University of Kansas | School of Engineering
Similarities and Differences between LTE, UMB &
WiMax
Presented By: Brandt Elster
Department of Electrical Engineering
and Computer Science
University of Kansas | School of Engineering
Outline
•WiMax News
•Definitions
•Background & History
•Motivations and Objectives
•Deterrents
•Services and QoS
•Network Architecture
•Physical Layer & MAC Protocols
•Comparison of the Technologies
•Future of the Technology
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WiMax News Today
• Today there was a large announcement regarding the future of mobile WiMax
• Since Dan Hesse became the new Sprint CEO there were doubts he would continue
Sprint’s future in their WiMax venture named XOHM.
• Immediately upon becoming CEO he terminated an existing agreement to work along side Clearwire
and collaborate on separate WiMax networks that were able to roam on each others to increase
coverage
• Today Sprint and Clearwire put out a joint press release stating they had formed a joint
venture that would be named Clearwire to build one WiMax network.
• This new company has received investments from the following companies: Google, Intel,
Comcast, Time Warner Cable, and Bright House networks
• These companies have combined together for a total investment of $3.2 billion
• They will receive an estimated 22% ownership of the company
• Sprint will maintain the largest share at 51% and Clearwire will control 27%
• The deal is estimated to be worth a total of $14.5 billion
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Definitions - LTE
• Long Term Evolution is more commonly referred to as LTE
• LTE is the 4th generation network that was designed through the Third Generation
Partnership Project (3GPP).
• It is an all IP network
• Its primary goals were to improve efficiency, lower infrastructure costs, create a higher QoS,
all while making use of new spectrum opportunities, and better integrating with other open
standards
• Predominantly created by Ericsson, Nortel and Nokia-Siemens
• Should result in release 8 of the UMTS standard
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Definitions - UMB
• Ultra Mobile Broadband is commonly referred to as UMB
• UMB is the 4th Generation wireless broadband access network developed through the CDMA
Development Group (CDG)
• It is an all IP network
• It was designed from the ground up to provide the type of access required in the modern
mobile world, with great flexibility and interoperability
• Standardized by the 3rd Generation Partnership Project 2 (3GPP2)
• Proprietary technology developed by Qualcomm
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Definitions - WiMax
• Mobile WiMax is short for Wireless Interoperability for Microwave Access
• There is actually a difference between mobile WiMax and fixed WiMax
• Today we are only going to talk about the mobile version of WiMax
• WiMax is the 4th Generation wireless broadband access network developed by the IEEE
• It is the 802.16e or upcoming 802.16m standards
• It is an all IP network
• Many hardware manufacturers are already supporting WiMax due to it’s open standards.
Some of the larger ones include Samsung, Motorola and Intel.
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Background & History
• Analogy for the differences between TDMA, FDMA, SDMA, CDMA
• Take a large room with a decent number of people in it. There are multiple different
conversations going on throughout the room.
• TDMA – Everyone in the room would take turns speaking. Each group of people would be assigned
a specific time slot.
• FDMA – Each group in the room would speak at a different pitch (frequency) far enough apart that
they can be differentiated.
• SDMA – Each group’s speaker would talk in a specific direction, only people in front of them would
be able to hear. If the room is big enough you could have multiple people speaking in the same
direction as long as they were far enough apart.
• CDMA – Each group would be assigned a specific language to communicate with. They would be
able to easily discern their specific language and all others would be small and ignorable
background noise.
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Background & History
• OFDMA
• Basically an enhanced version of FDMA
• Allows for the elimination of guard bands by using orthogonal signals.
