WiMAX - EyeforWireless - Aalborg...

1

Research Report(Part of the BluePrint Wi-Fi

subscription package)

Lead Analyst: Caroline Gabriel

ARCchart ltd. 3 Finsbury Square London EC2A 1LN UK Tel: +44 207 826 9000 Fax: +44 207 826 9001 Web: www.arcchart.com Email: [email protected] No part of this publication may be copied, photocopied or duplicated in any form or by any means without prior written permission from the publishers. The information contained in BluePrint Wi-Fi is derived from sources which we believe to be accurate, but is not guaranteed. All rights reserved.

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Copyright © 2003 ARCchart ltd. All Rights Reserved

WiMAX WiMAX

WiMAX: The Critical Wireless Standard



BluePrint Wi-Fi (ARCchart) 2

1. Contents

1. Contents......................................................................................................................... 2

2. Introduction .................................................................................................................... 4

3. The 802.16a Standard ................................................................................................... 6

WiMAX – Not just another standard ..................................................................................... 6

Markets for WiMAX ............................................................................................................... 6

Business users .................................................................................................................. 6

Last mile to the home ........................................................................................................ 6

Hotspots............................................................................................................................. 7

Remote regions ................................................................................................................. 7

China ................................................................................................................................. 7

Background and 802.16........................................................................................................ 7

Technical specifications of 802.16a..................................................................................... 8

Fundamental technologies in 802.16a .............................................................................. 8

Dynamic frequency selection in unlicensed spectrum...................................................... 9

Bandwidth on demand (frame by frame)......................................................................... 10

WiMAX leadership............................................................................................................... 10

Chip advances..................................................................................................................... 11

HIPERMAN ......................................................................................................................... 11

Operators ............................................................................................................................ 12

The vendors ........................................................................................................................ 13

4. Relationship With Other Wireless Technologies ......................................................... 15

WI-FI.................................................................................................................................... 15

Extended WI-FI ................................................................................................................... 16

Cellular Technologies.......................................................................................................... 17

Handoff project .................................................................................................................... 18

Mobile-Fi.............................................................................................................................. 19

802.20 technology............................................................................................................... 20

Two IEEE camps................................................................................................................. 21

Overlap with WiMAX ........................................................................................................... 22

Hostility from the 3G industry.............................................................................................. 23



Vendor support.................................................................................................................... 24

5. The Last Mile: WiMAX and Broadband Wireless Alternatives .................................... 25

BWA alternatives to WiMAX ............................................................................................... 26

IP and smart antennas........................................................................................................ 27

6. Conclusions ................................................................................................................. 30

7. APPENDIX: Wi-Fi and WiMAX Compared.................................................................. 31

8. APPENDIX: WiMAX Players ....................................................................................... 32



2. Introduction

The past few months have seen a storm of debate about the economics and return on

investment of Wi-Fi hotspots. What almost all the arguments entirely ignore is the standard

lurking on the horizon, which will turn current assumptions on their head. This is the 802.16x

wireless metropolitan area network (WMAN) specification, which is being developed and

promoted by the WiMAX industry group, whose most powerful members are Intel and Nokia.

As with Wi-Fi, the WiMAX label has now become widely acceptable as a name for the

standard itself.

Intel has called 802.16 “the most important thing since the Internet itself”, and even allowing

for a dose of self-serving, it is not talking entirely in hyperbole.

In July, WiMAX showed off its first system profiles and interoperability tests at the WCA

annual conference in Washington DC, in a significant step towards making the 802.16a

standard, ratified by the IEEE in March, a commercial technology.

While a fully mobile version of WiMAX is in the wings, this first release will cover fixed

wireless, and its supporters are focusing in particular on broadband last mile in unwired

areas, and on backhaul for hotspots. Intel will start to make WMAN chips this year and we

should see WiMAX products early in 2004.

These vendors are finally giving broadband wireless the teeth it needs, with a standards

base, to take on wired options for the last mile and for long distance networking. The WiMAX

(Worldwide Interoperability for Microwave Access) group was actually set up two years ago

by Nokia, Ensemble and the OFDM Forum, but gained a new lease of life in April when it

was revived by Nokia in collaboration with Intel and added five new members, with nine

more joining in May.

The non-profit group takes a similar role to the Wi-Fi Alliance in WLANs, backing

development of wireless Man products based on 802.16 and working on standards

certification and interoperability testing.

The initial version of the standard operates in the 10-66GHz frequency band and requires

line of sight towers, but the 802.16a extension, ratified in March, uses the lower frequency of

2-11GHz, easing regulatory issues, and does not require line of sight. It boasts a 31 mile

range compared to Wi-Fi’s 200-300 yards, and 70Mbps data transfer rates.

WiMAX president Margaret Labrecque says that collaborating on mass market products will

achieve similar economies of scale to those seen in Wi-Fi WLAN devices. She says base

stations will cost under $20,000 and support 60 enterprise customers with T1-class

connections.

Systems based on the mobile version of the standard, which should ship towards the end of

next year, about six months after fixed wireless products, will be able to achieve long

distance wireless networking and will have far greater potential than Wi-Fi hotspots to

provide ubiquitous coverage to rival that of the cellular network.



There is a plethora of wireless standards emerging in 2003 from the IEEE and IETF, but

only WiMAX addresses all the key elements that are needed to make high end wireless a

reality, and which existing proprietary last mile and broadband wireless access (BWA)

technologies have failed fully to provide – a single standard for fixed broadband access and

mobility, wireless WLAN backhaul, low cost of deployment, high scalability and the support

of vendors with the power to drive the standard forward rapidly.

Intel is the foremost among these vendors and it is no coincidence that Labrecque is an Intel

employee. As the head of Intel’s investment arm, Intel Capital, Sriram Viswanathan – the

most eloquent of WiMAX’s supporters – says: “802.11 is the first key disruption. 802.16 is

the next.”

In this research paper we examine the significance and potential impact of WiMAX, the

obstacles in its path and its technological functions. We also look at how it interoperates and

potentially clashes with other wireless standards in the WLAN and cellular markets, and its

ability to replace wired systems in last mile and enterprise markets.



3. The 802.16a Standard

WiMAX – Not just another standard

Broadband wireless access provides more capacity at lower cost than DSL or cable for

extending the fibre networks and supporting multimedia and fast internet applications in the

enterprise or home. But it has been held back by the lack of a standard, so that solutions

have been based on proprietary, single-vendor efforts. Standardization through the IEEE

802.16 specification raises the potential to:

• Stall wired broadband and make wireless the key platform of the future

• Extend the range of Wi-Fi so that the myth of ubiquitous wireless can become a

reality

• Provide an alternative or complement to 3G

• Provide an economically viable communications infrastructure for developing

countries and mobile blackspot regions in developed nations

Markets for WiMAX

The greatest media excitement about WiMAX has centred on its potential mobility and its

role as a backhaul or even replacement for public Wi-Fi. However, its initial raison d’etre and

still its primary focus is on broadband fixed wireless access for homes and businesses. This

sector is populated by a horde of mainly American niche players with expensive equipment

using various versions of smart antennas, OFDM and sometimes mesh to provide often

effective alternatives to wired communications. ArrayComm, Alvarion, IPWireless, Navini

and Beamreach are high profile names, though the majority of these specialists will refocus

their products around WiMAX in the coming year (see later chapter).

Business users

Only 5 percent of commercial structures worldwide are served by fibre networks, the main

method for the largest enterprises to access broadband, multimedia data services. In the

wired world, these networks are extended to the business or residence via cable or DSL,

both expensive options because of the infrastructure changes required. DSL typically

operates at 128Kbps to 1.5Mbps and slower on the upstream.

Enterprises can use WiMAX instead of T1 for about 10 percent of the cost, while SMEs can

be offered fractional T1 services. Base stations will cost under $20,000 and support 60

enterprise customers with T1-class connections.

Last mile to the home

A low cost alternative could end the wars between the cable and ADSL operators and really

make the broadband home revolution happen.



Hotspots

Wi-Fi hotspot operators may be able to build a spot for a few thousand dollars’ worth of

equipment, but then they need to anchor it to the public network, and this is normally done

with expensive T1 or DSL. WiMAX backhaul could significantly reduce hotspot costs,

although there is also the potential for Wi-Fi to be bypassed altogether by WiMAX

‘hotzones’.

