Article about UWB by David Geer

Page 1

July 2006

Published by the IEEE Computer Society

I N D U S T R Y T R E N D S

ltrawideband technology

has been regarded with

considerable promise for

several years. Vendors want

to use the short-range,

high-speed wireless UWB for many

potentially popular applications,

such as home networks, connectiv-

ity between PCs and peripherals or

monitors, and the transfer of large

files between devices. In these areas,

they see UWB as having significant

advantages over similar technologies

such as Bluetooth and Wi-Fi.

Vendors haven’t released UWB

products yet. But according to analyst

Stuart Carlaw with ABI Research, a

market-analysis firm, global UWB

hardware shipments will reach 300

million units by 2011.

Currently, though, the lack of a

unified standard has hurt UWB

adoption. There are two principal ap-

proaches to the technology, and com-

panies have held off making products,

hoping an IEEE standardization ef-

fort could yield one protocol on

which they could focus their efforts.

However, the IEEE was unable to

get the UWB Forum and the

WiMedia Alliance—proponents of

the two main approaches—to agree

to merge their widely divergent tech-

nologies into a single standard.

Vendors are now preparing to re-

lease products, such as dongles or

wireless hubs, based on one or the

other UWB version. But products

based on one version will be incom-

patible with devices based on the

other because the two approaches

are so different. This will cause

problems for products used within

the same network or that must com-

municate with one another.

Meanwhile, vendor Freescale

Semiconductor recently left the

UWB Forum and decided to pro-

mote its own ultrawideband version.

Thus, just when it seemed poised to

take off, the UWB market is facing

considerable division and uncertainty.

ABOUT UWB

University and government re-

searchers in the US and the then-

Soviet Union worked separately in

the late 1960s on the first UWB-like

technologies, for applications such

as radar and secure communica-

tions. As chips have become more

powerful and less expensive over the

years, UWB has become affordable

and sufficiently powerful for com-

mercial use.

UWB appeals to vendors because,

as a wireless, short-range technol-

ogy, it is faster than Bluetooth or Wi-

Fi. UWB is also power-efficient and,

unlike Wi-Fi, doesn’t use a complex

security scheme. This makes it ideal

for handheld devices, which use bat-

teries and have limited processing

power.

However, UWB works by trans-

mitting across multiple frequencies,

which increases the possibility of in-

terference with other signals.

Because of this, most countries have

banned UWB.

In 2002, though, the US Federal

Communications Commission (FCC)

authorized commercial use at low

power levels to limit interference.

And recently, Europe’s Electronic

Communications Committee an-

nounced support for UWB, while

Japan appears poised to do the same.

How UWB works

UWB works via chip-based radios

that modulate signals across the en-

tire available ultrawideband spec-

trum, which in the US is from 3.1 to

10.6 GHz, explained WiMedia

Alliance president Stephen Wood.

This is different than most wireless

technologies, which operate only in

a single assigned band within a fre-

quency spectrum.

The UWB Forum’s version of ul-

trawideband provides a maximum

data rate of 1.35 Gbits per second

and a maximum transmission range

of 3 meters. The WiMedia Alliance’s

version offers 480 Mbps and 10

meters.

Bluetooth—a short-range radio

device-connectivity technology that

operates in the 2.45-GHz frequency

band—sends data at only up to 3

Mbps but offers a transmission

range of up to 100 meters. Wi-Fi—

a family of wireless LAN and

Internet-connectivity technologies

operating in the 2.4- or 5-GHz fre-

quency bands—provides transmis-

sion rates up to 54 Mbps and sends

data up to 92 meters, although this

range might increase considerably in

the near future.

UWB

Standardization

EffortEnds

in Controversy

David Geer

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Computer

I N D U S T R Y T R E N D S

The UWB Forum is focusing on

technology for television-centric,

home-multimedia connectivity, elim-

inating the wires between home-en-

tertainment devices such as TVs,

set-top boxes, and DVD players, he

noted.

The group is also targeting broad-

band radios in cell phones that have

MP3 players so that users can easily

upload and download large MP3

files, added Robert Eisses, the

forum’s marketing manager and also

vice president of sales and market-

ing for vendor Icron Technologies.

High-definition multimedia con-

tent delivery requires quality-of-

service guarantees to ensure clear

images and uninterrupted service.

Thus, PulseLink’s technology uses

an isochronous MAC, which guar-

antees data delivery within set time

constraints, thereby providing con-

tinuous, uninterrupted bandwidth.

In addition, CWave lets devices

form their own networks, with one

of the participating nodes acting as a

controller.

