The Research On Orphan Node Network Algorithm In ZigBee Networks

With the continuous optimization of ZigBee protocol,wireless sensor networks based on ZigBee technology have been widely used in wireless industry,precision agriculture,home and building automation,military,consumer appliances and medical services.Because the default distributed address allocation mechanism of ZigBee standard has many problems such as many isolated nodes and low utilization of address resources,it is very important to design a stable and reliable address allocation algorithm to improve the autonomous configuration capability of ZigBee network.The existing improved algorithms of ZigBee network address,such as borrowed address algorithm,centralized algorithm,network reorganization algorithm and node priority algorithm,can improve the problem of isolated nodes,but will destroy the network topology,increase communication overhead and address allocation time-consuming.In this paper,firstly,the general situation of ZigBee network is introduced.According to the different principles of the algorithm,the address allocation algorithms of ZigBee network are analyzed and compared.Then,the deficiencies of DAAM and existing ZigBee network address allocation algorithms are analyzed and compared.Two improved algorithms are proposed as follows.Aiming at the problems of the spread of isolated nodes and low utilization of address resources in the distributed address allocation algorithm of ZigBee network,an isolated node entry algorithm for ZigBee network based on node transfer switching is proposed.This algorithm designs concise command frames suitable for transfer switching algorithm to determine transfer nodes and exchange nodes.It modifies the frame control part of network layer of ZigBee protocol to establish the communication mechanism between parent and child nodes,change the connection state and respond to the node's request to enter the network.On the one hand,by querying the type of sub-nodes recorded in the neighbor table and the order of assignment,the sub-nodes of the transfer node re-assign addresses to the sub-nodes of the transfer node.The sub-nodes of the transfer node in turn query the information in the neighbor table and re-assign addresses to the sub-network to maintain the original network structure.On the other hand,the information of neighbor nodes can be obtained through the information exchange between nodes,and the exchange between terminal nodes and routing isolated nodes can alleviate the spread of isolated nodes.The simulation results show that in the process of transferring switching nodes,the network connection rate of the routing node equipment is greatly improved,the link disconnection of the transfer node is effectively reduced,and the spread of isolated nodes is alleviated.At the same time,the success rate of address allocation is improved,the average time of address allocation is reduced and the utilization rate of network address is improved.Aiming at the problems of single network scale and poor adjustability of preset parameters of existing ZigBee network loan address allocation algorithm,a new algorithm for ZigBee network loan address allocation based on recursive reduction model(ABRRM)is proposed on the basis of maintaining the original tree network topology.The algorithm constructs a recursively reduced routing node model by using the network parameters and the information of the relationship between the maximum number of routing nodes at each layer and the network depth index in DAAM algorithm.By setting network parameters,three selection intervals of borrowed address routing nodes are formed.Based on this,a new formula of address offset and address assignment of isolated nodes is designed to make full use of the remaining address space of the routing nodes in the model,so as to maximize the allocation of addresses for isolated nodes.Theoretical analysis shows that the Borrowed Address Assignment algorithn has the same time complexity and storage complexity as DAAM algorithm.The simulation results show that the borrowed address allocation algorithm is practical in many network scales.It effectively utilizes the address resources of ZigBee network on the basis of maintaining the original tree-like network topology,reduces the number of isolated nodes of ZigBee,improves the success rate of address allocation,reduces the average address allocation time and average communication overhead.