A Study On MAC Protocols Of Terahertz Ultra-High Data-Rate Wireless Personal Area Networks

Predictions indicate that short-range wireless data-rates of tens of Gbps will be required by 2020, and currently available wireless technology cannot support these demands despite significant progress in spectrally efficient techniques. Terahertz frequency has great bandwidth to provide ultra-high speed wireless communication, and attracted the attention of a large number of scholars. Terahertz ultra-high data-rate wireless personal area networks(TUD-WPANs) are a kind of wireless ad hoc network, which can meet the 10 to 50 Gbps communication traffic demand in the no more than 10 meter operating range by using terahertz frequency band for high-speed data transmission, and has broad application prospects. However, there are few achievements of TUD-WPANs MAC protocols due to the uncompleted physical layer technology, and currently the related research of the MAC protocols are all based on IEEE 802.15.3c.On the basis of the relevant existing MAC protocols(such as IEEE 802.15.3c, HEF-MAC, HTLD-MAC, etc.), this thesis focus on communication characteristics of the TUD-WPANs, conduct in-depth research in hybrid access protocol CSMA/CA+TDMA and proposed two new MAC protocols, the main contents include the following two aspects:1. To address the problems existing in the current MAC protocols that can be used in TUD-WPANs, such as the waste of the invalid CAP period, the unsatisfaction of time slot requests but still remaining channel resource, and the sub-frame received correctly but it also need to be retransmitted caused by failure extraction, a MAC protocol of High Channel Utilization(HCU-MAC) for TUD-WPANs is proposed. By adaptively canceling the CAP period, designing a more comprehensive slot allocation mechanism with fairness consideration based on the existing algorithm, and joining reverse aggregate process when data aggregation, HCU-MAC protocol can improve channel utilization, reduce retransmission overhead and data delay, ensure the nodes fairness of channel access, and is better suited for heavy traffic communications of TUD-WPANs.2. A High Throughput and Low Latency MAC protocol(HTLL-MAC) is proposed to address the following issues: the network cannot work stably with dynamic equilibrium superframe structure for the defective design of the existing access solutions, the reduction in channel utilization caused by unreasonable size of contention window when node retransmitting its channel time request frame, and the remaining time slots in CTA has never been fully used. By designing a new access mechanism to trigger PNC transmit beacon frame at the appropriate time, and inform other nodes to avoid collisions, the network can work efficiently and stably while dynamic equilibrium superframe structure been fully used at the same time. In addition, with the dynamically change size of the retransmission contention window and make full use of the CTA remaining time slots, HTLL-MAC can accelerate the data forwarding process and reduce data latency. Simulation results show that HTLL-MAC have good network performance in a variety scenarios of TUD-WPANs.Finally, the summary of this thesis and the future research directions of TUD-WPANs are given.