Research on Synchronizationalgorithm of WiMAX Physical Layer Based on IEEE802.16e
|School||Nanjing University of Posts and Telecommunications|
|Course||Circuits and Systems|
|Keywords||IEEE802.16e OFDMA Time synchronization Frequency synchronization Multiple access interference|
With the development of mobile communication technology, People’s demand on the speed of data transmission and multimedia services is highly increased. Orthogonal Frequency Division Multiplexing (OFDM) has been more and more attended by its’good resistance to multipath interference and high spectral efficiency. The Orthogonal Frequency Division Multiple Access (OFDMA) which is based on OFDM, has all the advantages of OFDM, besides this, it also introduces the concept of sub channel, and it has been known as next-generation wireless access technology. OFDMA technology also has its own deficiencies, such as frequency selection sensitive, sensitive to time deviations. Overall, to maintain the excellent performance of OFDMA systems, a high degree of synchronization of the system is necessary.In this article ,we choose to do research on the synchronization problem of OFDMA system, which is based on the protocol IEEE802.16e.First ,OFDMA system downlink synchronization problems are analyzed, deviation’s impact to the OFDMA system is calculated by building system model and some classic OFDMA system downlink synchronization algorithms are introduced. A symbol timing synchronization algorithm in frame detection has been improved by extending the correlation length of the preamble and increasing the correlation in non-adjacent leading word. The simulation results show that the improved algorithm’s frame detection rate has increased in different false alarm’s probability.Then, the OFDMA system uplink synchronization problem is analyzed. The system uplink multiple access interference (MAI) is analyzed by building the system model. A time domain TO estimation algorithm is improved by adding CFO estimation meanwhile, and then we get a simple data-aided joint estimation algorithm. Simulation results show that, compared to the frequency domain TO and CFO joint estimation algorithm, the improved algorithm has low complexity, loss of detection rate and high detection accuracy, and it can accommodate more users under the same conditions. It can guarantee the synchronization of the system and improve the system performance.Finally, it is a summary and outlook to this article.