Study Of Collision Problems In Random Access Process Of LTE System

In order to keep ahead in the field of mobile communication in the future for a long time,3GPP has started up the LTE plan, LTE system has introduced the new air interface and other advanced technologies, so that the transmission rate is higher, the access delay is smaller, and the system capacity is bigger. As a key technology in the media access control (MAC) of mobile communication system, random access has a great influence on the performance of the whole system.Because of the high requirement for capacity and delay in LTE system, studying on random access technology will inevitably become the important content in LTE system. The core research on random access is how to reduce the collision of users in random access process and how to cut down the access delay of users. This paper has studied around the collision problem in random access process, looking for the rational and effective methods of solving the collision problems. The main works of this paper are as follows:1) Researching two kinds of random access protocols in mobile communication system. Classifying the random access scene in LTE system and analyzing the causes of the random access under different scenarios and their triggering conditions;2) Analyzing two random access modes in LTE system-competitive random access and non-competitive random access, because users has a high probability of collision in competitive random access, this paper mainly studies the random access process based on competitive model. Then it has analyzed the possible anomalies including collision in random access process;3) Putting forward an improved preamble management scheme in random access process. In order to verify the performance of the improved scheme, building the simulation model of random access process. Using several frequently-used backoff algorithms in different management schemes, then comparing the performance of different schemes, in order to verify the improved preamble management scheme is effective and practical;4) In order to make the random access users have more opportunities to get wireless resources, thereby reducing the collision problem, this paper, from the angle of resource management, putting forward UE state detection algorithm to dynamically analyze the active state of the users. Then combining with the experimental environment to arrive at the realizations of the algorithm, so as to verify the feasibility of the algorithm.