Remote regions

The most lucrative market for the proprietary BWA vendors has been remote regions,

especially in developing countries but also in rural areas of the US, where there is no wired

or cellular infrastructure nor the will or cash to invest in building it. The main alternative to

BWA in this market is satellite. Still early in its lifecycle – and potentially a powerful

technology to integrate with WiMAX – satellite has severe limitations of upstream bandwidth,

spectrum availability and also suffers from high latency.

China

One of the most potentially lucrative markets for remote region BWA is, of course, China,

and discussions have been held between the Chinese government and IEEE with a view to

making 802.16 the Chinese national standard for fixed broadband wireless access at

3.5GHz. Chinese operators are already rolling out WiMAX base stations even before

standard, low cost silicon is ready, and Alvarion recently supplied this type of equipment to

China Unicom for a network covering, initially, six cities.

Background and 802.16

Although the 802.16 project started as far back as 1998, the body of work was done in 2000-

2003 in an open consensus process. The aim was to make broadband wireless access

more widely and cheaply available through a standard for wireless metropolitan area

networks.

The overall vision for 802.16 is that carriers would set up base stations connected to a public

network. Each base station would support hundreds of fixed subscriber stations, probably

mounted on rooftops. The base stations would then use the standard's medium access

control layer (MAC) - a common interface that makes the networks interoperable - to nearly

instantaneously allocate uplink and downlink bandwidth to subscribers according to their

needs.

802.16 MANs could also anchor 802.11 hotspots, which serve as wireless local area

networks (LANs), as well as servicing end users directly. With the mobile standard, users

will be able to use the WMAN base station to communicate via handsets as they move

within the 50 mile range.

The first version of the standard, 802.16, was published in April 2002 and addressed fixed,

line of sight connections for the ‘first mile/last mile’ link. It focused on efficient use of various

licensed frequencies in the 10-66GHz bandwidth.

802.16 standards have never taken a lowest common denominator approach. Unlike Wi-Fi,

few proprietary vendors of equivalent equipment can outdo the performance of WiMAX. It



offers the highest performance broadband , technology except for broadcast and, on the

wired side, MMDS, and is on a level with satellite.

Although, even with the upcoming mobile version of standard, WiMAX cannot be as wide

area as 2G/3G, it delivers far higher rates and, with sufficiently widespread deployment,

could significantly cut into the usage of cellular networks in many areas.

The next version of the standard, 802.16a, published in April 2003, is the one that has really

kick-started WiMAX into being adopted as the dominant wireless broadband technology.

This is also for fixed wireless but extends the range of WiMAX from 31 to 50 miles and

operates in the low frequency 2-11GHz spectrum and so can be adopted by unlicensed

operators. It uses point-to-multipoint or (optionally) mesh topologies and does not require

line of sight. Specifically, it uses licensed bands at 3.5GHz and 10.5GHz internationally and

2.5-2.7GHz in the US; and unlicensed 2.4GHz and 5.725-5.825GHz.

An important aspect of 802.16x is that it defines a MAC (media access control) layer that

supports multiple physical layer (PHY) specifications. This is critical to allow equipment

makers to differentiate their offerings – for instance with novel approaches to smart antenna

use – without becoming non-interoperable; and to customize the equipment for the

frequency band in use.

Next on the agenda are:

• 802.16c/d, published in Jan 2003, address interoperability by providing detailed

system profiles and specifying combinations of options, as the basis for compliance

and interoperability tests. The WiMAX Forum presented the first of these tests at

the WCA conference in July 2003 and further work will be done by this body and

the IEEE throughout this year. The ‘c’ protocol relates to protocols, test suite

structures and test purposes while ‘d’ fixes errata and protocols not covered in ‘c’,

and creates the system profiles.

• 802.16e, which adds mobility to the standard and really throws down the gauntlet to

cellular. This element of the standard has the particular interest of Nokia, which can

see a new revenue stream at both base station and handset level. The draft will be

ready in August or September 2003.

• Probably, an important new project to enable handoff between Wi-Fi and WiMAX

(see page 18).

Technical specifications of 802.16a

802.16 operates at up to 124Mbps in the 28MHz channel (in 10-66GHz), 802.16a at 70Mbps

in lower frequency, 2-11GHz spectrum.

Fundamental technologies in 802.16a

OFDM

Support for OFDM (orthogonal frequency division multiplexing), which can continue to be

implemented in various ways by different operators (the precise variant of OFDM can often

be their key differentiator).



OFDM is well established and is incorporated in some new generation carrier services as

well as being fundamental to digital TV. It transmits multiple signals simultaneously across

one cable or wireless transmission path, within separate frequencies, with the orthogonal

element spacing these frequencies to avoid interference. It is also supported in the 802.11a

WLAN standard.

802.16a has three PHY options: an OFDM with 256 sub-carriers – the only option supported

in Europe by the ETSI, whose rival HiperMAN standard is likely to be subsumed into

WiMAX; OFDMA, with 2048 sub-carriers; and a single carrier option for vendors that think

they can beat multipath problems in this mode. OFDM will almost certainly become

dominant in all wireless technologies including cellular and its industry body, the OFDM

Forum, is a founder member of WiMAX Forum.

Support for Smart Antenna

Smart antenna mechanisms are one of the most important methods of improving spectral

efficiency in non-cellular wireless networks. 802.16 standards allow vendors to support a

variety of these mechanisms, which can be a key performance differentiator.

Dynamic frequency selection in unlicensed spectrum

Mesh

Mesh Mode is an optional topology for subscriber-to-subscriber communication in non-line of

sight 802.16a. It is included in the standard to allow overlapping, ad hoc networks in the

unlicensed spectrum and extend the edges of the WMAN’s range at low cost. Mesh support

has recently been extended into the licensed bands too.

Figure 1 :Mesh networking

Source: Proxicast

Although it has highly complex topology and messaging, mesh is a good alternative to the

usual NLOS, as it scales well and addresses license exempt interference. It allows a

community to be densely seeded with WiMAX connections at low cost, with robust

communications as there are multiple paths for traffic to take (see diagram).



Spectral efficiency

This is critical to support difficult user environments with hundreds of users per channel at

high bandwidth and a mixture of continuous and burst traffic.

Protocol independent core

WiMAX can transport IPv4, IPv6, Ethernet or ATM and others, supporting multiple services

simultaneously and with quality of service.

Bandwidth on demand (frame by frame)

Quality of Service

The ‘b’ extension to 802.16 is concerned with quality of service (QoS), which enables NLOS

operation without severe distortion of the signal from buildings, weather and vehicles. It also

supports intelligent prioritisation of different forms of traffic according to its urgency.

Mechanisms in the Wireless MAN MAC provide for differentiated QoS to support the

different needs of different applications. For instance, voice and video require low latency

but tolerate some error rate, while most data applications must be error-free, but can cope

with latency. The standard accommodates these different transmissions by using

appropriate features in the MAC layer, which is more efficient than doing so in layers of

control overlaid on the MAC.

Adaptive Modulation

Many systems in the past decade have involved fixed modulation, offering a trade-off

between higher order modulation for high data rates, but requiring optimal links, or more

robust lower orders that will only operate at low data rates. 802.16a supports adaptive

modulation, balancing different data rates and link quality and adjusting the modulation

method almost instantaneously for optimum data transfer and to make most efficient use of

bandwidth.

FDD and TDD

The standard also supports both frequency and time division duplexing (FDD and TDD) to

enable interoperability with cellular and other wireless systems. FDD, the legacy duplexing

method, has been widely deployed in cellular telephony. It requires two channel pairs, one

for transmission and one for reception, with some frequency separation between them to

mitigate self-interference. In regulatory environments where structured channel pairs do not

exist, TDD uses a single channel for both upstream and downstream transmissions,

dynamically allocating bandwidth depending on traffic requirements.

Security

802.16 also includes measures for privacy and encryption: authentication with x.509

certificates and data encryption using DES in CBC (cipher block chaining) mode with hooks

defined for stronger algorithms like AES.

WiMAX leadership

Since the new-look WiMAX Forum was formed in April, the momentum behind 802.16a has

gathered force and the standard has progressed with remarkable speed. Strong leadership

is vital in the continuing evolution and rapid adoption of WiMAX and will help to set it apart

from other mobile standards which are beset by politics.



