CONTROL CHANNELS ARE KEY TO ACCELERATING THE DOWNLINKDocument Transcript
wireless.iop.org TECHNICAL INSIGHT FOR WIRELESS PROFESSIONALS
FEBRUARY/MARCH 2005 ISSUE 37
HSDPA CONTROL CHANNELS
3G standards battle rages
EDGE beneﬁts from rethink
Mobile broadband comes of age
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UWB link hits 667 Mbit/s data rate ZTE and Portugal
Telecom sign deal
An ultra wideband (UWB) wire- ment systems and also in wireless
less link has achieved a data rate local-area networks (WLANs). Portugal Telecom and ZTE have
of 667 Mbit/s. The transmission The technology could also be signed a memorandum of under-
was made using UWB technol- used to transmit data over a standing that covers R&D activ-
ogy developed by US-based range of wireline networks, ities in Europe and China. The
Pulse~LINK. Claimed to be the including power lines. Portuguese mobile and fixed-line
fastest UWB transmission ever,
the data rate was measured after
• NTT DoCoMo has con-
firmed that it achieved a down-
operator and Chinese telecoms
equipment supplier will also
forward correction error was link data rate of 1 Gbit/s using an jointly bid on tenders.
applied to the data. air interface intended for use in Portugal Telecom’s chief execu-
“Our actual over-the-air data 4G cellular networks. The Japan- tive Miguel Horta e Costa said
rate at present is 1.3 Gbit/s,” said ese operator said that a variable that the agreement will help the
Pulse~LINK’s chief technology Pulse~LINK’s John Santhoff looks forward spreading factor spread OFDM company to export products and
officer John Santhoff. He ex- to corrected data rates in excess of 1 Gbit/s air interface with multiple-input, services to China.
plained that further optimization from the company’s UWB technology. multiple-output antenna diver- The agreement will give ZTE
of the technology will bring the sity was used in a laboratory access to markets where Portugal
corrected data rate into the giga- correction technology that is said demonstration performed in Telecom operates. ZTE also
hertz range. to be more efficient at extremely August 2004. The system had a hopes that its relationship with
Pulse~LINK expects to release high data rates. The company 100 MHz bandwidth. DoCoMo Portugal Telecom will open doors
a UWB RFIC shortly, and is also expects that its UWB devices will expects to begin field trials of the to participation in Europe-based
developing a new forward error replace cables in video entertain- technology in 2005. international R&D projects.
Nortel in Chinese HSDPA call uses commercial base station
3G partnership Canada’s Nortel claims to have
made the first HSDPA call using
China Putian and Nortel are to a commercial UMTS base sta-
form a new company to develop, tion. The call was made using the
manufacture and market 3G company’s network equipment
equipment in China. Called (including a software upgrade to
Putian-Nortel Networks, the HSDPA), and received by a hand-
firm will be launched in mid- Nortel’s president Bill Owens looks forward set using Qualcomm’s MSM6275
2005 and is expected to be head- to more business in China thanks to a new HSDPA chipset. The chipset,
quartered in Wuhan. China joint venture with China Putian. which also supports GSM and
Putian will own 51% of the joint EDGE, is currently available on a
venture, with Canada’s Nortel “strengthen our capability to sampling basis. US-based Qualcomm’s MSM6275 chipset
owning the remainder. offer industry-leading solutions The demonstration was per- has completed an HSDPA call with a 3G
China Putian’s president Xing for our customers and new formed at Nortel’s Chateaufort base station from Nortel.
Wei said that the deal will “sig- prospects in China”. facility in France, and involved a
nificantly accelerate the interna- China Putian is developing live air connection to a moving Nortel has joined forces with
tionalization of our 3G offerings”. products for the TD-SCDMA automobile to demonstrate the the 3G operator mmO2 to
Nortel’s president Bill Owens 3G standard, which is expected stability of the connection in a deploy HSDPA in mmO2’s
said that the joint venture will to be used in China. real-world environment. UMTS networks in Europe.
tions, increasing capacity is the end of the decade”.
Cellular operators focus on capacity cheap,” said Pelligrini. Most base Another analyst at ABI has
stations can be upgraded with described the market for RF
Cellular operators in industrial- operators remain very reluctant software, rather than much more power amplifiers and power
ized counties are focusing their to invest in new infrastructure. expensive hardware. In addition, devices as being “in a tenuous
attention on increasing the Pellegrini concedes that 3G Pelligrini believes that operators state”. Lance Wilson predicts that
capacity of existing infrastructure roll-out has boosted infrastruc- are finding ways of increasing the current slump in sales will
rather than installing new equip- ture spending, but cautioned that revenue by developing new ser- continue throughout 2005. He
ment, says a report from US- “[operators] are still afraid of over- vices that do not require addi- also identified 3G as “the one
based ABI Research. According extending, and the biggest factor tional infrastructure. He predicts bright spot”, but conceded it
to analyst Brian Pellegrini, driving down spending is the that poor infrastructure sales will “cannot provide enough turnover
spending on new equipment rose high cost of base stations”. lead to “some consolidation in in revenues of in-shipped units to
slightly in 2004, but network “Compared to buying base sta- the industry between now and turn the market segment around”.
wireless europe wir eless.iop.org February/March 2005
3GPP releases A-GPS performance Europeatharmonizes
UMTS 2.6 GHz
specifications for UMTS handsets
The Third Generation Partnership pany’s director of applications services, and operators are con-
Project has released performance engineering, Nigel Wright, told cerned that the provision of
specifications for the implemen- Wireless Europe: “It will be quite a handset location over the Internet
tation of assisted global position- while before formal A-GPS con- could allow third parties to pro-
ing system (A-GPS) technology formance testing begins.” This is vide LBS, robbing operators of
on UMTS handsets. The specifi- because the test cases must first revenue,” explained Wright.
cations define general test condi- be implemented on the appropri- The Open Mobile Alliance is
tions for GPS signals and handset ate test equipment, and then the addressing this issue through the
location, as well as test condi- test systems must be approved by development of a secure user
tions for the UMTS network. an appropriate industry body plane wrapper for A-GPS, which
Also defined are a wide range such as the Global Certification would allow operators to control
of performance requirements for Forum. Spirent has already location information. Wright
A-GPS implementation such as implemented A-GPS test cases in said that this project is delayed by
measurement parameters for its UMTS Location Test System about one year, which has damp-
handset-based and handset- (ULTS), which will debut this ened enthusiasm for A-GPS. The UMTS Forum’s chairman Jean-Pierre
assisted A-GPS. Sensitivity and month at the 3GSM World While it is very likely that a Bienaimé believes that additional
accuracy requirements are pro- Congress in Cannes, France. similar specification for GSM spectrum will assure the long-term
vided in addition to the mini- Wright believes that European will be created, Wright com- success of UMTS services.
mum requirements for dynamic operators have been cautious mented that there is very little
range. Performance requirements regarding A-GPS and the loca- interest from operators. While The European Conference of
in the presence of multipath sig- tion-based services (LBS) that the this may be down to the techni- Postal and Telecommunications
nals are defined as well as the use technology can enable. While cal challenges of implementing Administrations (CEPT) has rec-
of A-GPS while on the move some concerns linger over the A-GPS on GSM, Wright believes ommended that the 2500–
with periodic position updates. deployment of A-GPS in Europe, that European operators are 2690 MHz band should be
The specifications were written Wright believes that operators are reserving A-GPS to their 3G net- reserved for use by licensed
by the test and measurement holding back for business rea- works because it could be used as UMTS services. The spectrum is
vendor Spirent, with input from sons. “Most A-GPS in Europe a differentiating technology to expected to be licensed in 2008.
the cellular industry. The com- will be used for commercial data lure subscribers away from 2G. The CEPT has recommended
that the 2500–2570 and 2620–
2690 MHz bands should be
OTA test centre is paired for UMTS FDD deploy-
ment with frequency blocks in
second in Europe multiples of 5 MHz. The 2570–
2620 MHz band has been identi-
Roke Manor Research has opened fied with either UMTS TDD
a facility for the testing of mobile services or as a FDD downlink
phones according to standards band. The CEPT stated that spe-
defined by the Cellular Telecom- cific details regarding the width
munications and Internet Associ- of guard bands and licensing
ation (CTIA). The UK facility conditions should be defined by
can perform over-the-air (OTA) individual countries.
testing, which must be done The decision has been
before a handset can be certified applauded by the UMTS Forum,
for use in the US. This is the sixth The Roke Manor chamber is one of six facilities accredited by the CTIA for OTA testing. which represents the operator
facility worldwide, and the second community. Its chairman Jean-
in Europe to be accredited by the senior RF engineer at ETS- matter of course”. Pierre Bienaimé said: “Additional
US-based CTIA for OTA testing. Lindgren, explained that similar Roger Hopper, principal group frequencies in the 2.6 GHz range
The test chamber was provided requirements could be intro- manager at Roke Manor, said: will help to assure the long-term
by US-based ETS-Lindgren, and duced in Europe and Asia in the “We currently have six projects market success of UMTS ser-
the test system and software was near future. He also observed undergoing testing in the cham- vices, while allowing for a natural
supplied by UK-based EMV. that “most major [handset] man- ber and [we] are in the process of evolution of the technology”.
While the CTIA is currently the ufacturers produce products for bidding for a number of high The 1900–2170 MHz band is
only organization requiring OTA the global market, so CTIA com- profile contracts.” Roke Manor is currently reserved for UMTS in
handset testing, Martin Wiles, pliance testing is becoming a owned by Siemens of Germany. most European countries.
February/March 2005 wir eless.iop.org wireless europe
NEWS IN BRIEF Mobile broadband boom
Huawei breaks into western Europe There is little doubt that high-speed downlink packet
Huawei Technologies is to supply UMTS infrastructure equipment to the access (HSDPA) will be one of the hottest topics on
Netherlands-based operator Telfort. The deal is a western European first for the agenda at 3GSM in Cannes. HSDPA boosts
Huawei of China, and covers both core and radio-access network equipment
UMTS data rates in much the same way that EDGE
for Telfort’s national network. Huawei will also help Telfort to develop mobile
services, and will establish a research and development centre in Amsterdam accelerates GSM, and theories abound as to why
that will focus on end-user applications. operators appear to be obsessed with this 3.5G
technology before their 3G networks have garnered
Guard bands to be released for GSM significant subscriber numbers.
