipated. Cities and their private partners found that hundreds - if not thousands - of Wi-Fi access
points were needed to provide adequate coverage, and most of the times, the expected initial access
point number was far from being realistic, as noted from the Boston case.
From this city review, we conclude that the technology expectation where not clearly set, and that the
improper use of technology for the required purpose was a major driver for failure. In fact, Wi-Fi
creation was to cover small size area’s that do not exceed the size of a block, and engineers tried to hack
its limited capacity to cover city wide area’s is a major drawback point to make Wi-Fi a WiMAN solution.
Furthermore, the IEEE.802.11 technology remains unlicensed, and many issues are faced with a Wi-FI
network, such as interference and low support for a QoS, and efficient user capability. The Wi-Fi
technology will remain a limited and unfeasible technology for bigger purposes.
From the previous Technology Analysis, other cities project perspectives, and the current Technology
market standing, the choice of Technology for this project has to also consider cost for the city and cost
of the consumer, and the value this technology is giving for the roll out cost.
3. Network Solution for Pittsburgh
3.1 Desired Goals for the City
3.1.1 WiMAN needs to Target Three Major Markets
In the concern of keeping the city ahead in the field of science, research, education and public services,
the City of Pittsburgh requires that its projected municipal network will target three major markets:
 Institutional (Government)
 Residential
 Business.
In addition, the wireless network will also serve as a desirable City amenity stimulating interest in the
City and providing convenience for citizens and visitors alike. In effect, the public / private partner’s
network needs to provide extensive coverage of broadband capabilities to the entire City. Even
residents or businesses that cannot receive digital cable or DSL services will be able to receive
broadband services.
Furthermore, one of the important benefits for the city in the deployment of this network is to help in
improving and lowering costs for its field services like: Meter reading, roads optimization and security.
109
http://www.progressive.org/mag/aaron0808.html
39
3.1.2 Goals of Pittsburgh within the Flow
In comparison to other cities deployment of a similar WiMAN project, we found that the following cities
have similar goals:
 City of Chicago
 City of Minneapolis
 City of Baltimore
To support the goals of the city comes also the public demand to have access to a better adopted
wireless Broadband Internet. In fact, many citizens in Pittsburgh and other US cities, claimed in a survey
that: “..one in four US wireless subscribers would switch cellular carriers for access to the benefits of
Wi-Fi/mobile convergence… “ii
The public and business consumer s, will not only be satisfied by an acceptable WiMAN and broadband
speeds, since the public will extensively use the WiMax network as a replacement of their current wired
or indoor Wi-Fi connections.
Most subscribers today, use extensive multimedia and rich content on the internet, from video to Voice
data. The WiMAN network solution presented in this report takes note of this public requirement along
with the city goals. 110 It is also clear, that the public and business demands go beyond and are not
limited to the multimedia experience on the internet, and that the expectations should be set clear of
what to find in a WiMAN service.
3.2 Pittsburgh Demographic Information
In order to estimate a correct city wide network, we need to understand the diverse population density
throughout the city. This fact plays an important role in the network architecture design and the
deployment of this service. The estimated population of Pittsburgh, from the US Census website, is
about 325,337. The following map below represents the population density in the perimeter of the city.
110
http://www.businessweek.com/magazine/content/08_44/b4106000615564.htm
40
Population density (people per square mile) in 2000, from Decennial Census, Summary File 3 sample
data (U.S. Census Bureau)
N/A
0.000 - 192.795
192.795 - 412.592
412.592 - 655.116
655.116 - 922.840
922.840 - 1,247.940
1,247.940 - 1,725.293
1,725.293 - 2,736.900
2,736.900 - 80,483.768
Source: http://www.dataplace.org/
http://www.dataplace.org/map/index.html?place=x76769&cid=21672&centerX=8904036.288710153&centerY=4901724.919225373&zoomlevel=6
41
3.2.1 Daytime Population Change
In another perspective, the density of the city is changing from day to night. For instance the Downtown
population density changes dramatically during the day. This is also the case with other neighborhood in
the city, where the commuting and the day activity shapes the population density. This dynamic change,
42
needs to be taken in consideration where deploying the Network. Potentially, more bandwidth and
focus can be put on this area dynamically, where for instance, during the day, high density areas can
benefit from more bandwidth than low density areas, during the day\night. Although this fact doesn’t
not change the network design dramatically, but is important when it comes to network load balance
and bandwidth usage by consumers in specific network cells and zones.