There are significant names missing from WiMAX so far – its initial focus on last mile is

indicated by the bias of the membership towards fixed wireless, OFDM specialists (the

802.16 specification is built on an implementation of OFDM from Wi-Lan of Canada), rather

than enterprise focused suppliers or mobile carriers. Some major vendors will be taking the

usual gamble of trying to establish such market presence for their proprietary solutions as to

sideline the industry standard – Motorola with its Canopy broadband fixed wireless platform

springs to mind. But these companies will join – Cisco being a critical target – and in the

meantime, the really impressive aspect of WiMAX has been its clear focus and unity of

purpose.

So far, perhaps because of its fairly low numbers, with most of these being smaller

companies, it has avoided the complex politics and hidden agendas of most industry bodies

– though this comes at the cost of a direction that is highly dominated by Intel and Nokia.

Chip advances

The main obstacles to long distance wireless are limitations on battery power and power

efficiency. Regulations keep power levels low and the range of Wi-Fi signals short to avoid

overcrowding of airwaves. But advances in fast digital signal processors mean that weak,

jumbled signals can be deciphered, lengthening the distance that is practical for a

transmission, as well as improving distance and speed potential. Battery improvements will

also be vital to make a WiMAX cellphone a practicality.

Nokia is working on battery and handset chip designs to this end, citing two years as the

likely timescale, while Intel is increasingly involved in next generation battery and processing

power for mobile devices, including digital radios that can intelligently move to the most

efficient available network – cellular, Wi-Fi, Bluetooth, WiMAX or UWB.

Currently, it looks as if Intel will entirely dominate the WiMAX chip market. Fujitsu and

STMicroelectronics are also creating silicon but nearly all the next generation developments

in radio and wireless processor chips that will be important to fixed and mobile 802.16 are

being led by Intel, as is the political agenda.

HIPERMAN

An alternative standard to 802.16a is the European Telecommunication Standards Institute’s

BRAN HA (Broadband Radio Access Networks HiperAccess) or HiperMAN. This is likely to

be subsumed into 802.16a. April, Nokia and Siemens Information and Communication

Mobile said they would coordinate an effort to integrate the two standards to achieve a

single worldwide standard combining the best of both specifications and provide a migration

path from current proprietary products to an IP-optimised solution.

ETSI has two specifications, Hiperaccess, which operates above 11GHz, and HiperMAN for

below 11GHz, which will be harmonized with 802.16a OFDM.

This illustrates the advantage WiMAX has derived from its strong and single minded focus,

which has enabled it to largely avoid the political upheavals that have disrupted other efforts

such as Wi-Fi and Mobile-Fi.

Contrast the political fiasco that scuppered the fast Wi-Fi standard, 802.11a, with the clarity

of the 802.16a process. 802.11a had some technological shortcomings, notably its lack of



backward compatibility with 802.11b, but its low uptake compared to the ‘g’ version was

largely because it was continually delayed by wrangling between the IEEE and the

European ETSI standards body. ETSI’s HiperLan standard and 802.11a use the same

frequency and so there was pressure to unify the two, but this was achieved painfully, with a

separate implementation of ‘a’ for Europe, which has further delayed product roll-out and

confused users.

In contrast, WiMAX has set out from the start to harmonize 802.16 and HiperMan, and the

specifications it showcased in July demonstrated that unification. All this with remarkably

little political in-fighting – the difference between leaving standards bodies to sort out their

own futures, and putting a technology in the hands of vendors with a clear commercial

objective, and deadline.

Operators

For mobile operators, there is a doubled edged sword. WiMAX is particularly disruptive

because no physical last mile installation is required and the base stations will cost under

$20,000 using commodity standard hardware. As with Wi-Fi hotspots, fixed and mobile

operators will have an equal interest in extending their networks through WiMAX, and also

ensuring that any revenues lost to 3G and wired services are at least preserved within the

company. But WiMAX also gives the opportunity for small, alternative operators to enter the

game.

License exempt wireless ISPs will start to offer WiMAX fixed wireless service. There are

already about 1,800 such WISPs in the US, many just focused on Wi-Fi but some already

eyeing the metro area. Before WiMAX, such operators had to either use Wi-Fi, or turn to

proprietary BWA gear to provide features that Wi-FI lacks such as QoS.

As the FCC and equivalent authorities in other parts of the world become more friendly to

freeing up new spectrum, more broadband WISPs will spring up, especially if the US

administration gives into pressure to open up some unused MMDS wireless broadband

spectrum.

Figure 2: Worldwide sub-11GHz subscriber base - 802.16a and proprietary

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

2003 2004 2005 2006 2007 2008

Subs

crib

ers

(mill

ions

)

MidEast/Africa

Asia

Europe

Americas

Source: Intel Capital



WiMAX operates in a mixture of licensed and unlicensed spectrum, and the initial products

will be focused on 2.5GHz and 3.5GHz licensed and 5.8GHz unlicensed bands (though the

full standard supports a far wider range of bands). The licensed spectrum gives operators

the chance to apply for franchises for fixed wireless broadband provision, especially in rural

and remote areas, and to build the infrastructure with low cost, commodity hardware -

something Intel is promoting assiduously as a means to increase investment in Centrino-

enabled PCs (it now has a director of rural broadband access).

The unlicensed aspect means that independents have the chance to provide backhaul

services for hotspots, which have the potential to create a nationwide wireless network. If

the operators can control this, as they have been trying to do with Wi-Fi, they will be able to

offer parallel, integrated services and achieve a stopgap as they struggle towards ubiquitous

3G – one with lower margins than cellular perhaps, but swifter ROI on lower upfront

investment. They certainly have the power and resource to take control from alternative

network suppliers, but they may also be condemning their 3G investments to stillbirth.

But the genie is out of the bottle now, and while the operators hesitate, the equipment

makers are driving ahead, Intel in the vanguard, and Nokia, which has supported WiMAX

from its earliest days, looking forward to the mobile standard and to the chance to add a new

form of base station business to its ailing networks unit.

The vendors

Recently, a much publicized article in The Wall Street Journal pointed out how Wi-Fi has

already slipped out of the hands of the start-ups. Unlike in other technology booms, none of

those start-ups looks set to grow up to be a dominant player; instead, the established giants

have sidestepped to take control of the new sector, Intel and Cisco in particular.

The same process is likely to happen in WiMAX, certainly at the chip and hardware level. In

fact, the main question is whether anybody can stop Intel and Nokia completely dominating

this market, blocking entry to everybody else with their aggressive early action.

Of course, the availability of low cost equipment will help to make the business models of

some of the BWA specialists more viable, and partnership with Intel could ensure the

survival of companies such as Alvarion.

However, cheap components will also lower barriers to entry and cause a shakeout in which

many of the less well funded developers of smart antenna, OFDM systems will perish.

Similarly, as WiMAX becomes a mainstream option for last mile and rural BWA, it is likely to

attract the attention of large operators looking for new revenue streams and some of the

alternative and niche operators may be pushed out too.

As well as Intel, the first WiMAX products are likely to come from:

• Enterprise WLAN maker Proxim, which has WiMAX equipment in the labs

• Ensemble Communications

• Flarion, the Cisco-backed last mile player, which has a trial running in South Korea

of wireless broadband gear using its smart antenna technology and supporting

802.16a. Korea is seen as the territory where wireless broadband is adopted most



rapidly. However, Flarion’s chief interest is in the rival 802.20 standard, or Mobile-Fi

(see later chapter).

• Fujitsu Microelectronics will be first with silicon. It is developing an 802.16a device

that integrates the physical and media access control layers, which will include an

ARM9 processor and will be ready later this year. The chip will cost about $300.

Fujitsu will work with multiple providers of front end devices and recommend those

compatible with its device.

• Taiwan-based Gen-WAN Technology has launched broadband wireless network

equipment using 802.16a, offering base stations, fixed and mobile terminals,

repeaters and network management systems. It will market its system, called

BWIA, initially for public safety and military purposes, where WiMAX offers more

reliable signals than cellular in emergency situations.

• Wi-Lan, one of the critical start-ups in WiMAX, has come to market with pre-

standard system-on-chip solutions and will support the full standard soon. Its

patented Wideband OFDM technology is included in the 802.16a standard and it

has a manufacturing and development agreement with Fujitsu Microelectronics.

• Broadcom and Texas Instruments are also making noises about WiMAX and are

expected to get into the market alongside Intel and Fujitsu. This is a sector where

the chipmakers will define the core set of capabilities and control the core functions

so that they take the primary role in driving proliferation of 802.16.

