It's no secret that the 3rd Generation of Mobile Communications (3G) will power
the next major business boom - by merging mobile telecommunications with the
Internet. From fax, voice and e-mail through data, video and multimedia -
virtually all of today's essential services will soon be available to mobile
customers -"on the move".
The main challenge facing 3G network operators is how to manage both symmetric
circuit switched services, such as speech or video, as well as asymmetric packet
switched services, such as mobile Internet data flows. TD-SCDMA (Time Division
Synchronous Code Division Multiple Access) successfully combines two leading
technologies - an advanced TDMA system with an adaptive CDMA component to
overcome this challenge.
3G Service Requirements:
High Data Rates for New Data-Intensive Applications
Packet-Oriented Transmission
New Mobile Internet Applications
TD-SCDMA-based systems satisfy all these requirements and let operators benefit
from: a smooth and low risk migration from 2G to 3G, rapid time to market for 3G
services and an increase of their systems' capacity. Because the evolution to 3G
is often based on an existing GSM network, this migration path eliminates both
the risk of setting up a new core network and high investments. As a result, the
initial investment and cost of operation are reduced and return on investment is
accelerated - a classic "win-win" scenario. 3G Migration - from GSM to UMTS and beyond
The need for mobile network operators to migrate from their existing 2G to
modern 3G networks are growing daily - just like the number of their mobile
subscribers. At the same time, new data services are being introduced requiring
ever greater bandwidth. Simply stated, these two facts result in so much
traffic, that current 2G capabilities are just plain overloaded. TD-SCDMA
provides the advanced technologies needed for tomorrow's 3G operations, TD-SCDMA
paves the way to an easy, step by step migration to 3G and even beyond.
The first step
The TD-SCDMA base station, Node B using a 3G spectrum, is set up where
enhancement of the GSM core network is most urgent. The Node B is connected to
the MSC of the existing GSM network via an enhanced base station controller.
Voice services are handled by the MSC, while data services of up to 384Kbps, are
supported by the SGSN functionality. This seamless integration of a 3G air
interface in the existing GSM infrastructure results in a short term
availability of 3G services without the need or cost of installing a completely
new core network.
The second step
During the coexistence phase of GSM and 3G networks, Node B will be
connected to the 3G core network via standardized interfaces. This newly
upgraded system allows continued use of existing handsets, reduces technical
migration related risks and requires a significantly lower investment than other
3G technologies.
The third step
Further network evolution will lead to IP based core networks, where the base
stations remain unchanged. The existing handsets remain operational.
Thanks to the compatibility of TD-SCDMA with an existing GSM infrastructure,
incremental upgrades to modern 3G networks are possible. And its outstanding
capability for handling IP-based traffic lets your network also take the pole
position for future network scenarios.
TD-SCDMA Features
Advanced 3G services allow high speed data, packet data, multimedia and
excellent voice quality by connecting TD-SCDMA RAN to the GSM/GPRS network.
Access to new UMTS spectrum resources increase the network capacity.
Outstanding Spectrum efficiency (1.6 MHz bandwidth, 3 to 5 times higher than
GSM, handling more traffic with fewer base stations) ensures economic use of
spectrum.
Support of all radio network scenarios (Wide Area - Macro, Local Area - Micro,
Hot Spots - Pico and Corporate Networks) allows full service coverage.
Best suited for mobile Internet 3G applications provided by the inherent
flexibility of the technology.
Flexibility for asymmetric traffic, data rates and radio resource allocation,
allows optimum adaptation of the radio access to the actual traffic load within
the network.
Key Technologies - TDMA/TDD Principle
Employs a single carrier to both send and receive traffic. Optimizing the use of
your radio resources.
Time Division Multiple Access (TDMA) in combination with Time Division Duplex (TDD)
significantly improves network performance by allowing radio resources to
process network traffic in both directions, per uplink and downlink. TDMA uses a
5 ms frame for repetitive transmissions. This frame is subdivided into 7 time
slots, which can be flexibly assigned to either several users or to a single
user who may require multiple time slots. TDD principles permit traffic to be
uplinked (from the mobile terminal to the base station) and downlinked (from the
base station to the mobile terminal) using the same frame and different time
slots. For asymmetric services used with Internet access, where high data
volumes are transmitted from the base station to the terminal, more time slots
are used for the downlink than the uplink.
For symmetric services used during telephone calls, where the same amount of
data is transmitted in both directions, the time slots are split equally between
the downlink and uplink. This capability of adapting the uplink/downlink format
according to the data loads within a single frequency band increases the overall
capacity of the air interface. This making TDMA/TDD operations ideal for 3G
services.