• Signals are considered to be orthogonal if their dot products are equal to 0
• Signals are able to overlap without causing interference to the other
• Signals are modulated and demodulated using the Fast Fourier Transform
• SC-OFDM
• This is a single carrier equivalent of OFDMA
• Each transmission is given only one carrier
• This allows the peak-to-average power to be lower thus increasing the capable average power of
the power amplifier
• This is helpful because the user terminal is generally battery powered and this includes both battery
life and range
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Background & History - LTE
• Part of the 3GPP standard
• Essentially it is HSPA rev 8
• It was given the name Long Term Evolution by the 3GPP
• The name follows their generally naming scheme. They try to make their name represent their
monopoly over the wireless arena
• GSM stands for Global Standard for Mobile & UMTS stands for Universal Mobile Telephone
Standard
• Originally started as GSM
• Capable of virtually no data communications
• Pioneered the first short messaging service (SMS)
• Supports handoffs with all UMTS and GSM networks
• There is discussion to build in the ability to support handoffs with CDMA networks
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Background & History - LTE
• GSM was the 2G technology that both GPRS and EDGE are based on
• GPRS was the first step
• Stands for General Packet Radio Service
• It is considered to be a 2.5G
• Capable of speeds from 56 up to 114 kbit/s
• Supports a very robust voice channel and low bandwidth data options.
• Main data use was text internet & downloading of reduced size pictures and music
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Background & History - LTE
• EDGE was the next step
• Stands for Enhanced Data rates for GSM Evolution
• It is considered to be a 2.75G
• Capable of speeds from 1 Mbit/s
• Reduced latency to 100 ms
• However just like GPRS, the main data use was text internet & downloading of reduced
size pictures and music
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Background & History - LTE
• Following EDGE came UMTS
• Stands for Universal Mobile Telephone Standard
• UMTS was the first truly 3G technology to come from 3GPP
• UMTS is a completely different technology than GSM.
• It required a completely new network be built over the top of any existing networks
• UMTS uses W-CDMA instead of the TMDA that powered GSM
• The primary difference between W-CDMA and CDMA2000 is that W-CDMA uses 5 MHz blocks of
spectrum and CDMA2000 uses only 1.25 MHz blocks, hence where the “wide” came from
• The first revision of UMTS was capable of speeds up to 2 MB/s
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Background & History - LTE
• HSPA was the final step for W-CDMA
• HSPA stands for High Speed Packet Access
• There are three different enhancements to HSPA, HSDPA, HSUPA and HSOPA
• HSDPA stands for High Speed Downlink Packet Access
• It predominantly increases the download speed of the network.
• HSUPA stands for High Speed Uplink Packet Access
• It predominantly increases the upload speed of the network
• HSOPA stands for High Speed OFDM Packet Access
• This technology replaces the entire infrastructure of UMTS and replaces it with a new OFDM
infrastructure
• It is a separate technology from LTE but is part of the overall picture. Most likely it will never be
implemented but it’s technologies will be morphed into LTE
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Background & History - LTE
• Table of different UMTS Technologies and their specifications:
Technology
Release Data
Downlink Speed
Uplink Speed
UMTS
2000
384 kb.s
128 kb/s
HSDPA
2000
7.2 Mb/s
384 kb/s
HSUPA
2005
7.2 Mb/s
5.76 Mb/s
HSOPA
2009
100 Mb/s
50 Mb/s
LTE
2010
100 Mb/s
50 Mb/s
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Background & History - UMB
• Part of the CDMA 2000 standard
• First named EV-DO rev C
• Renamed to Ultra Mobile Broadband by the CDMA Development Group (CDG)
• Originally started as cdmaOne
• A 2G Qualcomm technology
• Capable of virtually no data communications
• Will be capable of call handoffs with all legacy CDMA2000 networks
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Background & History - UMB
• cdmaOne was the 2G technology that both 1xRTT, 1xEV-DO, and 1xEV-DV are based on
• 1xRTT was the first step
• It is considered to be a 2.5G
• Capable of speeds up to 144 kbit/s
• Also referred to as just 1x
• Supports a very robust voice channel and low bandwidth data options.
• Main data use was text internet & downloading of reduced size pictures and music
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Background & History - UMB
• The next step was 1xEV-DO (Evolution Data Only)
• Later renamed Evolution Data Optimized to remove the negative connotation
• Most commonly referred to as just EVDO, or simply EV
• First truly 3G technology and first real wireless broadband technology.