• The first Intel technology partners from the BWA arena, which will use the

upcoming Intel products in their previously proprietary base stations, are Alvarion

and Aperto Networks. Alvarion has an important contract to supply China Unicom

with WiMAX equipment for its initial roll-out in six cities.

• AirTap Communications is one of the early entrants into the market for WiMAX

networks in the US, serving SMEs and large enterprises in a range of metro

districts.



4. Relationship With Other Wireless Technologies

Figure 3: The mobile standards compared

3G Wi-Fi: 802.11

WiMAX: 802.16

Mobile-Fi: 802.20

Max speed 2Mbps 54Mbps 100Mbps 16Mbps

Coverage Several miles 300 feet 50 miles Several miles

Airwave Licensed Unlicensed Either Licensed

Advantages Range, mobility

Speed, price Speed, range Speed, mobility

Disadvantages Slow, expensive

Short range Interference issues?

High price

Wi-Fi

The WiMAX Forum is keen to present 802.16 as complementary to the local area IEEE

standard, 802.11 or Wi-Fi. In many ways, this is right—802.16a, as we have seen, provides

a low cost way to backhaul Wi-Fi hotspots and WLAN points in businesses and homes, and

as uptake of Wi-Fi increases, the requirement for this backhaul will grow too.

But there is conflict too. WiMAX makes redundant the efforts of Wi-Fi specialists to extend

the reach of their favourite technology and also places 802.11 into a far smaller role than its

supporters have, often unrealistically, carved out for it. This is the opportunity for wireless

technologies finally to grow up and offer the speed, multimedia support and ubiquity that Wi-

Fi can never deliver.

The newer standard holds all the real power. By providing a backbone for hotspots, based

on standards rather than the various proprietary WLAN expansion technologies out there, it

makes the idea of a ubiquitous wireless network to rival cellular far more realistic than it ever

was with Wi-Fi alone, despite the claims of the enthusiasts. The equipment makers are

eyeing it keenly – amid all the doubts about the sustainability of the hotspot boom, anything

that offers them a new product line plus helps to preserve the interest in Wi-Fi is to be

welcomed.

802.16 is a highly complex standard which contains, from day one, many of the features that

are being retrofitted, with various degrees of clumsiness and baggage, into Wi-Fi, which was

originally conceived to be very simple and is now taking on a burden of responsibility beyond

its technological reach.

WiMAX has the advantage of not being – at least until Intel has a long distance Centrino – a

consumer technology. Although this has kept its profile lower than Wi-Fi’s, it has not suffered

from the over-hype and its development is freer of vendor politics and posturing than its

short distance cousin’s.

“We are trying to avoid referring to them by their letter," says 802.16 working group chair Dr

Roger Marks. "At the moment we're not really going out to create something that you would

sell to consumers. 802.16 is about base stations that connect the core networks as part of



serious investments and it will be a different kind of business, so we don't really need to

identify the separate amendments."

And while 802.16 was conceived as a back end technology, 802.16e has the capacity to be

adapted for individual computers, and has the QoS features to support voice - hence the

interest from Intel and its Centrino plans.

WiMAX has various features that make it suitable to the longer distance, although some like

QoS may be incorporated into 802.11, which has failed to come up with specifications of its

own in this area with any credibility. The 802.16a spec uses various physical layer (PHY)

variants but the dominant one is a 256-point orthogonal frequency division multiplexed

(OFDM) carrier technology, giving it greater range than WLANs, which are based on 64-

point OFDM.

Another key difference of 802.16 is its use of time slots, allowing greater spectral efficiency

for quality of service capabilities.

Margaret Labrecque, president of WiMAX, said that vendor collaboration on mass market

products will achieve similar economies of scale to those seen in Wi-Fi WLAN devices, and

a far lower cost alternative to wired broadband, or T1 circuits in enterprise sites.

Systems based on the mobile version of the standard, which should ship towards the end of

next year, about six months after fixed wireless products, will be able to achieve long

distance wireless networking and will have far greater potential than Wi-Fi hotspots to

provide ubiquitous coverage to rival that of the cellular network. Whether used directly or as

backhaul for Wi-Fi, WiMAX fills the gaps in the hotspot system, and possibly enables it to

challenge the cellular network as it cannot realistically do right now, whatever the hype says.

See the appendix for a full comparison of Wi-Fi and WiMAX.

Extended Wi-Fi

Some companies are still sticking with Wi-Fi rather than WiMAX as a metro area wireless

standard. There are various approaches to extending Wi-Fi’s range and capacity, but all are

based on proprietary extensions. Their supporters take the view that they can offer a

solution now, particularly to the enterprise, but with the speed of development of WiMAX,

this argument will not hold weight for very long.

There are many vendors that aim to work around Wi-Fi’s distance and capacity limitations

and its weaknesses when operating in a point-to-multipoint or mesh mode – required to

compete with broadband wireless access solutions. There is even likely to be an IEEE

activity to create a standard for a meshing version of 802.11x. In theory, this could really

shake up the hotspot infrastructure market, although all the arguments in favour of ‘mutant

Wi-Fi’ centre on its availability now, giving operators a quick solution especially should

WiMAX get delayed. But a mesh Wi-Fi standard will certainly take longer than WiMAX to hit

the streets, especially if it fails to get a major vendor behind it.

Of the currently available solutions to extended Wi-Fi, Vivato is the most high profile.

Although it has focused mainly on the enterprise with its wireless switching products, it has

recently targeted operators with a 2.4GHz outdoor switch that boosts Wi-Fi using smart



antennas and proprietary enhancement technology to operate over WiMAX-class distances,

around 50km, though only at Wi-Fi speeds and in point-to-point mode.

Some small operators are taking the Wi-Fi route too, in an effort to deploy fixed wireless

rapidly. Broadband Central is accelerating its roadmap to offer broadband fixed wireless via

802.11x, expanding from its original 11 states to a further 11. The company sets up central

Wi-Fi broadcast access point masts that give a one mile radius of Wi-Fi, and then set up

customer locations with an antenna.

Other Wi-Fi extenders take the approach of fiddling with the media access control layer

rather than directing beams in a more efficient way, Vivato’s approach and that of many

BWA specialists too. Some of these have got prices down to less than initial WiMAX

equipment is likely to be, around $300 per subscriber (though WiMAX, starting around $500,

is sure to drop to this level rapidly). However, given that these are proprietary technologies

from start-ups and still have some limitations compared to WiMAX, it seems unlikely that

many operators will choose them rather than waiting 6-9 months for 802.16.

The most constructive approach is that Wi-Fi and WiMAX are strongest when working

together however. Some mobile operators are looking at offering a single PCMCIA card for

roaming between 802.11 and broadband services – Walker Wireless of New Zealand will

offer one for IPWireless, but the big device makers will be developing cards for Wi-

Fi/WiMAX, and of course, the debut of an Intel roaming card in the Centrino range will

revolutionize the roaming hotspot user’s experience. In the end, the technologies will coexist

in a creative way, with WiMAX increasingly the dominant partner, and the non-standard

alternatives will fade into the background.

Cellular Technologies

The US Federal Communications Commission is freeing up more airwaves for metropolitan

wireless networks by loosening restrictions on spectrum now held by Sprint, WorldCom, the

Catholic Church and universities. Such moves threaten the asset value of the 3G carrier’s

spectrum licenses, since potentially competitive services can now be run over unlicensed

bands (although in the US, this is to forget that 25 percent of the cellular operators’ spectrum

was given away free in the early 1990s).

The FCC's head Powell is staying neutral in the fight over whether to go all unlicensed, but

is working to open up large chunks of spectrum for all comers. Inspired by the success of

Wi-Fi, the FCC plans to open up a huge amount for unlicensed use, recently adding

Figure 4: Performance of some common wireless technologies

Channel bandwidth

Max data rate

Max Bps/Hz

802.11a 20MHz 54Mbps 2.7

802.16a 10, 20MHz;

3.5, 7, 14MHz;

3, 6MHz

70Mbps 5

EDGE, (GPRS+) 200KHz 384Kbps 1.9

CDMA2000 1.25MHz 2Mbps 1.6



255MHz to bring the unlicensed total to 664MHz. By comparison, the early version of Wi-Fi

ran on just 83MHz. Europe is acting more slowly, but all territories will gradually take a

similar direction and free up larger amounts of unlicensed spectrum, sacrificing licensing

revenue for the government to the expected stimulus to business and the economy of better

mobile communications.