http://www.atlantaregional.com/arc/documents/regsnap_DaytimePop.pdf
3.3 Choice of Technology: mobile WiMAX
From our finalized comparison and research, the best next generation wireless solution for the city of
Pittsburgh is WiMAX. Moreover, it has the strength for embedded chip which the others don’t have.
WiMAX Embedded Chip
With that in mind, Intel and several of the other
founding members of the WiMAX Forum set out to
make WiMAX chips that would be mass-produced and
inexpensive. It has worked. Embedded WiMAX chips
for laptops, for example, are already cheaper than
their embedded 3G counterparts. For example, a
WiMAX module will typically add about $60-$80 to the
price of a laptop, while embedded 3G will add $150$200. But beyond that, these cheap WiMAX chips are
poised to be embedded in all kinds of devices,
including
 Parking meters
 Home energy meters
 Vending machines
 Toys
 Traffic lights
 Cars and other motor vehicles
43
3.4 Network Deployment Process
3.4.1 Network Architecture Concept
The basic concept of this citywide wireless project is WiMAX technology for all area of Pittsburgh as a
main wireless solution and existing Wi-Fi Downtown service is used as a backup plan for who doesn’t
have WiMAX device yet. This is a result from our fine research and comparison. From the installation
perspective, former WiMAX
Pittsburgh, PA - Cell Phone Towers111
Wi-Fi Downtown Pittsburgh112
111
http://www.cellreception.com/towers/towers.php?city=pittsburgh&state_abr=pa
112
http://www.city.pittsburgh.pa.us/mayor/assets/06_WiFiFactSheetweb.pdf
44
3.4.2 WiMAX Network Diagram Samples:
iii
A typical network sample once deployed in a city
45
Example of a fixed wireless network architecture
iv
46
3.4.3 Deployment Plan
1.
2.
3.
4.
5.
6.
7.
8.
9.
Release RFI to the service provider companies and vendors.
Release RFP to the service provider companies and vendors.
Select a service provider company and a vendor.
Detail co-Research
Pilot Test
Installation & Development
Mass Test & Stress Test
Get rid of Dead Zone
Go Live.
3.5 Adoption Plan
3.5.1 Current WiMAX Subscription Rate
Scottsburg, IN, the first citywide WiMAX technology serviced city, has various rates depending on the
data rate limitation. They also have separated rate for both personal and commercial. Baltimore, MD,
The first WiMAX technology implemented city by XOHM, the first nationwide network using WiMAX, has
simply two different rates depending on the periods, day and month.
3.5.1.1 WiMAX in Scottsburg, IN113
C3bb (Citizens Communications Corporation(Service Provider) Broadband) Pricing114
a. Residential Rates:
Speed
512 kps
1 mbps
Includes up to 3 e-mail addresses
Price
$35 per month
$70 per month
$50 Installation Charge
b. Business Rates:
Speed
128 kps
256 kps
512 kps
113
114
Price
$40 per month
$70 per month
$100 per month
http://www.alvarion.com/upload/contents/291/alv_cs_Scottsburg_LR.pdf
http://c3bb.com/images/c3bb_brochure.pdf
47
$200 per month
1.5 mbps
Negotiated
> 1.5 mbps
Dedicated Closed Networks also Available
Includes up to 10 separate e-mail accounts
$100 Installation charge
3.5.1.2 WiMAX in Baltimore, MD by XOHM115
Price
$5.00
$30.00
Limited Time Offer (excludes taxes)
Unit Period
Day
Month
$15/month off $45/month for the first 6 months.116
3.5.2 Current 3G Data Plan
Current two major 3G service providers are AT&T and Verizon. Those two major 3G carriers provide
plans based on totally different factors.
