An 802.16x WiMAX FAQ (Draft)
Wireless broadband is clearly at a crossroads. Convergence is taking place between the technology road maps of WiMAX/802.16 and advanced 3GPP, 3.5G-4G cellular systems. These technologies are on a collision course and will provide similar bandwidth and significant market overlap by 2010. - Adlane Fellah, Maravedis Inc. -
A.) What is WiMAX?
WiMAX is an acronym that stands for Worldwide Interoperability for Microwave Access, is a certification mark for products that pass conformity and interoperability tests for the IEEE 802.16 standards. IEEE 802.16 is working group number 16 of IEEE 802, specializing in point-to-multipoint broadband wireless access.
The OFDM signaling format was selected for 802.16 in preference to competing formats such as CDMA due to its ability to support NLOS performance while maintaining a high level of spectral efficiency maximizing the use of available spectrum. In the case of CDMA (prevalent in 2G and 3G standards), the RF bandwidth must be much larger than the data throughput, in order to maintain processing gain adequate to overcome interference. This is impractical for broadband wireless below 11 GHz, since for example, data rates up to 70 Mbps would require RF bandwidths exceeding 200 MHz to deliver comparable processing gains and NLOS performance.
The original WiMAX standard, IEEE 802.16, specified WiMAX in the 10 to 66 GHz range. The 802.16a amendment added support for the 2 to 11 GHz range, of which some parts are unlicensed internationally and other require domestic licenses. The first version of the 802.16 standard released addressed Line-of-Sight (LOS) environments at high frequency bands but the significant difference between the higher and lower bands lies in the ability to support Non-Line-of-Sight (NLOS) operation in the lower frequencies, something that is not possible in higher bands. Most business interest will probably be for the lower frequencies as specified in the 802.16a standard, as opposed to the higher frequencies.
The current 802.16-2004 standard specifies a metropolitan area networking protocol that will enable a wireless alternative for cable, DSL and T1 level services for last mile broadband access, as well as providing backhaul for 801.11 hotspots. It specifies a protocol that among other things supports low latency applications such as voice and video, provides broadband connectivity without requiring a direct line of sight between subscriber terminals and the base station (BTS) and will support hundreds if not thousands of subscribers from a single BTS. The standard is intended to accelerate the introduction of wireless broadband equipment into the marketplace, speeding up last-mile broadband deployment worldwide by enabling service providers to increase system performance and reliability while reducing their equipment costs and investment risks.
The WiMAX protocol is a way of networking computing devices together; for example to provide internet access, in a similar way to Wi-Fi. WiMAX is both faster and has a longer range than Wi-Fi. However, WiMAX does not necessarily conflict with Wi-Fi, but is designed to co-exist with it and may indeed complement it. This complementarity to Wi-Fi also extends to all flavors of wired ethernet (IEEE 802.3), token ring (IEEE 802.5) and non-IEEE standards that use the same LLC including FDDI and cable modem (DOCSIS).
Because IEEE 802.16 networks use the same Logical Link Controller (standardized by IEEE 802.2) as other LANs and WANs, it can be both bridged and routed to them.
WiMAX can connect IEEE 802.11(Wi-Fi) hotspots to the Internet and provide a wireless extension to cable and DSL for last mile (last km) broadband access. The technology provides shared data rates up to 70 Mbit/s, which, according to WiMAX proponents, is enough bandwidth to simultaneously support more than 60 businesses with T1-type connectivity and well over a thousand homes at 1Mbit/s DSL-level connectivity.
The WiMAX specification improves upon many of the limitations of the Wi-Fi standard by providing increased bandwidth and stronger encryption. It also aims to provide connectivity to network endpoints without direct line of sight in some circumstances.