WiMAX is a serious threat to 3G because of its broadband capabilities, distance capabilities

and ability to support voice effectively with full QoS. This makes it an alternative to cellular in

a way that Wi-Fi can never be, so that while operators are integrating Wi-Fi into their

offerings with some alacrity, looking to control both the licensed spectrum and the

unlicensed hotspots, they will have more problems accommodating WiMAX. But as with Wi-

Fi, it will be better for them to cannibalise their own networks than let independents do it for

them, especially as economics and performance demands force them to incorporate IP into

their systems. Handset makers such as Nokia will be banking on this as they develop

smartphones that support WiMAX as well as 3G.

WiMAX can slash the single biggest cost of deployment: access charges for linking a

hotspot to a local phone or cable network. A high frequency version of 802.16 would allow

entrepreneurs to blast a narrow, data-rich beam between antennas miles apart – an idea

that independents have tried before without success, for instance, Teligent and Winstar,

which went bankrupt in the late 1990s.

A standards-based long distance technology will avoid many of the problems of high upfront

costs, lack of roaming and unreliability that those ahead of their time pioneers encountered,

but it will still need to gain market share rapidly before 3G takes an unassailable hold. Given

the current slow progress of 3G, especially in Europe, and the unusually streamlined

process of commercialising WiMAX, the carriers are indulging in wishful thinking when they

say nothing can catch up with cellular.

Handoff project

In September, significant steps should be taken towards a standard that could turn the

wireless communications industry on its head and assure the dominance of the WiMAX

metro area standard.

This is the proposed Handoff Project of the IEEE, which was set in motion in March and

which will hold its second major meeting on 8-9 September in Denver, Colorado.

The Handoff Executive Committee Study Group has a mandate to consider the viability of

developing a standard for a common handoff framework for all 802 standards – WiMAX, Wi-

Fi, short range technologies such as UWB – and also for IEEE wired networking standards.

The committee is headed by David Johnston, an Intel employee, Ajay Rajkumar from Lucent

and Nokia’s Michael Williams – as usual, the leadership of the key groups indicates the

vendors that are putting the greatest time and investment into the work and therefore see it

as most critical to their strategies going forward. There will also be work on handoff between

WiMAX and cellular networks, an area where Lucent has been a pioneer.

Such a standard, though in its very early stages and likely to take several years to come to

fruition, would make all the arguments about different wireless standards irrelevant.

Transmissions could be seamlessly passed between the most appropriate local, metro area



and wide area networks, especially with the development of radios that intelligently choose

the best connection, as Intel is planning.

Such a scenario will truly fulfil the promise that is currently enshrined in the far more limited

roadmap towards 4G, the marriage of IP and cellular. Incorporate WiMAX into that mix too,

and wireless communications could really become ubiquitous and robust for data and

multimedia use.

The work would allow for devices with interfaces to multiple 802 networks to roam between

them. Key issues to be addressed, according to the committee, are compatibility with other

work on handoff, particularly the more basic projects on the Wi-Fi side, 802.11k and 802.11f;

interworking with upper layer protocols, especially IPv6 and IPv4; and security.

At the first meeting in May, the main concern was defining the scope of the project, for

instance, that work will focus only on the bottom two layers, the physical (PHY) and the

medium access control (MAC). The September meeting will make big decisions on

technological approaches such as how to build layer 2 constructs to reduce handoff latency

and support real time applications; and

Also important is monitoring of handoff work in other standards groups, especially the

Internet Engineering Taskforce’s WLAN projects, the 3GPP cellular body and other IEEE

groups, particularly 802.11x; as well as work being done on layer 3 and above by the 3GPP

and other bodies.

Johnson of Intel sees security as the biggest potential hurdle. “Security is a complex issue

addressed elsewhere (linksec, 802.1x, 802.10, 802.11i, EAP). Trying to include security

procedure in handoff specifications would hugely expand the scope and conflict with other

groups,” he said. “But a handoff standard must not undermine security so the work should

include validating that it is compatible with existing 802 security architectures.” The solution

is likely to be to exclude security specifications from the standard but ensure that the final

technology is compatible with other bodies’ security work.

Mobile-Fi

Standards battles are normally conducted in dusty committees and arouse little interest

among technology purchasers until the vendors move the specifications into real products

and real marketing wars. The IEEE’s wireless standards are proving an exception to this.

The relative speed with which these standards are being ratified and commercialised and

the intense public interest in Wi-Fi and its relatives mean that the various 802.xxx

specifications of the usually shadowy IEEE are being thrust into the spotlight.

Perhaps the most key factor, though, is that the big vendors see, for the first time since the

Internet boom, a genuine brand new source of revenue, and one at a sufficiently early stage

that they stand a chance of stamping their control upon it. In the case of the youngest IEEE

mobile standard, 802.20 or Mobile-Fi, however, some powerful names are feeling

threatened rather than excited, which makes it probable that this particular specification will

not be allowed to achieve the importance of its Wi-Fi and WiMAX cousins.

The big names are gathering behind two IEEE standards that, for all their claims of being

complementary, are heading for a collision that involves more than bickering in technical

committees, but could instead be the cover for a serious battle for influence over the



evolving wireless market. On one hand we have WiMAX, on the other, 802.20, nicknamed

Mobile-Fi, the first standard to be specifically designed from the outset to carry native IP

traffic for fully mobile broadband access. It will provide symmetrical wireless rates from

1Mbps to 4Mbps in licensed spectrum below 3.5GHz over distances of about 15km. This

makes it lower powered than WiMAX but more intrinsically mobile, offering latency of 10ms

even in a fast moving vehicle, compared to 500ms for 3G.

But 802.20 has three critical weaknesses – WiMAX is starting to take on some of its remit;

WiMAX has stronger and more aggressive support from key vendors; and the mobile

operators, while relatively friendly towards 802.16, are hostile to 802.20.

802.20 technology

The stated mission of IEEE 802.20 is to develop a packet-based air interface optimised for

transport of IP services, that will enable “worldwide deployment of affordable, ubiquitous,

always-on and interoperable mobile broadband wireless access networks that meet the

needs of business and residential markets”.

Broadband wireless services:

Service provider

802.16e Evolving from fixed wireless ISPs

802.20 Start-up wireless operator or evolving cellular operator

3G Cellular voice operator adding data support

Technology

802.16e Extension to 802.16a MAC and PHY

Optimised to integrate with fixed stations

Packet oriented

Low latency

802.20 New PHY and MAC

Optimised for packet data and smart antennas

Optimised for full mobility at high speed

Packet oriented

Low latency

3G W-CDMA or CDMA2000

Evolution of voice-optimised GSM and CDMA

Circuit oriented, though evolving to packets on the downlink

High latency data architecture

Spectrum

802.16e Licensed bands between 2GHz and 6GHz

802.20 Licensed bands below 3.5GHz

3G Licensed bands below 2.7GHz

The metropolitan area 802.20 standard will operate in licensed bands below 3.5GHz and

promises to support far more simultaneous users than cellular systems, with greater spectral

efficiencies and lower latency. Mark Klerer, former chair of the 802.20 working group and an

executive director at Flarion, the standard’s main technical contributor, said Mobile-Fi will



have double the spectral efficiency of current cellular systems at 1bit/second/Hz/cell, with

low latency and built-in quality of service, to give a similar experience to wired connections.

Having been designed from the outset, uniquely, to use IP – which has been cobbled in to

3G and WiMAX – it is particularly targeted at voice over IP and native IP applications, as

well as fast response uses such as financial transactions and gaming.

As with Wi-Fi and WiMAX, Mobile-Fi follows the IEEE model of designing a new PHY

(physical layer or layer 1 protocol) and MAC (media access control or layer 2 protocol)

around the IP packet (layer 3). Cellular 3G technologies are also incorporating IP by

retrofitting their technologies and looking to full IP integration with 4G, but they use a circuit-

rather than packet-based approach. The circuit-based route involves high latency and poor

reliability, which have forced 3G adaptations into cumbersome workarounds such as

spoofing and translation, and a centralized network architecture that goes against the nature

of distributed IP.

Two IEEE camps

This emerging standard – it will not be ratified until late 2004, if then - increasingly seems to

be positioned against the mobile version of WiMAX, 802.16e, which has strong interest from

Nokia. Although the two come from different technical starting points and solve slightly

different problems, the broadening remit of WiMAX threatens to make 802.20 redundant.

