The Full-duplex Medium Access Control Technique In Edge Wireless Networks

With the advent of the 5G era and the massive deployment of IoT applications,edge wireless networks urgently require larger network capacity,smaller transmission latency,and higher spectrum utilization to support the explosive growth of data traffic and diverse applications.At this time,the in-band full-duplex(IBFD)technology,which is a candidate technology of 5G,attracts many researchers' attention.With IBFD,packets can be simultaneously transmitted and received on the same frequency.However,how to translate potential full-duplex transmission opportunities into network-level performance improvement requires the cooperation of the MAC(Media Access Control)layer and higher layer protocols.Among them,the performance limit of upper layer is directly determined by the MAC layer.Therefore,we focus on the design and implementation of the full-duplex MAC protocol in this paper.In order to solve the channel contention problem in IBFD radios with inter-node interference and asymmetric traffic,this paper proposes a centralized full-duplex MAC protocol,pFD-MAC.In pFD-MAC,we first design a novel polling-based transmission mechanism and make comprehensive investigations on the effect of polling profile in full-duplex communication.By characterizing the inter-node interference into a directed non-conflict graph,we study the polling profile generation problem in which our objective is to minimize the packet transmission time.The problem is then theoretically formulated and proved to be NP-hard.Then,we develop a heuristic traffic-aware algorithm and apply it to work with the packet transmission procedure in parallel.Full-duplex communication opportunities are highly exploited by organizing per-node upstream/downstream traffic according to the generated polling profile.Moreover,to achieve fairness without sacrificing throughput,deficit-round-robin(DRR)algorithm has been applied with respect to the access time considering concurrent transmission time.Simulation results reveal that our proposed protocol can achieve improved performance in terms of throughput and transmission delay while maintaining fairness,compared with two state-of-the-art centralized MAC protocols.Considering the limitations of centralized full-duplex transmission scheduling and the dynamics of wireless communication environment,this paper presents RLFD,a distributed full-duplex MAC protocol based on CSMA mechanism.And we assumed that the AP uses full duplex radios and clients work in half duplex mode in the protocol.In order to fully utilize the full-duplex transmission opportunities,the transmission scheduling problem is theoretically formulated and it can be reduced as a MAB(multi-arm bandits)problem.In order to solve the full-duplex transmission scheduling problem and adapt the dynamic communication environment,we propose a Windows-Constrained Bayesian(WCB)optimization algorithm,which mainly includes: 1)design a Reward function to stimulate higher network throughput;2)introduce a learning amplification factor to accelerate the convergence of the algorithm;3)using a window-constraint function to make the algorithm adapt to the dynamic communication environment.In addition,we also designs a packet transmission mechanism based on the RTS/CTS mechanism,and the performance of the transmission mechanism is theoretically analyzed by Markov chain.The simulation results show that our proposed algorithm can highly utilize full-duplex opportunities and maintain a good network performance in the dynamic communication environment.Finally,considering that the deployment of full-duplex APs(Access Points)not only affects the quality of network coverage but also determines the full-duplex transmission opportunity in the AP-based full-duplex wireless networks,this paper makes a commprehensive investigations on optimizing the full-duplex transmission opportunities by carefully deploying full-duplex APs.Firstly,we theoretically analyze the effects of full-duplex APs deployment on network throughput.Exact full-duplex transmission probability is derived in presence of Rayleigh fading with different AP locations.Our analysis reveal that a good AP deployment profile can exploit more full-duplex transmission opportunities and greatly improve network performance.The full-duplex AP deployment problem is then formulated as an integer non-linear programming(INLP)problem in which our objective is to obtain optimized network throughput.Then we develop a heuristic local beam search algorithm to solve the formulated problem and optimal deployment profile can be produced.By simulations,we compare the differences between full-duplex AP deployments and traditional half-duplex networks,and investigate the impact of different full-duplex AP deployment profiles on full-duplex network throughput.The simulation results verify that the proposed heuristic algorithm can approximate the optimal solution obtained by the grid search algorithm at a very low cost in the full-duplex AP deployment problem.