The UK telecoms regulator Ofcom has called for the release of spectrum in
the guard bands between DECT and GSM services. Ofcom has recommended
On page 42, Nortel’s John Hoadley tells me that the
that the spectrum be used for wireless communications such as GSM at power presence of cdma2000 1X EV-DO networks in Korea
levels of less than 200 mW. This would involve the use of picocellular base and the US is focusing attention on HSDPA as a way
stations with typical ranges of 200 m outdoors and 50 m indoors. Services for UMTS operators to keep pace with their CDMA
would be compatible with existing GSM handsets. The bands will be at 1781.7– rivals. Meanwhile in Europe, where EV-DO is not a
1785 MHz and 1876.7–1880 MHz, and could be made available this year.
threat, some industry observers such as Stirling Essex of
UbiNetics predicts early HSDPA roll-out UbiNetics believe that the region’s UMTS networks
Many 3G networks in Europe will reach their capacity limits by the end of this will be a runaway success in 2005, and that HSDPA
year, causing operators to accelerate the roll-out of the high-speed downlink will be deployed in 2006 to address capacity shortages.
packet access (HSDPA) upgrade to UMTS, predicts the UK-based wireless
Operators and consumers will ultimately benefit
technology firm UbiNetics. “There is little doubt in my mind that HSDPA will
be ready for widespread deployment in Europe within 12 months,” said from the accelerated development of HSDPA, but it is
Stirling Essex, the company’s head of strategic marketing. Essex added that important to remember that there are still significant
HSDPA trials performed by the Japanese operator NTT DoCoMo indicate that challenges associated with the development and
HSDPA is “relatively easy to deploy”. delivery of data services. On page 11, Tim De Luca-
TD-SCDMA video phone unveiled in China Smith explains why handset configuration problems
Datang Mobile has demonstrated a video phone that operates on the time- are slowing the uptake of new services, and argues that
division synchronous CDMA (TD-SCDMA) 3G standard. Claimed to be the over-the-air configuration is the way forward. At the
world’s first TD-SCDMA video phone, the handset supports end-to-end video network level, much work needs to be done to ensure
telephony at 15 frame/s on a 64 kbit/s wireless data link. It employs a video
that new services can be deployed in a timely manner.
telephony stack from US-based Dilithium Networks. TD-SCDMA networks are
expected to be licensed in China, where the handset maker Datang is based. On page 19, Kieran Dalton explains the need for a
“network operating system”, which he claims will do
Cognitive radio groups expand for mobile data services what UNIX and DOS did for
Two new industry groups focusing on cognitive radio have been launched by an emerging computer industry several decades ago.
the Software Defined Radio (SDR) Forum. The Cognitive Radio Working Group
will provide guidance and standards for the development and implementation
of SDR technologies. The special interest group will focus on the business
and regulatory issues facing the emerging cognitive radio industry. According
to Bruce Fette, Technical Committee Chair of the SDR Forum, “SDR is the While HSDPA can offer higher data rates, these come
best solution to address the adaptability component of cognitive radio.” at a price. On page 23, Faris Muhammad navigates
through myriad new control channels and modulation
Ericsson joins WiMAX Forum schemes that ensure HSDPA achieves the highest
Ericsson is the latest major cellular equipment maker to join the WiMAX
Forum, which is an industry organization that promotes the development of possible data rate. And like EDGE before it, there are
the IEEE 802.16 and ETSI HiperMAN wireless broadband standards under the concerns about whether HSDPA can deliver 10 Mbit/s
WiMAX banner. The technology could be used to provide fixed and nomadic data rates throughout a UMTS coverage area without a
high-speed data services, and some in the industry believe that it could radical reoptimization of the radio network. While
complement or even compete with 3G data services. WiMAX could also be
used to backhaul cellular networks, particularly micro- and nanocellular base
these challenges are real, it’s probably best not to lose
stations. The Swedish equipment vendor plans to offer WiMAX products as any sleep over them – at least until UMTS networks
part of its Public Ethernet product line and as a complement to wireline begin to attract significant numbers of subscribers who
digital subscriber line (DSL) equipment. The company has stated that WiMAX are willing to pay for high-bandwidth services.
“targets a different [market] segment than 3G”, and that it does not believe
that the technology is appropriate for mobile applications.
Hamish Johnston, Editor
February/March 2005 wir eless.iop.org wireless europe
A N A LY S I S 11
Over-the-air protocols simplify
Tim De Luca-Smith argues that the complexities of device configuration are affecting the growth of data services.
Handset configuration is becoming a real vices based on factors such as the device’s
challenge for the cellular industry. Configur- GSM GPRS capabilities and the WAP version
ation-related problems are often to blame for network delivery protocol to be used.
long delays between the deployment of new The provisioning element of the platform
services such as MMS and the generation of is then free to deliver appropriate settings,
new revenue. While advancements in SIM over-the-air automatic such as WAP, MMS, e-mail and Internet set-
card and terminal technology have paved the provisioning of settings
device detection tings, over the air. This is done using a pro-
SIM or network-based
way for advanced data services, it is still very and transport server tocol that is appropriate for the handset –
difficult for network operators to ensure that OMA, SyncML, Openwave or device-specific
their many subscriber devices are configured protocols, for example.
to access the latest mobile services. Both terminal-switch detection mecha-
Configuration is a challenge because new terminal nisms go some way towards creating a device
mobile phone ownership is in a constant state management infrastructure that encompasses
of flux. Users are changing handsets more fre- the entire lifecycle of a mobile subscription.
quently than ever, and many people have When a new handset-and-SIM combination is detected, In the early days of GSM, a mobile subscrip-
more than one terminal. This makes existing the relevant information is used to determine the device tion was relatively static, but faster handset
methods of device configuration – such as capabilities. The necessary configuration settings can development cycles and the operators’ com-
preconfiguration of handsets by operators – then be sent over the air to the device. mercial need to deploy the latest advanced
inappropriate. A growing number of hand- services mean that subscription management
sets are not purchased from operator-owned SIM in a new terminal – an event called a is a growing challenge.
retail outlets, and are not preconfigured. “terminal switch”. There are two indepen- The slow growth of services such as MMS
Handsets are often being taken from one net- dent methods for doing this: one employs a highlights the need for over-the-air device
work to another by churning customers, or network-based mechanism and the other uses configuration. While much of the blame for
swapped between friends and family. a SIM-based application. the slow uptake of MMS has been placed on
If a handset is not preconfigured, a sub- SIM-based terminal switch detection uses poor interoperability, surprisingly little atten-
scriber must contact the operator and request software resident on the SIM to identify its tion has been given to the issue of device con-
the relevant settings to use the latest services. host terminal. This can be triggered according figuration and its impact on service usage.
In the absence of must-have applications, the to predefined rules – on initial power-up or Conversely, the success of SMS has been
chances of this happening are slim. As a on a weekly basis. Once the application has largely attributed to its ubiquitous nature,
result, a substantial proportion of handsets identified a new terminal, it submits the infor- requiring no manual input of service settings.
on any given network are unable to access a mation over the air to the operator. Network- As subscriber figures in Europe plateau,
full range of services. based terminal switch detection requires a operators are putting more emphasis on cus-
Several European operators have developed specific trigger from within the operator’s tomer retention rather than acquisition. By
new automatic device-configuration plat- bearer network. This trigger can be activated removing the complexities of handset config-
forms, which promise to increase the per- by network events such as a device attaching uration, customers are granted immediate
centage of correctly configured devices in a to the network. It “listens” and extracts infor- access to the operator’s portfolio of revenue-
network and reduce the costs associated with mation about the subscriber and handset. It generating services. There is no need to
preconfiguration. Automatic device detec- then supplies the automatic device configu- contact customer care or to follow set-up
tion and configuration allows an operator to ration platform with terminal switch infor- procedures on the operator’s/handset manu-
identify remotely individual device types – mation according, again, to predefined rules. facturer’s website. This form of customer sat-
and their capabilities – as they become active Once a terminal switch has been deter- isfaction is, of course, key for building loyalty
on the network. It is then possible to send the mined, the information regarding the exact and brand. By simplifying access to interest-
correct settings to a device over the air, elim- device type is passed through a database ing and relevant services, service usage – and
inating the need for end-users to configure called the terminal capabilities repository to revenue – can only go one way. ■
their own handsets. determine the capabilities of the handset.
Automatic device configuration schemes This ensures that the network provides the Tim De Luca-Smith is communications
must first detect when a subscriber uses their handset with the relevant settings and ser- manager at Sweden-based SmartTrust.
wireless europe wir eless.iop.org February/March 2005
A N A LY S I S 13
GPRS leads the way for M2M
The telecoms industry has finally embedding GPRS capabilities in M2M
applications. The UK-based company
woken up to the potential for machine- exploits the modem modules and expertise of
to-machine data communications. the French mobile-phone maker Sagem to
Christos Papakyriacou explains how create a range of modems specifically for
GPRS is driving things forward. M2M communications. While M2M and
wireless remote monitoring are definitely the
Network operators are beginning to realize technologies of the future, there is still more
the commercial benefits of offering data-only development needed to support GPRS,
machine-to-machine (M2M) communica- which throws up challenges to the develop-
tion services in addition to traditional voice- ment of new M2M modems.
and-data services. Specific data-only tariffs Alpha Micro started using GPRS because
are now being introduced, which is a signifi- Alpha Micro’s Trac M2M modem employs GPRS. While it is a widely deployed and recognized stan-
cant shift from the situation two years ago, GPRS is ideal for transmitting small amounts of data, it dard throughout the world, and because it is
when data-only communication was hardly does pose IP-related challenges to M2M developers. a cost-effective method of regularly sending
even heard of, let alone considered something small amounts of data. On the downside,
worth investing in. to the potential of data-only cellular services. GPRS is not the best way to facilitate two-
The growing acceptance of GPRS technol- Indeed, manufacturers are beginning to way communication. When an electronic
ogy is one reason why things have changed. invest in redesign processes to incorporate device is fitted with a GPRS modem, it is not
Until recently, subscribers have been sceptical technology such as GPRS into their equip- automatically allocated with a permanent
of GPRS or misunderstood its potential. In ment. This would allow manufacturers and Internet protocol (IP) address by the mobile
reality, GPRS is ideal for any type of wireless users to communicate with equipment such operator. Once the modem begins to estab-
data communication – including M2M. as photocopiers, vending machines or secu- lish a connection in preparation for transmit-
For example, GPRS technology is perfectly rity systems. ting data, it is then allocated with a
suited to point-of-sale equipment such as a Investment in GPRS by companies outside temporary IP address. This makes it difficult
credit card terminal. Credit-card transactions the cellular communications industry reflects for the user to communicate at will with a
involve the exchange of small amounts of a clear belief in those industry sectors that device in the field.
data, which GPRS is able to handle cost- GPRS is here to stay. After all, many of these
effectively. The terminal can be fully mobile companies employ design and manufactur- Speedy transmission
instead of tied to a telephone line, and unlike ing processes that are much longer and more Fortunately, by working closely with service
current systems that use dial-up modems, costly than those in the mobile phone indus- providers, it is now possible to allocate per-
GPRS is always on, allowing constant and try. Consequently, it is unlikely that they manent IP addresses to units in the field.
rapid communication. would invest in embedding GPRS in their This allows instant access to the device and
products unless they saw a clear competitive enables emergency messages to be sent, for
Saving money advantage in doing so. example to stop trains or change traffic lights.
In the past, data and GPRS services were The range of possible M2M applications is This gives machines a real opportunity to
always tied onto the back of voice SIM cards, staggering: everything from security systems talk to each other.
giving the impression to customers that using and petrol stations to signage and electronic Looking towards the future, 3G networks
GPRS is expensive. In actual fact, a monthly billboards can all be updated, monitored and will expand the possibilities of M2M services.
subscription to a data-only GPRS service contacted using GPRS. Road-traffic moni- Data transmission will be even faster, and it
works out at roughly half the price of a voice toring will be transformed by equipping will be possible to send images and streamed
service. The provision of data-only SIM cards cameras with GPRS. These cameras can then media across cellular networks. With further
by leading operators such as Vodafone is be placed on any road, and still and video investment and support from major network
spurring on the establishment of data-only images can be transferred without the need of operators, the M2M industry has the poten-
cellular services. Vodafone has gone as far as a telephone line. Beyond western Europe, tial to be one of the largest growth markets
to set up a dedicated team in the UK to GPRS is ideal for offering M2M services in over the next 18 months. ■
establish a strategy for the development of developing countries, which lack traditional
data-only services. wire-line communications infrastructure. Christos Papakyriacou is managing director of
The electronics industry has also woken up Alpha Micro has been at the forefront of UK-based Alpha Micro.
wireless europe wir eless.iop.org February/March 2005
A N A LY S I S 15
BACKHAUL particles that constitute fog can cause some
problems for FSO-based systems. Fog parti-
Optical wireless cles act as millions of tiny mirrors that can
reflect and scatter the optical signal. As a
result, fog can reduce the distance range of
systems: sorting optical wireless systems, and dense fog can
limit the operation to less than 100 m.
facts from fiction However, many installed systems have yet to
experience performance degradation due to
fog, even in the worst conditions.
By Jim Cady Incredibly, the myth that FSO-based sys-
Optical wireless systems based on free-space tems can be disrupted by flying birds – or
optics (FSO) offer a secure and cost-effective An optical wireless system in the US capital: free-space even “cook” them with laser beams – persists.
way to backhaul networks, but the technol- optics technology can operate even during the torrential In reality, today’s FSO-based systems incor-
ogy still suffers from a number of myths rain storms that are common in Washington, DC. porate multiple beams, which transmit and
regarding its performance. FSO is a little- receive via as many as four separate paths.
understood technology, and the industry has and prying eyes. Instead, questions tend to This makes it virtually impossible for a bird
to contend with a range of questions such as: focus on network availability. As with any to block a signal, unless that bird is stationary
“do flying birds disrupt the signal?”; “can wireless technology, availability depends on – and the size of a human!
