Service Research and Feature Applications of TD-SCDMA
For the future TD-SCDMA users, what they care most is the service TD-SCDMA could provide
for them, which is their real need and the core issue. For the operators, the diversity of services is
the essential means to attract users, increase the ARPU, and realize service differentiation. The
deployment of services is also a key factor in achieving the coordinated development of the
industrial chain, as well as a decisive factor for the success of the TD-SCDMA standard.
Backed by technical advantages, some differentiated services can be provided by TD-SCDMA
thanks to its relatively lower cost, higher spectrum efficiency and flexible configuration of uplinks
Based on the difference between TD-SCDMA system and 2G mobile communications system, the
data services offered by TD-SCDMA system can be divided into four categories.
Featured Services of TD-SCDMA ： LCS (Location) service and PoC. Such services have
their unique advantages with the support of the TD-SCDMA wireless technology. They are
realized in a different way in other standards, or cannot be realized in other standards.
Differentiated Services: videophone and streaming media. At present, the 2.5G network is
unable to or hard to deploy such services. However, they can be realized smoothly in the 3G
Enhanced Services: WAP, MMS, Intelligent network, Coloring Ring Back Tone/Coloring
Echo Background Tone, etc. These services are provided in the current 2.5G network, but the
high speed of 3G system can present users with a better experience of them.
Transplanted Services: SMS, USSD, Mobile Payment, Coloring Ring Back Tone, Coloring
Echo Background Tone, Intelligent network, etc. These services have been realized in 2G or
2.5G systems, and it is of no difference to realize them in 3G.
Figure 1. Development Trend of TD-SCDMA Service
There are three stages for the industrial development of the TD-SCDMA communications
technology, which are introduction period, growing period and flourishing period. The developing
strategies are different for TD-SCDMA in different periods.
(1)Strategy for the introduction period: Construction of TD-SCDMA is just in rough shape at this
point. The transplanted services and enhanced services are needed to suit the habit of users. The
voice service is regarded as the major service in this period, with the data service as its
supplement. Furthermore, differentiated services should be provided to the users at this time to
attract usage. Till this point, the voice service is still the major force of mobile services. This
phenomenon will not change fundamentally in the short run following the advent of 3G.
Therefore, the TD-SCDMA network is mainly voice-centric service, with due supply of data
services. In view of the current conditions, compared to the 2G system, TD-SCDMA has its
advantage in its ability of providing not only data services, but also the voice service. The cost of
the voice service for a single user is much lower than that of the 2G system.
(2) Strategy for the growing period: TD-SCDMA network should be improved and optimized
continuously in this stage to meet the basic requirements of the users. The differentiated services
should be extensively deployed to attract usage and increase the ARPU. The voice and data
services are of equal importance for the development in this stage. The feature services could be
developed at this time to diversify differentiation in the competition.
(3) Strategy for the flourishing period: The network in this stage is in full swing. The IMS
multimedia sub-system could be introduced to gradually integrate service to the IMS system so as
to make use of the features of the IMS system in service development. At this stage, the service is
data-centric, with the voice service as its supplement. Moreover, VoIP technology will gradually
take the place of the existing CS voice technology and will develop into an integrated IP network.
Thus far, the TD-SCDMA industry alliance has established a service working group. Based on the
development of domestic 3G terminal services, there will be three stages of the service level: the
first stage is before the end of 2005. The main task in this stage is to realize the functions available
on the 2G terminals or other 3G terminals, including SMS, WAP, MMS, WEB browsing, E-mail,
etc., and at the same time add some 3G multimedia functions, mainly the streaming media and the
videophone. The year 2006 will be the second stage. The task in this stage has three emphases.
The first emphasis is to go on with the realization of part of 2G service functions, such as
complementary services, Java games, intelligent network services, etc.; the second emphasis is to
develop advanced or new services of TD-SCDMA, such as PoC, LCS, IM, M2M, etc.; the third
emphasis is to conduct research on the next generation TD-SCDMA technology, such as HSDPA.
According to the plan, after completion of the second stage, TD-SCDMA will not only realize
service functions, but also demonstrate its technical advantages and surpass systems of other
modes. The third stage is beyond the year 2007, when the studies on terminals will be mainly
about IMS technology, service integration and new service models.
In the planning of TD-SCDMA terminal services, the service functions of PoC, LCS and
multimedia can best reveal the technical advantages of TD-SCDMA. First, TD-SCDMA has its
unique advantages in the location-based services. Due to the application of advanced technologies
such as intelligent antenna and uplink synchronization, the system can measure an angle through
the intelligent antenna and measure the distance by synchronized CDMA, with no additional
equipment needed to provide users with accurate location information like direction and distance.
