Research On Random Access Algorithm Based On Rach Overload In LTE Systems

LTE is the evolution of 3G, which is the most studied, most mature wireless access technology that has the brightest prospect. With the popularity of personal communication and development of M2M communication that brings the new challenges and opportunities for wireless communication. The more and more UEs in wireless communication systems cause the high RACH overload, besides, the capacity of wireless communication system is limited, so, how to make the UEs successfully access the network is the most important field of our research in the future.The overwhelming UEs will lead to the RACH overload in random access, the most effective solution is to adopt effective preamble detecting algorithm and improved backoff strategy. If UE does not receive RAR successfully or contention resolution fails, it will proceed power ramping and delay the subsequent Random Access transmission by a backoff time. But the power ramping will waste power and increase system's interference, what's more, to backoff after the failure of contention resolution doesn't check the overload of RA channels in time, which will bring a huge amount of signalling overhead, yet still unable to solve the RA channel overload problem caused by bursty random access effectively.The article briefly introduces a new kind of random access algorithm and mechanism based on power detecting, which can check RA channels in the initial time of random access procedure, besides, UE can backoff using certain backoff algorithm and proceed random access again without power ramping after the failure of contention resolution. When there are a a huge amount of random access events attemp, this algorithm will be able to decease the RA delay, improve the RA success probability, thus solve the RACH overload problem effectively.