• An alternative to EVDO was 1xEV-DV (Evolution Data & Voice)
• The standard was not completed in time so it was ultimately passed up
• Theoretical speeds of 3.1 Mbit/s downlink and 1.8 Mbit/s uplink.
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Background & History - UMB
• EVDO began as Rel 0.
• Significant speed improvements over 1x
• 2.4 Mbit/s downlink
• Supports the following applications
• broadband Internet
• 153 kbps uplink
• MP3 music downloads
• Includes the following protocols and more
• Hybrid ARQ
• Incremental Redundancy Feedback in the
• 3D gaming
• TV broadcasts
• Video and audio downloads
Downlink
• Downlink and Uplink Rate Controls
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Background & History - UMB
• The current and most up to date standard of the CDMA2000 protocol is EVDO Rev A
• It is currently being deployed over Rel 0
• Capable of producing speeds of 3.1 Mbit/s downlink and 1.8 Mbit/s uplink
• Uses enhanced access channel MAC
• Controls who sends and who receives and when
• Advanced QoS support
• Increased spectral efficiency
• 1.2 times Rel 0 forward link sector capacity and 3.4 times reverse link sector capacity
• Low latency, below 50 ms
• Supports all the services of Rel 0 but adds higher quality video and faster loading times for
streaming services
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Background & History - UMB
• Rev B would be the next upgrade
• It is likely to be skipped for Rev C in 2009 similar to how EVDV was bypassed
• Speeds of up to 14.7 Mbit/s downlink
• Utilizes statistical multiplexing
• Hybrid frequency reuse
• Supports OFDM
• Adds multi carrier support
• Rev A uses 1.25 MHz carriers, most likely 3 per user would be used for Rev B, or 3.75 MHz
• This is unique from HSPA because the carriers do not need to be adjacent
• This allows operators to combine spectrum from multiple blocks
• Adds the ability to do High Definition video streaming, multiplayer online gaming, and
replacement of home HSI and hotspots
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Background & History - WiMax
• It evolved from the WiFi standards in an effort to create a technology that could cover a larger
footprint.
• Example, if WiMax is a cell phone, then WiFi would be a cordless phone.
• Fixed WiMax was designed as a technology that could be used to blanket a city with
mobile internet to replace building costly short range WiFi networks.
• Mobile WiMax took the same technology and evolved it into version that could work with
devices that are no longer stationary
• WiMax comes from the IEEE 802 set of standards.
• The IEE 802 standards are a family of standards that deal with Local Area Networks
(LANs) and Metropolitan Area Networks (MANs)
• WiMax is the 802.16 standard.
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Background & History - WiMax
• History of the IEEE 802 standard
• IEEE 802.3 is collection of IEEE standards that define the Media Access Control Layer,
Physical Layer and Data Link Layer of the wired Ethernet standard
• IEEE 802.11 is Wireless LAN & Mesh a.k.a. WiFi
• It is a group of standards for wireless local area networks (WLAN)
• These typically operate in unlicensed spectrum bands located near 2.4 GHz and 5 GHz.
• Maximum range of WiFi is roughly 70m indoors using the 802.11n standard and is capable of
producing 74 Mbit/s
• IEEE 802.15 is Wireless Person Area Networks (PAN)
• This standard includes Bluetooth and ZigBee
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Background & History - WiMax
• Brief Discussion of 802.11 Wifi
• Wifi is predominantly used in the 2.4 GHz range due to range limitations with the 5GHz
frequency band
• It divides these frequency bands into channels that are 22 MHz wide with 5 MHz spacing in
between.
• WiFi networks consist of two main components. The Access Points (APs) and the clients. The AP
continuously broadcasts it’s SSID or name every 100 ms at 1 Mb/s. Sending at 1 Mb/s ensures that
all users are at least capable of sending at that speed.
• WiFi is not capable of collision detection. It instead does collision avoidance using RTS/CTS. It
also uses acknowledgements to make sure that the packet is received.
• Generally WiFi networks connect back to a 802.3 Ethernet connection, but they can connect 2
devices to one another (AdHoc Networks) or connect a computer directly to the internet.
