Research On Medium Access Control Protocol And Cross-layer Cooperation Technology Of Wireless Ad Hoc Networks

Wireless Ad Hoc networks(WANET)are a widely used,rapidly evolving network with a huge development potential and application prospect.Meanwhile,the introduction of many new technologies and concepts to wireless communications and networks not only enriches the application scenarios and functions of the WANET,but also increases the complexity of the system design,resulting in increasingly demanding requirements of network performance in various aspects.This dissertation focuses on the media access control(MAC)technology,cross-layer cooperation technology and other hot technical issues in WANET,and proposes some novel techniques to improve throughput,reduce transmission delay,save energy and adapt to flying ad hoc networks(FANET).The content of this dissertation and innovative contributions are specified as follows:(1)The multi-hop transmission technology in WANET network with multi-channel transmission is studied,and its transmission performance requirement is analyzed.A MAC layer access and transmission scheme is proposed based on assistant node selection and a novel channel allocation algorithm.Also,the protocol uses channel state information to assist channel allocation and designs the retransmission mechanism.The network throughput,delay and transmission fairness are simulated and analyzed by combining the transmission environment factors,which proves that the protocol can enhance WANET transmission performance and fairness.(2)Combining the carrier sense mechanism of the competition protocol with the time division multiple access(TDMA)mechanism of the non-competition protocol,a hybrid access protocol based on power control in MAC layer is proposed.Based on the original carrier sense and TDMA transmission mechanism,the proposed protocol optimizes the transmission scheme,by reducing the transmission times of overhead and unnecessary control information in the competition phase,and fully using the time slots in the TDMA phase.By integrating these two mechanisms,the protocol TCH-MAC based on the power control architecture of MAC layer is designed.Theoretical analysis demonstrates that the protocol can not only reduce the transmission energy consumption,but also improve the transmission performance such as network throughput.(3)The characteristics of high dynamic and stereoscopic application scenarios in FANET are analyzed.And an energy efficient MAC layer hybrid protocol is proposed accordingly where the 3D and high speed scenario is optimized.The protocol is designed for the application characteristics of sensor nodes in FANET such as UAV,and the transmission mechanism of the transmitting and receiving phase is separately designed to improve transmission performance.The analysis of Markov state transition model and simulation results show that the proposed protocol can reduce energy consumption to prolong the service life of nodes.(4)Aiming at the limitation of single-layer transmission model in WANET,a cross-layer model of MAC layer and physical layer is proposed.A network access mechanism based on distributed coding cache is developed,which enables the network to use idle time slots for caching in the low load phase,and reduces the traffic congestion of the network in high load period to occurring to sudden high-load communication situations.Then the network layer is added to the cross-layer model,and a cross-layer transmission mechanism based on network,MAC and physical layer is proposed.The mechanism can utilize the network layer routing information to perform node location and distance information acquisition,so the transmission power can be jointly adjusted across the MAC layer and the physical layer according to the information obtained from the node,achieving energy efficient transmission.The simulation results demonstrate the significant performance improvement of the proposed access and transmission mechanism on the network transmission and energy efficiency.