What is WiMax(Worldwide Interoperability for Microwave Access)?
WiMax is a standards-based wireless technology that provides high-throughput broadband
connections over long distances. The two driving forces of modern Internet are broadband and
wireless. The WiMax standard combines the two, delivering high-speed broadband Internet
access over a wireless connection; because it can be used over relatively long distances, it is
an effective "last mile" solution for delivering broadband to the home and for creating
wireless "hot spots" in places like airports, college campuses, and small communities.
WiMAX is a connection-oriented technology and affects only the Physical Layer and the
MAC portion in the Data Link Layer of the OSI Model. Therefore the 802.16 specification
mainly describes the scheduling of communication between towers and WiMAX devices.
OSI Layers affected by 802.16 Physical Layer and Data Link Layer
WiMAX supports two types of connection types, Frequency Division Duplexing(FDD) and
Time Division Duplexing(TDD). In FDD, one frequency is sent from the base tower to another
station tower and from the station tower to the base tower. For TDD, the base tower transmits at
one frequency to a station tower and receives data from the station tower at another frequency.
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Example of FDD; the base tower constantly communicate to all towers at one frequency and
each station tower is responds back at another frequency.
Example of TDD the base tower sends data at certain time intervals and allots time to wait to
hear from station towers.
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Ultimately, WiMAX can be envisioned as a mesh network where each node(tower/access
points) can communicate with each other in order to extend the range of WiMAX and,
therefore, allows robust communication as there are multiple routes a signal can take.
The WiMax Forum is the organization dedicated to certifying the interoperability of WiMax
products. Those that pass conformance and interoperability testing achieve the "WiMax
Forum Certified" designation and can display this mark on their products and marketing
materials. Some vendors claim that their equipment is "WiMax-ready", "WiMax-compliant",
or "pre-WiMax", if they are not officially WiMax Forum Certified.
Standards
The technology and standards that underlie WiMAX were developed by the IEEE (Institute of
Electrical and Electronics Engineers), which is one of the world’s leading professional
associations for the advancement of communications and computer technology. The set of
standards for broadband wireless access (BWA) is known as IEEE 802.16.
The IEEE began developing technologies for wireless networks in 2000, and published its
first standard in April 2002. The range of frequencies compatible with IEEE 802.16 allow for
non-line-of-sight connectivity between a devise and a transmission tower, meaning that the
transmission signal can pass through and around structures.
The standard IEEE 802.16d-2004 (previously IEEE 802.16d) deals specifically with wireless
connectivity between fixed and stationary devices, and is known as fixed or “nomadic”
WiMax. Fixed WiMax can be used in a home or office, cafe or basically anywhere a
computer has access to customer premises equipment (CPE) which is normally a special
modem enabled for WiMax. It is also referred to as nomadic WiMax because a modem or a
devise such as a laptop computer with a WiMax embed chip can be moved from one location
to another.
The mobile standard 802.16e-2005 (previously IEEE 802.16e) allows for the reception of
transmission signals while in motion, up to 120 kms per hour, via portable devices such as
laptops, personal digital assistants (PDA) and mobile phones. The fixed and mobile standards
have evolved separately due to the complexity of mobile handoffs from one transmission
station to another.
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IEEE technologies. Source: OECD and IEEE
The technologies behind WiMax are suited for large geographic networks of contiguous cells
up to many hundreds of kilometres if required, in contrast with Wi-Fi which is exclusive to
small local networks of less than 50 metres. Figure 1 above illustrates a breakdown of
common network sizes, with the technologies behind WiMax covering the two largest
geographic areas: wide area networks (WAN) and metropolitan area networks (MAN). Local
area network (LAN) technologies, such as those underlying Wi-Fi, have been very successful
at delivering data under a range of 50 metres and personal area networks (PAN) such as
Bluetooth’s technologies provide access within 10 metres.
Comparison with Wi-Fi
Possibly due to the fact both WiMax and Wi-Fi begin with the same two letters, are based
upon IEEE standards beginning with "802.", and both have a connection to wireless
connectivity and the Internet, comparisons and confusion between the two are frequent.
Despite this, the two standards are aimed at different applications.
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WiMax is a long-range system, covering many kilometers that typically uses licensed
spectrum (although it is also possible to use unlicensed spectrum) to deliver a point-topoint connection to the Internet from an ISP to an end user. Different 802.16 standards
provide different types of access, from mobile (analogous to access via a cellphone) to
fixed (an alternative to wired access, where the end user's wireless termination point is
fixed in location.)