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Background & History - WiMax
• Brief Discussion of 802.11 Wifi
Protocol
Release
Date
Freq
Typical
Thruput
Max Data Indoor
Rate
Range
Outdoor
Range
Legacy
802.11
1997
2.4 GHz
.9 Mb/s
2 Mb/s
20 m
100 m
802.11a
1999
5 GHz
23 Mb/s
54 Mb/s
35 m
120 m
802.11b
1999
2.4 GHz
4.3 Mb/s
11 Mb/s
38 m
140 m
802.11g
2003
2.4 GHz
19 Mb/s
54 Mb/s
38 m
140 m
802.11n
June 2009 2.4 GHz
5 GHZ
74 Mb/s
248 Mb/s
70 m
250 m
802.11y
June 2009 3.7 GHz
23 Mb/s
54 Mb/s
50 m
5 km
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Motivations - LTE
• Chosen European standard likely to be used throughout the world
• Large companies have committed to it
• Vodaphone (part owner Verizon Wireless)
• AT&T
• High speed data throughputs
• 100 Mbps Downlink
• 50 Mbps Uplink
• Cost effective compared to UMTS based technologies
• Backwards compatible with all UMTS/GSM technologies
• High QoS for a wide range of applications
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Motivations - LTE
• Can be deployed within existing GSM & UMTS frequency bands along side existing networks
• Can use only a portion of the frequency band in the beginning and then can take more
existing spectrum as old networks are phased out.
• Designed for high mobility
• Optimized for 0 – 15 km/h
• High performance still achievable for less than 150 km/h
• Will still support anything up to 500 km/h
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Motivations - UMB
•Motivations for EVDO Rev C (UMB)
• Backwards compatible with all CDMA 2000 Networks
• High speed data throughputs
• 280 Mbps Downlink
• 75 Mbps Uplink
• Low latency connections
• An average of 16 ms (32-byte, RTT) end-to-end network latency
• High QoS for a wide range of applications
• Seamless mobility
• Efficient frequency re-use deployment
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Motivations - WiMax
• Time to market:
• Has already seen a small launch in the United States – Clearwire
• Has seen similar deployments around the world.
• Large companies have committed to it
• Sprint-Nextel (XOHM)
• SK Telecom (WiBro is a variant of WiMax and has been launched in South Korea)
• There have been discussions to morph WiMax into the LTE Umbrella and make it a stepping
stone to LTE
• This may be a play simply to discredit WiMax and make it sound inferior
• The newest revision of Mobile WiMax (802.16m) is expected from the IEEE sometime this
year and should bring the theoretical speeds for a mobile application up to a level of those
expected from LTE & UMB.
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Deterrents
•Long Term Evolution (LTE)
• Time to market:
• Not expected to have a widespread deployment until 2012
• Components not available until late 2009
• 4 years behind Mobile WiMax
•Ultra Mobile Broadband (UMB)
• Time to market: Components first available in late 2009 to 2010.
• No corporate commitments throughout world
• Even the majority of current CDMA carriers have chosen other platforms
•Mobile WiMax
• Speeds are not up to the level of UMB & LTE
• Downlink capable of 46 Mb/s (without MIMO)
• Less than half that of UMB & LTE
• *note that 802.16m is expected to raise these figures to 100 Mb/s and should be out sometime this year and available around
2010. Note this is still 2 years before LTE is expected to widely deployed.
• Not officially classified as 4G by European standards due in part to insufficient speeds
• Unproven, a lot is riding on the success of Sprint’s consumer launch (XOHM)
• Success could lead to more build outs worldwide turning it into a global standard
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Deterrents
•All three technologies face another crucial issue. Backhaul
• As speed increase the need for more and more leased lines increases. Fiber alleviates some
pressure but is limited in roll outs and is relatively expensive.
• Alternative options include but are not limited to
• Microwave
• Fixed WiFi or WiMax
• Dark Fiber
• ADSL or SHDSL
• PDH or SDH/SONET infrastructures
• E1/T1, E3, T3, STM-1/OC-3 …
• Cable Coaxial lines
• None of these options is widely available in the U.S., Especially in the mass rural parts of the
county.
