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The Access Procedure Design for Low Latency in 5G Cellular Network

Low latency and massive connectivity are significant features of 5G network. With Internet of Things (IoT) communication scenarios, there may be huge quantities of user equipments (UEs) in idle state to access network for transmission uplink data at the same time. If these UEs access network following the LTE-A (Release 12) access procedure, it will cause huge signaling overhead and latency deterioration. In this paper, we propose an optimized access procedure with low latency and low signaling overhead. In proposed procedure, radio bearer (RB) and S1 bearer are controlled and managed by the eNodeB and MME respectively, which reduces the latency through the establishment of RB and S1 bearer in parallel. The eNodeB transmits only one signaling for configuration radio bearer including SRB1, SRB2 and DRBs, which reduces the signaling interaction rounds between the UE and the eNodeB. Simulation results show that the proposed access procedure has a better performance than LTE-A. Minimum access latency is 32ms in proposed procedure compared with 57ms in LTE-A. Under the light traffic load, the average access latency is decreased to 43%. According to CDF of access latency, the access latency offers a 31% reduction compared with LTE-A to ensure 90% of UE successfully access. Under the heavy traffic load, the average access latency is decreased 55%, and the latency offers a 52% latency reduction compared with LTE-A to ensure 90% of UE successfully access. In addition, the proposed procedure can ensure that 100% of UE can be accessed successfully within 160ms. Further, the proposed procedure can offer around 1.2 times gain over LTE-A in access success probability, which indicates the signaling congestion is mitigated. The proposed access procedure is more suitable for low latency requirements of 5G network.