Study On Relay Node Selection Algorithm In Relay Networks And Realization Of The Network Platform

With the growing demand for the networking of physical world, Internet of Things(Io T) shows a promising furture. IOT that applied to Wireless Local Area Network(WLAN) tends to be a increasingly large-scale and high-density deployment, which needs more users and greater coverage. In the low frequency and power WLAN, to realize dense deployment and wide range of coverage, Relay-based multi-hop network has been used. In this networking, a large number of nodes are attributed to different Relay nodes, and different channels in each Relay are used to reduce the conflicts between nodes. At the same time, forwarding mechanism of Relay node is used to shorten the transmission distance and reduce the transmission power of each node. However, due to the fact that the data interaction between some nodes is performed periodically, some Relay nodes frequently stay idle with a large number of Relay nodes open. Due to the considerable energy consumption caused by idle Relay nodes, it will inevitably result in the unnecessary waste of energy.To solve the energy problem, a coverage control Relay node selection algorithm is proposed in this paper. First, alternative Relay node groups are determined through primary election and selection based on the relevant node deployment theory. Then, a simulation model is built. Through MATLAB, a comprehensive comparison of coverage rate, dormancy rate and coverage energy consumption among Relay node groups is made to determine the location and number of open Relay nodes. The proposed algorithm can effectively regulate the number and location of Relay nodes, reduce the number of open Relay nodes and set some Relay nodes into hibernation on the premise of meeting certain coverage requirements. As the power consumption is reduced when nodes in sleep mode, the energy consumption is lower.In order to verify the performance of multi-hop networking, a Linux-based demonstration platform is built and the adaptive switching mechanism of nodes is designed. Under this switching mechanism, a station can adaptively switch between direct-mode(direct association with an AP) and Relay mode based on the current link quality. The advantages of the proposed mechanism is further verified by the throughput, latency and packet loss rate. Besides, in conformity with the verification requirements, the virtual users and virtual cells are employed in the platform so as to reduce the cost.