• Sprint is supposedly using Microwave to provide the backhaul to their WiMax towers where
fiber is not yet available.
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Spectrum Allocations
•Long Term Evolution (LTE)
• 1.25 MHz to 20 MHz chunks
• Can operate in all 3GPP frequency bands in paired and unpaired spectrum allocations
• Can sit in the same band as existing 3GPP networks. Allows for LTE to be phased in while
older technologies are phased out.
•Ultra Mobile Broadband (UMB)
• 1.25 MHz up to 20 MHz
•Mobile WiMax
• Any frequency below 66 GHz
• Fixed channel sizes of 3.5 MHz, 5 MHz, 7 MHz, 10 MHz, and 20 MHz.
• Mobile channel sizes of 5 MHz, 8.75 MHz and 10 MHz.
• This does not phase Sprint or Clearwire as both have almost 120 MHz of spectrum in their areas,
but smaller companies could face issues when only operating in 10 or 20 MHz blocks.
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Services and QoS
• Streaming of high quality video and audio
• Video calling
• VOIP for phone calls
• Provide enhanced data speeds for both handheld devices and laptop connect cards
• Could replace the traditional wired networks as they are much cheaper than fiber to the curb,
and speeds look to be the same if not higher than those offered via wired today
• This would be for the following services
• HSI to replace DSL/Cable Modems
• Digital Phone for the Home
• IPTV or TV over IP to replace standard cable or satellite provider
• This would give previously only mobile operators the ability to sell the very lucrative triple
play that, up until now, only existing LEC and cable operators have been able to.
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Services and QoS
Category
Current Environment 4G Possibilities
[Source: UMTS Forum,
"Standardising the future
of mobile
communications with
LTE (Long Term
Evolution)." Towards
Global Mobile
Broadband (2008): ]
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Services and QoS
• Companies are also looking to build 4G chips into more electronic devices than just cell
phones and laptops
• Looking for every electronic device to have a 4G connection to the internet
• Fridge could download recipes and auto update shopping list with what you need
• Digital camera’s would be able to instantly upload photo’s to photo sharing and social
networking sites, as well as having the ability to send them via email directly from the
camera
• MP3 players could download songs from anywhere, similar to the Apple iPod Touch but
without the need for a WiFi connection
• Cars would be able to auto diagnose issues and email the mechanic to notify them of
issues
• These are just a couple of the endless possibilities that 4th generation networks are trying
to tap into
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Network Architecture
[Source: Dahlman, Erik. 3G
Evolution HSPA and LTE
for Mobile Broadband. First.
London: ELSEVIER, 2007.]
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Network Architecture - LTE
•
LTE combines the following network protocols into a single air interface, utilizing the
individual advantages of each one
•
OFDMA
•
MIMO (2x2 or 2x4)
•
ARQ within the RLC sub layer and HARQ within the MAC sub layer
•
FDD & TDD
•
SC-FDMA
•
Up to 64 QAM DL and 16 QAM UL
•
Turbo Coding (rate – 1/3, 2 8 state constituent encoders and a contention-free internal
interleaver)
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Network Architecture - LTE
•The core network architecture of LTE has been given it’s own name. It is called System
Architecture Evolution (SAE)
•SAE is relatively similar to the GPRS Core Network that includes some basic modifications.
•Most notably a simplified architecture
•Spectrum allocations from 1.25 MHz up to 20 MHz
•Can support 200 simultaneous VOIP users across a cell consisting of 5 MHz
•Provides interference reduction through power control and link adaptation techniques
•A common node B. Acts as a common gateway for all of the access technologies that
access the network
•Can support handoffs between both 3GPP networks and non-3GPP networks
•This should allow legacy CDMA2000 operators to interface their old networks with LTE
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Network Architecture - LTE
[Source: Myung, Hyung G.. "Technical Overview of 3GPP Long Term Evolution (LTE)."2007.]
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Network Architecture - UMB
•
UMB is a proprietary technology to Qualcomm Inc.