FSO systems work on swaying buildings?”; a number of variables. The weather is a key There is also a common belief that FSO-
and “will falling snow block the beam?” factor for FSO-based systems, and this is based systems fall prey to misalignment when
Modern FSO technology can trace its where the myths persist. buildings sway in the wind or expand and
roots back to the First World War, when mil- Perhaps the most common misconception contract during the hottest and coolest parts
itary organizations needed secure communi- is that optical wireless systems do not per- of the day and night. However, the introduc-
cations systems that did not require cable and form well in rainy weather. The truth is that tion of beam-tracking technologies and mul-
that were able to withstand intentional inter- heavy rainfall – even tropical and monsoon tiple-beam architectures enables systems to
ference or radio-jamming. It was important conditions – do not disrupt communica- easily adjust to building movements that are
in these military applications that commu- tions. Indeed, the larger the raindrop, the less undetectable to the eye.
nications were secure and that the equipment impact it has on optical wireless signals. A related misconception is that FSO-based
was both portable and simple to set up. The Optical wireless systems can remain opera- systems cannot be mounted on cellular tow-
introduction of the laser in the 1960s tional when subjected to driving rains, wind ers. In reality, the same beam-tracking tech-
enabled the transmission of digital informa- and flying debris. This was demonstrated in nologies and multiple-beam architectures
tion as pulses of light. 2004 when Hurricane Charley struck Collier allow a modern FSO system to easily adjust
No-one quibbles over the ability of optical County in Florida. The category 4 hurricane and realign during any movement by a tower
wireless systems to provide high-capacity did not affect the county government’s opti- structure. ■
communications links at a low price-per-bit cal wireless system, which remained opera-
cost, and everyone agrees that the technology tional throughout the entire ordeal. Jim Cady is president and chief executive of
is secure from severe weather, interference Unlike rain, however, the minuscule water US-based LightPointe.
3G S TA N D A R D S great strides have been made in reducing the 450 MHz band. This was previously used for
cost, size and power consumption of these first-generation analogue networks.
Worldwide 3G handsets. Industry analysts at The Yankee
Group predict that there will be about 60 mil-
lion W-CDMA subscribers worldwide by the
Meanwhile, in the US, the nation’s largest
GSM operator is planning to proceed to
W-CDMA. However, Cingular will need to
standards battle is end of this year, making it clear that 3G tech-
nology is becoming a true commercial system.
use its existing spectrum at 850 and
1900 MHz, because the US government is
in a crucial phase In North America, Japan and Korea, the
cdma2000 1XRTT standard has been infor-
mally given 3G status, after the original 3G
not expected to license new spectrum for 3G
this year. The government will begin licens-
ing 3G spectrum for “advanced wireless ser-
By Doug Grant version (cdma2000 3XRTT) proved too com- vices” in July 2006 at the earliest. A further
This year will be a turning point in the ongo- plex to pursue. Two versions of cdma2000 1X complication is that the 3G spectrum in the
ing battle for market share among 3G stan- have been defined. EV-DV supports both US will not be the same as that used in the
dards. Officially, there are five terrestrial air data and voice traffic, while EV-DO is for rest of the world. This is a challenge for
interface standards, but only a few are gain- data only. Both systems are in the commer- chipset and handset manufacturers, who
ing significant commercial traction. cial stages of development. Cdma2000 3G must add yet another band to their handsets
European UMTS operators have recovered technologies offer backward compatibility to support international roaming.
from their financial woes and “buyer’s remorse” with the 2G cdmaOne standard and operate While clear progress towards 3G has been
associated with high licence fees, and have in the same frequency bands, which eases the made in North America, the situation in
deployed a significant amount of W-CDMA transition to 3G. China – which is the world’s largest cellular
infrastructure. Heavily discounted 3G hand- While GSM/UMTS still dominates west- market – remains unresolved. At present, the
sets are now being offered in a bid to move ern Europe, some operators are turning to 1X two primary operators in China, China
users from oversubscribed 2G networks, and EV-DO to make use of spectrum in the Mobile and China Unicom, both use GSM,
wireless europe wir eless.iop.org February/March 2005
with China Unicom also operating some
CDMA networks. In addition, the two wire-
line operators, China Telecom and China
Netcom, operate a quasicellular service called
Little Smart, which is based on the Japanese Will peer-to-peer networks provide greater bandwidth,
PHS standard. This system does not provide or will they put operators in another fine mesh?
the roaming and vehicular-speed mobility of
a true cellular system. Low-cost, low-power
handsets are used, and the cost of a call is 10–
20% of that of a cellular connection. While
not technically or legally a cellular system,
Little Smart has given these wire-line opera- The ubiquity of e-mail and the Internet proves that mesh networks provide
tors a taste of the wireless opportunity, and a remarkably powerful, scalable, and low-cost transmission medium.
they are expected to seek 3G licences.
While it looks certain that four operators
Indeed, the success of the Internet has created a need for new mesh
will vie for 3G licences, the Chinese govern- technologies like BitTorrent.
ment has been silent on the timing and Most nodes on the Internet are bandwidth-limited. Unless a user can
details of how licences will be issued, and afford a Google-sized server farm and a fibre-optic connection to the
which standards will be covered. Most Internet, it is difficult to transfer large quantities of information. BitTorrent
observers now anticipate that the licences will
be issued some time in 2005. spreads the load, with every user hosting part of the content.
The Chinese situation is further compli- Wireless networks suffer from similar bandwidth restrictions. Air
cated by a home-grown Chinese 3G standard interfaces are not getting much better in terms of range, spectral efficiency
that is recognized by international standards or data transmission rates, and the challenges associated with providing
bodies. Known variously as time-division
synchronous CDMA (TD-SCDMA), UMTS-
high-speed data services within reasonably large cells will be around for
narrowband time-division duplex (NTDD) many years to come. This suggests that it may be time to accept that the
or low chip rate (LCR), the technology uses “last-mile” delivery medium – the Internet or
narrower channels than W-CDMA. Unlike
W-CDMA and cdma2000, TD-SCDMA The greatest wireless – is improving only slowly, while the
demands for content grow much faster.
uses the same frequency band for the uplink
and downlink, which makes more efficient challenge facing Mesh networks discard the concept of cells
with base stations at their centre. Instead, each
use of radio spectrum. In China, 160 MHz of
spectrum is reserved for unpaired operation, mesh networks is mobile device becomes both client and server. It
which suggests that the government plans to
issue licences restricted to TD-SCDMA tech- human rather captures data relevant to itself and forwards
data intended for other users. Both the capacity
nology. Many 3G licences awarded world-
wide include both paired spectrum bands than technical and data rate of a mesh network increase with
suitable for W-CDMA and unpaired bands the density of users. However, users must
suitable for TD-SCDMA operation. ensure that their devices are always switched on, and of course the users
The success of any new cellular standard must be present in the first place. As a result, an overlay of traditional cell
is largely dependent on the availability of
handsets that consumers will accept. They sites might be required to ensure service continuity.
must be small, lightweight, last a long time Perhaps the greatest challenge facing mesh networks is human rather than
on a battery charge, and the cost must be technical. Success is contingent on the consensual behaviour of subscribers,
commensurate with the value provided in who must accept that their handset battery will be drained as it forwards
terms of features and convenience. This data to other users. BitTorrent solves this problem through a give-and-take
means that handset chipsets must be avail-
able to support the handset features and cost. approach, whereby a user can only receive content from BitTorrent if they
While W-CDMA and cdma2000 have had a agree to participate as a host.
head start in development and are now in There are also the usual technical problems, including how to overcome
their second or third-generation implemen- transmission delays inherent in multi-hop networks; and how to coordinate
tations, chipsets for TD-SCDMA are now
emerging from the development labs, and
the mesh in the presence of highly mobile users.
consumer-grade handsets are being used in Today, peer-to-peer networks like BitTorrent show that mesh networking
field trials. This will level the playing field as can work from both an engineering and a social point of view. Adapting the
the battle for the airwaves in China begins engineering to wireless will be a lot of fun, but perhaps the first stage is to
in earnest. ■ educate the public about this new way of working. ■
Doug Grant is director of business
development for wireless products at US-based Mark Paxman is a managing consultant at PA Consulting’s Wireless Technology
Analog Devices. Group. He can be contacted at firstname.lastname@example.org.
February/March 2005 wir eless.iop.org wireless europe
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DATA SERVICES 19
Network operating system
will unite telecoms and IT
Operators, equipment providers and the IT industry are joining forces to develop a carrier-network
operating system to ease the deployment of wireless data services. Kieran Dalton explains.
Cellular networks are becom- This architecture is based on
ing increasingly complex, with openly defined interfaces and
each new service or service protocols, which enable the
concept pushing at the limits separation of service logic from
of technology. The evolution the service platform. As a
from simple voicemail through result, systems integrators and
to text and multimedia messag- independent vendors will be
ing, WAP gateways, location able to compete alongside core
centres, push-to-talk servers equipment vendors. In addi-
and so on represents an incre- tion, architectures based on
mental but relentless expansion information technology (IT)
in the diversity of protocols and computer platforms will
and interfaces required to become commonplace.
implement wireless services. A full carrier-network oper-
The challenge for the net- ating system encompasses and
work operator is how to enhances individual vertical
exploit the capability and systems to provide a harmo-
capacity of the network service nized and managed interface to
environment in an economic A carrier-network operating system will speed the development of wireless the telecoms network. In many
manner. The answer lies with a services for business users. ways this reflects the benefits
“carrier-network operating sys- that the UNIX and DOS oper-
tem”. Based on open standards, this architectural approach may ating systems conferred on an emerging computer industry sev-
be more costly than isolated solutions, but it will ultimately be eral decades ago. It provides an abstracted interface to the
more flexible and provide natural scalability. capabilities of the telecoms network, and removes the need for
Historically, new services have been introduced as single- specialist knowledge of network protocols and triggers.
function systems – often described as vertical silos. There has
been no cross-functional capability, and the service silos them- Defining functions
selves have limited connectivity to external resources or data. An operating system provides a set of software functions to
The most obvious examples of this vertical integration are the access capabilities within the network. Defining these functions
intelligent network services, where the service creation, control has been the task of the Third Generation Partnership Project
and switching elements are usually sourced from a single net- (3GPP)/ETSI and Parlay Group standards bodies. These orga-
work-equipment provider. This has resulted in little competi- nizations have defined the Open Service Access (OSA) applica-
tion or innovation in the market for traditional voice services. tion programming interface, which provides a set of functions
This shortcoming was highlighted by analyst firm The Yankee for the individual service capabilities within a network. These
Group at the 2004 European Wireless Leadership Summit in functions range from call control through charging to presence
London, which identified “service enablement” as one of the key and a range of other capabilities. They are supported by tech-
initiatives for mobile network operators. Silo services deployed nology mappings including Standard Java and Enterprise Java
today reflect market immaturity, and make it difficult for oper- environments. This allows OSA to be embedded within stan-
ators to exploit existing investments. Fortunately for newer ser- dard software tools, enabling developers to create applications
vices, such as those based on messaging and location, there is a that include business logic that is supported through the mobile
move away from this tightly coupled relationship, and the basis network. This is a subtle and significant change to creating
for a service architecture is starting to emerge. applications that are simply delivered across the network.
wireless europe wir eless.iop.org February/March 2005
DATA SERVICES 21
The first step is to define the carrier- cial contracts of the telecoms domain.
network operating system and provide the The simplicity offered by Parlay X, in terms
relevant information to third-party service of both service development and control
developers and providers. Initially, this will through OSA/Parlay, has encouraged early
enable systems integrators to extend existing advocates such as the US-based operator
services used by businesses to incorporate net- Sprint to endorse Parlay X as a key tool for
work capabilities and to create market oppor- carrier-network
delivering innovation from the edge of the
tunities for a new generation of service operating system network. The Sprint Business Mobility pro-
providers and independent software vendors. Parlay gramme encourages service providers to inte-
However, in the longer term, network func- grate with the Sprint network to deliver new
tionality must be embedded in any new IT, innovative services to their corporate and
media or telecoms domain. To achieve this, consumer customers. Early advocates of this
it is important that parallel developments model include IT giants such as Microsoft
occur in the IT industry. network resources and IBM, who will encourage operators to
Traditional IT solutions have grown inex- exploit mature products from vendors such as
orably in terms of cost and complexity over Parlay and Parlay X form the core of the Ericsson, Alcatel and UK-based AePONA.
the last decade. However, as development carrier-network operating system. In summary, a carrier-network operating
times and maintenance costs have spiralled, system will provide the basis for service
the focus has shifted towards establishing a new service archi- enablement within telecoms networks. This will create the envi-
tecture that would promote re-use and modularity. As a result, ronment for supplier competition, component re-use and a level
Web services are underpinned by a service-oriented architecture, of service innovation that has been lacking to date. Parlay and
which is a collection of services that can communicate with each Parlay X, with their inherent service-oriented architecture, pro-
other. Each service provides a well defined self-contained func- vide the basis for this network operating system, particularly
tion. Complex services can be realized by coordinating – or with their support for next-generation networks and service
orchestrating – two or more component services. migration through abstraction.