[Note: It should be duly noted that claims of 50 km (31 mile) range for 802.16, especially claims that such distances can be achieved without line of sight, represent, at best, a theoretical maximum under ideal circumstances. The technical merit of these claims has yet to be tested in the real world. A very rudimentary non-scientific test was done in Michigan on mostly flat land with 30% tree coverage. It suggests that distances of roughly 15 km can be achieved without line of sight. This, of course, can vary greatly depending on terrain and weather.]
It is anticipated that WiMax will allow interpenetration for broadband service provision of VoIP, video and internet access, simultaneously. Most cable and traditional telephone companies are closely examining or actively trialing the potential of WiMax for "last mile" connectivity. This could result in better price points for both home and business customers as competition results from the elimination of the "captive" customer bases both telephone and cable networks traditionally enjoyed. In areas without preexisting physical cable or telephone networks, WiMax could allow competitors joint access to any subscriber within range; home units the size of a paperback book that provide both phone and network connection points are already available- and advertised as "plug and play" easy to install. There is also potential for interoperability of WiMax with cellular networks. WiMax antennas can "share" a cell tower without compromising the function of cellular arrays already in place. Companies that already lease cell sites in widespread service areas have a unique opportunity to diversify- and often already have the necessary spectrum available to them (i.e. they own the licenses for radio frequencies important to the speed and/or range of the WiMax connection). WiMax antennae would be connected to a service provider's "head end" via either a light fiber optics cable or a directional microwave link. Some cellular companies are evaluating WiMax as a means of increasing bandwidth for a variety of data-intensive applications.
Early WiMAX products are likely to be aimed at network service providers and businesses, not consumers. It has the potential to enable millions more to access the Internet wirelessly, cheaply and easily. Proponents say that WiMAX wireless coverage will be measured in square kilometers while that of Wi-Fi is measured in square meters. According to WiMAX promoters, a WiMAX base station would beam high-speed Internet connections to homes and businesses in a radius of up to 50 km (31 miles); these base stations will eventually cover an entire metropolitan area, making that area into a WMAN and allowing true wireless mobility within it, as opposed to hot-spot hopping required by Wi-Fi. Its proponents are hoping that the technology will eventually be used in notebook computers and PDAs. True roaming cell-like wireless broadband, however, will require 802.16e.
B.) The IEEE Std 802.16-2004: WiMAX for Fixed Systems
The current 802.16 standard is IEEE Std 802.16-2004, approved in June 2004. It renders the previous (and 1st) version 802.16-2001 obsolete, along with its amendments 802.16a and 802.16c. IEEE Std 802.16-2004 addresses only fixed systems.
• 802.16-2004 IEEE Standard for Local and metropolitan area networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems.
• 802.16.2-2004 IEEE Recommended Practice for Local and metropolitan area networks -- Coexistence of Fixed Broadband Wireless Access Systems
• 802.16-2001 which specified WiMAX in the 10 to 66 GHz range was obsoleted by 802.16-2004
• 802.16a which added support for the 2 to 11 GHz range and which was finalized in January 2003 was obsoleted by 802.16-2004
• 802.16c amendment was obsoleted by 802.16-2004
• 802.16d was the draft for 802.16-2004
B1.) The IEEE 802.16e Amendment: WiMAX Mobility Enhancements
• An amendment 802.16e is in process and it adds mobility components to the IEEE Std 802.16-2004 standard. This amendment is expected to be completed by the end of 2005.
While OFDM is the modulation of choice for fixed applications, various modulations are being pushed by various technology players for 802.16e with OFDMA being the leading contender but WiMax silicon pioneer Wavesat is pushing hard to promote OFDM 256 FFT for mobile applications to guarantee backward compatibility.
B.2 The IEEE 802.16f Amendment: WiMAX MIB Enhancements
• 802.16f is also in process. It adds management information base (MIB) to 802.16-2004
B.3.) ETSI's HiperMAN (Europe)
WiMAX's equivalent or competitor in Europe is HiperMAN. WiMAX Forum, the consortium behind the standardization, is working on methods to make 802.16 and HIPERMAN interoperate seamlessly.
