TD-LTE Synchronization And Random Access Algorithm At High Speed

After the information construction of high-speed railway in China,civil aviation is speeding up the information construction.In the near future,passengers can enjoy the service of air communication.However,ultra-wide coverage and a maximum speed of1200 km/h requirements make a high demand on compatibility and anti-Doppler performance of wireless communication network.Therefore,it's very necessary for LTE system in high-speed mobile scene to explore and optimize with the times.As the first step in the communication process,the random access process is an important part of LTE communication network.How to access and maintain good performance in high-speed mobile scene is the primary problem that LTE system needs to solve.Under the above background,this paper makes an in-depth study on the random access technology of TD-LTE system under high-speed mobile scene:The first chapter analyzes the process of downlink synchronization and uplink random access,and emphatically analyzes the SC-FDMA technology,then clarifies the importance of uplink random access technology in TD-LTE system.The second chapter introduces the uplink synchronization technology,the generation and launch of random access preamble sequence,the design of physical random access channel,and focuses on the general process of the receiving end in TD-LTE system,including extracting random access preamble sequence,PDP operation,the division of search window,the detection of preamble sequence and timing estimation,etc.In the third chapter,the influence of high-speed mobile scene on random access is analyzed.The existing LTE random access algorithms in high-speed mobile scene are deeply studied.Based on this,an improved algorithm is proposed.The algorithm is mainly using the aircraft's positioning function and speed measuring functions,sending the preamble sequence compensated frequency offset in advance.So,it could expand the coverage area and reduce the Doppler effect.The effectiveness is verified by matlab simulation platform.In the fourth chapter,based on the virtex-6 FPGA chip,the FPGA modules of random access detection algorithm were specifically designed,and the performance verification was obtained by using the modelsim function simulation.Finally,the modelof TD-LTE system was built on the MicroTCA hardware platform,and the correctness of the algorithm was verified by testing.The fifth chapter makes a brief summary the main content of the full text,and points out the direction for future improvement and efforts.