Research On Co-channel Interference Mitigation In N-frequency TD-SCDMA System

At the early stage of TD-SCDMA network, because the whole network shared the signalfrequency, there was serious Co-channel Interference and poor network performance. Later,using the N-frequency technology, interference in the public channel carrier was reduced.However, there is still Co-channel Interference in the dedicated traffic channels, andCo-channel Interference leads to a serious decline in the network KPI(Key PerformanceIndication); it impacts network capacity and service quality, and reduces systemic reliabilityand efficiency. Therefore, Co-channel Interference has been one of the main problems thatplague the quality of TD–SCDMA network.Due to time-division duplex, short spreading code and less spreading gain inTD-SCDMA system, Co-channel Interference has a serious impact on network performance.One of important challenge is to reduce Co-channel Interference, and it is very important toenhance the capacity of the TD-SCDMA system and its key indicators. Co-channelInterference suppression technique is a substantial in wireless network performanceimprovement.In the thesis, it describes the principle of TD-SCDMA Flexible Frequency Reuse (TFFR)algorithm. Then it gives a dedicated analysis of Co-channel Interference on the network KPI,especially on the rate of handover success and the rate of voice dropping. And it alsoevaluates Co-channel Interference suppression algorithm on the improvement of network KPI.Meanwhile, it describes the key technologies that are impacted by TFFR, especially accesscontrol, dynamic channel allocation, handover control and congestion control, etc.This thesis also simulates and analyzes TFFR algorithm on the improvement of networkKPI, using OPNET and VC to set up the system-level simulation platform; and the algorithmis proved to have a good performance and achieve the desired result. Moreover, the improveddesign of TFFR is proposed. It can provide some reference for the future study of networkingplanning and the actual network system.