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.
In April, 2005, the WiMAX Forum announced a formal agreement with the European Telecommunications Standards Institute (ETSI) that ensures a single global standard for wireless metropolitan area network (MAN) technology. The Forum also announced that all Korean WiBRO operators have joined the WiMAX Forum, along with Samsung and LG Electronics.
B.4.) TTA's WiBro (Korea)
WiBro is a broadband wireless internet technology being developed by the Korean telecoms industry. In February 2002, the Korean Government allocated 100MHz of electromagnetic spectrum in the 2.3GHz band, and in late 2004 WiBro Phase 1 was standardized by the TTA (Telecommunications Technology Association) of Korea. WiBro base stations will offer an aggregate data throughput of 30 to 50 Mbit/s and cover a radius of 1-5 km.
SK Telecom and Hanaro Telecom Korea’s second-biggest Internet service provider, announced a partnership to roll out WiBro nationwide in Korea, excluding Seoul and six provincial cities, where independent networks will be rolled out, but Hanaro abandoned its Wi-Bro license in April.
tinyurl.com
In November 2004, Intel and LG Electronics executives agreed to ensure compatibility interoperability between WiBro and WiMAX technology, Korea Telecom (KT) plans an April 2006 commercial launch of WiBro.
tinyurl.com
In April, 2005, the WiMAX Forum announced that all Korean WiBRO operators have joined the WiMAX Forum, along with Samsung and LG Electronics.
C.) The WiMAX "Go to Market" Compatibility Issue
Although it has one name, WiMAX is going to be two different go-to-market technologies. The first is for fixed wireless and falls under the IEEE 802.16-2004 standard approved last year. The second, for mobile applications, will be under the 802.16e specification expected to be finalized this fall. But the two almost certainly will not be interoperable, so any provider using 802.16-2004 equipment – the equipment being certified now – will have to install 802.16e equipment in the future if it wants to add mobility. - Brad Smith, Wireless Week -
wirelessweek.com
[The above statement needs further qualification, IMO]
D.) The WIMAX Value Chain
Virtually everyone that's anyone in wireless has become involved in the value chain forming around WiMAX technology and almost without exception (QUALCOMM, TI) have joined the WiMAX Forum whose members are listed here:
wimaxforum.org
Intel of course is the most aggressive driver of WiMAX and they have forged partnerships with ArrayComm, Alcatel, AT&T, LG, NextNet (Clearwire), NTT DoCoMo, PicoChip, SK Telecom, Sprint, Symbian, and TTPcom. Motorola is also extremely aggressive in this domain and even Ericsson, a long time holdout has joined WiMAX Forum.
E.) WiMAX IC Vendors
Commercialization starts with wireless ICs and silicon vendors that will produce WiMax chips include Analog Devices, Athena Semiconductors, Atheros Communications, Atmel Corporation, Cygnus Communications, Freescale, Fujitsu, Intel, Integrated Devices, Philips Semiconductors, Metalink, Picochip, Provigent, Redpine Signals, Sequans Communications, Skyworks, Telecis Wireless, Texas Instruments, and Wavesat.
The first 802.16-2004 Rev D compliant chip shipped in January 2005 to BWA equipment manufacturers by Montreal-based Wavesat Inc. The DM256 is a baseband IC developed by Wavesat and manufactured in France by Atmel. The chip is said to meet all WiMAX and 802.16-2004 specifications for both the base station and subscribers systems.
Intel shipped its highly integrated WiMAX chip, formerly code named "Rosedale," in April. The Pro/Wireless 5116 chip has two ARM9 cores and an OFDM modem, and targets low cost, low chip-count access points and gateways supporting WiMAX. A week later Fujitsu Microelectronics America (FMA) started shipping an SoC targeting WiMAX BWA equipment for metropolitan area networks (MANs). The MB87M3400 targets base stations and subscriber access equipment, and can be used in equipment carrying up to 75Mbps of data.
