Research On Ultra-reliable And Low Latency Communication In Wireless Network With Mobility

There is general consensus that the future of many emerging fields such as industry automation,intelligent transportation,and telemedicine depends on Ultra-Reliable and Low Latency Communication(URLLC).It is also the focus of this thesis.We investigate the geometry of URLLC and their performance in wireless network with mobility.And We consider the diversity policy to improve the retransmission success probability.And we investigate how to satisfy the quantity-of-service(Qo S)by taking downlink transmission as an example.and the delay components includes backhaul latency,queueing delay and transmission delay in the UL and DL.The reliability components highly depend on transmission.With ultra-low latency and finite-blocklength channel code,it is impossible to achieve the Shannon capacity limit.We need the finite blocklength regime theory to characterize the maximal transmission rate.Firstly,we have evaluated the performance in the URLLC services under mobility models.This thesis proposes two specific mobility models(uniform mobility models and gauss mobility models),which simulate the mobility of the nodes in mobile wireless network.The network performance,e.g.,the coverage rate,local delay and mean throughput have been analyzed to ensure the Qo S under practical mobility models.The simulation results verify theoretical results.These conclusions are summarized as follows: Since the random mobility of the interference source decreases the spatio-temporal correlation of interference and interruption,fast mobility has been shown to reduce the local delay and improve coverage rate and mean throughput in the mobile cellular network.Random mobility of the interferers positively affects the network performance.In the block mobility model,when the mean coherence time K as the related time parameters continue to increase,the frequency at which nodes update their locations and the mean speed decrease.On this condition,the performance of URLLC deteriorates owing to the high time correlation of interference.The mean coherence time K greatly affects the local delay in the low K regime,while its impact shrinks in the high K regime.Secondly,we try to optimize URLLC performance through time diversity and space diversity retransmission policy.It is concluded that increasing the number of time slots,subchannels or random retransmissions effectively improve the signal-to-interference ratio.The requirement on transmission error probability can be relaxed with retransmissions.The success probability of URLLC has been significantly improved through retransmissions,the performance gain increases with the times of retransmissions.Both of two retransmission policies improve the performance of URLLC.