WiMedia Alliance

The Intel-led WiMedia Alliance

has 214 members, consisting of PC,

consumer electronics, and cellular

service providers and handset mak-

ers. Participants include Hewlett-

Packard, Hitachi, Microsoft, Nokia,

Panasonic, Sony, and Texas Instru-

ments. The alliance is focused on

using UWB for computer, consumer

electronics, and mobile-phone con-

nectivity.

ECMA International (also known

as the European Computer Manu-

facturer’s Association) has already

adopted WiMedia as a standard,

and the International Organization

for Standardization and the Euro-

pean Telecommunications Standards

Institute are in the process of doing

the same.

WiMedia transmits data via high

volumes of low-power electromag-

netic pulses. The technology also

uses multiband orthogonal fre-

quency-division multiplexing (MB-

OFDM), which splits a signal into

Thus, noted Michael J. Marcus,

director of the Marcus Spectrum

Solutions radio-technology consul-

tancy, UWB will offer much more

bandwidth than Bluetooth and

Wi-Fi.

UWB doesn’t have its own scheme

for data security, so devices must

provide it via encryption or other

separate approaches.

UWB can function as an underly-

ing transport platform over which

other technologies will operate.

With this in mind, the WiMedia

Alliance and the Bluetooth Special

Interest Group are working together

on a combined technology. They ex-

pect prototypes to be available by

2007 and products by 2008.

Using UWB

UWB would be good for transfer-

ring large files, like those used in

multimedia, quickly and wirelessly

over short ranges between nearby

devices, such as a PC and a digital

camera or MP3 player.

Thus, Wood noted, UWB could

work with mobile e-commerce. For

example, a smart phone could use

UWB to buy a DVD from a kiosk

and subsequently upload it to an

MP3 player.

Proponents also want to use the

technology to replace wires that con-

nect PCs to monitors and that con-

nect DVD players and set-top boxes

to TVs, according to PulseLink pres-

ident Bruce Watkins, a member of the

UWB Forum’s board of directors.

UWB’s first commercially success-

ful implementation may be in

WiMedia-based wireless universal se-

rial bus connections, predicted

Christopher Kissel, an analyst with

In-Stat, a market research firm.

USB—which, like Bluetooth, could

operate over UWB—is an external

bus that connects computers and con-

sumer electronics with peripherals.

Some supporters hope to use

UWB to enable mesh networks,

which devices could automatically

form whenever they are within

range of one another. In mesh net-

works, each node can communicate

peer-to-peer with the other nodes

without having to use a hub, ex-

plained Wood. UWB mesh networks

could function as wireless LANs.

A TALE OF TWO APPROACHES

The two primary UWB versions

use very different technical ap-

proaches.

UWB Forum

The UWB Forum, originally led by

Freescale, has 220 members includ-

ing international telecommunica-

tions vendors and service providers,

universities, and wireless companies.

Participants include Fujitsu, Johnson

Controls, Siemens, and Vodafone.

The forum is now led by Pulse

Link and supports the company’s

CWave binary-phase-shift-keying

UWB technology. BPSK modulates

a signal into two phases, represent-

ing the ones and zeros of binary data.

This enables the signal to carry data.

PulseLink’s technology sends sig-

nals in continuous waves over the

entire UWB band and assigns differ-

ent codes to separate transmissions.

Each transmission goes only to the

receiver configured to accept signals

with the appropriate code. This ap-

proach increases bandwidth by let-

ting a single channel carry multiple

transmissions simultaneously.

The technology uses chipsets with

two or three radio chips: one to

transmit and receive signals, an op-

tional one to amplify incoming sig-

nals, and one to control the physical

and media access control (MAC)

layers, explained Watkins.

“We will combine them into one

chip over time,” he said, “but they

were broken into [multiple] chips

initially to reduce engineering risk

and to speed time to market.”

The lack of a

unified standard

has hurt

UWB adoption.

Page 3

July 2006

ment, thereby enhancing their mar-

ketplace appeal.

Standardization attempt

Between 2003 and earlier this year,

the IEEE tried to merge the UWB

Forum’s and the WiMedia Alliance’s

technologies into a single standard.

However, the groups backing each

major version never came close to

agreeing on a compromise approach.

The two UWB versions are very

different, which made it difficult to

bring them together into one stan-

dard, noted Stan Bruederle, research

vice president for wireless connec-

tivity with Gartner Inc., a market re-

search firm.

In addition, said the WiMedia

Alliance’s Wood, the IEEE began its

standardization attempt after com-

panies had already begun serious de-

sign work for chips based on one or

the other UWB version. This made

them less likely to support a com-

promise, he explained.