This concept from the IT domain is also shared by OSA/
Parlay, which is a set of standardized, open interfaces for using Future challenges
network capabilities. OSA/Parlay allows client applications to However, there are still issues to be resolved. A true network
create end-user services through combining individual service operating system, particularly one used for a distributed
capabilities. Where OSA/Parlay and Web services differ is in machine such as a telecoms network, requires interrupt sup-
the level of coupling between the client application and the port and processor control. For a telecoms network, this equates
enabling service. OSA/Parlay assumes a tight coupling, using a to the ability to manage multiple asynchronous service invoca-
standard defined interface specification endorsed by 3GPP. Any tions and the feature interaction between these disparate ser-
client application that conforms to this specification may access vices. While vendors like AePONA provide ready-to-use
OSA/Parlay functionality offered by an operator. OSA/Parlay and Parlay X solutions to achieve this, it is impor-
Web services, however, assume loose coupling, where the tant in the long term that they are aligned with the emerging
interface is described publicly in a central directory. Client standards for multiple points of service control. This will main-
applications may retrieve this description and use it to create a tain the modularity and interoperability promoted by Parlay.
connection to the service. Loose coupling allows applications AePONA and other vendors in the Parlay community have
to discover and employ services without prior knowledge of the made clear their commitment to maintaining the currency of
service, thanks to a more descriptive communication protocol. their standards-based solutions over time.
Consequently, tightly coupled applications are more efficient. Similarly, any operating system requires a defined-file struc-
However, the market requirement, driven by the available tools ture and data format. While initial attempts within both Parlay
and software practices, is for loosely coupled solutions. and the Open Mobile Alliance at defining a generic user profile
To extend telecoms functionality into the business domain, have stalled, it is important that data access, if not the data for-
and to incorporate telecoms capabilities into a broad range of mat and storage, becomes standardized. Again, early innovators
services, a carrier-network operating system must be compatible will offer solutions for data correlation and aggregation; how-
with the loosely coupled world of Web services. This is where ever, any long-term solution will require standardization.
Parlay X comes in, as illustrated in the figure. Despite the many challenges, the basis of a carrier-network
Parlay X provides a higher-level abstraction of the base service operating system has been defined, and companies such as
capabilities defined by OSA/Parlay. Each of the Parlay X services AePONA are offering standards-based solutions. The fusion of
offers an individual function that may be wrapped as a distinct disparate service elements into a service enablement layer has
service and incorporated within a Web-services architecture. As been achieved, and benefits are emerging in terms of innovation
it conforms to the publicly defined standards endorsed by 3GPP, and revenues. In embarking on this, it is important to recog-
Parlay X can be thought of as a tightly coupled service that is nize that the network itself is an enabler – it is the services the
delivered using loosely coupled techniques. Thus it is compatible network provides that contain value and opportunity. ■
with the programming methodologies and tools of the business
world, yet retains the control, service agreements and commer- Kieran Dalton is chief technical officer at UK-based AePONA.
wireless europe wir eless.iop.org February/March 2005
New control channels
boost HSDPA performance
HSDPA employs variable modulation and coding schemes to adapt to changes in downlink signal
quality. Faris Muhammad explains the myriad of new control channels that make this possible.
The high-speed downlink incremental redundancy.
packet access (HSDPA) Further enhancements to
enhancement to W- reduce requirements on
CDMA provides a smooth link performance include
evolutionary path to higher L1-based fast H-ARQ and
data rates for UMTS net- transmit/receive (Tx/Rx)
works. HSDPA delivers antenna diversity. Parallel
higher capacity through channels are facilitated by
improved spectral effi- multicode in R5. In R6,
ciency, which provides HSDPA will introduce
higher data rates, shorter antenna array processing
response times and better technologies to enhance
quality of service. It also the peak data rate to about
supports the sharing of 30 Mbit/s. This will
channels between users, involve smart antennas
ensuring that channel using beam forming for
resources are utilized effi- handsets with one antenna,
ciently for packet data. and multiple-input multi-
As part of Release 5 (R5) ple-output (MIMO) for
of the UMTS standard, handsets, PDAs and laptop
HSDPA introduces a new downlink (DL) transport channel computers with up to four antennas.
that supports asymmetric and bursty packet-data services. This In HSDPA, the base station determines the channel quality of
increases practical peak data rates to about 10 Mbit/s and each HSDPA-active handset based on power control, QoS,
improves the DL shared channel (DSCH) throughput com- acknowledge/non-acknowledge (ACK/NACK) ratio and hand-
pared with current Release 99 (R99) channels. set-specific quality feedback. Fast scheduling and link adapta-
This is supported through the introduction of fast and com- tion are then performed promptly depending on the active
plex channel-control mechanisms based on a short fixed-packet scheduling algorithm and the user prioritization scheme
transmission time interval (TTI), adaptive modulation and cod- employed by the base station.
ing (AMC) and fast layer-1 hybrid automatic repeat request A number of additional channels and a layer are introduced in
(L1 H-ARQ). To facilitate this fast scheduling with a per-TTI order to implement HSDPA features. The high-speed shared
resolution that corresponds to the instantaneous air interface control channel (HS-SCCH) is the DL signalling channel that
load, the HSDPA-related medium-access control (MAC) func- carries key physical layer control information. This informa-
tionality has been relocated to the base station. tion enables the demodulation of the data on HS-DSCH and
R5 HSDPA introduces a shared MAC-high speed (MAC-hs) supports the data sent on HS-DSCH in the case of retransmis-
layer and a special high-speed DSCH with the necessary control sion or an erroneous packet. The information includes chan-
channels. This is similar to the R99 DSCH, but without fast nelization code set, modulation scheme, transport block size,
power control. Transmission time is allocated to the handset on H-ARQ process information, redundancy and constellation ver-
a TTI (sub-frame) basis. Modulation, effective code rate, power sion, and new data indicator.
and other transmission parameters can be adjusted dynamically The high-speed dedicated physical control channel (HS-
by the TTI-based AMC. DPCCH) is the uplink (UL) signalling channel that carries the
New technologies in R5 HSDPA include higher-order modu- necessary control data in the UL. These are ARQ acknowledg-
lation schemes and low redundancy coding combined with ments and DL quality feedback information to be used in the
wireless europe wir eless.iop.org February/March 2005
base-station scheduler. It carries an ACK/NACK indication, to modifying the effective code rate, the modulation scheme, the
reflect the results of the cycling redundancy checking after the number of codes used and power per code.
packet decoding and combining. It also carries the DL channel The scheme used by HS-DSCH is based on R99 rate 1/3
quality indicator (CQI) to indicate which estimated transport turbo encoder, but adds rate-matching in order to obtain a finer
block size, modulation type and number of parallel codes could resolution of the effective code rate. To achieve very high peak
be received correctly with reasonable block error rate in the DL. data rates, 16QAM is used in addition to the R99 quadrature
The high-speed physical downlink shared channel (HS- phase shift keying scheme. 16QAM modulation and fast link
PDSCH) is the physical channel that carries the user-specific adaptation can be combined to optimize the instantaneous use
packet data in the DL from the transport channel HS-DSCH. It of the varying radio channel. The variation in the channel can
has a fixed spreading factor of 16 and multicode transmission be tracked almost instantaneously because the TTI is only 2 ms
using up to 15 codes. The peak data rate is 10 Mbit/s range with (compared with 10 or 20 ms in R99), and scheduling and link
16 quadrature amplitude modulation (16QAM). The HS- adaptation are determined for each TTI. 16QAM makes better
DSCH interleaving period TTI is reduced to 2 ms to achieve use of the available bandwidth, but demands more receive
shorter round-trip time between the handset and base station power per bit. Therefore 16QAM is more suited for bandwidth-
for retransmissions. restricted applications (nearer to the base station) than for
With the introduction of HS-DSCH, additional intelligence power-restricted applications.
in the form of a new MAC-hs layer is required so that the base Fast packet scheduling functions are performed by the MAC-
station can control retransmission directly. This expedites hs in the base station. These functions manage the HS-DSCH
retransmission and reduces delay with packet data operation. resources, select the coding/modulation scheme and the Tx
The prime function of the new MAC-hs is to manage H-ARQ power for the HS-DSCH data packets. The handsets that
functionality, scheduling and priority handling. should be scheduled within a particular TTI are determined
The fast power control and variable spreading factor of R99 using CQI reports coming from the handsets. Channel condi-
DSCH is replaced in the R5 HS-DSCH by variable modulation tion-dependent scheduling rather than sequential scheduling
and coding schemes. These cover a wide dynamic range in order can increase the capacity significantly and make better use of
to cope with the varying DL radio and channel quality condi- air interface resources. Fast scheduling also allows guaranteed
tions at the handset. HSDPA adapts to these conditions by bit-rate services using packet scheduling without the need for a
Conference 25-28 April 2005, Lisbon
IIR are delighted to announce the first ever HSDPA event. IIR's Strategically
Deploying will provide a clear understanding of the business case for mobile
operators to invest in HSDPA, the migration challenges, costs and benefits
and the services it will enable.
The conference takes place 26-27 April 2005, Sana Malhoa Hotel, Lisbon.
The week begins with a pre-conference introduction to HSDPA workshop
on 25th April and the main conference will be on 26-27 April. The event
then concludes on 28th with a post-conference technical briefing.
Hot Topics to be discussed include:
■ Determining When, Where And How To Deploy HSDPA
■ Identifying And Overcoming The Strategic And Technical Challenges Of
Migrating From 3G to 3.5G (HSDPA)
■ Assessing How Mobile Operators Can Efficiently Implement HSDPA Whilst
Optimising Earlier Technology Investments
■ Comparing HSDPA With Alternative Wireless Broadband Access
■ Highlighting The Services That HSDPA Will Enhance And Enable And
Assessing How To Maximise ROI And ARPU
■ Planning For Future 3G Network Capacity Requirements: Assessing The
Costs And Benefits Of HSDPA
■ Examining The Predicted Data Rates For HSDPA And Determining To What
Extent They Can Be Achieved In Live Networks
■ Examining The Technical Specifications Of HSDPA PC Cards And Handset
Development And Determining When These Will Be Commercially Available
February/March 2005 wir eless.iop.org wireless europe
dedicated channel. Handsets are prioritized by the scheduler rate processing and HS-DPCCH signalling. The Third Genera-
according to the channel conditions, the amount of data pend- tion Partnership Project (3GPP) has defined a number of hand-
ing in the buffer for each user, the elapsed time for that user set categories. These allow for different levels of handset
since last served, and pending retransmissions for a handset. complexity that are based on a maximum number of supported
The H-ARQ scheme enables the handset to quickly request HS-DSCH codes, minimum inter-TTI interval, L1 peak data
retransmission to compensate for errors resulting from the link rate, ARQ type and modulation scheme. New functionalities,
adaptation process. H-ARQ also offers improved error-rate per- capabilities and features require testing, and therefore a new
formance compared with conventional ARQ. generation of R5-capable test equipment is a necessity.