3.5.2.1 AT&T117
AT&T has plans depending on the devices basically. They also charge based on the amount of data if the
plan is not unlimited.
a. BlackBerry
b. PDA & Smart Phones
115
http://www.xohm.com/en_US/shop/service-options/daily-on-the-go.html
http://www.xohm.com/en_US/shop/service-options/on-the-go.html
117
http://www.wireless.att.com/cell-phone-service/cell-phone-plans/data-cell-phone-plans.jsp?_requestid=29184
116
48
c. Laptop
d. iPhone118
Unlimited data plan (mandatory): $30.00/month
3.5.2.2 Verizon119
Verizon’s plans are separated by the allowed amount of data regardless of the type of mobile devices.
Also they don’t have unlimited data access.
118
119
http://www.wireless.att.com/cell-phone-service/specials/iphone-info.jsp
http://download.intel.com/network/connectivity/products/wireless/mobilize-your-internet.pdf
49
3.5.3 Current City-Owned Wi-Fi Downtown Pittsburgh Data Plan120
Wi-Fi Downtown Pittsburgh will provide wireless access to the Central Business District/Golden Triangle,
North Shore and Lower Hill District at various service tiers, including: US Wireless Online FreeConnect™,
which allows free access for up to two hours each day and US Wireless Online DayConnect™, which
provides usage at a higher bandwidth and can be purchased in increments of $7.99 per day, $14.95 per
month or $119.99 per year. FreeConnect users will be provided a minimum of 512 Kbps of bandwidth,
while DayConnect users will receive 1 Mbps. DayConnect users also will benefit from VPN and other
security encryption protocol support.
3.5.4 Current WiMAX Device
New mobile WiMAX Laptops & Mobile Devices121
Major laptop & mobile device manufacturers already launched mobile WiMAX laptops & mobile devices.
Those laptops use Intel’s embedded combo Wi-Fi/WiMAX module.122 That means no data cards or
modems are required to get online anywhere in mobile WiMAX coverage.
Nokia
Nokia N810 Internet Tablet - WiMAX Edition
This XOHM ready internet tablet fits in your pocket and lets you get online with
XOHM WiMax or Wi-Fi, so you can keep in touch, update your blogs and social
sites, and enjoy the web anywhere in XOHM coverage.
Acer
Acer Aspire 6930
120
http://www.city.pittsburgh.pa.us/mayor/assets/06_WiFiFactSheetweb.pdf
http://www.xohm.com/en_US/shop/partner-products/
122
http://download.intel.com/network/connectivity/products/wireless/mobilize-your-internet.pdf
121
50
The Aspire 6930 offers high-definition multimedia presentation of movies, games
and other digital media and features a 16-inch HD LCD screen.
Lenovo
Lenovo ThinkPad X301
The Lenovo ThinkPad X301 is designed for an enhanced wireless connection and
the latest digital display technologies. It’s a thin and light ultraportable notebook
with a 13.3” LED backlit widescreen display.
Lenovo ThinkPad SL300
Toshiba
Toshiba Satellite® U405-ST550W
The Satellite® U405-ST550W is an ultraportable laptop for people on the go. It
features a 13.3” widescreen display and compact footprint.
3.5.5 Solutions for Current Laptop & Mobile Devices123
Modems & Data Cards
Current devices also can use mobile WiMAX through modem, ExpressCard or USB. Those devices will be
used as compatibility solutions until most mobile devices have WiMAX adaptors.
123
http://www.xohm.com/en_US/shop/devices/
51
XOHM Modem
The XOHM Modem connects your computer or Wi-Fi router to the internet. It’s
easy to set up, making it simple to get online at home. Use it anywhere in the
XOHM coverage area.
