Research On Optimization Of ZigBee Routing Algorithms

Because of advantages in cost、energy and speed, ZigBee is widely used in wireless communication and has becomed a hot topic. Almost devices in ZigBee are powered by batteries and the lifetime of the equipment will be grandually depleted and sometimes end with the batteries charge, so the network energy has become a subject due to the infeasibility of replacing the batteries. And the data transmission delay is large and the reliability is poor because that the hops of data transmission is too many and not optimal. Now the subject of how to reduce the hops of data transmission and network maintenance cost, and furthly improve the reliability of data transmission and reduce the energy consumption of ZigBee by improving the routing algorithms of ZigBee has become one of important subjects, and has been the center of attention.In the paper three routing algorithms of the network layer of ZigBee protocol of Cluster-Tree、AODVjr and their combined algorithm ZBR are firstly be analyzed and thier thought of and operational mechanism have been studied as key issues. Due to the shortcomings of the limitations of the selection of the next hop in Cluster-Tree algorithms and large and meaningless RREQ packets during the route discovery in AODVjr algorithms, and the ZBR algorithm, a combination of both being too smiple and stilling many uncertain factors to choose from the two algorithms, a imporved idea is posed in the paper. Firstly the two routing algorithms are improved and the appropriate improvements haved been made for the combination of both. Spedific improvements as follows:(1)The Cluster-Tree algorithm makes full use of the neighbor table. Removing the invalid neighbor nodes and reducing the amount of calculation by judging the relationship between the current node and the destination node in the calculation of the distance of the neighbor node to the destination node. To choose the neighboring node which is nearest from the destionation node as the next hop node by taking advantage of the relationship between the neighboring nodes of the current node and the destionation node, rather than sending the data to the parent node or the child node simply;(2) In the AODVjr algorithm, the numbers of sending times of the RREQ packets are limited to remove the long packets according to the depthes of the current node and the destination node in the network, and the more accurate upper bound of hops are calculated in accordance with the Cluster-Tree algorithm;(3) Taking the energy of nodes and the routing price into account and defining the energy levels which is updated in a real time, so that routing nodes in the different energy levels can use different routing strategies for routing.Finally, the paper uses NS2 simulation for the original ZBR algorithm and the improved algorithm by building the environment of NS2 simulation in Linux. The simulation results indicate that the improved algorithm has outstanding performance in energy savings of network and the rate of packets delivery and end to end delay.