The handset tries to decode each received transport block Aeroflex has addressed the development needs of HSDPA
and pass the result to the base station. The H-ARQ process handset makers in its 6401 handset test platform. The 6401
allows the base station to quickly respond to a handset request to can emulate a number of HSDPA cells on different carriers with
retransmit. The handset then combines information from the arbitrary numbers of physical channels on each cell. A built-in
previous transmission with the new retransmission, aiming for scalable multichannel fading simulator, additive white Gaussian
success in a second attempt. noise sources and DL channel diversity are supported. This
The base station can choose from two H-ARQ methods, enables the test of HSDPA-capable handsets during both the
depending on the amount of soft memory available at the hand- development and 3GPP HSDPA conformance phases.
set. The first is the soft (chase) combining method, in which the For most applications, traffic in the DL is far greater than
same packets are resent to the handset. This method requires less the UL. However, for peer-to-peer applications such as video
handset buffer memory, and is the only method used at the conferencing, data flows equally in both links. To enable high-
highest data rate. The second method is called incremental quality video to be passed, it is therefore essential to ensure that
redundancy, and involves retransmissions that are not identi- the UL performs as fast as the DL. Work has begun already on
cal. It offers slightly better performance, but uses more handset developing the standards for high-speed uplink packet access
memory because the retransmissions require more processing. (HSUPA), and many of the techniques used in HSDPA will also
This approach is more suited to lower data rates. be used for HSUPA. ■
HSDPA-enabled handsets will be able to perform H-ARQ
operation, multicode processing, HS-SCCH reception, fast data Faris Muhammad is technical consultant at US-based Aeroflex.
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wireless europe wir eless.iop.org February/March 2005
Complexity increases as EDGE
bridges the generation gap
While EDGE radios contain elements of both GSM and UMTS technology, Patrick Morgan
explains that GSM/EDGE/W-CDMA integration can benefit from a radical rethink.
Radio designers are at the front
line of the battle to deliver
more advanced handsets that
offer seamless interoperability
between 2G and 3G networks.
The current drive to employ
the EDGE enhancement to
GSM has added a new level of
complexity to handset design,
because devices must support a
new modulation scheme called
8-PSK, as well as the GMSK
modulation used by GSM.
However, the challenges do
not end with the modulation
scheme. EDGE is a GSM tech- The Aero II transceiver from Silicon Laboratories employs low-IF technology to improve sensitivity.
nology and therefore employs
the time-division duplexing (TDD) approach, whereby an GSM/GPRS handset requires a radical rethinking of the entire
antenna-switch module alternates the radio between transmit radio architecture. On the receiver side, amplitude modulation
and receive modes. This is fine for GSM-only handsets, but (AM) suppression must be achieved in the presence of GSM/
makes it difficult to design the latest dual-mode GSM/UMTS GPRS blockers that are of constant amplitude, while EDGE
devices, which must support the 3G W-CDMA air interface. and W-CDMA blockers are amplitude-modulated.
Instead of using TDD, W-CDMA employs frequency-division In order to broadcast EDGE and CDMA signals, the trans-
duplexing (FDD), whereby the transmitter and receiver work mitter must be highly accurate to guarantee high linearity from
simultaneously via a duplexer. the baseband to the antenna. The transmitter must also pro-
W-CDMA employs the QPSK modulation scheme, which vide high power-added efficiency. A key feature of FDD is the
involves both amplitude and phase modulation. GSM/GPRS/ simultaneous operation of the transmit and receive blocks,
EDGE channels are spaced at 200 kHz, whereas 5 MHz are used which means that the blocks must work well together. In par-
in W-CDMA. Finally, the channel bit rates for GSM/GPRS/ ticular, the designer must ensure that the receiver can suppress
EDGE are based on a 13 or 26 MHz clock, whereas W-CDMA blockers produced by the transmitter.
uses a chip rate based on a 19.2 MHz clock. And if this wasn’t
complicated enough, in order to support worldwide roaming, Detecting offsets
handsets must function in at least five frequency bands – 850 GSM/GPRS handsets often use direct-conversion receivers,
and 900 MHz, and 1.8, 1.9 and 2.1 GHz. which have a low component count and hence a low cost.
While this diversity of standards and specifications can seem However, direct conversion can suffer from DC offsets in the
overwhelming, there are two important factors working in the baseband. This problem arises from a variety of sources includ-
designer’s favour. First, both EDGE and W-CDMA use linear ing inherent circuit offsets, self-mixing of the local oscillator, ref-
modulation schemes, so some of the challenges for designers of erence clock harmonics, or blockers received at the antenna.
multimode handsets can be addressed in a common approach. Some DC offsets can be detected and suppressed by a calibra-
Second, chip manufacturers are using silicon integration to tion procedure. However, AM blockers such as those introduced
address some of the complexity-related issues and create credible by EDGE and W-CDMA are extremely difficult to detect, and
technology for the radio portion of advanced handsets. usually cannot be removed by filtering without some loss in
Integrating EDGE and/or W-CDMA functionality in a the desired signal.
wireless europe wir eless.iop.org February/March 2005
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A more robust approach to only architecture currently in
the suppression problem is to 850 RFIA LNA
production for both GSM/
prevent DC offsets from reach- 900 + PGA
+ I EDGE and CDMA/WCDMA
ing the baseband processor. 1800 handsets. Unlike polar modu-
RFID LNA Q
This is done by replacing the 1900 + PGA ADC
+ PGA Q lation, which requires a special
direct-conversion receiver with LNA
or customized PA, the linear
a low-intermediate frequency 0 / 90 LOW-IF digital transmitter architecture is
(low-IF) receiver architecture VCO + frequency compatible with PAs from
as illustrated in the figure synthesizer multiple vendors.
(right). Unwanted DC offsets As multimode handsets
are mixed away to the interme- DC offsets in a GSM/EDGE/W-CDMA can be prevented using a digital low-IF become more common, radios
diate frequency, which allows receiver architecture. This improves the receive sensitivity of the handset. based on a digital low-IF
them to be filtered out. This receiver and a linear transmit-
improves the receive sensitivity because it precludes the need ter should deliver excellent performance. In addition, silicon
for the baseband DC offset correction algorithms used by direct- vendors are likely to continue their integration efforts to reduce
conversion receivers. Measurements on production handsets the total handset radio bill-of-materials (BOM) to a value simi-
show that low-IF techniques can improve sensitivity by lar to that of GSM/GPRS.
0.5 dB or more, with negligible impact on blocking perfor- Chip makers are pursuing two different approaches at the
mance. Silicon Laboratories’ Aero II transceiver uses this low- radio front end. One approach involves combining the switch/
IF receiver architecture. duplexer and receive-path SAW filters in a single package, and
The offset phase-locked loop (OPLL) is the most common the other is the integration of the PA and switch/duplexer. At
transmitter architecture in GSM/GPRS handsets. This tech- the transceiver level, the complete integration of sensitive com-
nique meets the demanding modulation-spectrum requirements ponents – including loop filters, VCO tuning components, and
for GMSK by doing an excellent job of filtering in-band noise. a digitally-controlled crystal oscillator – improve performance
Out-of-band noise is typically suppressed by the additional fil- by shielding the local oscillators from external noise sources.
tering of the transmitter voltage-controlled oscillator (VCO) This design also eliminates costly high-precision discrete com-
phase noise to meet the receive band noise requirement. ponents such as film capacitors from the radio BOM.
However, the OPLL only supports phase modulation, while As transceiver integration
EDGE and W-CDMA require amplitude modulation to imple-
ment 8-PSK and QPSK respectively. Therefore with both the
RF designers face extends further into the future,
CMOS manufacturing tech-
transmitter and the receiver, designers must consider the entire
radio architecture when creating multimode handsets.
unprecedented nology could eliminate mixed-
signal functions from the
challenges in baseband processor. A single
mixed-signal CMOS trans-
One way forward is to deploy a polar-loop transmitter, in which
the signal is applied to the power amplifier (PA) through sepa-
designing radios ceiver would include the
rate amplitude and phase feedback pathways. A variant of polar for multimode converters and filters, the trans-
loop called polar modulation operates without feedback, which mit-path digital-to-analogue
eliminates the need for a coupler. handsets. converters and filters, auto-
Both schemes require precise matching of the amplitude and matic frequency control, and
phase delays through the feedback loops. Simulations indicate PA ramp digital-to-analogue converters and front-end control
that the modulation spectrum will not meet the required speci- drivers. Such a transceiver could interface directly to an all-digital
fications at the 400 kHz offset if the delay mismatch is approxi- baseband processor via a high-speed digital interface such as
mately 30 ns or greater. However, a maximum 30 ns time DigRF. This would allow the baseband processor to be more eas-
constant constrains the filter bandwidth on the transmitter ily scaled and manufactured by the latest process technology,
VCO to be at least 5 MHz, which limits suppression of the out- reducing the overall cost and increasing the performance.
of-band VCO phase noise. While it is true that RF designers face unprecedented chal-
An alternative approach involves the addition of a companion lenges in designing radios for multimode handsets, solutions
chip and is architecturally simpler than polar modulation. The do exist for most of these problems. New architectures and
companion chip is added to an existing GSM/GPRS transceiver devices will support the wide range of standards used for mobile
and comprises a direct up-conversion mixer and a variable gain data. As silicon integration continues, it looks likely that CMOS
amplifier. In GSM/GPRS mode, the companion chip is manufacturing technology will eventually bring multimode to
bypassed. However, during EDGE or W-CDMA operation, the same price point as standard GSM/GPRS handsets, and
the OPLL is unmodulated and held in continuous-wave mode. along the way should provide an easily implemented solution
This acts as a local oscillator, which up-converts the baseband to ease the RF designer’s troubles. ■
I/Q signal. This architecture preserves the excellent GSM/GPRS
performance of the OPLL, while also positioning the radio to Patrick Morgan is Wireless Product Marketing Manager at
take advantage of future trends in silicon integration. This is the US-based Silicon Laboratories.
wireless europe wir eless.iop.org February/March 2005
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Push-to-talk will reap the
benefits of standardization
Operators must encourage standardization in order to enjoy the financial rewards of
providing push-to-talk services, explains Niclas Medman.
Push-to-talk (PTT) represents far, but they have not followed
a golden opportunity for any standard, and therefore do
mobile operators to deliver not support interoperability.
innovative services based on While users may be happy
standardized mobile technol- with their service today, there
ogy that can be adapted and could be serious problems on
reused for a range of future the horizon. Users of propri-
mobile multimedia services. It etary PTT systems are often
has the potential to become a restricted to handsets from one
major new revenue source for manufacturer, and are unable
European operators, providing to interconnect with other
a way to boost traffic on their operators’ networks. Operators
existing data networks without with these proprietary systems
the need for large up-front may find that compatible net-
capital investment. work equipment is available
PTT services enable mobile from one vendor, and ulti-
phone users to communicate mately they could be limited
“walkie-talkie” style with indi- in their ability to expand or
viduals or groups of people. develop PTT services.