$79.99
XOHM ExpressCard
The XOHM ExpressCard connects your laptop to the internet and extends your
service beyond hotspots. Use it anywhere in the XOHM coverage area. Plus, it
comes with the XOHM ExpressCard Adapter so you can use it on computers with a
standard PC Card slot (PCMCIA slot).
$59.99
XOHM USB
The XOHM USB plugs into any standard USB port to provide a wireless broadband
internet connection to your laptop or desktop computer. At home or on the go, use
it anywhere within XOHM coverage.
$59.99
3.5.6 Data Plan Recommendation
Pittsburgh city keeps the rates of current Pittsburgh Downtown Wi-Fi for the Residential and give a
different rate for the commercial. This data plan helps the citizen use the service not for 1 day but for
more than 1 month because it is much cheaper. Moreover, WiMAX device rental can increase the
number of users who doesn’t have WiMAX embedded mobile devices. Rates are not separated
depending on the speed, device or the amount of data which can cause the user’s confusion.
52
Plan
Period
Data
Residential Rate
1 Day
1 Month
1 Year
1 Month
Device Rental
Commercial Rate
$3.99
$14.95
$119.95
$2.99
$7.99
$29.95
$299.95
$4.99
4. Cost analysis and cost estimative ranges.
4.1 The Capital Expenditure - CAPEX
In an effort to estimate a realistic price tag to the city’s mobile WiMax WiMAN, a comparison or study of
existing live projects should be considered. For this purpose, we studied the capital expenditure cost of
companies deploying large scale WiMAN’s in the following city:
Chicago, IL, Baltimore, MD and Scottsburg, IN.
The criteria’s behind the city selection is based on the fact that to estimate the cost of deployment for
the city of Pittsburgh, and to have this cost within actual ranges, a large, medium and small cities have
to be considered in order to have reasonable averages. Chicago, represents a large city, Baltimore,
represents a medium sized city and Scottsburg, a small size city reference.
City
Chicago
Size(sq\mile)
Population(2007 Census)
Density(pers/sq mile)
237
2,850,000
12,025
Baltimore
92
637,000
6,924
Scottsburg
4.8
6,000
1,250
Pittsburgh
55
312,800
5,687
Table: Cities demographic information
For the city of Chicago and Baltimore, a mobile WiMax solution provider has deployed the project. The
company called, Xohmv the service name for Sprint, has released a small amount of numbers to the
public, concerning the actual cost of deployment in these cities. Only the number of Base Stations (BS)
and the total amount of Capex, (Capital Expenditure, which reflects the amount to acquire or deploy
assets) for 5 cities in total has been released. In fact Xohm has spent 134 millionvi deploying WiMAX in
Chicagovii, Baltimoreviii, Bostonix, and Washington DCx.
These numbers collected from these cities are required for the cost estimation. Furthermore, in the
understanding of the WIMAX technology, a key factor of the cost of a WiMAX WIMAN network is the
53
Base Station. For the city of Chicago, Xohm has deployed 600 base stations, for the city of Baltimore
300.
54
The following are the different approaches to reach a cost estimate:
Cost Estimation 1
First, we found the number of Cell Phone Towers and the relation between the number of the BS (Base
Station) and the number of Cell Phone Towers. The number of BS in Pittsburgh was calculated using a
proportional method.
Table 1.
Chicago
Baltimore
Scottsburg
Pittsburgh
BS
(Base Station)
600125
Cell
Tower124
60
300126
Area
Population
(sq Mile)
237
2,850,000
Density
(pers/sq Mile)
12,025
25
92
637,000
6,924
127
3
128
203,832
340
240
24
55
312,800
5,687
26
599
The total cost is calculated from Reference 1. and the number of BS.
We can assume that the number of BS (Base Station) with Backhauling is the same with the number of
Cell Towers because it has a tower and wired optical network. Also we need 216 more BS (This can be
called as RS (Relay Station)) which will be connected to BS (Base Station) with Backhauling wirelessly in
mesh network topology. So they don’t need ‘Backhauling to the core network’ and the price is 40% of
MR-BS.129
Table 2.