Moreover, data services such as PoC, streaming media (e.g., Video on Demand, TV-on-mobile)
and Internet downloading, are asymmetric services, of which the requirement of downlink rate is
high, while the demand of uplink rate is lower. Through the adoption of TD-SCDMA, the
asymmetric transmission feature of TDD will be fully leveraged, the efficiency of radio resource
usage will be increased, and the operational cost will be lowered. Specific analyses regarding this
are given below.
1. PoC Service
POC service is also called Push-to-Talk service, where a mobile user can talk to one or more
people by pushing just one button on the keypad. The features of TD-SCDMA are especially
suitable for the application of POC. In the TDD working mode, the transmission of uplink and
downlink data is controlled via the transmission time. The transmission and reception time can be
controlled and changed in a flexible manner, making the technology especially suitable for the
highly efficient transmission of asymmetric services such as simplex and half-duplex
communications. The intelligent antenna provides terminal positioning and tracking capacity,
flexible frequency allocation and supports asymmetrical uplink and downlink data, thus bringing
low-cost and flexible service capacity to the POC technology. (Specifically as follows:)
（1）Easy frequency selection for convenient POC service employment
Due to the adoption of TDD mode in TD-SCDMA, it is easier to choose suitable frequency band
compared with other 3G technology in the employment of POC service. Unlike FDD, which
requires symmetry of uplink and downlink in the use of frequency band, only an independent
1.6MHz frequency band is needed for the employment of TDD in TD-SCDMA. Given the
shortage of frequency resources, TD-SCDMA is more suitable to operators for its rapid
employment and planning of POC service, which would guarantee provision of multi-band mobile
phones to users in certain sectors (e.g., the military force, public security, etc.) with special
（2）High rate of transmission for a better quality of POC service
The speed of packet data transmission in TD-SCDMA can reach 384kbps. While in the PoC
service, the voice capacity is a key measure of performance. In the packet domain, there are two
ways to improve the communications capacity: one is to improve the voice coding (Compression
Ratio), the other is to provide higher transmission rate. At present, based on the mature voice
compression technology, the high transmission rate of TD-SCDMA means better communication
（3）Variable transmission rate supports various QoS requirements in POC service
The services provided by POC include voice, text, or even video services (hopefully in the future).
Such services require completely different QoS. For example, the bandwidth requirement of voice
service is higher than that of the text, but lower than that of the video. The time lapse required by
the voice service is longer than that of the text. The reliability requirement of the text service is
higher, while certain transmission errors can be allowed for voice. Different transmission rate can
be provided in different TD-SCDMA environment. This feature of variable transmission rate is
more suitable for the transmission of media stream in POC service.
（ 4 ） Strong support of the half-duplex communications increases the efficiency of frequency
usage in POC service
The voice service of PoC is half-duplex. That is to say, the user can either speak or listen at one
time. TD-SCDMA adopts the TDD duplex mode, which enables one-way communications by
adjusting the switch point between uplink and downlink in a flexible manner. Such an operation
can also increase the spectrum efficiency.
（ 5 ） Accurate positioning of the intelligent antenna expands the application range of POC
The technology of intelligent antenna is adopted in TD-SCDMA for convenient, simple and rapid
provision of accurate positioning service. Combined with the presence service, more location-
based information can be provided. Moreover, such locations can be integrated into the PoC
service platform to enable users to accurately locate the other party during mobile
communications. This function is very important in some vertical applications of PoC service.
（6）Large system capacity supports more POC users
The capacity of TD-SCDMA is larger than any other 3G systems, and a lot larger than the current
2G/2.5G system. The large capacity means more users in the PoC service. On the other hand, it
enables the system to provide other services in addition to the PoC service. That is to say, PoC
service has little impact on other services.
（7）Self-owned intellectual property rights provide better information security for PoC service
The adoption of TD-SCDMA in POC service suits not only public networks that aim at public
operation, but also private communications networks the sectors like the military, power, oil field
and water conservancy, etc., to enable a tremendous progress in their ICT capacity. In this respect,
TD-SCDMA has its advantage of self-owned intellectual property rights. Our domestic
manufacturers have basically mastered the core technologies, including the core chipset, and own
the related intellectual property rights. Therefore, services for private networks can be customized
according to their application features, for example, the provision of the encryption function and
various kinds of dispatching applications.
