Research On Random Access Technology In LTE Uplink System

LTE is the mainstream technology of mobile communication with the evolution from3G to4Gwhich uses a lot of key technology of4G (such as OFDM and MIMO). It has a revolutionarychange of wireless access and network architecture with the main stream of3G. It is the trend of themobile communication to be broadband and the broadband access to be mobile.Random access technology is a key technology in mobile communication system and has a greatinfluence on the performance of the throughput and delay of LTE system.The requirements of delayand capacity of LTE system is also very high, so the research on random access has become one ofthe most important researches. The random access procedure is completed in the uplink of LTEsystem, the main function is to establish the uplink synchronization and assign the terminal timeand frequency resource.In this thesis, based on the analysis of the random access technology, the function, theclassification and procedure of random access in LTE system is also introduced in depth. Then thisthesis discusses the schemes of random access preamble management. The characteristics of thetranditional preamble management scheme are described. This thesis proposes an improvedpreamble management scheme based on priority. The simulation results show that the scheme notonly can ensure the access success rate and solve the time delay problem, but also can reduce thewaste of radio resources. The scheme of preamble management based on priority can effectivelyimprove the performance of the access capability.The application mechanism of backoff algorithm in random access of LTE is also researched inthis thesis. Based on the analysis of basic backoff algorithm, this thesis proposes an improvedalgorithm based on the optimal access control, and the comparison of the performance of delay andthroughout between the improved backoff algorithm and basic backoff algorithm is showed throughsimulation. Finally by the test platform of LTE system in the engineering project, the capability ofthe algorithm based on the optimal access control is tested.