124
Number of Cell Phone Towers: http://www.cellreception.com/towers/towers.php
http://markets.on.nytimes.com/research/stocks/news/press_release.asp?docKey=600200810011132PR_NEWS_USPR_____CG360465VISLDST34TJMO1EP4CQRD08FL&provider=PR%20Newswire&docDate=October%201%2C%202008&press_symbol
=US%3BMOT
125
126
http://www.betanews.com/article/Handson_with_Sprints_Xohm_network_in_Baltimore_Does_WiMAX_deliver/1
224289560
127
www.bsu.edu/research/media/powerpoint/03-city-of-scottsburg.ppt
128
This is the total area of six counties around Scottsburg where WiMAX network is covered. And the area and
population of each county are gotten from government’s census.
129
Reference 1. F
55
MR-BS(Base Station) w/o New Tower-deployment
RS(Relay Station) w/o New Tower-deployment
24 * $150,000130
$3,600,000
216 * $60,000
$12,960,000
Total
$16,560,000
So the total cost for Pittsburgh will be about 16.6 million using our assumption.
Reference 1. Example calculation of CAPEX for BS-RS. 131
CAPEX
Index
A
B
C
D
E
F
MR-BS
Three-sectored BTS Tx + Rx + antenna + cables
Site acquisition + preparation + cabling + power
Backhauling to the core network
New Tower-deployment
Total BS CAPEX
Total RS CAPEX
Price
$70,000
$50,000
$30,000
$80,000
$230,000
40% of the BS
Reference 2.
Scottsburg, IN132
130
131
132
133
Baltimore, MD133
Reference 1. A+B+C
http://www.fujitsu.com/downloads/MAG/vol44-3/paper09.pdf
http://www.cellreception.com/towers/towers.php
http://www.cellreception.com/towers/towers.php?city=baltimore&state_abr=md
56
Chicago, IL134
Pittsburgh, PA135
Cost Estimation 2.
The total cost heavily relies on the amount of base stations. So we concern the way to figure out the
number of base stations. There are two criteria: population density and square miles. But we don’t know
the exact coefficient of these two factors. So we developed a linear simulation approach.
We assume that population density is independent from square miles. So it is mathematically
reasonable to do linear simulation with these independent factors.
We got some data of other city’s WiMAX applications through our research.
BS(Base Station)
Area(sq Mile) Population Density(/sq Mile)
Chicago
600136
237
2,850,000
12,025
Baltimore
300137
92
637,000
6,924
Scottsburg
26138
599139
203,832
340
134
http://www.cellreception.com/towers/towers.php?city=chicago&state_abr=il
http://www.cellreception.com/towers/towers.php?city=pittsburgh&state_abr=pa
136
http://markets.on.nytimes.com/research/stocks/news/press_release.asp?docKey=600200810011132PR_NEWS_USPR_____CG360465VISLDST34TJMO1EP4CQRD08FL&provider=PR%20Newswire&docDate=October%201%2C%202008&press_symbol
=US%3BMOT
135
137
http://www.betanews.com/article/Handson_with_Sprints_Xohm_network_in_Baltimore_Does_WiMAX_deliver/1
224289560
138
www.bsu.edu/research/media/powerpoint/03-city-of-scottsburg.ppt
139
This is the total area of six counties around Scottsburg where WiMAX network is covered. And the area and
population of each county are gotten from government’s census.
57
Pittsburgh
?
55
312,800
5,687
We need to use these data to find a formula for base station number.
The formula we use is:
X·density+Y·area=station
So right now, we need to get X and Y. In order to do this, we need to use two cities’ data. We choose
Chicago and Scottsburg. The reason is that Chicago is a big city, while Scottsburg is a small town. The
coverage in Scottsburg is vast, while the population there is very small. So we see here Scottsburg and
Chicago are two extreme distance points in the linear simulation. And the result would be more accurate
since the two points are far away.