•
There is only a limited amount of information available regarding the actual architecture and
physical properties of the technology.
•
This a summary of the available information available from Qualcomm white papers.
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Network Architecture - UMB
•
According to the CDG UMB combines the following network protocols into a single air
interface, utilizing the individual advantages of each one
•
CDMA
•
OFDMA
•
MIMO
•
SDMA
•
FDD
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Network Architecture - UMB
•Spectrum allocations from 1.25 MHz up to 20 MHz
• Can support 1000 simultaneous VOIP users across 20 MHz FDD
•A flat network architecture
• Simplifies core network design
• Eliminates the need for centralized base station controllers (BSCs)
•A converged-access network (CAN) design that enables seamless mobility
•A multi-route feature that enables fast switching between base stations and provides requisite
support for latency-sensitive applications
•Layer 2 and layer 3 tunneling mechanisms to simplify the network interface
•Adaptive interference management
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Network Architecture - UMB
[Source: "UMB Network
Architecture." Qualcomm
Inc Dec 2007 02 Apr
2008 <7.
http://www.qualcomm.co
m/common/documents/w
hite_papers/UMB_Netwo
rk_Achitecture.pdf>. ]
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Network Architecture - WiMax
•
Mobile WiMax combines the following network protocols into a single air interface, utilizing
the individual advantages of each one
•
TDM access with variable frame sizes (2 - 20 ms)
•
OFDM
•
MIMO
•
Adaptive Antenna System (AAS)
•
QPSK, 16 QAM, 64 QAM
•
Convolutional Codes, Convolutional Turbo Codes, Block Turbo Codes, and Low-Density
Parity Check (LDPC) Codes
•
Hybrid ARQ
•
TDD, FDD & H-FDD
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Network Architecture - WiMax
•The following channel bandwidths are supported:
• 5 MHz, 7 MHz, 8.75 MHz, 10 MHz and 20 MHz
•These spectrum allocations can be anywhere within the following licensed spectrum bands
• 2.3 GHz, 2.5 GHz, 3.3GHz, 3.5GHz
•While WiMax can support both TDD and FDD, it is only truly supporting TDD at this point. The
ability to do FDD should be built into a later revision.
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Network Architecture - WiMax
"Network Architecture." HiperMAX-micro. Airspan. 7 May 2008 <http://www.airspan.com/products_wimax_microcell_hipermax.aspx>.
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Physical Layer & MAC Protocols - LTE
•The physical layer was defined with the bandwidth constraints of LTE in mind.
• This is important in allowing it to easily adapt to various spectrum allocations
• It is also important to get as much data throughput as possible through the connection
•LTE uses up to 64 QAM for the downlink and up to 16 QAM for the uplink. In contrast, its
broadcast only channel uses on BPSK.
•LTE also uses turbo coding for all transport blocks
• It uses a rate 1/3 code
• It also has 2 8-state constituent encoders as well as a contention-free QPP internal
interleaver
• The turbo coding scheme uses a trellis termination technique.
• Before the turbo coding, transport blocks are segmented into byte aligned segments with a
maximum information block size of 6144 bits.
• Error detection is supported by the use of 24 bit CRC.
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Physical Layer & MAC Protocols - LTE
•Both the downlink and the uplink share the same frame structure.
•Both can use either a FDD or TDD mode of operation.
•LTE frames are defined as 10 ms
•The frames are divided into 10 subframes
•Each subframe is further divided into two slots
•Each .5 ms slot can consist of either 6 or 7 ODFM symbols
•This structure is shown below
[Source: Myung, Hyung G.. "Technical Overview of 3GPP Long Term Evolution (LTE)."2007.]
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Physical Layer & MAC Protocols - LTE
•LTE has three access procedures
• Cell Search
• Cell search is the protocol for when the mobile handset (terminal) finds a cell tower (cell)
that it potentially would like to communicate with
• The mobile handset needs to identify the cell tower and needs to estimate the frame timing
of that cell tower.
