- Same radius coverage for various services
TD-SCDMA systems can ensure continual coverage of various services. Various UMTS services have different spread spectrum factors, so the coverage is via concentric circles of different radii, that is, 'concentric coverage'. This can bring major trouble for network planning. For example, if continual coverage of voice services is to be ensured, that of high-speed data services is not. If the continual coverage of the high-speed data service is ensured, that of the voice services is greatly overlapped, resulting in severe interference between them. TD-SCDMA system design is such that various services have the same basic coverage radius, i.e. 'same radius coverage' to ensure continual coverage of various services.
- Weak breathing effect
The TD-SCDMA system does not have an obvious breathing effect. Breathing effect is the phenomenon where the coverage radius shrinks as the number of users in a cell increases. The main cause of a breathing effect is that the CDMA system is a self-interference system, so the breathing effect is an inherent defect of the CDMA system. Another phenomenon of the breathing effect is that the change in the number of each type of service user will cause change of the coverage radiuses of all services. This can create major trouble for network planning and network optimization. TD-SCDMA is a system that integrates CDMA, FDMA, TDMA and SDMA. It suppresses major interference by using low-bandwidth FDMA and TDMA to effectively reduce breathing effect causes. At the single timeslot, CDMA technology is used to improve capacity. The interference between multiple users at the single timeslot is the only cause of the breathing effect, and such interference is overcome via joint detection and smart antennas. TD-SCDMA is not an interference limiting system, but a code channel limiting system, as the coverage radius hardly changes with the increase of users, resulting in a minimal breathing effect.