Research On Location-based Relay Selection Strategy In D2D Communication System

It is no doubt that the explosive growth of mobile data traffic has increased the burden of cellular networks,and the D2 D communication technology can solve this problem.Relay selection in D2 D communication system has always been a research hotspot.Most of the previous researches on the selection of relay in D2 D communication system consider the situation that the relay position is fixed,which is inconsistent with the reality,Therefore,it is necessary to study the impact of location information on the relay selection strategy.Based on the stochastic geometry framework,the reliability and security of D2 D communication system under the relay selection strategy assisted by location information are quantitatively analyzed.The security and reliability are measured by the secrecy outage probability and outage probability respectively.First,the optimal relay selection strategy is proposed by considering the exact position information and channel state information of the relay,and the secrecy outage probability and outage probability of D2 D system under this strategy are studied.However,obtaining the instantaneous state information of each relay requires frequent information feedback,which will lead to excessive system overhead.Then,in order to reduce the feedback overhead of the system,only the precise location information of the relay is considered to select the relay,a nearest location-based relay selection strategy is proposed,and the secrecy outage probability and outage probability of D2 D link transmission using this strategy are given.The study found that with the help of the relay transmission reduces the security of D2 D link communication.Therefore,the only under the premise of considering the location of the relay information,we further proposed to set a security guard region for each relay.On this basis,a nearest location relay selection strategy with secure guard region was proposed,and the secrecy outage probability and outage probability of D2 D links are derived.Then,in order to further reduce the feedback overhead and operation com plexity of the system,considering the region location of the relay without obtaining the exact location information of each relay,a region-aware relay selection strategy is proposed,and the secrecy outage probability and outage probability of the D2 D system under this strategy are derived.Finally,the proposed relay selection strategies are validated by Monte Carlo simulation.The simulation results show that,in terms of reliability,under the same parameter settings,the transmission outage probability of D2 D link using the optimal relay selection strategy is the lowest,followed by the nearest location-based relay selection,and the highest outage probability of D2 D link using the nearest location relay selection strategy with secure guard region.Compared with the nearest location-based relay selection strategy,the region-aware relay selection strategy can achieve the same communication reliability with smaller feedback bits.In terms of security,the secrecy outage probability of transmission using the nearest location relay selection strategy with secure guard region is the lowest,which indicates that adding security protection area for each relay can effectively improve the security of communication of D2 D link.