Research on Inter-Cell Interference Cancellation in LTE System
|School||Southwest Jiaotong University|
|Course||Communication and Information System|
|Keywords||Inter-cell interference (ICI) Co-channel interference Probability of data-aided ( PDA ) Interleaving multiple access ( IDMA ) Iterative interference canceller Orthogonal frequency division multiplexing ( OFDM ) MIMO|
The inter-cell interference (ICI) is an inherent problem, which determines the capacity of the system. In the cell system, the cell edge users by adjacent cell interference, so their throughput is quite low. The inter-cell interference cancellation technology can eliminate the co-channel interference, and to improve the performance of the cell edge. Orthogonal Frequency Division Multiple Access (OFDMA) LTE downlink multiple access scheme was chosen because of its high spectral efficiency and other advantages. , OFDMA can not eliminate interference through spread spectrum code division multiple access (CDMA) type, the LTE in the main data probability assistance (PDA) with interleaving multiple access (IDMA) combined with iterative interference cancellation technology. PDA can be achieved iterative multi-user (cell) detection, and IDMA can get to a significant performance gain, thereby suppressing inter-cell interference. First, the establishment of a multi-cell interference MIMO system, and considered three existing PDA detection algorithm, which is the minimum mean square error detection algorithm (MMSED), mean soft decision detector (SDD) algorithm and maximum a posteriori probability detection (MAPD) ??algorithm. MMSED and SDD algorithm belongs soft the interference cancellation detection (SoICD) algorithm, the MAPD algorithm is a generalized Turbo detection algorithm. Simulation results show that the algorithm is based on the same principle of detection but MMSED algorithm in complexity and performance to be inferior to SDD. The SDD algorithm advantage of low complexity, good stability, showed excellent performance in dealing with weak interference, the disadvantage is the lack of the processing power of the strong interference. And MAPD algorithm advantages demonstrated excellent performance in dealing with strong interference, the disadvantage is the high complexity, lack of stability in dealing with weak interference. Then, in order to achieve their complementary advantages, the paper presents an improved of the PDA detection algorithm - grouping MAPSDD algorithm, it is a good mix of SDD MAPD algorithm. Different according to the intensity of the interference signal, the paper proposed three programs based on improved algorithm. The simulation results show that the interference of different strength using different detection scheme is feasible and flexible. An integrated detection scheme based on an analysis of the simulation result can be obtained: strong interfering signals them with the desired signal can be assigned to the same group, using the packet MAPSDD algorithm detected; SDD can be used algorithm for detecting the interference signal; For weaker interference signal, you can use the Gaussian approximation approach. This will not only improve performance, but also reduce the complexity. Finally, create two types of multi-cell interference in the MIMO-OFDM system simulation and analysis in three MIMO BLAST-OFDM and STBC-OFDM system, the interference cancellation algorithm performance. Simulation results show that improved the algorithm in MIMO-OFDM system also showed similar performance.