Commercial PTT services are The industry began to
available in a number of mar- address these issues in August
kets, especially in the US. Else- PTT services allow users to stay in touch at the push of a button. They also 2003, when several leading
where, activities are still more represent an important step in the development of voice-over-IP services. infrastructure and handset
focused on trials and small- vendors proposed a new multi-
scale service introductions. The wider global uptake of services vendor open-industry specification called PTT over Cellular
has been held back by the preponderance of operator-specific (PoC). This was done in collaboration with industry standards
services, a limited number of handset suppliers, and the fact that bodies, and the specification was submitted to the Open Mobile
sometimes a new dedicated radio or core network must be set up Alliance (OMA).
to offer PTT. To overcome these problems, operators must
deploy systems that address the vital issues of interoperability, Setting standards
end-to-end performance and potential for future development The set of PoC specifications uses a subset of the Internet pro-
on their existing networks. tocol (IP) multimedia subsystem (IMS), as specified by the
PTT technology is now entering standard GSM/GPRS/ 3GPP (for GSM/GPRS) and 3GPP2 (for cdma2000) industry
EDGE, W-CDMA and cdma2000 networks via the relatively bodies, ensuring interoperability and scalability. IMS can also be
straightforward introduction of application server, signalling, used to offer new, revenue-driving services, as well as to enhance
subscriber management and media-handling functionality in existing ones by adding more IMS components if needed.
the network. The relevant equipment can be installed in the Phase 1 of the specifications defines how access-independent
same rack. However, there are a number of critical factors that PTT services should be implemented in standard GSM/GPRS/
must be addressed in order for PTT services to be a long-term EDGE and cdma2000 networks. This ensures that a variety of
mass-market success. terminals can interconnect with a PoC system. Phase 2 builds on
Achieving the standardization and interoperability of PTT the Phase 1 specification by adding network-to-network inter-
technologies and equipment is a fundamental requirement for connect and presence capabilities. Work is progressing within
success. Several different PTT systems have been rolled out so the OMA, and the first release of the PoC standard is based on
wireless europe wir eless.iop.org February/March 2005
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path from equipment installed today to future Being an IP-based strategic advisory service company North-
stream has calculated that, in the case of
technologies is of crucial importance to cellular
operators. The lowest-risk scenario is to start service that uses GSM/GPRS networks, the investment required
in the radio access network for a circuit-
with a Phase 1 PoC installation and then imple-
ment software upgrades in a smooth, stepwise
network resources switched PTT solution is more than six times
that needed for a packet-switched PoC solution
It is essential that there are a variety of PoC-
very efficiently with equal performance.
The potential mass market for PTT is too big
compliant consumer products available that are
properly verified and tested. This will ensure
makes PTT a very to ignore, and too important to get wrong from
a technology perspective. Standardization,
that users can use PTT services wherever they
travel, and that operators can offer a wide range
cost-effective openness and multivendor collaboration are
vital for success. That is why several vendors,
of standards-compliant devices to private and
business users. But most importantly, PoC stan-
service for the including Ericsson of Sweden, are working to
ensure that PTT services are not only standard-
dardization is the only way to remove restric-
tions on whom a user can contact by supporting
operator to deliver. ized, but that they also meet consumer expecta-
tions for ease of use, performance and cost.
different handsets and different networks. Ericsson itself veri- The best way to ensure PTT success is to focus effort on key
fies terminals that follow the PoC specification through its issues – interoperability, end-to-end performance, and rapid roll-
Multi Vendor Terminal Verification offering. Solutions compli- out – that have the biggest overall impact on the uptake of PoC
ant with the PoC specification will offer broad service availabil- technology. To help meet these industry-wide requirements,
ity that is important for rapid service uptake through both Ericsson has established PTT hosting centres around the world.
interoperability and roaming. These run PoC services for operators and comprise an IMS core
Performance is another key issue. To control call set-up per- and PoC application server. The company has a global network
formance and latency in relation to PTT services, there are end- of interoperability testing centres, where any manufacturer can
to-end network performance issues that should be considered. test its PoC-compliant PTT products. A full PoC specification
Using the PoC specification is one way to ensure that PTT ser- set and a PoC Test Tool suite are available online from Ericsson.
vices will perform well today and into the future, as IMS is These resources can be downloaded free of charge by develop-
designed for mass-market, real-time multimedia services. ers and manufacturers for design and interoperability testing.
The OMA PoC is based on “always on” packet data technol-
ogy (compliant solutions offer near-instant connections for Planning for the future
users and do not use up valuable network capacity as circuit- Implementing PTT services based on the PoC standard will
switched connections would) when users are not actually talk- help operators to avoid single-vendor dependencies and open up
ing. As an IP-based specification, PoC offers almost unlimited opportunities for roaming and interconnect agreements. Putting
opportunities for service evolution. Of course, being an IP- an open, standards-based mobile multimedia platform in place
based service that uses network resources very efficiently makes also helps to reduce the cost of implementing future IP-based
PTT a very cost-effective service for the operator to deliver. mobile services, through the reuse of IMS components.
For most users, latency is unlikely to be a major issue as long The rationale is to introduce multimedia services using the
as it is kept below a threshold of, say, a few seconds. Ensuring common IMS infrastructure and service enablers. This approach
such threshold values, however, will be critical, and IMS-based confers the advantage that most of the main IMS architecture
PoC systems employ measures to do this. Latency can be mini- elements are already in place, including a rich set of essential
mized in other ways, for example through tuning the radio net- infrastructure and service enablers. Operators are able to imple-
work to optimize performance for packet-based voice services. ment a real-time, mass-market system for mobile multimedia
Operators planning to implement PTT services should carry in service-driven, business-motivated steps. Operators also get
out a radio network audit to determine how the network will an early route to fixed-mobile convergence, without the need for
be affected by the increased traffic over the packet bearers. This architectural changes. The functionality to support new ser-
includes performing latency measurements to ensure adequate vices and infrastructure will be added to PoC capabilities over
radio network performance. time in order to build up the packet-switched multimedia ser-
An end-to-end network performance audit – encompassing vice offering in line with market demands, and in accordance
everything from the PoC application server, through core and with standards defined by bodies such as 3GPP and OMA.
access networks, to PoC clients – provides an objective assess- When operators come to select the technical solution on
ment of network performance and behaviour in relation to which to launch and develop their PTT services, they should
industry standards and key performance indicators. As well as consider the bigger picture. With an open, interoperable, scal-
measuring and analysing the traffic characteristics and services able solution, they can capitalize on the mass-market opportu-
to be introduced, the end-to-end audit also helps to ensure that nity for PTT services, and have a platform for developing new
existing traffic is considered and protected. mass-market multimedia services in the future at minimal cost
As well as offering more efficient network utilization and bet- and with the shortest possible time-to-revenue. ■
ter potential for development, PoC packet-based solutions are
also less costly to implement than circuit-switched ones. The Niclas Medman is senior marketing manager at Ericsson of Sweden.
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Demand for indoor coverage
Fibre-optic cable will play a key role in ensuring that cellular voice and data services
are available throughout large buildings. Nadya Anscombe investigates.
When spectators at the 2004 remote end. Most remote units
Olympic Games in Athens comprise an optical-to-RF
tried to use their mobile converter, an RF amplifier, a
phones, they were often disap- duplexer and RF ports. The
pointed by the poor connectiv- latter are connected to a stan-
ity. Andrea Casini of the radio dard coaxial cable and ulti-
frequency (RF) equipment sup- mately to the antennas. The
plier Andrew blames the poor remote units are small, light-
service on the fact that the weight, easy to install, and
venues did not have a radio- maintain and consume mini-
over-fibre distributed antenna mal energy.
system (DAS). “At the Athens A key feature of fibre-optic
Olympics, network accessibil- systems is their extremely high
ity was poor with a dropped- bandwidth. This allows radio-
call rate of around 20%,” he over-fibre systems to simulta-
says. The Sydney Olympics in neously transport a wide range
2000 used Andrew’s Britecell of frequencies and air interface
DAS system. “The dropped- standards. These can range,
call rate was less than 1% in for example, from GSM at
Sydney,” says Casini. 800 MHz to wireless local-area
At the Sydney Olympics, all network (WLAN) at 2.5 GHz.
the base stations were housed Radio-over-fibre is currently
in one building, and remote used to provide wireless cover-
units were located throughout age within large buildings such
all venues. Singlemode optical as airports and corporate head-
fibre connected the remote quarters. While operators are
units to a rack of electronics increasingly focused on filling
that was located with the base Installation of radio-over-fibre equipment: the technology can be used to coverage gaps, they are finding
stations. “It was a very power- connect remote antennas to centrally located base-station equipment. that macro base stations are
ful system because coverage often unable to cover these
could be switched instantaneously between venues, depending buildings. This is especially true for 3G networks, which employ
on where the demand was coming from,” says Casini. higher-frequency signals that have difficulty propagating from
“Coverage could easily have been provided using a macro base outdoor base stations to the inside of large buildings.
station, but the problem was capacity, and for this, the radio- Today, in-building equipment sales are still relatively low
over-fibre DAS was the ideal solution.” compared with macro infrastructure. However, the increase in
popularity of data services in 3G networks, combined with a
Improved efficiency growing interest among operators to tap the lucrative corporate
Radio-over-fibre technology has been around for about 10 years, market, has led to a greater interest in radio-over-fibre systems.
but is only now beginning to gain popularity. It involves taking The growing ubiquity of indoor WLAN coverage has been
an RF signal, converting it to an optical signal and sending it another key driver for two reasons: WLAN systems can benefit
over optical fibre to a remote unit where it is converted back to from radio-over-fibre connectivity; and the growing popularity
RF. A key benefit of radio-over-fibre technology is that it sim- of WLAN is forcing cellular operators to improve their indoor
plifies the remote antenna unit. Most implementations elimi- coverage or lose data customers to WLAN providers.
nate the need for a local oscillator and related equipment at the The US-based analyst firm ABI Research believes that in-
wireless europe wir eless.iop.org February/March 2005
building solutions will exhibit renewed growth after several years The main obstacle to growth in in-building systems is money,
of relatively flat performance. ABI’s 2004 report In-Building says Wilson. Not the cost of the system, but deciding who is
Wireless Systems predicts that global revenues from in-building financially responsible. “It is often difficult to decide who
wireless systems will grow from $664 million in 2003 to should pay for what and how the profits are split,” he says.
$993 million by 2009, representing a six-year compound annual There are many people involved – the service provider, the
growth rate of 6.9%. ABI believes that in-building coverage is building owner, the tenant and so on. “Most service providers
evolving from a “nice-to-have” to a “necessity”, because customers are very reluctant to share profits, but not all buildings are suited
expect voice and data services wherever they happen to be. to a network used only by one carrier, especially if there are mul-
Andrew’s Casini agrees: “In my experience, operators are often tiple tenants in one building,” adds Wilson.
sceptical about in-building networks at first These complications are illustrated by the
because their business case is weak. But once
the network is in, payback time is always much “I think there is a recent move by BT to provide in-building
GSM infrastructure in the UK. The equipment
quicker than anticipated because until the net-
work is in place it was difficult to predict the pretty good chance will be installed in private business premises,
but would be owned and backhauled by BT.
amount of demand there would be. We have
found that if coverage and capacity are good,
that the Beijing However, BT does not own a GSM licence in
the UK, so the company intends to lease the
people will use the service. For example, the
networks we have installed in cruise ships,
Olympics will use equipment to GSM operators.
where the base station is connected via a satel-
lite link, have proved very popular.”
the latest telecoms An attractive technology
Despite its growing popularity, it will be several
Radio-over-fibre technology is ideal for large
structures such as cruise ships or large office
technology, and this years before the radio-over-fibre equipment
market reaches its full potential. It is currently
buildings. For smaller buildings, the RF signal
can be distributed via coaxial cable, but signal
is radio-over-fibre.” estimated that less than 10% of very large office
buildings contain in-building systems, but with
loss is a problem with long cable links.