Key Technologies - Smart Antennas
Permit focusing of transmission beams, minimizing cell interference and
increasing transmission capacity. TD-SCDMA base stations are equipped with Smart
Antennas, which target signals to and from specific terminals and reduce
intercell interference. The base station tracks the mobiles throughout the cell,
so that the signal-to-interference ratio of the mobile terminal is improved by
about 8 dB. In addition, Smart Antennas optimize the link budget and increase
the capacity of a TD-SCDMA operator's radio interface.
Increases transmission quality and air interface capacity. Joint Detection
eliminates the multiple access interference (MAI) typically associated with
multi-user access, through parallel processing of individual traffic streams.
Terminal Synchronization improves the uplink signal's quality by precisely
tuning the transmission timing of each individual terminal with respect to its
base station. Together, this very efficient combination of Joint Detection and
Terminal Synchronization enhances the coverage of a base station and allows TD-SCDMA
deployments for macro, micro and pico cell applications.
Technical Advantages
TD-SCDMA offers a smooth and seamless way of upgrading existing GSM networks for
advanced 3G mobile networks and services. When TD-SCDMA base stations are
installed in an existing GSM system, the radio network layout can be retained
and existing transmission links can be reused. What's more, technical risks are
reduced because this 3G services will develop from a well-known GSM network. TD-SCDMA
provides a spectrum efficiency 3 to 5 times greater than GSM. Together with the
added ability to handle symmetric and asymmetric services as well as flexible
data rates - each carrier can now be used with maximum efficiency. This allows
it handle higher traffic densities within each cell and in case of areas with
low traffic the cells can be increased.
Seamless GSM to 3G upgrades
Re-use of GSM resources
Reduced migration risks
3 to 5 times greater spectrum efficiency
Increased capacity Operational Advantages
The 3G air interface used in combination with your established infrastructure
dramatically shortens the time to market for new 3G services. And this also
speeds up your ability to provide customers 3G mobile Internet applications. It
also enables the network's spectrum to be easily increased, keeping in step with
user numbers, data throughput and quickly overcoming GSM capacity problems. At
the same time, the new TD-SCDMA components can be fitted into existing operation
and maintenance strategies.
3G air interface
Rapid market introduction of 3G services
Additional spectrum for GSM networks
Simple operation and maintenance Commercial Advantages TD-SCDMA gives GSM operators the opportunity to offer 3G services without making
major new infrastructure investments. In addition, the total amount of your 3G
investment can now be spread over a longer period of time. By efficiently
utilizing existing GSM infrastructure, the total 3G investment risk is reduced
to a minimum. This also means spectrum license fees can be used economically to
generate new 3G revenues from Internet, Intranet and multimedia applications
earlier.
Minimized new investment
Economic use of license fees
Early generation of 3G revenues Designed for success
TD-SCDMA meets the challenge presented by 3G mobile telecommunications systems
by mastering both symmetric circuit switched services (speech or video) as well
as asymmetric packet switched services (mobile Internet). TD-SCDMA is the
combination of the advanced TDMA/TDD system with an adaptive CDMA component for
synchronous operations. The radio transmission principles of the system allow
optimum utilization of the 3G radio spectrum and may be used in any unpaired
frequency band. The Chinese government endorses this international standard,
which can be implemented less expensively than comparable 3G systems. Due to the
basic TDMA operation and the efficient utilization of the radio spectrum, the
system is in a perfect position for seamless operation within existing GSM
infrastructure systems. This enables GSM operators to upgrade to 3G in a smooth,
cost-effective way and reuse their existing GSM core network infrastructure:
decisive factors for the overall economy of a 3G solution like TD-SCDMA.
Abbreviations
2G: Second Generation
3G: Third Generation
BSC: Base Station Controller
BTS: Base Transceiver Station
CDMA: Code Division Multiple Access
GPRS: General Packet Radio Service
GSM: Global System for Mobile Communication
HLR: Home Location Register
IP: Internet Protocol
LMT: Local Maintenance Terminal
MAI: Multiple Access Interference
MSC: Mobile Switching Center
PSTN: Public Switched Telephone Network
RAN: Radio Access Network
RNC: Radio Network Controller
SGSN: Serving GPRS Support Node
TDD: Time Division Duplex
TDMA: Time Division Multiple Access
TD-SCDMA: Time Division Synchronous Code Division Multiple Access
TRAU: Transcoding and Rate Adaptation Unit
UGSN: UMTS GPRS Support Node
UMSC: UMTS Mobile Switching Center
UMTS: Universal Mobile Telecommunications System
