Did I miss reading this? ITU approves 3G specifications.....
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ITU Approves IMT-2000 Specification
11/9/99 By: Robert Keenan, Managing Editor, Wireless Design Online
Over the past few years, third-generation (3G) technology has been on thee mind
of every engineer, network operator, manufacturer, and sales/marketing
professional working in the wireless market. Throughout this entire process, the
term 3G has evolved and changed to mean many things to many different people,
causing great confusion in the market.
After much talk and work, the International Telecommunications Union (ITU) is
trying to bring some clarity to the 3G picture. During a meeting in Helsinki last
week, the Geneva-based standards body ironed out some final details and
approved the IMT-2000 specification for 3G networks.
The IMT-2000 terrestrial standard consists of a set of radio interfaces that allow
performance optimization in a wide range of radio operating environments.
Specifically, the new specification supports a wideband CDMA (W-CDMA)
specification with three parts, a single-carrier standard for TDMA/GSM systems,
and a frequency-time Digital European Cordless Telephone (DECT) specification.
During a meeting in Helsinki, the ITU approved the IMT-2000 specification. This specification
offers three W-CDMA modes, a frequency-time mode, and a single-carrier mode.
According to the ITU, the IMT-2000 specifications will provide wireless multimedia
service capabilities. Specifically, emerging IMT-2000 systems are expected to
offer e-mail services, Internet access, multimedia capabilities, video conferencing
functionality, and a range of other data-intensive services.
The background
The background behind the new IMT-2000 specification is quite turbulent and
interesting. When the IMT-2000 specification was first being developed, the ITU
was pushing for a single specification that would enable ubiquitous coverage
across the world.
Although this was a noble effort, the ITU ran into many stumbling blocks in trying
to win acceptance of a single specification for the IMT-2000 standard. In
particular, arguments over intellectual property rights (IPRs) and political
pressures pushed the ITU toward a multiple standards approach. Therefore,
earlier this year the ITU conceded to a multi-standard approach to 3G.
The adoption of a multi-standard approach demonstrates that “there is no single
radio interface that will service 3G,” says Leo Nikkari, vice president of strategy
and industry relations for the Universal Wireless Communications Consortium
(UWCC).
Standard specifics
Overall, the new IMT-2000 specification includes five parts—three for W-CDMA
operation, one for TDMA/GSM operation, and one for DECT operation.
The CDMA is based on a harmonized specification conceived by Ericsson and
Qualcomm when they settled their IPR debates earlier this year (see Ericsson,
Qualcomm Merge W-CDMA Proposals). This specification, which was supported
by the Operator's Harmonization Group (OHG), combined three modes of CDMA
operation under a single standard.
The three modes housed under the combined specification include a
direct-sequence (DS) CDMA mode (called IMT-DS under the IMT-2000 Spec), a
multicarrier (MC) CDMA mode (dubbed IMT-MC under the IMT-2000
specification), and a time division duplex (TDD) CDMA mode (called IMT-TC
under the IMT-2000 specification).
The DS sequence mode is expected to offer a chip rate of 3.84 Mchips/s while
supporting asynchronous and synchronous operation incorporating the concepts
of all the 3G direct sequence proposals to the ITU. The MC mode will use a chip
rate of 3.6864 Mchips/s and will support synchronous operation to ensure it can
overlay existing cdmaOne networks. The TDD mode will have a chip rate of 3.84
Mchips/s and will draw from the various 3G ITU TDD proposals.
UWC-136
The single carrier portion of the IMT-2000 standard, known as IMT-SC, is based
on the UWC-136 proposal received from the Universal Wireless Communications
Consortium (UWCC; Bellevue, WA). According to UWCC, this standard
maintains the TDMA community's philosophy of evolution from 1G to 3G
generation systems while addressing the specific desires and goals of the TDMA
community for a 3G system.
This UWC-136 radio interface is designed to be an evolutionary step for 136.
There is a three-component strategy for evolving the 136 technology towards 3G
generation. The strategy consists of enhancing the voice and data capabilities of
the 30 kHz channels (designated as 136+), adding a 200 kHz carrier component
for high speed data (384 kb/s) accommodating high mobility (designated as
136HS outdoor), and adding a 1.6 MHz carrier component for very high speed
data (2 Mb/s) in low mobility applications (designated as 136HS indoor). The
combined result constitutes the UWC-136 radio interface specification.
The 136HS outdoor and indoor components were developed to satisfy the
requirements for an IMT-2000 radio transmission technology, with the additional
requirement for the consideration of commercially effective evolution and
deployment in current 136 networks. Such considerations include flexible
spectrum allocation, spectrum efficiency, compatibility with 136 and 136+, and
support of macrocellular performance at higher mobile speeds.
The DECT proposal
In addition to the above W-CDMA and UWC specifications, the ITU has also
provided a frequency time specification, called IMT-FT, under the new IMT-2000
standard. This specification is based on a DECT proposal provided by the
European Telecommunications Standards Institute (ETSI) for the IMT-2000
specification.
The individual layers of the IMT-FT specification are defined in different parts of
the common interface (CI) standard. The standard specifies a TDMA radio
interface with time division duplex (TDD). The RF bit rates for the specified
modulation schemes are 1.152 Mb/s, 2.304°Mb/s, and 3.456 Mb/s. The standard
supports symmetric and asymmetric connections, connection oriented and
connection less data transport as well as variable bit rates up to 2.88 Mb/s per
carrier. The network layer contains the protocols for call control, supplementary
services, connection oriented message service, connectionless message service
and mobility management, including the security and confidentiality services.
In addition to the CI standard, the IMT-FT specification includes access profile
standards that define minimum requirements for accessing specific networks and
the interworking to these networks. For example, the generic access profile
(GAP) standard defines the requirements when using the speech service and the
DECT packet radio service (DPRS) standard defines the requirements for packet
data transport.
Interoperability
Although the new standard is complete, Jim Takach, director of advanced
programs for the CDMA Development Group (CDG; Costa Mesa, CA), says there
is still a lot of work to go. In particular, Takach says there is a great deal of
interoperability work that needs to be addressed.
“Industry members can't sit back and say we're done because there is still work
to do,” Takach says.
Most of the interoperability issues arise at the network level. Many of the modes
included in the IMT-2000 standard, such as the three CDMA modes, are
expected to support both ANSI-41 and GSM-MAP networks. By supporting both
network architectures, the ITU and industry members are hoping to promote
global roaming in the 3G world
Takach says there are still issues in providing operability between the ANSI-41
and GSM-MAP network architectures. However, standards bodies are now trying
to iron these issues out. Takach says work will continue on internetworking
issues over the next few months. He expects to see harmonization on these
issues by the end of April.
Accelerating development
Now that the 3G standardization process has cleared a bit, the next question is:
When will the first 3G services rollout? Most industry members agree that Japan
will be the first market to rollout 3G services.
Will Strauss, president of Forward Concepts, a Tempe, AZ-based research firm,
says capacity issues will drive Japan toward accelerating the rollout of 3G
services. In fact, Strauss says, the industry should see 3G services start to
rollout in Japan in 2001.
The US and Europe, however, will be much further behind in their implementation
of 3G services. Strauss says the acceptance of 2.5G technologies like the
General Packet radio Service (GPRS) and EDGE will slow down the acceptance
and development of 3G services in these regions.
Out for ballot
Now that the standard has been approved, the ITU is now entering the balloting
stage. According to Takach, the balloting process will run for the next few
months. Overall, it should be completed sometime in the early to late spring time
frame. |