Wi-Fi is a shorter range system, typically hundreds of meters, that uses unlicensed
spectrum to provide access to a network, typically covering only the network
operator's own property. Typically Wi-Fi is used by an end user to access their own
network, which may or may not be connected to the Internet. If WiMax provides
services analogous to a cellphone, Wi-Fi is more analogous to a cordless phone.
WiMax and Wi-Fi have quite different Quality of Service (QoS) mechanisms. WiMax
uses a mechanism based on setting up connections between the Base Station and the
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user device. Each connection is based on specific scheduling algorithms, which means
that QoS parameters can be guaranteed for each flow. WiFi 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 guaranteed.
WiMax is highly scalable from what are called "femto"-scale remote stations to multisector 'maxi' scale base that handle complex tasks of management and mobile handoff
functions and include MIMO-AAS smart antenna subsystems.
Due to the ease and low cost with which Wi-Fi can be deployed, it is sometimes used to
provide Internet access to third parties within a single room or building available to the
provider, often informally, and sometimes as part of a business relationship. For example,
many coffee shops, hotels, and transportation hubs contain Wi-Fi access points providing
access to the Internet for customers.
Comparison of Mobile Internet Access methods
Standard
Family
802.16e
WiMAX
HIPERMAN
Primary Use
Radio Tech
Quoted speeds only
achievable at very
short ranges, more
practically 10 Mbps
at 10 km.
70
70
HIPERMAN Mobile Internet OFDM
56.9
56.9
WiBro
WiBro
50
50
Mobile range (900
m)
iBurst
iBurst 802.20 Mobile Internet
HC64
SDMA/TDD/MIMO
64
3-12 km
0.9
3GPP Release 7
.384
5.76
11.5
HSDPA
widely
deployed. Typical
downlink
rates
today
1-2Mbps,
~200kbps
uplink;
future downlink up
to 28.8Mbps.
16
Reported
speeds
according
to
IPWireless
using
16QAM modulation
similar
to
HSDPA+HSUPA
EDGE Evolution GSM
Mobile Internet MIMO-SOFDMA
Downlink Uplink
Notes
(Mbps)
(Mbps)
Mobile Internet OFDMA
Mobile Internet TDMA/FDD
UMTS
WCDMA
UMTS/3GSM Mobile phone
HSDPA+HSUPA
HSPA+
1.9
CDMA/FDD
.384
14.4
CDMA/FDD/MIMO 42
UMTS-TDD
UMTS/3GSM Mobile Internet CDMA/TDD
LTE UMTS
UMTS/4GSM General 4G
OFDMA/MIMO/SC>100
FDMA (HSOPA)
>50
Still in development
1xRTT
CDMA2000
CDMA
0.144
0.144
Obsoleted by EVDO
2.45
3.1
4.9xN
Rev B note: N is the
0.15
number of 1.25
1.8
MHz chunks of
1.8xN spectrum used. Not
yet deployed.
EVDO 1x Rev. 0
EVDO 1x Rev.A
EV-DO Rev.B
CDMA2000
Mobile phone
Mobile Internet CDMA/FDD
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WiMax, GSM and 3G
The use of mobile telephones has had spectacular success around the world, and as Internet
use continues to grow around the world, so does broadband access. However the actual use of
broadband lags significantly behind Internet use, primarily due to the availability of services.
As mobility and Internet converge closer into device specific business models, it will be
WiMax that enables the reality of the final step in this convergence process. As the WiMax
market matures over the next six to eight years, phenomenal growth will be derived from
closing this gap and converting basic Internet access to wireless Internet access, and
enhancing the dumb mobile telephone handset into a personal broadband communications
device.
This does not mean that WiMax will replace GSM and 3G services. WiMax is a natural
complement to GSM and 3G services. The use of the mobile telephone for voice services has
decreased significantly over the last three years, and according to numerous researchers,
including IDC, data is forecast to significantly overtake voice services as the driver for service
up-take in the next five years.
There are already many mobile networks around the world that intend to offer WiMax to
enhance their mobile broadband services. Sprint Nextel is amongst the largest mobile
operators betting their future on WiMax with a $3 billion commitment to cover America with
the technology. In North America, AT&T and Rogers Canada are not far behind. In Europe,
where 3G services are more dominant, GSM operators have not yet been as eager to changeover to WiMax.