Let’s substitute the variable by real numbers:
For Chicago: X·12025+Y·237=600
For Scottsburg: X·340+Y·599=26
So we get X=0.050, Y=0.015.
Then we test the formula using Baltimore’s case. We estimated 345 base stations totally in Baltimore,
while the real number is 300. So the result is close.
Then we use the result to get Pittsburgh’s base station number:
For Pittsburgh: Station=0.050·5687+0.015·55=283
So we assume Pittsburgh has 283 base stations.
The next step is to calculate the cost. We use the same strategy with cost estimation 1 here.
We use the same table as in cost estimation 1.
MR-BS(Base Station) w/o New Tower-deployment
RS(Relay Station) w/o New Tower-deployment
24 * $150,000
$3,600,000
(283-24) * $60,000
$15,540,000
Total
$19,140,000
So the total cost for Pittsburgh will be about 19 million using our assumption.
58
4.2 Revenue Estimation

The number of mobile subscribers is 4000, ramping up to 30,000 over a period of
3 years. The data rate starts out at 1 Mbps per Sub, ramping up to 1.4 Mbps Based upon
oversubscription of 20, the average data rate that needs to be supported is 50 Kbps initially
moving up to 70 Kbps We will charge $29.99 per month initially for this service and reduce the
rate $1 per year to $27.99 per month by year 3. With these assumptions the cumulative revenue
is 1.4 M by year 1 and $15 M by Year 3. The subscribers base is
illustrated below:
140
140
http://www.wimax.com/commentary/blog/blog-2008/clearwire-to-target-life-unwired-strategy-with-wimax
59
141
The Revenue is calculated with the number of WiMAX Users expectation of WiMAX forum , the
proportion of the population of Pittsburgh and the ration of COPEX and OPEX. We can expect that
BEP(Break Even Point) will come from year 2012.
Index
Formula
Year
A
Number of WiMAX Users(M)142
B
US Population(M)143
2010
2011
2012
9.59
14.79
22.62
310.23
313.23
C
A/B*100
User Rate (%)
3.09
4.72
316.2
7
7.15
D
Fixed
Population Ratio of Pittsburg
0.10
0.10
0.10
E
B*D
Pittsburgh Population(M)
32.52
32.83
33.15
F
C*E/100*$119.95
(1 year Subscription Fee)
Sales(M$)
1.01
1.55
2.37
141
http://www.dailywireless.org/2008/10/21/clearwire-show-us-the-money/
http://www.wimaxforum.org/documents/downloads/wimax_forum_wimax_forecasts_6_1_08.pdf
143
http://www.census.gov/population/www/projections/downloadablefiles.html
142
60
G
COPEX:OPEX=$230000:$33300144
OPEX(M$)
H
F-G
Revenue(M$)
2.40
2.40
2.40
-1.39
-0.85
-0.03
i
http://www.businessweek.com/technology/content/aug2007/tc20070814_929868.htm
http://www.itwire.com/content/view/10839/127/
iii
http://www.telsima.com/pic/StarMAX_NMS_1_v.jpg
iv
http://www.ictregulationtoolkit.org/en/PracticeNote.aspx?id=2976
ii
v
www.xohm.com, http://en.wikipedia.org/wiki/Xohm
vi
http://library.corporate-ir.net/library/12/127/127149/items/314763/3Q_08_Earnings_Relase.pdf
vii
http://www.dslreports.com/shownews/600-XOHM-Base-Stations-Ready-To-Roll-In-Chicago-98146
viii
http://www.crunchgear.com/2008/10/11/baltimores-xohm-speeds-scrutinized/
ix
http://pcs.co.uk/2008/10/xohm-partners-celebrate-4g-mobile-service-rollout-in-baltimore/
x
http://pcs.co.uk/2008/10/xohm-partners-celebrate-4g-mobile-service-rollout-in-baltimore/
144
http://www.fujitsu.com/downloads/MAG/vol44-3/paper09.pdf
61