The trunking communications will have a broad application prospect in the years to come. The
provision of PoC service on the public mobile network is a nice showcase of trunking services on
public networks, and more importantly, it will serve as a touchstone for the development of mobile
multimedia services, which will probably become the killer application in the future 3G network
and win strong support from operators, manufacturers, SPs and CPs. The series of technologies
adopted by TD-SCDMA for the application of PoC service have their own advantages and features
compared with other technologies. The operators, manufacturers and users will all benefit from
the deployment of PoC service in the TD-SCDMA network.
Figure 2. Network Structure of PTT service in TD-SCDMA
2. Location Service
The adoption of intelligent antenna and terminal synchronization technologies in TD-
SCDMA has made positioning of a single base station possible. Compared with WCDMA and
CDMA2000 systems, the TD-SCDMA system can provide a single base station with more
accurate signal source positioning (including Direction-of-Arrival and time lapse estimation)
without additional GPS module. In this way, the system security is improved with cost efficiency
and simplified design; and the speed of positioning turns faster, with more users getting more
accurate positioning service at the same time.
For individual users, the location service can provide the location information of users, together
with other information related to daily life, transportation, entertainment, service, public facilities
and location-based entertainment games, etc. On the other hand, rescue positioning, nursing,
vehicle dispatching, logistic management and location advertisement services can also be provided
to specific sectors.
3. Video Monitoring Service
The video monitoring service can capture real-time video signal through simulated or digital video
equipment, and send the video signal to the streaming media service platform on the network for
format transformation, and then play the video on the user-end through a mobile phone. Besides
its home usage, the video monitoring service can also be used in many other scenarios, such as
monitoring for kindergarten, roads, parks and warehouses to provide customers with an assuring
The video monitoring service has been successfully applied in the fixed network, WLAN and
2.5G network. The “baby online” service launched by Shen Zhen Telecom based on the Internet
has been well received by the public. Once the 3G network is put into operation, the mobile
network infrastructure can absolutely meet the requirements for video monitoring service, and will
contribute handsome profits in a short timeframe. According to the report of NTT DoCoMo, by
the end of 2004, there were more than 10 million video-enabled mobile phones in Japan, on which
the video monitoring service was available. Such a service has been widely accepted by the users.
Therefore, with the development of mobile communications technologies and the wide
commercialization of 3G in China, the application prospect of mobile video monitoring service is
TD-SCDMA has some remarkable differentiation advantages for realization of this service:
(1)Because the video monitoring service is a typical asymmetric service, there is much more data
on the downlink than the uplink. It is especially suitable for TD-SCDMA to provide this service.
TD-SCDMA technology can flexibly adjust the proportion of time slots between uplink and
downlink, fully meet requirements for the asymmetric service and effectively lower the cost
through improving the spectrum efficiency;
(2)The transmission rate of data is higher in the real-time video monitoring service. TD-SCDMA
system is advantageous in realizing such a service with its highly efficient supporting capability
for high speed data;
(3)The existing video monitoring solutions cannot realize distributed monitoring due to the
restriction of monitored locations. All countries have preserved frequencies for TDD. Therefore,
only the video monitoring service based on the TD-SCDMA network can truly realize monitoring
across the planet.
4. Streaming Media
The streaming media is a service supported by streamed transmission. In the wireless network, the
streaming media is mainly oriented toward the wireless packet network with wider bandwidth
(above 100kbit/s), such as GPRS/EDGE, UMTS, etc. It can be divided into video service and
audio service according to different streaming media sources. The increase of bandwidth in the air
interface of 3G network has provided a good foundation for the deployment of streaming media
service. Combined with the features of a wireless system with no restriction on time and location,
the mobile streaming media service is more appealing. The profit margin of voice service will
shrink in the future. Therefore, different competitive services are needed to increase ARPU
effectively. With the gradual introduction of the 3G network, new high-speed multimedia services
and data services can be deployed. The mobile streaming media can provide services like video-
on-demand, live video, audio-on-demand and live audio, etc., the content of which includes TV,
video, entertainment news, sports channel, music, news and cartoon, etc. The mobile streaming
media will become one of the hottest services in the future 3G network and is blessed with a bright
The TDD feature of the TD-SCDMA system enables a more efficient handling of asymmetric
services compared with the pure FDD technology. With the feature of the asymmetric service
supported by TD-SCDMA, high-quality audio and video programs can be enjoyed online with 2M
bandwidth, and images captured by a webcam can be transmitted to the mobile phone through the
streaming media encoding technology. By doing so, the monitoring of traffic, home and tourist
sites can be realized.