NTT DoCoMo and Softbank Mobile are testing WiMax in Japan, and KT and SK Telecom
have already launched networks in Korea. Vimpelcom was recently awarded WiMax
spectrum in Russia, and many Vodafone partner networks, such as SFR in France and MTCVodafone in the Middle East, already own WiMax spectrum licenses.
The advent of WiMax and its exponential growth over the next five years also does not mean
that it will replace 3G technologies already resident at mobile operators around the world.
Quite the contrary, WiMax and 3G technology are complementary, and along with other
technologies, these will in the near future come together into a seamless network that
integrates all technologies and will allow the user to choose what is the best solution based on
the needs of the user.
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WiMax in Turkey
Two years ago Intel and Turk Telecom began the first WiMax pilot in Turkey, connecting a
school in Yozgat to the internet. In June 2006, Turkish WISP Turbonet started trials with
Aperto WiMax equipment in Istanbul using a trial 3.5GHz licence. Since then, however, there
has been little activity in Turkey with the fate of both 3G and wireless broadband spectrum
uncertain.
Boasting some 34.8 million GSM subscribers as of September 2007, Turkcell has enjoyed
stratospheric growth in recent years as pent-up demand in the Turkish market exploded. But
the operator has been frustrated in its desire to move towards providing wireless broadband
services, according to Ahmet Akan, an executive in Turkcell's Research and Development
division. "We have been ready for four years for 3G but for regulatory reasons we can't get
the licences," he said at the WiMax 2007 event in Munich. "One year ago, the regulator said
there would be four 3.5GHz broadband licences but nothing happened."
However, in the wake of the ITU's decision to include WiMax as an IMT technology and
allocate more spectrum to IMT, Akan suggested that things may change. He said that he
expected the Turkish regulator to release four nationwide 3G licences and four nationwide
3.5GHz licences, each of 30MHz, in 2008. "Hopefully in Q1 2008 the regulator will have
made a decision and so maybe in the second half of next year we will have the licences
awarded," Akan told WiMax Vision. "First a UMTS auction and something like three months
after that we expect broadband licences to be given. If they offer them we also want to take
WiMax licences."
Turkcell has been trialling WiMax with Motorola, Alcatel-Lucent and other vendors and is
interested in providing a mobile service over 802.16e equipment. "We are thinking of starting
with 802.16e, mobility is important, the fixed case is someone else's business. We believe in
the technology and although we are a GSM operator we believe WiMax has a business case."
In the event that the regulator decides that incumbent mobile operators cannot bid for wireless
broadband licences, Turkcell would look to use its 100 per cent-owned ISP to bid for the
licence. Akan said that in Turkey, ISPs were eager to take WiMax licences.
Broadband penetration is low in Turkey, with about four million subscribers on ADSL
networks provided by the incumbent Turk Telecom. "Since we saw WiMax coming we
decided WiMax should be the one we are trying, we started trials one year ago," said Akan.
Turkcell sees "enough room for both UMTS and WiMax" in Turkey according to Akan
because of the size of the country and the difficulty deploying cellular networks in more
remote regions, such as the eastern part of Turkey.
Furthermore, Akan is confident that by the time licenses are awarded in Turkey and Turkcell
is ready to roll out networks, WiMax and 3G networks will be largely interoperable.
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What is WiBro ?
WiBro (Wireless Broadband) is a wireless broadband Internet technology being developed by
the South Korean telecoms industry. It is the South Korean service name for IEEE 802.16e
(mobile WiMAX) international standard.
WiBro adapts TDD for duplexing, OFDMA for multiple access and 8.75 MHz as a channel
bandwidth. WiBro was devised to overcome the data rate limitation of mobile phones and to
add mobility to broadband Internet access (for example ADSL or Wireless LAN). In February
2002, the Korean government allocated 100 MHz of electromagnetic spectrum in the 2.3 - 2.4
GHz band, and in late 2004 WiBro Phase 1 was standardized by the Telecommunications
Technology Association of Korea and in late 2005 ITU reflected WiBro as IEEE 802.16e
(mobile WiMAX). Two South Korean Telco (KT, SKT) launched commercial service in June
2006.
WiBro base stations will offer an aggregate data throughput of 30 to 50 Mbit/s and cover a
radius of 1-5 km allowing for the use of portable internet usage. In detail, it will provide
mobility for moving devices up to 120 km/h compared to Wireless LAN having mobility up
to walking speed and Mobile Phone having mobility up to 250 km/h. From testing during the
APEC Summit in Busan in late 2005, the actual range and bandwidth were quite a bit lower
than these numbers. The technology will also offer Quality of Service. The inclusion of QoS
allows for WiBro to stream video content and other loss-sensitive data in a reliable manner.
