| Wireless data traffic has increased dramatically over the past decade due to changes in the way information is created,shared and consumed in today’s society.This change is accompanied by the growing need for high-speed wireless communications anytime,anywhere.For this reason,a large number of scholars in the field of communication have targeted at the terahertz band,which has a large amount of bandwidth.However,the existing terahertz technology is not very mature,there are many problems,such as the communication distance is short due to the high frequency.Accordingly,scholars in research based on the existing terahertz technology,proposed the terahertz double channel MAC protocol,the protocol is the main core idea in the low frequency to the transmission control through the whole frame for terahertz channel reservation,and terahertz beam alignment,after the completion of the switch to the terahertz beam transmission channel for data.The directional data transmission proposed by terahertz dual channel MAC protocol can greatly improve the communication distance compared with the original terahertz omnidirectional data transmission.However,this method still has some disadvantages,such as redundant control overhead and beam overlapping interference.In this paper,based on the research of terahertz dual channel MAC protocol,some major problems are solved.The specific research work is as follows:1.The current terahertz multi-beam dual-channel MAC protocol used in air separation reuse method for communication,allowing for more nodes on terahertz channel for data transmission at the same time,the increase of throughput for the MAC layer is huge,but this will trigger a new problem,which may cause beam overlap interference exists between any two nodes,And there is a large control cost in the communication process.This paper proposes a high efficiency dual channel MAC protocol based on relay cooperative forwarding in terahertz networks(He-RCFMAC).The HE-RCFMAC protocol contains three new mechanisms.Firstly,the "streamlined RTS/CTS frame" mechanism is used for control frame interaction in Wi Fi channel,the aiming is to reduce the redundant control overhead in control frame.In this process,the "adaptive cooperative forwarding based on position information" mechanism is used to determine whether there is beam overlapping interference.If yes,data is forwarded through the trunk node.Otherwise,the source node directly sends data to the destination node.In the process of sending data,the dynamic frame aggregation mechanism is used to aggregate data frames and send the aggregated data frames to the destination node.This mechanism aims to further reduce the control overhead of redundant data frames.The results show that he-RCF MAC protocol has significant improvement in MAC layer throughput,data transmission success rate and channel utilization compared with the original protocol.2.The current MAC protocol of terahertz dual channel does not contain the priority scheduling policy of data frames,that is the nodes sending each data frame can compete for the channel with the same probability,but in the actual communication process,some data frames must be sent out first.This paper proposed a low-overhead dual channel MAC protocol based on priority scheduling in terahertz networks(LO-PSMAC).The LOPSMAC protocol contains three new mechanisms: Firstly,the source node with data transmission request competes for Wi Fi channel through the "CSMA/CA" mechanism of priority scheduling strategy.The source node with successful channel competition sends RTS frame to the destination node.After receiving the RTS frame,the destination node determines whether the transmission power of the source node is enough to communicate with the destination node through the "communication distance prediction" mechanism.If not,cancel the transmission,otherwise normal transmission.Then,TTT,DATA and ACK frames are exchanged in the THz channel through the mechanism of "Thin THz Band MAC Frames"(MAC frames in THz band are transmitted in THz band MAC frames).The results show that LO-PSMAC protocol improves significantly in MAC layer throughput,channel utilization and control overhead. |
