| In order to improve reliability of the monitoring system for high-voltage transmission line based on two-tier wireless networks in harsh e nvironments, system need to use the wireless sensor network link instead of WiFi link while WiFi devices are in case of paralysis. Since the system usually sends pictures or other large data for WSN, the Zigbee link must be able to meet this requirement. This paper provides a multi-channel transmission protocol based on linear clustering topology. By choosing several pairs of nodes from two adjacent clusters use multiple channels for simultaneous transmission of data, system can achieves a high inter-cluster communication rate.For a reasonable choice nodes and channels in communication between clusters, this paper provides an effective channel and node selection algorithm. The two factors of interference can be abstracted as specific values through periodic channel detection and calculation of channel SINR.This paper provides a quick send mechanism based on Selective and Repeat protocol (SR) to improve performance in inter-cluster transmission. Quick Send mechanism can reduce the number of ACK packets and the waiting time, so a pair of nodes can be guaranteed to the data transfer rates. Quick Send mechanism also provides 1 hop transmission reliability support functions. Agreement strictly limits the work time of cross cluster transmission, and has initiative query mechanism after the cross cluster transmission. Node can taking into account the inter-cluster work and cross-cluster work.This paper gives the actual performance of system at the last. Agreement can avoid a busy channel, and guarantee a low packet loss rate. The RTT of a 10KB data to 3 hop using single-channel is 2.5s. Most of the time in RTT is for data packets transmission. The throughput of system proportions to the number of channels. Each channel can provide throughput of 50Kbps. |
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