Initially 802.16e was positioned as providing ‘lightly mobile’ support for users moving

between fixed metro points. But its brief is expanding and early speculation that the two

would be aligned to create a single umbrella specification now seems ill-founded.

Instead of the two camps coming together, as the IEEE itself would encourage, the big

backers of 802.20, Motorola and Cisco, are getting restive and seem determined to try to put

their preferred standard in a dominant position, improving their own place in the mobile

market at the same time. Such an approach will be disastrous. WiMAX has a huge headstart

on Mobile-Fi –even its ‘e’ version is at least a year ahead of its rival, and the industry

support behind it is gathering pace rapidly. Also, it is a technology that can be

accommodated relatively easily by the mobile operators.

By contrast, Mobile-Fi will be incorporated in products after WiMAX is already adopted – the

standard will not be ratified until the end of 2004 - and it is seen as deeply threatening by the

powerful cellular industry, with several 3G players having taken recent and possibly effective

steps to squash it.

So why do these two groups not seek to work together on a broad specification for different

types of mobile broadband wireless connections, rather than competing? The politics are

symbolic of some of the most fundamental clashes going on in today’s technology business,

with stakes massively high as vendors seek to create a new market for themselves after the

buffeting of the recent recession.

So we have Intel ranged against Motorola in almost every area – in IEEE, in the UWB

standards battle, and in the cellular world. Once at arm’s length from each other, the two

chip giants have locked horns this year and are using every weapon, including the important

one of standards processes, to try to be the alpha male in mobile communications. The

contrasting financial results of the second quarter threw their current positions into painful



relief for Motorola – the company looks like a wounded giant and is becoming increasingly

desperate in its bid to keep Intel away from its smartphone base.

The other big names behind the two would-be standards are Nokia, on the WiMAX side, and

Cisco, which backs Flarion, the key technology driver behind 802.20. Once again, we see an

epic battle represented within the walls of the IEEE. The traditional enterprise networking

supplier, moving rapidly into wireless and even smartphones, but finding itself threatened by

rivals from the telecoms world; and the upstart, the handset maker daring to fancy itself as a

vendor of enterprise mobile solutions and bringing its operator allies along for the ride.

Overlap with WiMAX

All these politics have polarized the IEEE projects this year. In March, the standards body

ratified 802.16a, the non-line of sight, fixed wireless version of WiMAX, and kicked off the

802.20 process. At this stage, Intel and Nokia had only just decided to put their full weight

behind WiMAX and both technologies were still obscure. They were positioned, quite

realistically at the time, as complementary. WiMAX had come from a background of

addressing last mile requirements using fixed wireless, while 802.20 was seeking to

standardize various efforts to provide a fully mobile broadband solution using IP. Even the

mobile variant of WiMAX, 802.16e, was still widely seen as an extension to a fixed wireless

standard rather than a fully mobile standard in its own right.

Now, 802.20 activists no longer regard ‘e’ as a distant cousin. The role of WiMAX has been

enhanced considerably, driven by the new prominence of public Wi-Fi. Last mile was an

issue mainly for wireline broadband carriers – whether they should cut their costs and

accelerate their roll-out using wireless rather than wired technologies; whether other vendors

would threaten them with wireless alternatives. As such, though important in its own world, it

was relatively obscure as far as mainstream technology vendors were concerned.

But once the potential of WiMAX to dramatically enhance the potential of Wi-Fi by

backhauling hotspots and providing wireless networking over 30 miles and more, it became

far hotter property. For Intel, it was a way to make wireless notebooks and devices even

more attractive by increasing their capabilities through a more powerful technology than the

limited Wi-Fi. For Nokia, even more significantly, what had started as a potential new string

to its ailing base station unit, suddenly became a means of creating a whole new handset

business too, with the company promising WiMAX cellphones by 2005.

This encroached well into 802.20 territory. This effort was initially driven mainly by the

pioneers of fourth generation wireless IP technologies, notably Flarion and Navini Networks,

which refused to have anything to do with 802.16e, claiming theirs was a purer IP solution.

The politics became clear at an 802.20 meeting in June. At this, senior executives from

Lucent and NTT DoCoMo (as well as Motorola) became heads of the IEEE Working Group,

replacing executives from Flarion, Navini and smart antenna pioneer Arraycomm. Navini

claims that the new chiefs, particularly NTT, had staged a “political coup” to wrest control

from 4G technologists and ensure that 802.20 did not gain ground against either 3G or

802.16e. Apparently, members of 802.16e and representatives from cellular carriers gained

voting rights and used them to install their own candidates and sabotage the process.



Figure 5: Flarion provides some of the base technology for 802.20

Source: Flarion

The IEEE is reviewing the election and may enforce a change of line-up at a meeting this

week, but whatever the in-fighting, the little drama highlights the issues facing 802.20, and

why it, and Motorola/Cisco, should give up any idea of trying to make it dominant.

Hostility from the 3G industry

Two forces are ranged against it. One, as we have seen, is 802.16e, no longer even

pretending to coexist peacefully with its sister standard, but instead backed by companies

that want to direct the future of mobile connections unhindered. The other is the 3G cellular

industry. While WiMAX, like Wi-Fi, can be seen as a 3G alternative, it also offers

opportunities to mobile carriers, to get into the last mile market and to build up their own

hotspot networks as an integrated service with 3G, the direction that most operators are

taking. Carriers seem to think that, as long as they can adopt Wi-Fi and WiMAX earlier and

develop a better business model than the independents, these will be technologies that they

can turn to their advantage.

They are almost certainly right about this. But 802.20 is a different matter. It, too, could be

adopted by mobile operators, and some have run trials of wireless IP with partners such as

Arraycomm as a potential complement to 3G, or a way forward should their 3G investments

never pay off. However, the big operators are fearful that, as more spectrum is put on offer,

especially in the US, potentially for very low prices, new entrants or current small operators

could use low cost 802.20 networks to launch rival mobile networks that would be more

attractive to end users than 3G. In the mean time, to launch 4G services themselves, they

need to sacrifice some of their own precious spectrum.

The big players, notably NTT DoCoMo, are driving 4G – which integrates IP and cellular

communications – along the route of their own CDMA and TDMA protocols, in which they

have so much investment and expertise. The 802.20 proposal uses OFDM in a pure form as

an alternative to 3G protocols (as does WiMAX). Only Nextel has been involved in a positive

way in 802.20 from the beginning, probably because of its deeply entwined relationship with



Motorola. Navini and other vendors are convinced that the 3G players have packed out the

IEEE committee with a determination to kill Mobile-Fi before it is born.

Even if this is paranoia, and the cellular operators are merely trying to control rather than kill

the process, by the time 802.20 products are out there, they will not only have WiMAX to

contend with but broadband IP services will be common on 3G/4G networks. To have any

chance of survival, 802.20 needs to work with the 3G groups such as 3GPP, form better

relationships with the carriers, and so provide technology that works with 3G. All this will

take far more time and political nous than 802.20 has at its disposal.

Vendor support

Even if the IEEE refuses to allow the NTT election, a decision it has to make this week,

802.20 has no chance of succeeding without powerful vendor support. Not that Motorola and

Cisco are to be disregarded of course, but so far they have been far less aggressive in

backing Mobile-Fi than Intel has been about WiMAX. They seem to be disrupting WiMAX by

presenting their own alternative, without making very positive moves in favour of Mobile-Fi.

A comment from IPWireless, which is not part of any IEEE group but has been a pioneer of

mobile IP, is telling. “I’m not worried about 802.16e. If Intel’s name hadn’t been associated

with the press release, nobody would have taken any notice,” said senior director of

marketing, Jon Hambridge.

That is the whole point. Nobody would have got excited about WiMAX without Intel’s and

Nokia’s activities because it would have lacked the vendor interest that takes a standard

from obscure committees to real products and market strength. After all, the IEEE ratifies

standards, it has no responsibility for ensuring their uptake or success. That is the role of the

industry players, which score the double whammy of helping to set the standard and then

using it to encourage users to step up their spending. Motorola has the potential to do a

similar job for 802.20 but it is in a more ambiguous position. With the carriers’ new found

hostility, it will not want to alienate the main buyers of its cellphones too recklessly.