Texas Instruments who currently supplies commercial F-OFDM chips to Flarion sampled three radio frequency (RF) chipsets, the TRF11xx chipset at 2.5GHz, the TRF12xx chipset at 3.5GHz and the TRF24xx chipset at 5.8GHz in April. TI's new chipsets are designed to support IEEE802.16d/e standard RF front end for wireless base stations, access points as well as equipment backhaul, point-to-point microwave and public safety band applications and will support both emerging WiMAX and WiBro applications based on the IEEE802.16 standard, as well as the more traditional fixed wireless access. These RF chipsets are capable of supporting frequency division duplex (FDD), half frequency division duplex (HFDD) and time division duplex (TDD) modes with a real interface at low IF to the data conversion subsystem.
E.) WiMAX Certification
In July 2005 the WiMAX Forum opened its test laboratory at Cetecom SA’s facility in Malaga, Spain. The lab aims to test kit based on the fixed-wireless 802.16-2004 specification. Products that pass both conformance and interoperability testing will be tagged “WiMax certified” and ready for commercial availability.
The WiMax Forum is believed to have outlined four "waves" of WiMax testing, the first of which is scheduled to begin in October and will likely focus on testing of time-division duplex (TDD), or unpaired spectrum, kit in the 3.5GHz band. The second wave is expected to include testing of frequency-division duplex (FDD), or paired spectrum, kit in the 3.5GHz band. Equipment for use in the 2.5GHz and 5.8GHz bands will follow at a later date. The final wave of 802.16-2004 testing is scheduled to be complete around May 2006.
lightreading.com
F.) WiMAX Spectrum Considerations
Maravedis discusses the database they are constructing here:
wimaxtrends.com
As they point out: The evolution of spectrum availability and overall regulation will greatly impact the future of mobile broadband wireless systems.
G.) A Basic WiMAX Glossary
BS Base Station
BWA Broadband Wireless Access
BWIA Broadband Wireless Internet Access
DSL Digital Subscriber Line
ETSI European Telecommunications Standards Institute
FDD Frequency Division Duplex
IEEE Institute of Electrical and Electronic Engineers
LOS Line-of-Sight
MAC Medium Access Control
MAN Metropolitan Area Network
NLOS Non-Line-of-Sight
OFDM Orthogonal Frequency Division Multiplexing
OFDMA Orthogonal Frequency Division Multiple Access
PHY Physical Layer
QoS Quality of Service
SoHo Small Office Home Office
SS Subscriber Station
STC Space-Time Codes
TDD Time Division Duplex
TDM Time-Division Multiplexed
TDMA Time-Division Multiple Access
WiMAX Worldwide Microwave Interoperability Forum
WISP Wireless Internet Service Provider
H.) BWA and WiMAX Resources and Links
• Broadband Wireless Internet Access:WiMAX [Steve Stroh]
bwianews.com
• IEEE WirelessMAN
wirelessman.org
• Om Malik's Broadband Blog [Om Malik]
gigaom.com
• Rethink Research
rethinkresearch.biz
• Telephony Online: WiMax
telephonyonline.com
• The Final Mile [Timothy Sanders]
thefinalmile.net
• VoIPAction: WiMAX and WiMAX Access News
voipaction.com
• Wi-Fi Planet
wi-fiplanet.com
• Wikipedia on WiMAX
en.wikipedia.org
• WiMAX Forum
wimaxforum.org
• WiMAX Forum 802.16a Whitepaper (dated but good)
wimaxforum.org
• WiMax.com
wimax.com
• WiMAX Networking News [Glenn Fleishman; Nancy Gohring]
wimaxnetnews.com
• WiMAXPro
wimaxpro.com
• WiMaxxed
wimaxxed.com
• WiMax.com
wimax.com
• WiMAX Trends
wimaxtrends.com
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- Eric - |
