Future application II

Besides the fundamental implementation mentioned before, services like PoC, LCS and multimedia can best reveal the advantages of TD-SCDMA.

1. PoC Service
POC service is also called Push-to-Talk service, provides one-to-one and one-to- many voice communications service over cellular networks. [1] 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. More details are described as follows[2]:

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. TD-SCDMA is more suitable to operators for its rapid employment and planning of POC service. It can guarantee provision of multi-band mobile phones to users in certain bands (e.g., the military force, public security, etc.) with special requirements.
2).High rate of transmission for a better quality of POC service
The speed of packet data transmission in TD-SCDMA can reach 384kbps, which is a key measure of performance in POC service. At present, voice compression technology is mature , TD-SCDMA improve communication quality due to the high transmission rate .
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, which means 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 service
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.

Reference:
[1]IMS, TD-SCDMA Shape a Bright Future Together, http://wwwen.zte.com.cn/endata/magazine/mobileworld/2008year/no2/articles/200811/t20081119_162227.html
[2]Service Research and Feature Applications of TD-SCDMA, TD-SCDMA Forum