So it seems that 802.20 will fade into insignificance, or will be redirected into a niche

application, notably one area where it excels – mobile communications in fast moving

vehicles (the standard specifically supports vehicular mobility, at speeds up to 250km per

hour). Undoubtedly its real supporters, led by Flarion, will establish it in their own market and

will gain some wins with second rung operators, especially in developing countries.

Interoperability via 802.20 will benefit them here and work done under the IEEE auspices

will filter through into operators’ 4G developments and into WiMAX.

The best result will be if both camps come together, with the 802.20 rump adopting WiMAX

specifications into their products and the best of 802.20 finding its way into 802.16e.

Ironically, this has a far better chance of happening once Motorola accepts defeat and seeks

out another weapon to push forward its strategies, and the vendor stand-off collapses with

the victory of WiMAX.



5. The Last Mile: WiMAX and Broadband Wireless Alternatives

Various technologies are being trialled for delivering broadband wirelessly to the last mile:

• to extend the edges of the 3G network and fill in coverage gaps

• to provide a lower cost alternative to cable and DSL

• to provide enterprise campus-wide or multi-site wireless networks by providing

backhaul for WLANs.

The key technological approaches are:

• WiMAX

• Wireless Local Loop based on IP and OFDM, including wireless voice over IP

• Satellite

• Smart antenna

The history of broadband wireless has been largely one of disappointment to date. Pioneers

like Teligent, Nextlink and Winstar entered the market in the late 1990s with networks based

on cost effective LMDS (Local Multipoint Distribution System), but they played safe and

stayed in over-served metro areas of the US rather than remote regions, and having paid

huge federal fees for their licenses, all three companies filed for bankruptcy.

Carriers such as MCI and Sprint invested in an alternative, MMDS (Multi-channel Multipoint

Distribution System) but failed to gain significant market momentum. Hence the excitement

around Wi-Fi hotspots, hotzones and community networks, but coverage scalability beyond

a few nodes is hard to achieve without performance failures.

Enter WiMAX, promising a lower cost backhaul for these hotspots than T1 and the option of

a mesh network topology, as well as being a wireless extension to cable, fibre and DSL for

last mile.

WiMAX will drive broadband wireless access (BWA), but it has also come to the fore at a

time of renewed interest in wireless last mile, as operators look for new sources of revenue

and consumer demand for fast internet access grows exponentially.

Like Wi-Fi, BWA looks set to achieve the difficult task of creating a boom in a depressed

communications sector, by offering better price/performance for network users and a

revenue opportunity for squeezed suppliers. Europe has been slow to get excited about this

market, but now that BWA solutions based on IP are becoming realistic, even the 3G

operators there will need to examine these as an addition to their service.

In the US, last mile and wireless broadband solutions using unlicensed spectrum have been

given a huge boost by the freeing up of vast swathes of bands by the FCC. The US carriers

have also shown interest in last mile solutions to extend their networks and plug gaps. In

Europe, progress is slower because the carriers have a more ubiquitous network and a vast



financial investment in conventional cellular networks, and regulators have been less

forward thinking.

Licensed wireless technologies ArrayComm, Flarion Technologies, IP Wireless and other

vendors, many using smart antenna approaches, are the most viable wide area wireless

solutions available to operators and WISPs now though most customers will be looking to

those with a clear 802.16 roadmap.

Designed from the ground up to support metropolitan area services, they'll leverage the

existing cell tower infrastructure to deliver data services at prices far below those of 3G,

reliably and with coverage far better than that of Wi-Fi. With WiMAX, they will have a

broader market to address, with low cost operators working in unlicensed spectrum.

Cellular carriers cannot be ignored – their assets of licensed spectrum and vast cellular

tower infrastructure will be essential to ensure the survival of any new alternative. New

wireless broadband technologies may cut into cellular networks’ business, but they will

never be an either/or – cellular operators need last mile solutions to extend their systems

and subscriber bases at an economical rate, while the last mile pioneers will stand a better

chance of survival if they integrate with and make use of the support and infrastructure of

the operators if their technologies are not to be confined to niches. They will be able to use

802.16a base stations as alternatives, but these two systems are likely to interoperate as

they evolve, especially with giants like Nokia straddling both camps.

Nearly all the proprietary point/multipoint BWA vendors are doing the sensible thing and

refocusing to build their products around WiMAX silicon, ensuring lower costs of

manufacture and interoperability. Quickest off the mark are those that use 256 sub-carrier

OFDM, which is emerging as the winner among the PHY variants.

BWA alternatives to WiMAX

Not everyone is taking the WiMAX pledge though. Flarion is the leader among OFDM-based

vendors that are backing the metro area mobile wireless standard, 802.20 or Mobile-Fi,

instead.

IPWireless supports neither IEEE approach, but is still pushing its own mobile broadband

technology, which is based on an IP packet data implementation of the UMTS 3G standard,

operating at over 2.5 miles in urban areas at 16Mbps in 5MHz and 10GMz channels.

This technology is less powerful or long distance than WiMAX, though it does have the

advantage, especially for second tier mobile operators, of being similar to cellular networks

to implement and manage and providing good interoperability with the various flavours of

3G. Its natural home, then, is in extending the networks of the mobile carriers in outlying

regions, but it is keen to attack the hotspot sector too, an ambition that will be hard to realize

in the face of WiMAX.

However, the case that the company’s chief executive, Chris Gilbert, makes for IPWireless

over Wi-Fi hotspots is valid for all BWA technologies. He points out that users will not want

to have to hunt for hotspots, and that broadband alternatives can offer not only longer

distances from the base station, but also mobility – as supported by IPWireless and by the

mobile version of WiMAX, 802.16e.



Another backhaul option that has gained coverage recently is free space optical, a

technology that is primarily used to extend local fibre networks but can also be used for

backhaul. One supplier specifically targeting this new direction is Omnilux. FSO is more

expensive than wireless - $1,500 per node for Omnilux, which is cheap by FSO standards –

but each node operates at 100Mbps and has routing and quality of service capabilities plus

embedded Wi-Fi. Unlikely to be mainstream, but meshes of these nodes could also be an

attractive option for some enterprises.

And of course there is satellite. There have been several announcements recently of

combined satellite/Wi-Fi products that bundle an 802.11 access point with the satellite

system. Satellite provides the backhaul to a fixed antenna, which then transmits the

connection locally using Wi-Fi. This is a very expensive option of course, so mainly targeted

at areas where there is no alternative. For instance, an island in Alaska gained a ‘satellite

broadband hotspot’ last week, with Wi-Fi providing a simpler last mile option than other fixed

wireless approaches.

Another approach, entirely outside the cellular operators’ remit, is to extend the capacity of

Wi-Fi. Companies such as Vivato, Ricochet and 5G Wireless have been developing

technologies to extend the distances covered by 802.11 standards without the usual line of

sight requirement – although their future looks uncertain, given that WiMAX will solve the

problem in a year.

Companies such as 5G and Vivato do use standard IEEE approaches and so have an

advantage over some more individualistic solutions to providing a wireless alternative to

DSL in the broadband last mile, though they cannot come close to WiMAX’ 70Mbps or its

distances.

5G has conducted a trial in its home state of California, connecting buildings four miles

apart, with no line of sight, at sustained throughput speed of 3Mbps. It claims its technology

can achieve up to 5Mbps over eight to 10 miles. 5G claims that such performance makes

Wi-Fi a viable option for metropolitan areas and campus-based corporations and will look to

sign up ISP, corporate or municipal authority customers in the coming weeks.

Bandspeed acquired its proprietary, patent pending WWAN technology with Wireless Think

Tank last year. It operates in the 2.4GHz and 5.3GHz ranges and uses three co-located

radios as a base, supporting 750 clients within a radius of up to 10 miles. The cost of this

facility is $15,000. 5G is working on a new configuration that will support 2,072 clients per

co-location. This compares to the cost of an alternative approach, VPOP, used by some

wireless last mile providers, which supports 170 clients per location for $38,000.

IP and smart antennas

There is no doubt that IP-based technologies cope with many of 3G’s limitations in terms of

data transfer, and also provide a lower cost installation of local loop, which is not dependent

on ‘line of sight’ transmission as most early solutions were. But they are still weak on voice –

voice over IP has quality issues and requires specialized phones. In less than five years,

though, we should have VoIP cellphones that will finally establish IP as the dominant

technology for mobile broadband communications, sidelining the descendants of both 3G

and 802.11x.



