Cross-layer Protocol In Sensor Networks. Multi-radio

With the rapid development of wireless communications, integrated circuits and embedded computing technologies, wireless sensor networks (WSNs) consisting of low-power and multi-functional sensor nodes are widely used and studied extensively. Therefore, this article studies combined channel allocation and routing, jointly channel assignment and link scheduling for Multi-Radio Multi-Channel wireless sensor networks, as well as multi-query and random routing joint cross-layer problem for wireless sensor networks.The main contributions of this thesis are as follows.1. Considering the limited orthogonal channels in Wireless Sensor Networks (WSNs), a distributed channel allocation algorithm (DCA) for Dual-Radio WSNs is presented. Based on DCA, a routing forwarding strategy (RFS) is proposed in this paper as well. DCA avoids conflictions within a path and reduces conflictions among different paths with a small number of channels. Nodes reselect forwarding nodes by switching channels timely in RFS, and then further dropping the conflict between the paths, effectively transmit data in parallel. Simulation results indicate that DCA and RFS can reduce the latency of data forwarding and the average energy consumption of nodes, as well as increase the throughput significantly.2. Based on the problem that less orthogonal channels in wireless sensor networks prone to conflict communication among nodes, a Dual-Radio Multi-Channel link scheduling algorithm based on hierarchical networks (LSHN) is proposed in this paper. The whole network nodes are divided into different hierarchy and used different channel at firstly, so the conflictions among different hierarchy are reduced. Then based on link scheduling algorithm, the conflictions within same hierarchy are avoided. LSHN can implement the data parallel transmission with zero-conflict in different nodes, and it can finish the data collection in wireless sensor networks in a preferable way. Experiment results indicate that LSHN can reduce the data collection time obviously, and hence increase the throughput of the networks.3. Aiming at the problem of multiple queries in WSNs, a random routing algorithm is proposed. Every query node randomly generates a path and sends a query message along the path. When multiple query messages pass through a common node, they are shared by using the copy of each query message at this node. Subsequently, these multiple queries are executed collaboratively, which improves the query efficiency without additional communication cost and energy consumption. Theoretical analysis and experimental results indicate that the proposed algorithm has a higher query success ratio for the scenarios of both the single query and the multiple queries.