To All, ERICY Position
POSITION STATEMENT - Wideband CDMA
(WCDMA)
1. THE DECISION FOR WCDMA
On January 29, 1998, ETSI decided on WCDMA as the radio
technology for the paired bands and TD/CDMA for the unpaired
bands of Universal Mobile Telecommunications Services
(UMTS).
In Japan, the standardisation body ARIB has opted for exactly
the same WCDMA radio communications technology. This
decisions has since been endorsed in the USA by the ANSI
committee T1P1 - a US body with the responsibility to
standardize GSM in North America.
Consequently, WCDMA is the common radio technology
standard for third-generation wide-area mobile communications
in both Europe, North America and Asia.
In ARIB, WDCMA is referred to as Core A. In ETSI, it is
referred to as the Alpha concept. However, the technology
remains exactly the same - WCDMA radio technology at 5 MHz
bandwidth and specific parameters as chip rate and frame length
based on an evolved GSM core network.
Moreover, the new 2 GHz frequency band has already been
allocated by the ITU to third-generation services (IMT-2000) in
both Europe and Asia.
In the light of the vast GSM footprint in Europe, Asia and North
America - with 200 networks in operation in 110 countries and
around 100 million subscribers in June, 1998 - the selection of
WCDMA means there is now a common third-generation
technology standard.
1.1 The Standardization Procedure
The selection of WCDMA followed an extensive and thorough
standardization process. Also, the participants of these
standardization bodies represent the entire global communications
industry. In the process of standardizing WCDMA, all
proponents were encouraged to submit their technologies. After
extensive refinement and evaluation, WCDMA came out ads the
preferred technology through a consensus decision. The final
proposal was jointly put forward by Alcatel, Ericsson,
Matsushita, Motorola, NEC, Nokia, Nothern Telecom and
Siemens.
Thus, the global industry has submitted its technologies and
participated in the work. All technology proponents have had an
equal and fair opportunity to participate in this process and to
contribute and promote their technologies.
A fair selection was then made in an open-ended process which
adhered to established standardization procedures. These
processes in the respective standardization bodies have all related
to the establishment of 3G standards in line with the timetable
required by the ITU.
1.2 Intellectual Property Rights
An integral part in the selection of any mobile communications
standard is the full commitment from the industry and all its
players that any IPRs that relate to the standard will be licensed
on fair, reasonable and non-discriminatory terms. To facilitate
WCDMA as an open-ended and truly global standard, initiatives
were taken in conjunction with the January 29 ETSI decision for
WCDMA to further limit any effects of potential aggregated
royalties.
Any additional demands of changes to the standard after the
decisions have been made are simply out of order. Furthermore,
to link such demands to IPR would - in the tradition of
standardization and in the spirit of creating an open global
standard - be blatantly counterproductive to the interests of the
entire wireless industry.
2.WCDMA TECHNOLOGY
Wideband CDMA is a completely new technology. Narrowband
CDMA (IS-95) was pioneered in the USA and now Europe and
Japan have selected WCDMA as their 3rd-generation standard.
Naturally, the WCDMA standard is a different technology
targetting 3G requirements. It has been based on extensive
research conducted between 1989 and 1997.
From the start, WCDMA has been designed for high-speed data
services and, more particularly, Internet-based packet-data
offering up to 2 Mbps in indoor environments and over 384 kbps
for wide-area.
Over a five-year period, WCDMA has been tested and verified
in parallel R&D programs in both Europe and Japan. In order to
achieve the necessary requirements on third-generation mobile
communications, including trade-off between maximum capacity
and operation in 5 MHz allocations, the so-called chip rate has
been set at 4.096 MHz. This is essential in order to deliver the
third-generation capabilities required by the UMTS and
IMT-2000 specifications.
Furthermore the TDD component of UMTS, TD/CDMA, has
been harmonized with WCDMA and thus provide efficient
support for assymetric services and un-coordinated system
operation in local areas, too.
WCDMA supports multiple cell layer operation in line with
studies showing that two times 15-20 MHz licenses is
recommended for third-generation capabilities and has thus been
optimized for these requirements. Indeed WCDMA also
operates in two times 5 MHz allocations by fulfilling the FCC
rules. The selection of parameters, e.g. the so-called chiprate, has
been made to optimise system capacity and performance in line
with those requirements.
WCDMA R&D has had the advantage of including leading-edge
research to optimize this new radio technology to deliver the
mission-critical coverage and capacity for third-generation mobile
communications. The WCDMA concept is based on a totally
new channel structure for all layers (L1-L3) built on technologies
such as packet-data channels and service multiplexing. The new
concept also includes pilot symbols and a time-slotted structure
which has led to the breakthrough features listed below:
Adaptive antenna arrays which direct antenna beams at
users to provide maximum range and minimum
interference. This is also crucial when implementing
wideband technology where limited radio spectrum is
available.
Hierarchical cell structures that allow the mix of macro and
micro cells in urban areas to boost capacity.
Inter-frequency hand-off technology so that on-going calls
can be handed over between carriers in different cells and
frequencies.
Combining hierarchical cell structures and inter-frequency
hand-off leads to a breakthrough with a new system layout
that creates a very robust network.