These all appear to be (and may be) the stronger advantages over the fixed WiMAX standard
(802.16a). Some Telcos in many countries are trying to commercialize this Mobile WiMAX
(or WiBro). While WiBro is quite exacting in its requirements from spectrum use to
equipment design, WiMAX leaves much of this up to the equipment provider while providing
enough
detail
to
ensure
interoperability
between
designs.
WiBro has South Korean government support with the requirement for each carrier to spend
over US$1 billion for deployments. The Koreans sought to develop WiBro as a regional and
potentially international alternative to 3.5G or 4G cellular systems. But given the lack of
momentum as a standard, WiBro has joined WiMAX and agreed to harmonize with the
similar OFDMA 802.16e version of the standard. What makes WiBro roll-outs a good 'test
case' for the overall WiMAX effort is that it is mobile, well thought out for delivery of
wireless broadband services, and the fact that the deployment is taking place in a highly
sophisticated, broadband-saturated market. WiBro will go up against 3G and very high
bandwidth wire-line services rather than as gap-filler or rural under-served market
deployments as is often exampled as the 'best fit' markets for WiMAX.
Latest development on the world about WiBro like above:
KT Corporation and SK Telecom launched WiBro around Seoul on June 30, 2006 On April 3,
2007, KT launched WiBro coverage for all areas of Seoul including all subway lines.
- WiBro, 3G, and WLAN complement each other and are partially competing
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Key Factors of WiBro
Frequency Band
Channel Bandwidth
Duplex
Multiple Access
Modulation
Cell Coverage
Maximum Data Rate
Sector throughput
User throughput : DL
: 2.3GHz (Korea)
: MHz
: TDD / 5msec frame
: OFDMA
: QPSK, 16QAM, 64QAM
: ~1km
: DL : 18 Mbps, UL : 6 Mbps
: 3 Mbps, UL :1 Mbps
What is HIPERMAN ?
HIPERMAN stands for High Performance Radio Metropolitan Area Network and is a
standard created by the European Telecommunications Standards Institute (ETSI) Broadband
Radio Access Networks (BRAN) group to provide a wireless network communication in the 2
- 11 GHz bands across Europe and other countries which follow the ETSI standard.
HIPERMAN is a European alternative to WiMAX (or the IEEE 802.16 standard) and the
Korean technology WiBro.
HiperMAN is aiming principally for providing broadband Wireless DSL, while covering a
large geographic area. The standardization focuses on broadband solutions optimized for
access in frequency bands below 11 GHz (mainly in the 3.5 GHz band). HiperMAN is
optimised for packet switched networks, and supports fixed and nomadic applications,
primarily in the residential and small business user environments.
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HIPERMAN will be an interoperable broadband fixed wireless access system operating at
radio frequencies between 2 GHz and 11 GHz. The HIPERMAN standard is designed for
Fixed Wireless Access provisioning to SMEs and residences using the basic MAC (DLC and
CLs) of the IEEE 802.16-2001 standard. It has been developed in very close cooperation with
IEEE 802.16, such that the HIPERMAN standard and a subset of the IEEE 802.16a-2003
standard will interoperate seamlessly. HIPERMAN is capable of supporting ATM, though the
main focus is on IP traffic. It offers various service categories, full Quality of Service, fast
connection control management, strong security, fast adaptation of coding, modulation and
transmit power to propagation conditions and is capable of non-line-of-sight operation.
HIPERMAN enables both Point to Point-Multipoint communication and Mesh network
configurations. HIPERMAN also supports both FDD and TDD frequency allocations and HFDD terminals. All this is achieved with a minimum number of options to simplify
implementation and interoperability.
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References
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http://www.google.com
http://www.wisegeek.com/what-is-wimax.htm
http://www.tmcnet.com/channels/wimax/what-is-wimax.aspx
http://www.wisoa.net/site/what-is-wimax/
http://www.wisoa.net/site/what-is-wimax/standards/
http://www.wisoa.net/site/what-is-wimax/wimax-and-gsm/
http://nislab.bu.edu/nislab/education/sc441/JustinKen/JustinKen/Networking%20Web
page/index_files/Page735.htm
http://www.wibro.or.kr/new/overview01.jsp
en.wikipedia.com
www.wibro.gr
http://www.wimaxvision.com/newt/l/wimaxvision/article_view.html?artid=20017485157
http://www.wimax.com/education
http://computer.howstuffworks.com/wimax1.htm
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