The Research On Orphan Node Reduction Algorithm In ZigBee Wireless Sensor Networks

ZigBee is a new short distance wireless communication technology which has advantages of low-cost, low-power consumption and low complexity, and the technology has been widely used in wireless sensor networks. With the constant improvement of ZigBee protocol, the wireless sensor networks based on ZigBee technology will be widely used in home automation, industrial controlling, intelligent medical, military and agricultural production, wireless positioning and other fields. There are problems of more orphan nodes, lower success rate of address assignment caused by the shortage of ZigBee network distributed address allocation mechanism and so on. So it is very important to design a very reliable and high performance address allocation algorithm for improving the performance of ZigBee networks. Nowadays, there are four kinds of improved address assignment algorithms, address assignment algorithm based on borrowed address in ZigBee networks, address assignment algorithm based on centralization in ZigBee networks, address assignment algorithm based on address reconfiguration in ZigBee networks and address assignment algorithm based on priority in ZigBee networks respectively. For the problems of depth detour, orphan nodes, lower success rate of address assignment and higher average communication overhead in the existing ZigBee networks address assignment algorithm, this paper proposes ZigBee network construction algorithm based on topology optimization and borrowed address assignment algorithm based on the depth model in ZigBee networks.In order to solve the problems of depth detour and orphan nodes caused by the the shortcomings of distributed address allocation algorithm and the existing network construction algorithm in ZigBee networks, this paper proposes a network construction algorithm. In the process of network construction in ZigBee networks, the algorithm acquires the one-hop neighbor node information by exchanging information between nodes, such as received signal strength indication, link quality indicator, and so on. The algorithm uses one-hop neighbor node information, make the node which is common node does not join the network in the one-hop range of its parent and the potential parent node has higher priority to join the network to optimize the network topology, to improve the problem of depth detour and reduce orphan nodes. The simulation results show that on the basis of reducing network depth detour, the algorithm can effectively reduce the number of orphan nodes and improve the success rate for address assignment. The algorithm has obvious advantages in the case of middle and large scale ZigBee networks.In order to solve the problems of orphan nodes and address space imbalance caused by the the shortcomings of distributed address allocation algorithm and the existing borrowed address assignment algorithm in ZigBee networks, on the basis of maintaining the original network topology, this paper proposes a borrowed address assignment algorithm based on the depth model. When the address space which DAAM algorithm defined is less than half of 16-bit address space, the algorithm assigns 16-bit network address DAAM algorithm unused as addresses for router nodes in ZigBee networks. Router nodes can assign addresses for orphan nodes to reduce orphan nodes and maintain the original network topology. Meanwhile, the tree routing algorithm to suite the borrowed address assignment algorithm is proposed. Theoretical analysis shows that the algorithm and DAAM algorithm have the same time complexity and the same storage complexity. At the same time, the maximum tree hop counts of the tree routing algorithm based on the borrowed address assignment algorithm and ZigBee tree routing algorithm are twice as the maximum depth in ZigBee networks. The simulation results show that on the basis of maintain the original network topology, the borrowed address assignment algorithm can effectively reduce orphan nodes number. Meanwhile, the algorithm improves the success rate for address assignment, reduces the average communication overhead of address assignment and the average time of address assignment etc. The algorithm has obvious advantages in the case of small and middle scale ZigBee networks.