Wideband CDMA and the 3G standards
process
1. BACKGROUND
The global march towards a 3rd-generation (3G)
wireless standard has engaged the entire wireless
industry in research and standardization efforts over a
nearly 10-year period. The goal from the beginning has
been to find the best new technology optimized for
end-user requirements into the next century.
New 3G requirements include high-speed data and
Internet access, full-motion video and a range of other
multi-media functions and services.
The International Telecommunications Union (ITU), an
agency of the United Nations, is coordinating 3G
standardization in a broad-based and highly
participatory process called IMT-2000. That process
ensures that various technical solutions undergo fair
and open review. Technical merit is the primary criteria
for recommending a 3G technology.
The proposals for a 3rd-generation wireless standard
recently filed with the International Telecommunication
Union (ITU) show worldwide support for a powerful
new technology, WCDMA.
WCDMA is a completely new concept. It is not
related to nor limited by any 2nd-generation digital
wireless technology and it is designed specifically to
meet 3rd-generation wireless requirements.
This paper reviews the case for WCDMA and its
progress to date through the 3G standardization
process. The case for WCDMA revolves around the
following points:
Global convergence and harmonization
Compatibility with existing network standards
Technical merit
Fairness vis-a-vis backward compatibility with
2nd-generation wireless standards
Balanced claims regarding IPR
2. GLOBAL CONVERGANCE AND
HARMONIZATION
The submissions of 3rd-generation IMT-2000 radio
technology to the ITU on June 30, 1998 reflect strong
convergence around the WCDMA standard. Of the
10 terrestrial radio systems proposed, six build on
WCDMA. It is featured in proposals from Europe,
Japan, the United States, South Korea and China.
WCDMA is a key ingredient in each of these six
proposals that also include the TDD mode of the
UMTS standard. In the case of China, the proposal is
for WCDMA on top of a TDMA&TDD structure.
Therefore, WCDMA is the only technology to garner
truly global support.
The six proposals are known by various names:
ARIB/JAPAN – WCDMA
ETSI/SMG – UTRA/UMTS
T1P1/USA – WCDMA/NA
TIA TR46/USA – WIMS
TTA/South Korea – Global CDMA II
CATT/China – TD-SCDMA
But all of these submissions to the ITU are based on
WCDMA as the enabling technology.
In addition to global convergence around WCDMA,
there has also been notable progress in "harmonizing"
the WCDMA standard with other technical proposals
– including TD-CDMA technology and cdma2000,
the broadband version of narrowband IS-95.
For example, ETSI's submission to the ITU, called
UTRA (for UMTS Terrestrial Radio Access), draws
on both WCDMA and TD-CDMA technology.
ETSI's January 29, 1998 decision to adopt UTRA
was made only after the careful evaluation of multiple
submissions. It was based on a joint proposal from a
truly broad spectrum of the global communications
community, including such vendors as Alcatel,
Ericsson, Matsushita, Motorola, NEC, Nokia, Nortel,
Siemens and Sony.
Harmonization between WCDMA and cdma2000 has
been provided for through the work of ARIB's Ad
Hoc-S group. These efforts took place at the request
of cdma2000 supporters. The outcome of the group's
work has already been incorporated into the ETSI and
ARIB WCDMA standards. Many leading companies
have expressed a willingness to implement the Ad
Hoc-S results as a basis for a global WCDMA
standard.
This does not mean, of course, that regionally-based
standards like cdma2000 should not have a place in a
possible IMT-2000 "family" of standards. These
alternate standards ensure that all operators regardless
of 2nd-generation technology choice have an
evolutionary path to 3G.
In terms of a global standard, however, WCDMA is
clearly the preferred technology. Free of any
2nd-generation constraints, it offers a superior
technical solution and one better attuned to the 3G
needs of the global community.
3. ACCOMMODATES IS-41 AND GSM-MAP
EQUALLY WELL
IS-41 and GSM MAP are core network standards
with the broadest user base around the world. Any
truly global 3G standard must accommodate both
these network standards. WCMDA clearly does.
4. TECHNICAL MERITS OF WCDMA
Based on extensive research conducted between 1989
and 1997, WCDMA is a completely new technology
targeting true 3G requirements.
WCDMA has been designed from the start for
high-speed data services and, more particularly,
Internet-based packet-data offering up to 2 Mbps in
indoor environments, and up to 384 kbps in wide area
or mobile environments.
