Research On Rate Adaptive Transmission Scheme Based On Subcarrier Quality In Heterogeneous Wireless Network

In the multi-technology coexistence environment of heterogeneous wireless networks,diversified wireless devices usually share the 2.4GHz ISM band.The data transmission between diversified devices face many challenges,such as spectrum limitation,wireless interference,and the inherent problems of hidden terminals as well as exposed terminals of the wireless network.The above challenges lead to a low transmission success ratio,and the reduced system performance.How to improve resource utilization and optimize the system performance has become one of research hotspots,which academics and industry pay close attention to.The adaptive transmission strategy which utilizes dynamic channel depth perception is an effective scheme.The fine-grained channel quality evaluation can provide support for the rate-adaptive transmission strategy.Based on the importance of data,the data is intelligently mapped onto corresponding subcarriers.With the above strategy,the system throughput has been significantly improved,and the system performance has also been enhanced.In this thesis,combined with the needs of the project "Key Technology Research on Transparent Coexistence of Heterogeneous Wireless Networks [2020JM-416]" from the Shaanxi Natural Science Foundation,conducts a comprehensive study on the rate adaptive transmission strategy of heterogeneous wireless networks.The main contributions are described as follows:(1)Taking the bit error problem on weak subcarriers and low throughput caused by frequency selective fading into consideration,we propose a point-to-point adaptive coding rate(ACR)algorithm for Wi-Fi protocol.Thanks to the in-depth analysis of the state of subcarriers,reliable subcarriers are used to transmit important data,which improves the transmission success ratio and the system throughput.The experimental platform is built by the WARP node,and experimental results as well as performance analysis verify that the ACR algorithm can improve the transmission success ratio,the system throughput,and the system robustness.(2)After exploring the classical interference avoidance algorithm in time dimensions,frequency dimensions and space dimensions,we propose a rate adaptive transmission algorithm for two types of nodes under the coexistence environment of Wi-Fi and Zig Bee.For the node of the Wi-Fi network,the channel is ranked according to the ratio of reliable subcarriers in the channel.Simultaneously,the data to be transmitted is intelligently mapped to subcarriers.Specifically,reliable subcarriers are used to transmit important data,weak subcarriers are used to assist data transmission,and conflicting subcarriers do not transmit data.The above strategy effectively guarantees the throughput and robustness of heterogeneous communication systems.For the node of the Zig Bee network,a fine-grained idle channel evaluation strategy is implemented,through which the spectrum resources shared by heterogeneous networks can be fully utilized to obtain higher throughput.The experimental platform built by WARP node and CC2530 node,and experimental results as well as performance analysis verify the effectiveness of the proposed algorithm.