Two subsequent compromise pro-

posals failed to garner consensus.

Freescale wanted the IEEE to certify

both major approaches and let man-

ufacturers decide which technology

they want to use. The UWB Forum

proposed a specification that would

have let devices support both tech-

nologies and use whichever is most

appropriate for a given application.

Freescale’s Cable Free

In April of this year, Freescale

pulled out of the UWB Forum to start

14 500-MHz-wide bands, shown in

Figure 1, and uses OFDM to in-

crease bandwidth.

According to the WiMedia Al-

liance’s Wood, having many bands

provides flexibility and makes it

easier for users to work only with

specific narrow bands, if required

by an application or a governmental

regulation.

OFDM increases bandwidth by di-

viding a larger channel into multiple

narrow channels, which can each si-

multaneously carry signals, explained

Charles Razzell, a senior principal en-

gineer with Philips Semiconductors.

The channels are orthogonal to their

neighbors and thus many of them can

be packed close together without in-

terfering with one another.

Developers designed WiMedia to

work well with CMOS manufactur-

ing processes and thus the necessary

components can be integrated easily

onto a single radio chip, noted Wood.

“A single-chip solution is cheaper,

consumes less power, and can be in-

cluded in smaller devices,” he said.

Users can change the chip’s func-

tionality, if required by government

regulations or technical advances,

via software updates.

WiMedia’s MAC approach allows

PCs, TVs, and other devices to

form their own networks without

a centralized controller. Consumer-

electronics vendors lobbied for this

capability, which enables their prod-

ucts to work together directly with-

out the need for additional equip-

an initiative promoting Cable Free,

the company’s ultrawideband version.

Freescale wanted to concentrate

on developing a market-ready tech-

nology, while the UWB Forum and

WiMedia Alliance are geared more

toward developing specifications,

contended Calvin Harrison, the com-

pany’s UWB marketing manager.

Cable Free uses Direct-Sequence

UWB. The technology works in one

wide frequency band, giving it a

large area over which to spread its

signals, according to Matt Welborn,

senior wireless architect for Free-

scale’s UWB operations.

Cable Free also sends data as

high volumes of low-power electro-

magnetic pulses. To increase band-

width, the technology can handle

multiple transmissions simultane-

ously within a single channel. It as-

signs different codes to each trans-

mission passing through the channel

to make sure each goes only to the

proper recipient.

The technology offers a maximum

data rate of 110 Mbps and a maxi-

mum range of 10 meters.

WB Forum and WiMedia

Alliance vendors are continu-

ing to develop their technolo-

gies by, for example, making them

faster. They are also demonstrating

prototypes and applying for FCC ap-

proval for individual products.

Later this year, Wood said,

WiMedia chips will ship to manu-

3,432

MHz

Band

3,960

MHz

Band

4,488

MHz

Band

5,016

MHz

Band

5,544

MHz

Band

6,072

MHz

Band

6,600

MHz

Band

7,128

MHz

Band

7,656

MHz

Band

8,184

MHz

Band

8,712

MHz

Band

9,240

MHz

Band

9,768

MHz

Band

10,296

MHz

Band

Channel 1

Channel 2

Channel 3

Channel 4

Channel 5

Figure 1.The WiMedia Alliance’s version of UWB is based on multiband orthogonal frequency-division multiplexing,which splits a

signal into 14 500-MHz-wide bands,forming five logical channels.Having many bands provides flexibility and makes it easier for

users to work with specific narrow bands,if required by an application or a governmental regulation.

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I N D U S T R Y T R E N D S

one approach into a de facto stan-

dard, according to West.

WiMedia has the edge because the

key proponents are important com-

panies with considerable marketing

resources, she stated. However,

Wood said, both approaches will

find success at least in some niche

applications.

Explained Watkins, “They will co-

exist because we live in a market-dri-

ven, competitive economy that

facturers and appear in devices.

The UWB Forum’s technology will

hit the marketplace during the next

few months, predicted Kirsten West,

principal analyst for West Tech-

nology Research Solutions, a wire-

less-market analysis firm.

Proponents of each approach are

trying to get as many manufacturers

as possible to use their technology to

establish a strong marketplace posi-

tion. Commercial success could turn

always has and always will enable a

foothold for compelling, sufficiently

differentiated products.” ■

David Geer is a freelance technology

journalist based in Ashtabula, Ohio. Con-

tact him at david@geercom.com.

Editor: Lee Garber, Computer,

l.garber@computer.org

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see Computer’s author guidelines:

www.computer.org/computer/author.htm

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