Research On Handover Scheme Based On D2D Relay In TD-LTE Trunking System

With the further development of public network trunking system,the rate and quality of service which trunking subscriber required would sharply increase.Traditional LTE handover technology utilized hard handover,with the problem of long handover delay,high drop rate and unreliable service,which already cannot satisfy the requirement of trunking system.Assistant handover based on device-to-device(D2D)communications can effectively improve the transmit rate and signal to interference plus noise ratio(SINR)of trunking communication systems(TCM)during the handover process.However,numerous D2 D links will cause long delay,more signaling overhead and high energy consumption.Meanwhile,D2 D user which reused the cell spectrum inevitably caused interference,how to allocate the network resource to reduce the interference as much as possible seemed crucial.In the background,this thesis launched the research of optimization on handover scheme in LTE trunking system,including:First of all,from the LTE system handover procedure and handover measurement,the hard handover technology with the problem of long handover delay and high drop rate was pointed out.Then,this thesis summarizes and analysis the research production of handover scheme in trunking system.Then,this thesis also analysis the advantages and disadvantages of handover scheme based D2 D relay.Second,according to the existing handover scheme based on D2 D relay,the thesis proposed a trunking system handover algorithm based on cluster and multicast(TSHACM).This scheme adopted cluster head choosing and clustering algorithm based on Analytic Hierarchy Process(AHP)considering D2 D coverage,relative speed and remaining power,and obtained the cluster head terminal.This scheme can effectively reduce the number of cluster heads,extend the time of D2 D communication and make the network's cluster structure more stable,which would benefit to the continuity of service and high rate during the handover process.Simulation results show that the TSHACM effectively improves the transmit rate and SINR and reduces energy consumption of trunking users during the handover process than that of the traditional algorithm.Last,by modeling the interference problem in trunking system which is based on D2 D multicast,this thesis proposed a trunking system resource allocation algorithm based D2 D multicast(TSRADM).This algorithm aiming at maximizing the system throughput divides the resource allocation into two steps,one is resource block allocation and the other is power allocation.First step searches the best cell subscriber as partner aiming at minimizing the interference for multicast cluster,then allocates the resource block.Second step adopts the genetic algorithm to search the best power allocation scheme.Then,programming and simulation were finished.Simulation results validates the efficacy of the proposed algorithm in decreasing interference and improving the system throughput.