Historically, the in-building wireless market
ABI Research’s continued demand for high data-rate services,
this looks set to change.
has been dominated by passive repeater/coaxial Lance Wilson And even when all large venues have in-
cable systems. In these installations, the elec- building systems installed, there are many other
tronics and active system components are concentrated at the applications for radio-over-fibre technology. It can be used in
base station or repeater, and the signal is distributed via coaxial the implementation of “base-station hotels” where base-station
cable. Recently, active systems based on radio-over-fibre tech- equipment for a number of cells (macro or otherwise) is con-
nology have begun to capture a greater share of the in-building centrated at one site, and signals are fed to antennas at differ-
market. Fibre is used to transport digital signals to modular ent locations. This arrangement can be very attractive in dense
remote units. These contain electronics to convert the digital urban environments, where cells are closely spaced and it can
signal to RF, which is then transported via coaxial cables to be difficult – or very expensive – to house telecoms equipment.
nearby antennas. In many cases, in-building solutions are now Hotels could also facilitate the sharing of base-station equip-
hybrid systems, which consist of both active and passive com- ment among operators.
ponents and feature high-powered DASs. Because optical fibre is immune to RF interference, radio-
Lance Wilson, director of wireless research at ABI Research, over-fibre technology is attractive for security applications. It
believes that hybrid systems that will see the most growth can also be used in fixed wireless networks as well as temporary
because they provide an evolutionary upgrade path. “Because in- networks, for example for the military or emergency services.
building systems have historically been passive systems, when So will the next Olympic Games have a radio-over-fibre sys-
more data [throughput] is required, logistics often mean that tem? “I think there is a pretty good chance that the Beijing
hybrid systems are the best solution,” says Wilson. Olympics will use the latest telecoms technology, and this is
ABI estimates that the penetration of radio-over-fibre in- radio-over-fibre,” says Wilson. “If I were a wagering person, I
building systems will grow from 18% of the total in-building would bet on it.” ■
market in 2003 to 46% in 2009. Annual passive systems
deployed are expected to decline in the same time period. Nadya Anscombe is a technology journalist based in the UK.
Free subscriptions are available at:
February/March 2005 wir eless.iop.org wireless europe
PRODUCT FOCUS 37
DSP takes GPS to a new level
By Joseph Blanda of CEVA memory based implementation, a manufacturer
Digital signal processing (DSP) technology host processor system & AMBA BUS selects a DSP core appropriate for the appli-
(net assist/ peripherals
provides a clear path forward for addressing nav functions) cation and integrates it into a chipset. This
challenges in the development of small, host I/F
reduces both the power and size of the GPS
powerful global positioning system (GPS) peripheral UART or DPRAM implementation, freeing up these valuable
technologies that have minimal power UART resources for other multimedia applications.
requirements and are capable of supporting CEVA DSP data bus
data RAM Performance is also enhanced with a reduc-
all cellular standards including GSM, GPRS, (real-time
tion in CPU clock speed and random-access
CDMA and W-CDMA. According to Will search/track)
memory requirements. The battery life of a
Strauss, president of US-based market analyst RF
GPS channels sample DSP implementation is up to three times
(entire search RAM
firm Forward Concepts, a DSP-based GPS space) longer than previous receivers, even with
implementation benefits the handset manu- continuous tracking mode when GPS signals
facturer as well as the consumer. “It solves the CEVA’s DSP-based GPS implementation has minimal are sampled once every second.
most critical challenges of cost and power power and memory requirements when compared with Another key feature of CEVA’s DSP imple-
and for the end-user, it delivers a nearly traditional CPU-based designs. mentation is that it can operate either
instant and incredibly accurate location fix, autonomously or in assisted GPS (A-GPS)
which is vital for location-based services both speed and sensitivity. Thanks to sophis- mode. The latter involves the exchange of
adoption and usage,” he says. ticated satellite acquisition algorithms, appli- GPS-related assistance data over the cellular
Using industry-leading DSP cores – such as cation processing is minimized. network. This is a major improvement over
those produced by US-based CEVA – a com- The system can achieve a time-to-first-fix of systems that cannot operate without assis-
plete GPS chipset can be produced for less 2.5 s or faster at a –147 dBm signal level. This tance data. In autonomous mode, special
than $3. This includes the radio frequency complies with the E911 mandate in the US algorithms for decoding data from low-level
component. A DSP-based solution also min- and with other emergency services standards. signals allow performance down to –150 dBm.
imizes both the power requirements and the At –155 dB, the time-to-first-fix is 8 s or Below this level, assistance data is used to
overall size of the implementation (see figure). faster, which is acceptable for location-based achieve the ultimate sensitivity. In A-GPS
CEVA has developed and implemented the services (LBS) and location-sensitive services. mode, the system can operate in either hand-
industry’s first DSP-based GPS technology An outdoor/open-sky accuracy of better set-assisted or handset-based mode.
for mobile devices such as handsets and PDAs. than 5 m can be achieved at –130 dBm, and Many leading manufacturers are migrating
Already available for integration into cellular an urban canyon accuracy of better than to DSP-centric GPS implementations.
handsets and other wireless GPS systems, it 10 m is possible at –135 dBm. Indoors, 20 m CEVA is moving with them, and has recently
delivers instant and exceptionally accurate or better can be achieved at –148 dBm. The introduced its 10th generation GPS solution.
location information to within 5 m outdoors, maximum tracking sensitivity deep indoors is Among the business areas that have benefited
and reduces the time required to determine an –158/159 dBm. from DSP-centric GPS are mobile terminal
location – called the time-to-first-fix – to 2.5 s. Previous generations of GPS receivers were and other device chipsets, telematics, road-
In continuous tracking mode, positional infor- based on hard-wired components and a cen- toll systems and PDAs, with more to come.
mation can be updated up to once a second. tral processing unit (CPU) core. These www.ceva-dsp.com
A DSP-based GPS receiver enjoys signifi-
cant performance improvements in terms of
required higher clock speeds and significant •
Visit CEVA at 3GSM World Congress
memory to function effectively. With a DSP- 2005, exhibit stand E16 (Hall 2).
the desire among telecoms as long as GPS applications do more orbiting satellites
GPS challenges regulators to require cellular
operators to provide the location
not adversely affect other
functionalities within a mobile
20 000 km away.
The distance from each satellite
Large buildings, urban canyons of handsets making emergency device (such as call quality or is determined in 2.5 s, and this
and vehicle interiors are places calls, is also driving GPS battery life), users can be more information is used to calculate
where GPS technology can technology forward. easily converted and can become the user’s position to within 5 m.
struggle to work. Unfortunately, For cellular operators, the more GPS users for life. This is done using sophisticated
mobile-phone users spend much accurate a positioning system is, GPS struggles in certain trilateration algorithms –
of their time in such places, and the stronger the business case for situations because the signals are trilateration is essentially the 3D
this is forcing the GPS industry to LBS such as concierge services, much weaker than those from equivalent of 2D triangulation.
develop new technologies that road assistance, mobile cellular base stations. A GPS user And to complicate matters
can meet the growing demands of commerce and advertisements. in London, for example, would further, the received signals may
the cellular industry. On the For subscribers, prompt and receive several radio signals have bounced off nearby
applications side, the growing accurate services add new value simultaneously. These signals are buildings or other structures – or
interest in compact and to their mobile devices and very weak, buried in thermal may only result from partial
integrated LBS, combined with improve their lifestyle. Ultimately, noise, and come from four or satellite coverage.
wireless europe wir eless.iop.org February/March 2005
3GSM P R E V I E W
RFS Optimizer antenna
system eases 2.5/3G roll-out
Described as a sleek all-in-one cellular
antenna assembly, the RFS Optimizer will
be unveiled at the 3GSM World Congress
by Radio Frequency Systems (RFS). The
system comprises an antenna, tower-
mounted amplifier (TMA) and antenna-tilt
control unit (ACU). According to
Germany-based RFS, the assembly was
designed to reduce the cost and time
associated with cellular base-station site
acquisition and antenna installation.
The one-body tower-top system is fully
assembled and tested at the factory. RFS
says this can reduce site installation times by
up to 40% compared with a system that According to RFS, this ensures that tower or 2 m antennas.
employs discrete components. Optimizer and wind loads are kept to a minimum. RFS is also unveiling a new high-
Plus can accommodate both RFS and most Several versions of the assembly will be performance micro base-station antenna.
other popular commercial TMA launched at 3GSM: high-band broadband The Optimizer operates in the 1800, 1900
technologies. versions operating at 1900–2170 MHz, and and 2100 MHz frequency bands and is
The entire assembly is less than 1.5 kg multiband broadband versions covering 0.7 m in length.
heavier than an equivalent cellular antenna 880–960 MHz and 1710–2170 MHz. Both Stand G2 Hall 2
alone, and less than 500 mm longer. of the versions are available with either 1.3 www.rfsworld.com
achieved by combining real-time spectrum frequency bands.
Wireless analyser supports analysis with high-performance and flexible The chipset comprises three chips, and is
TD-SCDMA 3G standard modulation analysis. The triggering,
seamless capture and advanced time-
based on Agere’s Sceptre architecture. The
size of the chipset has been minimized by
correlated multidomain analysis capabilities integrating the baseband processing and
of the WCA200A are said to simplify the power management functions. This high
process of characterizing and level of integration also facilitates the use of
troubleshooting a TD-SCDMA device. slower clock speeds and reduces the leakage
According to Tektronix, the software current. This reduces energy consumption
allows the WCA200A to detect all relevant and results in a handset talk time of up to
changes in the TD-SCDMA signal that 4 h and standby time of up to 300 h.
occur during the call-setup and handover Passionata Yacht
processes. www.ager e.com
Stand B23 Hall 1
ZTE debuts W-CDMA handset
Chipset supports seamless portfolio at 3GSM 2005
The WCA200A wireless communication EDGE/UMTS handovers ZTE is launching its latest portfolio of
W-CDMA handset and infrastructure
analyser from US-based Tektronix has new A chipset and software for use in dual-mode equipment at 3GSM 2005. The Chinese
software that supports the time-division UMTS/EDGE handsets will be company is showcasing three W-CDMA
synchronous CDMA (TD-SCDMA) 3G demonstrated by Agere Systems at 3GSM. phones at the exhibition – including the
standard. According to Tektronix, designers According to the US-based company, the F808, which is claimed to be the world’s
of TD-SCDMA components can use the Sceptre HPU enables the seamless smallest 3G handset.
analyser to perform real-time spectrum handovers between UMTS and EDGE On the infrastructure side, the company
analysis using standardized, automated one- networks. will be demonstrating the 3GPP-compliant
button tests. These are defined according to The product includes a dual-mode V.3 product range. V.3 is said to offer an
measurement methods and limits defined software core that is based on a GPRS/ extended feature range and support
by the TD-SCDMA standard. EDGE protocol stack that has already been increased traffic, when compared with
The WCA200A combines real-time incorporated into millions of wireless previous versions. ZTE also says that the
spectrum analysis and vector-signal analysis handsets. The chipset can support UMTS new equipment can reduce operating
to support the development of 3G data rates of up to 384 kbit/s and EDGE expenditures, and offers a high level of
components, network and end-user data rates of up to 220 kbit/s. The system reliability.
equipment. Tektronix says that this is works in the 850, 1800 and 2100 MHz V.3 retains all the basic UMTS R99/R4
February/March 2005 wir eless.iop.org wireless europe
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pr c CS
3GSM P R E V I E W
Advanced architecture Triband modules use Matrix
supports VoIP requirements to determine location
US-based Continuous Computing will be The ITM338 and ITM339 triband
showcasing its Advanced Telecom GSM/GPRS modules from TTPCom will
Computing Architecture (ATCA) products be on show at 3GSM. Designed for use in a
at 3GSM. The core-network systems are range of wireless terminals, including
said to allow cellular operators to address the machine-to-machine applications, the
performance and scalability requirements of modules employ Matrix location software
voice-over-IP and 3G networks. from UK-based Cambridge Positioning
The technology is designed for use in the Systems (CPS).
development of a range of network elements According to CPS, Matrix can determine
including mobile switching centers, the location of the terminal to an accuracy
signalling gateways and home location of better than 100 m. The modules use
features of V.2, and provides an registers. ACTA components can also be existing GSM network infrastructure to
evolutionary path to future UMTS used to create serving GPRS service notes transfer handset location information to the
standards based on the Internet protocol and gateway GPRS service nodes. network using standard GPRS or SMS
(IP). As such, it uses complete and Stand D4 Hall 2 protocols. CPS says that this results in a
optimized IP software/hardware structures. www.ccpu.com significant reduction in the cost of rolling
Other advanced technologies and features out a high-accuracy mobile location
include support for omni-transmitter sector technology. Matrix also works effectively
receivers (OTSRs), four-fold receivers, Dual-band amplifier covers indoors and in urban environments where
transmission diversity and high-speed
downlink packet access (HSDPA). EDGE and HSDPA interfaces satellite-based systems struggle.
