Research On MAC Protocols For In-Band Full-Duplex Wireless Networks

In-Band Full Duplex(IBFD)wireless communication allows nodes to transmit and receive signal simultaneously in the same frequency band,which can improve the efficiency of spectrum and the throughput of system exponentially when compared with half-duplex(HD)wireless communication.The existing HD media access control(MAC)protocols don't allow multiple nodes to access the channel simultaneously for IBFD communication.To fully utilize the IBFD communication capability of nodes and further improve the performance of wireless networks,medium access control protocols should be researched according to the characteristics of IBFD wireless communication.In this paper,Asymmetric In-band Full Duplex-MAC(AFD-MAC)mechanism and Power Controlled in-band Full Duplex MAC(PC-FD MAC)mechanism are proposed and performance analysis is carried out.Firstly,in this thesis,we overview the research background and domestic and international research status of IBFD wireless communication technology.Then,the key technologies of IBFD wireless communication are introduced,including self-interference cancellation,inter node interference(INI)suppression and IBFD MAC mechanisms.After that,we summarize the research method of IBFD MAC mechanisms and compare the existing researches.In addition,RTS/CTS mechanism in the 802.11 MAC protocol is introduced and its limitations of application in IBFD wireless network are summarized.Secondly,an IBFD wireless network which consists of an AP with full duplex capability and multiple users with half duplex capability is considered in this paper.We propose an AFD-MAC mechanism which can establish asymmetric bidirectional links through one channel access operation.In this approach,the received signal strength is deliveried,which can assist the destination user to estimate the INI value and determine whether to establish an asymmetric bidirectional link.Therefore,the wrong transmission caused by the inter node interference can be avoided.Discrete-time Markov model is used to analyze the network performance.Simulation results show that AFD-MAC mechanism can improve the IBFD wireless network performance compared to RTS/CTS and A-Duplex mechanism.Finally,PC-FD MAC is proposed in the IBFD wireless network environment where the AP is an IBFD node and the user is an IBFD node or a HD node.In PC-FD MAC mechanism,symmetrical bidirectional link between two nodes and asymmetric bidirectional link among three nodes can be established.In addition,the AP node obtains the information of inter node interference through exchanging the control frames.Then,AP adjusts the transmit power of AP and the uplink user based on the power controlled method.In this way,inter node interference can be suppressed and the probability of asymmetrical bidirectional link established successfully can be increased in the wireless network.Discrete-time Markov model is built to analyze the performance of PC-FD MAC mechanism under saturation conditions.The simulation results show that,PC-FD MAC mechanism improves the wireless network performance.