• There are three main steps in performing a cell search
1. To assist in these steps the cell tower broadcasts a primary and secondary synch bit in the downlink
2. The mobile handset uses the primary synch bit to find the primary timing of the tower during a 5 ms
slot
3. The mobile handset needs to detect the cell-identity information and determine the frame timing. This
can be done by checking the pairs of slots where the secondary synch but should be transmitted
4. The cell tower now broadcasts the system information so that the mobile handset can determine the
remaining parameters.
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Physical Layer & MAC Protocols - LTE
•LTE has three access procedures
• Random Access
• This is when the terminal requests a
connection setup
• There are 4 steps to the random access
procedure
1. The terminal first sends a random-access preamble.
This allows the eNodeB to estimate the
transmission timing of the terminal
2. The network then sends a timing advance
4. The network then sends a contention-
command if the terminals transmission timing is off.
resolution message to the terminal. This
This also assigns uplink resources to the terminal
resolves and conflicts of multiple terminals
3. The mobile-terminal then sends it’s identity to the
attempting to access the same resources.
network. This is sent using the UL-Scheduling
protocols specific to the network.
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[Source: Dahlman, Erik. 3G Evolution HSPA and LTE for Mobile
Broadband. First. London: ELSEVIER, 2007.]
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Physical Layer & MAC Protocols - LTE
•LTE has three access procedures
• Paging
• When the mobile device is not in use it is allowed to go to sleep
• Paging sets the protocols for a network-initiated connection setup
• When the mobile device goes to sleep it automatically wakes up at pre-defined intervals
• These pre-defined intervals are set up to coincide exactly with the L1/L2 control signaling to prevent
the need for a dedicated channel like what is used in UMTS
[Source: Dahlman, Erik. 3G
Evolution HSPA and LTE
for Mobile Broadband. First.
London: ELSEVIER, 2007.]
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Physical Layer & MAC Protocols - WiMax
•WiMax uses QPSK, 16 QAM and 64 QAM in the downlink and QPSK and 16 QAM in the uplink
•WiMax also uses the following coding schemes:
• Tail-Biting Convolutional Code
• Convolutional Turbo Code
• Block Turbo Code (optional)
• Low-Densitiy Parity Check Code (LDPC) (optional)
• Zero Tailed Convolutional Code (optional)
•WiMax also uses a scheduling algorithm
• Each mobile handset competes for a slot only once (for initial entry into the network).
• Once it has won an access slot from the base station it cannot lose it unless it disconnects
from the tower.
• The tower can enlarge and contract the individual time slots, but no matter what, it remains
assigned to the specific subscriber station
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Physical Layer & MAC Protocols - WiMax
•The mobility versions of WiMax have three basic handover methods defined. They are:
• Hard Handover (HHO):
• The mobile handset scans the nearby base stations and gathers a list of all the possible
base stations.
• It uses this information to determine if a handoff is necessary. Both the base station and
mobile handset can decide to start the handoff
• Once this decision is made the handset immediately starts communicating with the new
base station
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Physical Layer & MAC Protocols - WiMax
•The mobility versions of WiMax have three basic handover methods defined. They are:
• Fast Base-Station Switching (FBSS):
• The mobile handset maintains a set of multiple suitable base stations
• One base station is selected as the anchor and is where all the communications will take
place.
• The mobile handset will continuously choose which ever base station has the best
connection from its list.
• The mobile handset can change the anchor at any time without any handover signaling
• Macro-Diversity Handover (MDHO):
• Just like in FBSS the mobile handset keeps an anchor and a list of base stations
• However this time the mobile handset communicates with all base stations
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Comparison of the Technologies
Aspect
LTE
UMB
WiMax
Access
Technology (DL)
OFDMA
OFMDA, SDMA,
CDMA*
OFDMA
Access
Technology (UL)
OFDMA
OFDMS, SDMA,
CDMA*
OFDMA
Capable Speeds
100 Mb/s DL
50 Mb/s UL
280 Mb/s DL
75 Mb/s
75 Mb/s
25 Mb/s
Channel BW
1.25 to 20 MHz
1.25 to 20 MHz
5, to 20 MHz
Spectral Efficiency 5 bits/sec/Hz
4-6 bits/sec/Hz
3.25 bits/sec/Hz
Time to market
2010
2009
2008
Legacy
GSM/UMTS
CDMA2000
WiFi
[Source: Scheim, Jacob. "A comparison of two fourth generation technologies:
WiMax and 3GPP-LTE."Comsys. 2006.]
