Research And Implementation Of Hierarchical WLAN Transmission Performance Enhancement In Complex Environment

The development of communication technology has brought profound changes to people's lives.The ever-increasing demand for network services and business needs poses higher requirements on network bandwidth,network delay and network system architecture.With the expanding application range of wireless networks,the traditional Transmission Control Protocol(TCP)congestion control algorithm and the Confirm-retransmission mechanism in wireless networks are the main obstacles to the current wireless network transmission performance improvement.At present,the construction of airport ground wireless network still faces the problems of serious interference and data transmission efficiency far below the design standards.In view of the above problems,this paper presents a layered wireless terrestrial network architecture suitable for airport environment.By introducing the research status of existing wireless network transmission performance enhancing technologies,we introduce the network coding technology and proxy server into the layered wireless network architecture technology.The main contents of this paper include the following aspects:In the process of designing and implementing the network coding scheme on the network coding based model(TCP/NC),this paper studies and analyzes the network coding scheme which is suitable for the application scenario proposed in this paper,and puts forward the following two innovations:1)TCP/NC model coding process,we propose the Encoding Block Manager(EBM)mechanism based on encoding blocks,and adjust the acknowledgment and retransmission mechanisms in the current network coding schemes to solve the problem of unnecessary packet retransmission.2)In the EBM,a dynamic adjustment mechanism of coding blocks compatible with the current protocol stack is introduced,and the time varying variable round-trip time(RTT)is used as a dynamic change indicator of network conditions to adjust the coding block size in real time to better adapt to the current state of the wireless network.Aiming at the hierarchical wireless network architecture made by asymmetric links proposed in this paper,a proxy server based on the Sessions Traversal Across Firewall Securely Protocol(SOCKS)is designed and implemented.By joining the proxy server at the edge access points(APs)of the network,a complete TCP connection is divided into several independent TCP connections,reducing the probability of the data sender erroneously performing congestion control.In the process of establishing the demonstration system,this paper simplifies the proposed layered terrestrial wireless network architecture and builds a complete demonstration system including terminal APs,aggregation APs and clients.The test results in the lab environment show that the performance of the proposed network coding scheme and the standard TCP in the throughput rate are quite comparable when the packet loss rate is smaller than 0.04%.As the packet loss rate gradually increases,the throughput between the two The rate of the gap between the more and more,when the packet loss rate of 3%,the proposed network coding scheme throughput of 2.8 times the standard TCP throughput.