Coherent demodulation in both uplink and downlink that
maximizes range.
Complete integration of FDD, based on WCDMA, and
TDD, based on TD/CDMA, technologies to offer
optimum outdoor/in-door coverage and to support the
complete range of services including voice, low- and
high-bitrate data and assymetric services.
Independence of expensive GPS satellite systems. There is
no need to synchronize WCDMA base stations through
GPS positioning.
3. BACKWARD COMPATIBILITY
R&D in the early 1990s showed it would not be possible to meet
third-generation requirements and still retain backward
compatibility with any second-generation technology on the
air-interface level. Consequently, a revolutionary solution was
required.
In practice, certain key parameters in WCDMA and GSM have
been harmonized in order to achieve an optimal solution for
dual-mode GSM/UMTS terminals as well as GSM/UMTS
hand-over.
This will facilitate today's users easy access to third-generation
services through dual-mode terminals - as will be the case with
UMTS/GSM terminals.
The R&D work invested into WCDMA in combination with the
ETSI/ARIB/ANSI decisions mean there is now a unique
opportunity to achieve a world standard that must not be lost.
Although an international co-operation between different
standards organizations is very challenging, the ETSI-ARIB
dialogue has been a very positive experience mainly because of
the mutually shared goals. Now both groups are working hard to
find a more efficient way how to proceed in their co-operation
towards a global 3rd generation system and not only a common
air interface. To achieve the global coverage in the standards
work the relevant US organizations ANSI/TIA/T1P1 have
coupled their efforts to these discussions as well. The first round
of these trilateral talks was held in Tokyo in February 1998.
Furthermore, the groundwork to achieve a technical standard
which can be deployed in all continents has been initiated by
ETSI. The standardization body has already agreed that UMTS
will fulfill FCC requirements to allow WCDMA to operate even
in 2 times 5 MHz FDD spectrum to suit the North American
environment.
3.1 Demands for Changes
There have been proposals to alter the chip rate of the agreed
ETSI/ARIB/WCDMA concept to cater for backward
compatibility with narrowband CDMA (IS-95). This run counter
to the objectives with both UMTS and IMT-2000 and was
therefore been disregarded since such alterations would dilute
system capacity and performance.
In short, the consequence of the proposal would have been to
eliminate the third-generation capabilities of WCDMA, such as
hierarchical cell structures, inter-frequency hand-off capabilities
and adaptive antenna arrays, etc (see above). The solution to
backward compatibility remains dual-mode terminals.
Likewise, other initiatives to seek harmonization by comparing
technical solutions from wbcdmaOne and WCDMA have been
conducted. Most important was a study in ARIB (Ah-S group),
initiated by proposals from wbcdmaOne proponents. These
studies were concluded February 1998.
The outcome of these studies have been incorporated into the
ETSI/ARIB WCDMA standard. Thus, there has been plenty of
opportunity to discuss various technical solutions based on their
respective merits in the due work process on more than one
occasion already.
In line with the schedule for introduction of 3rd-generation
services the detailed specification and implementation process
should not be interrupted or delayed by activities not belonging to
the process of the global industry.
Under any circumstances, IS-95/IS 41 and UMTS/evolved
GSM technologies rely on different network technologies. The
"GSM world" does not benefit from backward compatibility to
the IS-95 air interface; thus, the chip rate harmonization does not
offer any additional benefits to them.
In addition, in Americas the frequency allocation is different
compared to the rest of the world and wbcdmaOne is planning to
use so called multicarrier technology in the downlink in that
market area. In WCDMA direct spreading technology is a global
solution.
Technologies considered for wbcdmaOne are related to different
elements of backward compatibility to IS-95, this limits the
flexibility. This has led to fundamental limitations to wbcdmaOne
as compared to WCDMA, especially with respect to its
capabilities to support 3rd-generation capabilities. Some
examples are:
Support of adaptive antennas can not be made with the
same performance due to the common pilot channel
structure used in wbcdmaOne.
wbcdmaOne channel format makes power control less
efficient.
wbcdmaOne can not operate without external (GPS)
synchronization.
wbcdmaOne do not support interfrequency handover,
meaning that hierarcical cell structure and handover to
second generation systems can not be performed.
wbcdmaOne do not efficiently support bit-rate and service
flexibility.
wbcdmaOne do not have an integral TDD mode that
supports un-coordinated local area operation.
It is also important to empasise that WCDMA have taken into
account all the latest research on providing third generation
capabilities into this newly developed standard. Wereas
wbcdmaOne, with its backward compatibilities to IS-95, are
hamstrung by backward compatibility with older, 2nd-generation
CDMA technology. In addition, WCDMA is more mature,
well-developed than wbcdmaOne and it has been tested in the
field.
We therefore see that the only viable way to achieve a world
standard is to build on the agreed ETSI/ARIB standard and
retain its inherent third-generation capabilities. Adapting the
WCDMA radio technology by the TIA for IS-41-based
networks in the USA and elsewere - based on the same
dual-mode functionality as in the case of UMTS/GSM - would
provide third-generation capabilities to all mobile
communications' operators and end users in the USA that the
rest of the world will enjoy.
Last updated: 980629
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