The cellular carriers are working towards this IP world with their own implementations, under

the 4G label, but for the first time they will meet new and viable competition as they are

forced to use a technology platform that can also be offered by smaller (and less debt-

ridden) alternative operators.

IP-based alternatives to 3G are coming from a host of mainly US start-ups, including Flarion,

IPWireless, Soma and Navini, all using the OFDM (orthogonal frequency division

multiplexing) physical layer technology at the heart of 802.11a and some digital television.

This splits a high frequency signal into several lower frequency ones, that are then sent by

separate paths to achieve higher data rates than 3G.

Many of these start-ups rely on smart antenna technology in place of conventional base

stations, and could incorporate wireless Man standards as these develop. ArrayComm and

IPWireless have been two of the stars of this American dominated field, but and two other

promising start-ups are Navini Networks and BeamReach Networks.

Navini raised $25m in Series C funding earlier this year, bringing its total backing to date to

$91m, impressive in the current investment climate – though a drop in the ocean if Navini

fails to gain heavyweight partners for its ambitious smart antenna network plans.

But given the new spotlight on last mile and on alternatives to 3G and fixed wire, the climate

for start-ups such as Navini to gain powerful partners is improving greatly. Most carriers

outside Europe, and some within it, are testing alternative last mile technologies and Nokia,

Ericsson, Lucent and Nortel have all tested smart antenna networks using various

approaches, although they have so far not pushed these aggressively to operators,

presumably for fear of cannibalising their still lucrative business in selling conventional base

stations.

Smart antennas are one of the most interesting approaches to restructuring the network in

order to support more users at fast rates, offering broadband performance and quality over a

wireless link. Smart antenna suppliers cut the number of base stations by using multiple

antennas in parallel, making highly efficient use of the available spectrum. They can be

implemented as a more efficient technology for 3G carriers, but can also operate as a

separate network to challenge 3G.

Navini claims 70 percent lower TCO than first generation wireless broadband solutions and

50 percent lower than DSL. Its flagship product is the Ripwave base station and antenna

system, which uses adaptive phased-array antenna technology that can penetrate walls.

Ripwave modems connect to this network and offer broadband access to the internet and

links between Wi-Fi and long distance networks.

Another broadband fixed wireless player, BeamReach Networks, completed a $15m series

C round this year, claiming the money would enable it to ramp up for significant roll-outs in

the coming year, following a current trial of its technology with US carrier Verizon in Virginia.

BeamReach’s Airlink technology uses Adaptive MultiBeam OFDM, a smart antenna

technology that claims 16 times better cell coverage than and better spectral efficiency than

3G. BeamReach says that, while 2G and 3G networks sometimes now include basic OFDM

facilities, adaptive multibeam is more efficient because multiple frequencies can be reused

in each cell, and data is transmitted over two channels at different frequencies to improve



speed. Adaptive OFDM gives spectral efficiency of over 10bits/sec/Hz/cell compared to

under 1bit for broadband CDMA networks such as W-CDMA.

This contrasts with Navini’s approach, which is based on a technology called MCSB (multi-

carrier synchronous beamforming), which is similar to BeamReach’s but based on time

division rather than frequency division, which Navini claims is better for voice than frequency

based solutions such as OFDM. Navini, an Intel-funded wireless broadband vendor, is

looking to 802.20 as its key standard.

The start-ups will have to ensure that their efforts are standards-based and integrated with

the WiMAX work to stand a chance of survival. And with WiMAX reducing the barriers to

entry for new suppliers, they also need to establish a beach-head now to ensure that they

have sufficient installed base either to survive in a newly competitive sector, or to be

attractive to one of the larger players.



6. Conclusions

WiMAX is the most important of the host of wireless standards emerging from the IEEE and

3G bodies. Its impact will owe much to Wi-Fi, which has created the interest in and market

acceptance of wireless networking to enable WiMAX to flourish in the mainstream, not least

by attracting Intel into the sector. But its effect on the world of business and consumer

internet and wireless access will be far more profound.

Within five years, we expect WiMAX to be the dominant technology for wireless networking.

By that time it will be fully mobile as well as providing low cost fixed broadband access that

will open up regions where internet access has so far not been practical. As the cellular

operators move to IP-based fourth generation systems, they will embrace WiMAX as they

are doing with the far more limited Wi-Fi. WiMAX will be the catalyst for a shakeout of

operators, with some of the small independents falling to the large players, still hunting for a

more profitable revenue stream than 3G.

WiMAX will become the dominant solution in China, the world’s largest potential market for

broadband users. The standard has already been adopted by the government and will fill in

many of the gaps in the sketchy 3G coverage.

The hype around Wi-Fi will die down and 802.11 will return to its rightful place as a useful

but limited local area technology, fully integrated with WiMAX at the backhaul.

Intel will be a clear winner from its decision to drive WiMAX. Its next generation Centrino will

support WiMAX and therefore have a headstart in huge markets, including the rural regions

of the major nations.

Nokia too will profit from the rise of 802.16, both by adding a new base station business to

its ailing equipment unit and by developing two- or three-mode handsets for cellular, Wi-Fi

and WiMAX.

WiMAX will be the most significant technology to date in making wireless access ubiquitous

and, as more free spectrum is opened up, in creating a major shake-up of the traditional

shape of the wireless and mobile communications sector.



7. APPENDIX: Wi-Fi and WiMAX Compared

WiMAX Wi-Fi Licensed and license-exempt 128-bit Triple-DES and 1024-bit RSA security

License-exempt only WPA+WEP security, inadequate though 802.11i will improve

COVERAGE Optimised for outdoor non-line of sight Supports mesh networks Supports advanced smart antenna

Optimised for indoor use No mesh support within standards Smart antenna support proprietary

RANGE Optimised up to 50km Point to multipoint Handles many users widely spread out Tolerant of greater multipath delay spread up to 10ms PHY and MAC designed for multimile range Standard MAC

Optimised for 100 meters Point to point No ‘near-far’ compensation Designed for indoor multipath delay spread of 0.8ms PHY and MAC optimised for 100m range Range can be extended but then MAC non-standard

QUALITY OF SERVICE Grant request MAC Designed to support voice and video from the start Supports differentiated service levels e.g. T1 for business, best effort for consumer TDD/FDD/HFDD—symmetric or asymmetric Centrally enforced QoS

Contention-based MAC, no guaranteed QoS Standard cannot guarantee latency for voice or video No allowance for differentiated levels of service on a per user basis TDD only—asymmetric Proposed 802.11e QoS standard is prioritisation only

PERFORMANCE Bandwidth 10, 20MHz; 1.75, 3.5, 7, 14Hz; 3, 6MHz Maximum data rate 70Mbps Maximum 5.0 bps/Hz

Bandwidth 20MHz Maximum data rate 54Mbps Maximum 2.7 bps/Hz

SCALABILITY Channel bandwidths can be chosen by operator for sectorization Scalable independent of bandwidth with 1.5MHz to 20MHz width channels MAC supports thousands of users

Wide 20MHz channels MAC supports tens of users



8. APPENDIX: WiMAX Players

Companies with votes on the IEEE 802.16 groups:

Wi-LAN (3 votes) Runcom Technologies (3 votes) Nokia (3 votes) Intel (3 votes) Wavesat Wireless (2 votes) Telnecity Group (2 votes) Malibu Networks (2 votes) MacPhy Modems (2 votes) InterDigital Communications (2 votes). Harris (2 votes) Cowave Networks (2 votes) Comtech (2 votes) AVALCOM-RINICOM (2 votes) Xilinx WaveIP Vectrad Networks Thomson SiGlobe Corporation STMicroelectronics Redline Communications. Radiant Networks RF Magic Proxim Paul Thompson Associates Panasonic NIST Medley Systems Hitachi Cable Fujitsu Ensemble Communications. EPIN Technologies Cymil Communications CoWave Networks Broadstorm BeamReach Networks Aperto Networks Alvarion Airspan Communications Agilent Technologies Advantech AMT



Members of the WiMAX Forum Agilent Airspan Networks Alvarion Aperto Networks Atheros Compliance Certification Services Ensemble Communications Fujitsu Microelectronics America Hughes Network Systems Intel Intracom NewsIQ NIST Nokia OFDM Forum Powerwave Technologies Proxim Redline Communications RF Integration Siware SI Works SR Telecom Telenecity Group Towerstream Turbo Concept Wavesat Wi-LAN Winova Wireless

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