Research And Realization Of SoftMAC Protocol Based On Embedded System

In recent years,the popularity of wireless broadband services,the explosive growth of wireless terminal equipment and the concept of IoT's(Internet of Things)proposition and application put forward higher requirement to the performance of wireless networks,as the switch of node data transceiver,wireless network multiple access(MAC)protocol plays a decisive role in the fairness of channel utilization,network delay,power consumption,channel usage and congestion performance of the wireless network.Considering the research of MAC in wireless network are mostly concentrated in the validation of the theoretical analysis and simulation,the actual implementation was almost blank other than the commercial IEEE 802.11 protocol,FullMAC/HalfMAC scheme implemented based on hardware chips and SoftMAC scheme implemented in operating system and kernel network protocol stack.Among them,the protocol parameters of the first two schemes implemented on hardware platform change complexly,and their poor programmability and portability,long development cycle are also should be considered;the portability of SoftMAC scheme implemented on operating system and kernel network stack is also not good.Therefore,in order to develop a universal experimental platform for the research of MAC protocol in wireless network,compared with the traditional SoftMAC scheme,this paper discards the operating system and kernel network stack,and proposes a user mode SoftMAC design and realization scheme.The main content and innovation points are as follows:1?As the simple binary backoff(BEB)algorithm for the traditional IEEE 802.11 DCF mechanism,the network throughput and delay performances decreases sharply under the high load circumstance,therefor,an optimization algorithm is firstly given: adaptive network conflict based on backoff(CWN-BEB)algorithm;CWN-BEB can be perfectly compatible with DCF 802.11 protocol without introducing additional overhead,and can be implemented simply.Simulation results show that the CWN-BEB algorithm can converge to the DCF protocol in low load condition,and the time delay and the throughput performances of the CWN-BEB algorithm are better than the 802.11 DCF protocol in the case of high load.2? To provide QoS guarantee for the communication between vehicles in the vehicle networking,this paper presents a kind of VD-TDMA protocol based on competition MAC protocol.This paper makes a detailed analysis of several topology of freeway scene between vehicles,analyzes the difficulties which exist in the TDMA protocol,and proposes the Vehicle Dynamic TDMA protocol(VD-TDMA)based on totally distributed regional network.With the integrated design of node in and out of network and conflict resolution,nodes in regional network do not need to interact with each other specially,and can selfperceive conflicts and solve the conflicts.Finally,the corresponding software and hardware design is given.3?Introduce the basic architecture of the SIP user network protocol stack,analyzes the key role of user network protocol stack in the design and implementation of SoftMAC protocol concretely;state the advantages of SIP user network protocol stack based on calling method,data structure and memory copy...4?The CWN-BEB algorithm SoftMAC design and implementation scheme is shown based on SIP(Internet Protocol Simple)user state network protocol stack,and then we test the corresponding functional verification in the wireless serial port platform.Give the user state SoftMAC scheme of VD-TDMA protocol,and then the verification is carried out on the STM32 hardware platform.