Department of Electrical Engineering
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*UMB simply states the use of the technologies. There is no
mention on specifics for DL or U
**Includes latest release of 802.16M not currently available
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Future of the Technology
•Long Term Evolution (LTE)
• Should see deployments throughout Europe, US and Asia
• Vodaphone, China Mobile, Verizon Wireless, AT&T, T-Mobile (Europe & Australia),
Orange, NTT DoCoMo
• Estimates put 450 Million worldwide subscriber base by 2015
•Ultra Mobile Broadband (UMB)
• Looks to be a dead technology on arrival
• Qualcomm is now supporting LTE
•Mobile WiMax
• Currently deployed in US under brand XOHM
• On line in Chicago, Baltimore, Washington DC
• Consumer launch 2H 2008
• Deployed commercially in South Korea
• SK Telecom under the name WiBro
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References
•
•
•
•
•
•
•
•
Dahlman, Erik. 3G Evolution HSPA and LTE for Mobile Broadband. First. London:
ELSEVIER, 2007.
TIA, "cdma2000® High Rate Packet Data Air Interface Specification." TIA-856-A Apr 2004
Apr 2 2004 <http://www.tiaonline.org/standards/technology/cdma2000/documents/TIA-856A.pdf>.
Gozalvez, J. "1. Ultra Mobile Broadband [Mobile Radio]." Vehicular Technology Magazine,
IEEE Mar 2007:
"3G - Ultra Mobile Broadband." CDG : Technology. 2008. CDG. 2 Apr 2008
<http://www.cdg.org/technology/3g_umb.asp>.
ABI Research, " A Poor Market Outlook for Ultra Mobile Broadband (UMB) Says ABI
Research, but Qualcomm’s Future Still Secure." Business Wire 28 Dec 2007:
"UMB Network Architecture." Qualcomm Inc Dec 2007 02 Apr 2008 <7.
http://www.qualcomm.com/common/documents/white_papers/UMB_Network_Achitecture.pd
f>.
" ULTRA MOBILE BROADBAND (UMB) SPECIFICATION IS PUBLISHED." CDG : Mews &
Events. CDG. 2 Apr 2008 <http://www.cdg.org/news/press/2007/Sep24_07.asp>.
"CDMA Buzz-Words EV-DO Rev C as UMB." PhoneNews.com 05 Dec 2006 02 Apr 2008
<http://www.phonenews.com/cdma-buzz-words-ev-do-rev-c-as-umb-1615/>.
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References
•
•
•
•
•
•
•
•
•
•
"What Is cdma2000?." cdma2000 Technology Family: 1xRTT, EVDO, UMB, and EVDV 02
Apr 2008 <http://eogogics.com/talkgogics/tutorials/cdma2000>.
UMTS Forum, "Standardising the future of mobile communications with LTE (Long Term
Evolution)." Towards Global Mobile Broadband (2008):
Wikipedia. 2 Apr 2008 <http://wikipedia.org/>.
Scheim, Jacob. "A comparison of two fourth generation technologies: WiMax and 3GPPLTE."Comsys. 2006.
Litwin, Louis. "The principles of OFDM."RF Signal Processing. 2001.
Myung, Hyung G.. "Technical Overview of 3GPP Long Term Evolution (LTE)."2007.
Li, Bo. "A Survey on Mobile WiMAX."Wireless Broadband Access. 2007.
Scrase, Adriane. "Overview of the Current Status of 3GPP LTE."ETSI. 2008.
Collins, Gerry. "The Business Case for LTE."Nortel. 2007.
Laine, Michael Steve Stanley . "3GPP LTE (Long Term Evolution)."University of Kansas.
2008.
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Questions?
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