The Interference Suppression Scheme Research Of Downlink LTE-A Communication System

This thesis focuses on the interference mitigation of 3GPP downlink LTE-A system, and mainly studies the interference suppression methods in relay and CoMP system. The enhanced schemes can reduce the ICI by efficient frequency planning and improve the performance of communication links.Based on cellular systems with relay, the EFFR scheme dynamically assigns subcarriers to center and edge groups depending on load conditions and the channel state information by two algorithms. The center allocation algorithm assigns subcarriers to center users from different directions. The edge allocation algorithm allows the highly loaded sectors to borrow the remaining subcarriers from center band or other sectors considering the fairness requirements of all the users. Simulation results illustrate that the proposed EFFR scheme can outperform the traditional schemes by achieving higher throughputs and better spectral efficiency especially in highly loaded cells.In CoMP cellular systems, in order to mitigate the inter-cell interference (ICI) of full-buffer scheme, an efficient sectorization frequency planning (ESFP) scheme in CoMP downlink transmission based on static fractional frequency reuse (FFR) is proposed in full-buffer service. This scheme schedules subcarriers from different distributions and different orders to avoid interference and reduces the probability to overlap. According to interference analysis and the simulation result, the ESFP scheme effectively increases the resource utilization rate and decreases the system outage probability.In addition, the subcarrier scheduling algorithm based on QoS in CoMP system divides subcarrier into two overlapping regions, which are called basic band and free band. All the service can be divided into real time service and data service from the delays. The BS schedules subcarriers based on the different user's requirements and the service priority. The subcarrier distribution also considers the fairness requirements of data service users. In order to meet the different band and delay requirements, the users of high loaded can borrow the free band to improve the performance of cells.