Because WCDMA did not evolve from
2nd-generation technology, it incorporates the results
of leading-edge research. This R&D has yielded an
optimized technology capable of delivering
"mission-critical" coverage and capacity for
3rd-generation mobile communications. In terms of
technical superiority, therefore, WCDMA represents a
significant advance over other 3G standards that have
been proposed.
The WCDMA concept, for example, is based on a
completely new channel structure for all layers
(L1-L3), built on technology like packet-data channels
and service multiplexing. The new concept also
includes pilot symbols and a time-slotted structure that
has led to breakthrough features, such as the following:
- Adaptive antenna arrays, which direct antenna beams
at users to provide maximum range and minimum
interference. This is also crucial in implementing
wideband technology where limited radio spectrum is
available.
- Hierarchical cell structures that boost capacity in
urban areas by allowing a mix of macro and micro
cells.
- Inter-frequency hand-off technology. On-going calls
can be handed over between carriers in different cells
and frequencies.
- Combining hierarchical cell structures and
inter-frequency hand-off makes the network more
robust because it incorporates a breakthrough system
layout.
- Coherent demodulation, in both uplink and downlink,
maximizes useful 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-bit rate data and asymmetric services).
- Independence of expensive GPS satellite systems.
There is no need to synchronize WCDMA base
stations through GPS positioning.
- Utilizing direct spread, in an optimum fashion, clearly
outperforms multicarrier downlink.
5. BACKWARD COMPATIBILITY
As far back as the early 1990s, R&D had
demonstrated that it would not be possible to meet
3rd-generation requirements and also retain backward
compatibility with any 2nd-generation technology at the
air-interface level. Consequently, a revolutionary
solution along the lines of WCDMA was required.
The WCDMA parameters have been selected to
facilitate dual-mode operation with all 2nd-generation
systems. The solution: dual-mode terminals. Using dual
mode mobile phones, WCDMA is equally fair to all
2nd-generation digital standards used around the
world.
There have been proposals to achieve backward
compatibitility with 2nd Generation systems through
other means. These proposals, however, run the risk
of seriously diluting a 3rd-generation system's capacity
and performance. That's one of the reasons why ETSI
has rejected proposals to modify the previously agreed
upon WCDMA standard.
6. INTELLECTUAL PROPERTY RIGHTS
An integral part of any standards-setting process is the
full commitment of the industry, and all of its players,
that any IPRs related to the standard will be licensed
on fair, reasonable and non-discriminatory terms.
The fact that WCDMA is the result of research by so
many players means that many companies hold IPRs
that relate to WCDMA.
ETSI in its January 29 decision took specific initiatives
to limit the effects of potential aggregated royalties with
regard to WCDMA. This should facilitate the adoption
of WCDMA as an open-ended and truly global
standard.
In one instance, a company that has participated in the
ETSI and ARIB decision-making process has
threatened to withold licenses for what it claims are
valid WCDMA IPRs unless the standard is modified
to its benefit.
Despite a thorough investigation, Ericsson has found
no reason to believe that ETSI's present WCDMA
standard would infringe upon any valid IPRs claimed
by this company.
Ericsson is of the opinion that it has patents and/or
pending application(s) for patents that are essential to
the two different proposed 3G standards based on
WCDMA and cdma2000.
Ericsson is fully prepared to grant license to these
patents on fair, reasonable, and non-discriminatory
terms subject, however, to conditions of reciprocity
which are required to create fairness in a
multi-standard environment.
Ericsson wants each country, or region, to be able to
choose among the alternative global standards without
being hindered by unequal IPR policies. Ericsson will
therefore grant licenses to the alternative 3G standards
on the basis of full reciprocity on a global scale
between treatment of essential IPRs for these
standards. This means that Ericsson is not prepared to
offer licenses to anyone who do not apply such
reciprocity in its licensing commitments and who, by
such non-reciprocal action, hinder free choice on equal
terms between alternative standards.
In order to promote a healthy growth of the
telecommunications industry and equal access to
communications to all levels of society, Ericsson
supports a low royalty compensation approach.
7. THE FUTURE
The ITU standard-setting process will continue for
some time. Through the end of September 1998,
standards bodies in various parts of the world will
evaluate the proposals that have been submitted to the
ITU. The ITU then has until March 31, 1999 to
formulate a global 3G standard. This standard could
be a single global standard or a "family" of 3G
standards. Regardless of approach, WCDMA is likely
to play an important role in the world of 3rd
Generation wireless technology.
Last updated: 980922
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