Stand C21 Hall 1 (CPS)
The V.3 range of base-station equipment is TriQuint Semiconductor will be exhibiting Stand A3 Hall 1 (TTPCom)
available in macrocell and microcell versions its TQM7M6001 dual-band UMTS power www.ttpcom.com
for indoor and outdoor environments. amplifier module (PAM) at 3GSM. The
Remote RF units and baseband pooling device can be used to create the multimode
technology are also available. handsets that use one antenna to deploy the USIM card boosts phone
Stands H1 and H2 Hall 3
GSM, EDGE, UMTS (compressed mode)
and HSDPA air interfaces. handset memory capacity
Described as the the first USIM card to
combine 128 Mbyte of secure, high-capacity
Antenna modules reduce memory with high-speed data protocols for
cost and complexity multimedia data, the GIGAantIC USIM is
a new release from Oberthur Card Systems
Described as a range of fully integrated of France.
radio antenna modules, the Radionova The card employs MegaSIM memory
product line will be exhibited at 3GSM by technology from US-based M-Systems, and
Antenova. The UK-based company says that will be formally launched and demonstrated
the modules can be used to reduce the cost at 3GSM. Offering about 1000 times the
and complexity of mobile phones and memory capacity of a standard USIM, the
wireless-enabled electronic devices such as GIGAantIC is said to provide a
laptop computers. standardized, easily accessible and
The modules combine Antenova’s High The PAM employs an innovative biasing transferable memory resource. This,
Dielectric Antenna (HAD) technology with circuit, which is optimized for low idle according to Oberthur, alleviates the need
all the required RF components. The currents below 30 mA. According to US- to design additional card slots in handsets
antenna is highly resistant to the detuning based TriQuint, this results in increased and card bundling in smart phones.
effects of nearby components, and therefore handset talk time in the UMTS mode. The The USIM offers a number of smart-card
the same module can be used in a number PAM has a minimum output power of security applications, including digital rights
of different product designs. The antenna 27.5 dBm, which offers ample margin for management, encryption, and random
will also operate within multiple frequency front-end losses. This can be exploited to number generation. High-speed data
bands. According to Antenova, these develop cost-effective multimode phones protocols such as USB and MMC are
properties provide both maximum design that support compressed-mode handover supported, and the USIM is backwards
flexibility and the low-cost advantages of between GSM/EDGE and UMTS networks. compatible with previous cards. The cards
using a standard component. The PAM offers a linearity that is 7 dB will be commercially available in the second
The first module covers the GSM bands, better than ETSI-requirements for UMTS. half of 2005.
and this will be followed by components for This could be used to support future air Stand E48 Hall 2 (M-Systems)
UMTS and WiFi applications. interfaces. Stand B36 Hall 1 (Oberthur)
Stand E40c Hall 2 Stand J69 Hall 3 www.m-systems.com
www.antenova.com www.triquint.com www.oberthurcs.com
February/March 2005 wir eless.iop.org wireless europe
3GSM P R E V I E W
troubleshooting and optimizing 3G integrates Qualcomm’s Launchpad suite,
New mobile handset tester networks. This allows network operators which supports a range of application-
covers W-CDMA terminals and infrastructure vendors to accelerate the
network rollout process. The system could
related functions including advanced
multimedia, multimode-assisted GPS, user
The 4400 series of mobile phone testers also be used to develop best-practice interfaces and removable storage capabilities.
from Willtek Communications of Germany methods for teams performing diagnostics Stand A2 Hall 1
now supports the call-mode testing of and troubleshooting. www.qualcomm.com
W-CDMA terminals, thanks to a new The automated system addresses many
software option. The 4467 W-CDMA/ optimization parameters including dropped
UMTS Call Mode Option allows handset calls, setup failures, missing neighbours, Analyser troubleshoots
service centres and manufacturing facilities
to perform a final test on 3G handsets to
pilot pollution, poor coverage, system
interference and handover issues. CDMA and GSM base stations
ensure that they are fully operational before Stand A25, Hall 1 New from Anritsu of Japan, the Cell Master
leaving the factory or repair station. www.actix.com MT8212B adds a CDMA/GSM transmitter
analyser, interference analyser, built-in
source, channel scanner, and DS0/VF
Integrated handset baseband channel access to the Cell Master line of
covers EDGE and UMTS analysers. According to Anritsu, these
additional test capabilities provide RF
An integrated handset baseband that engineers and field technicians with a
supports UMTS and EDGE is a new handheld instrument that can be used to
product from Comsys Communication and ensure proper deployment, installation and
Signal Processing. The UEware multimode maintenance of GSM and CDMA networks.
baseband will be unveiled at 3GSM and
supports UMTS voice and data, GSM
The Call Mode Option supports a range voice, EDGE multi-slot class 12, type II
of transmitter measurements including multimode, dual transfer mode and HSDPA.
power, modulation quality and various According to Israel-based Comsys,
spectrum-related measurements. The 4467 UEware employs a scalable architecture and
also performs receiver measurements, which standard interfaces so that chipset vendors
ensure the quality of the radio receive path and device manufacturers can reduce
of the wireless terminal. product development costs and time-to-
According to Willtek, the new option market. The baseband is said to deliver
complements the 4466 W-CDMA/UMTS outstanding receiver performance, and
Non-Call Mode Option, which is used for offers easy integration with any UMTS
circuit testing and alignment. platform and protocol stack.
Described as a future-proof platform, the Stand D7 Hall 2 For GSM applications, the instrument
4400 series of testers are compatible with www.comsys.co.il can conduct traditional RF power and
future technologies such as HSDPA. A frequency error measurements, and can also
single instrument can test phones operating display time slot information on GSM
on a wide range of cellular standards New chipset is compatible signals. The analyser can make all major RF
including GSM/GPRS/EDGE, W-CDMA,
TD-SCDMA, cdmaOne and 1xRTT. with EDGE and HSDPA measurements on CDMA signals including
channel power, frequency error, occupied
Stand B27, Hall 1 The new Mobile Station Modem bandwidth and noise floor.
www.willtek.com MMSM6275 chipset from Qualcomm is The analyser weighs less than 2.5 kg and
compatible with the HSDPA and EDGE air is available with optional features, such as
interfaces and also supports GSM/GPRS and an interference analyser that determines the
3G network optimization W-CDMA. The MMSM6275 delivers peak type and bandwidth of interfering signals. It
system is automated data rates of 1.8 Mbit/s and is part of US-
based Qualcomm’s Enhanced Multimedia
is also available with a built-in signal source
for measuring the gain/loss of two-port
Actix has launched a version of its 3G RVS Platform, which includes integrated chipsets devices. It can be used for antenna isolation
network optimization system that that support all major air interfaces. measurements and repeater tests.
automates the diagnosis and prioritization According to Qualcomm, the Enhanced The spectrum analysis capability allows
of network problems. The system then Multimedia Platform chipsets are software- users to locate, identify, record and solve
recommends an appropriate resolution to compatible to ensure that advanced communication systems problems in the
any problems detected, and engineers can multimedia applications can be deployed on 100 kHz to 3 GHz frequency range. It has
confirm the diagnosis and proposed a range of handsets and network standards. dedicated routines for measuring field
resolution at the click of a button using the The MSM6275 is based on Qualcomm’s strength, channel power, occupied
system’s powerful visualization tools. radioOne zero intermediate frequency (ZIF) bandwidth, adjacent channel power ratio
According to UK-based Actix, this architecture, which is said to ease the (ACPR) and carrier-to-interference ratio.
automated facility introduces software-based development of small, low-cost, multiband Stand F28 Hall 2
intelligence into the process of rolling out, and multimode handsets. This chipset also www.eu.anritsu.com
wireless europe wir eless.iop.org February/March 2005
42 THE FUTURE
Wireless broadband comes of age
John Hoadley, vice-president for advanced wireless technologies at Nortel, believes that the cellular
industry is moving rapidly towards the deployment of mobile broadband technologies.
Why is HSDPA such a hot topic? broadband services will strain 3G networks.
Within the last year, operators have become MIMO schemes increase spectral efficiency
interested in moving towards what Nortel by exploiting the multipath transmission that
calls “wireless broadband” services based on occurs in urban (or suburban) areas. A device
cdma2000 EV-DO and HSDPA. Instead of such as a PDA or laptop computer can employ
just having a vision, they now have real plans up to four antennas to achieve MIMO.
for roll-out. While EV-DO and HSDPA are MIMO works well with OFDM – the two
on similar technology tracks, DO is ahead in technologies seem to go hand-in-glove. In
terms of time. The technology was launched addition, we see HSDPA, HSUPA and
in Korea in 2002 and it has changed the way WiMax all adopting MIMO.
that people use wireless there. Music is a huge
focus for younger users, while older users bene- How will UMTS TDD fit in?
fit from practical broadband services. There has not been very much interest in
UMTS time-division duplex (TDD); instead
Is the presence of EV-DO accelerating the focus is on HSDPA and HSUPA. In addi-
HSDPA development? tion, I believe that WiMAX has great poten-
In markets where cdma2000 and UMTS are tial for delivering broadband services, and if
available, DO is certainly becoming an issue Nortel’s John Hoadley believes that MIMO WiMAX can get some momentum, it could
for UMTS operators. As well as Korea, DO will improve spectral efficiency across a be a contender in the TDD bands.
is now available in North America, with number of air interfaces. While WiMAX will offer some degree of
Verizon offering services in 14 cities. This is a mobility, it is still unclear how it will fit in
bold experiment, but Nortel is optimistic that a strong market with other mobile technologies. The technology is certainly a
will form around wireless broadband in North America. strong proposition with Intel behind it, but whether it can go
From a technological perspective, DO has much in common beyond the fixed realm is another question. WiMAX could also
with HSDPA, including the use of hybrid automatic repeat find applications in cellular backhaul – including mesh networks.
request, adaptive modulation schemes and similar approaches to The key issue is whether WiMAX technology can evolve rapidly
shared channel use. As a result, HSDPA developers can benefit enough to complement, or even threaten, DO and HSDPA.
from much of the technology and experience of DO.
The timeframes associated with HSDPA development and How is the in-building market progressing?
deployment have shortened significantly during the past year Backhaul is still an important challenge in this sector. While
and a half. I think this is a very positive sign for the industry. interest is growing in UMTS picocellular equipment, we are
Because of our experience with DO, we were less surprised by certainly not seeing large deployments at the moment. A lot of
this than others. Indeed, Nortel has been talking about wireless development activity is currently happening in voice-over-
high-speed data for some time, and we are pleased to see strong WLAN systems for both homes and businesses. We are seeing
demand in Korea and Japan, where millions of users are paying prototype dual-mode WiFi/GSM phones, and significant
for high-quality services. This success has created genuine inter- progress has been made in addressing issues within the 802.11
est in other wireless broadband technologies such as WiMAX standards that could hinder voice services. Although it is still not
and flash orthogonal frequency-division multiplexing (OFDM). perfect, WiFi has progressed to the point where it is a viable
alternative for providing indoor coverage, in terms of capacity,
Will these technologies play key roles in 4G networks? security and quality of service.
4G is about both new high-speed air interfaces and the integra- There has been a move away from the concept of using
tion of third-generation technologies. If the industry succeeds in Bluetooth for in-building telephony. The wide acceptance of
migrating from DO to DO release A, and from HSDPA to WiFi, its low cost, and improvements in the standard make it
HSUPA, it will be on the right path to 4G. more attractive than Bluetooth. The challenge is to ensure that
In terms of new air interfaces, Nortel believes very strongly WiFi and cellular networks work well together in terms of hand-
that OFDM multiple-input multiple-output (MIMO) can off and transparency of features. ■
achieve significant improvements in spectral efficiency.
Spectrum remains a limited resource, and the success of wireless Interview by Hamish Johnston, editor of Wireless Europe.
February/March 2005 wir eless.iop.org wireless europe