A Study On MAC Protocols Of Terahertz Wireless Personal Area Networks

With the development of wireless communication technology, low frequency bandcan not satisfy people’s demand of data transmission rate, so terahertz wirelesscommunication technology is paid more and more attention now. Terahertz frequencyhas large available continuous bandwidth which can provide more than10Gbps datatransmission rate. However, the transmission distance of terahertz wave is very shortwhich is due to the transmission attenuation is very large when terahertz wave transmitin the air. Terahertz wireless personal area network is a kind of short rage ultra-high datarate wireless communication network which use terahertz wave as wireless carrierwaves to communications and the maximum data rate can reach10Gbps. This networkhas the characteristic such as ultra-high data rate, self-organizing, short communicationrange. There is still rare research in the field of MAC protocols for terahertz wirelesspersonal area networks at present, which largely affects the research and applications ofterahertz wireless communication technologies. Two MAC protocols suitable forterahertz wireless personal area networks which is based on the hybrid access protocolCSMA/CA+TDMA (such as IEEE802.15.3c) are proposed. The major contents of thisthesis are as follows:1. In view of the hybrid access method CSMA/CA+TDMA (such as IEEE802.15.3c) having the problems of not update the total time slots number requestedwhen retransmit channel time request frame, existing resources waste when there isunused time slots resources in CTAP period, not considering the large number of data interahertz wireless personal area networks which will induces fairness problems whenPNC allocates time slots resources, existing redundant overhead in Beacon frame, aHigh Efficient Fairness MAC protocol for terahertz wireless personal area networks isproposed to resolve these problems. By updating total time slots number requested,increasing the length of CAP period adaptively, deleting redundant overhead of Beaconframe and designing a new fairness time slots allocation algorithm, HEF-MAC protocolcan improve network throughput and decrease the data access delay and transmissiondelay. Theoretical analysis and simulation results show that the network throughput andfairness perform better than that of existing MAC protocols.2. A High Throughput Low Delay MAC protocol for terahertz wireless network environment is proposed based on the problems of unreasonable superframe structurewhich may not adjust the length of CAP and CTAP period adaptively, not reserved timeslots for retransmission data when transmit channel time request frame in hybrid accessmethod CSMA/CA+TDMA (such as IEEE802.15.3c and ES-MAC protocols). HTLD-MAC protocol can reduce the waste of time slots resource and maximize the networkthroughput by designing a dynamic equilibrium superframe structure which can realizedynamic adjust the length of CAP and CTAP period. A new channel time requestmechanism which reserve time slots resource for retransmission data based on channelquality and an adaptive dynamic acknowledgement based on channel quality areproposed and this can increase network throughput and decrease data access delay andtransmission delay by reserving time slots resource for retransmission data and choosingacknowledgement adaptively. Simulation results show that HTLD-MAC protocol canmaintaining higher network throughput and lower data transmission delay when thechannel quality is very poor.At last, the summary and future research directions of terahertz wireless networkMAC protocols are given.