Research Of GAF Geographical Routing Algorithm In Wireless Sensor Networks

Wireless Sensor network(WSN), which is widely used in medical, environmental applications, military, industrial and agricultural production, has developed rapidly in recent years and will be a new field of research of information technology in this century. Due to the limitation of the Sensor nodes’energy, energy efficient MAC, routing protocols, topology control mechanisms and application layer protocols should be mainly considered in the design of WSN Protocols stack. Besides, multi-layer protocol co-design strategy is more conducive to optimize the performance of energy consumption in WSN.Currently, it is not an effective solution that only relies on the routing protocols to reduce the energy consumption and achieve the load balance of the whole network, such as flat routing, hierarchical routing, geographical routing algorithms. GAF algorithm, combining topology control and routing technology together and adopting the hierarchical strategy and sleep scheduling mechanism, which saves the idle and monitor energy consumption of the nodes greatly and extends the network’s lifetime effectively.Three improved algorithms are introduced against the disadvantages of the topology partitioning mechanism of GAF to reduce further energy consumption and balance the load of the whole network. First, the nodes near the center of the cluster will die rapidly for heavy load caused by fixed topology partitioning mechanism, a cluster cyclic-shift algorithm is introduced to achieve both the load balancing of all nodes and the minimum of the total energy consumption of one cluster. Second, an improved topology control algorithm based on virtual-grid division is introduced, which has extended the coverage area of each grid in the limitation of the nodes’ transit power and increased the number of sleeping nodes to save energy. The last, due to the limitation of network connectivity in the direction of diagonal caused by square grid structure, an asymmetric cluster distribution algorithm is introduced, which has shortened the transmission range of data packets to sink node and optimized the transmission path.Simulation environment is set up by Matlab software and the performance of the three improved algorithms are verified. Theory analysis and simulation results show that the system load and survival time of the three algorithms have been effectively improved.