| The network layer of wireless sensor network (WSN) forms the transmission path based on data-centric concept. As the node energy and resources are limited, the design of routing algorithm should meet energy-efficient, low latency, load balance and other special requirements which are hot issues in current WSN research. Two routing algorithms are respectively proposed for load balance in large scale sensor networks:(1) the Load-balancing GAF Algorithm of Dislocated Grid for WSN (GAFDG)GAFDG is proposed which based on the GAF. The biggest difference between GAFDG and GAF is that the grids in GAFDG are dislocated arrangement, but the grids in GAF are aligned arrangement. Nodes are selected as cluster heads according to "the principle of minimum energy consumption" in GAFDG. Each cluster head of GAF can communicate with four cluster heads which respective in the up, down, left, and right the four adjacent grids except the cluster head in the edge grid. While each grid has six adjacent grids in GAFDG. Therefore, each cluster head of GAFDG can communicate with six adjacent cluster heads. Therefore, when the backbone network of WSN, which is constructed by all cluster heads, is communicating, GAFDG is better than GAF in orientation of routing. Theoretically proofing, the single-hop coverage area of GAFDG is wider 12% than GAF. Simulation results also show that energy consumption and network lifetime of GAFDG are superior to GAF.(2) the Load-balancing GAF Algorithm of Hierarchical Honeycomb Structure for WSN (GAFHH)GAFHH is proposed which based on the GAF Algorithm of Honeycomb Structure for WSN (GAFH). The major difference between GAFHH and GAFH is:the nodes within the same honeycomb grid construct a cluster in GAFH, while the cluster in GAFHH is constructed by the nodes that belong to several adjacent honeycomb grids. The monitoring area is divided into honeycomb grids in GAFHH, and the nodes belong to several adjacent honeycomb grids construct a cluster which is restricted by single-hop communication radius R of node, and each grid is unified numbered according to its position in the cluster. Selecting a middle grid as a active grid in each cluster, and adopting "the principle of maximum residual energy" to select a active node as a cluster head in each active grid. And all cluster heads construct the backbone network of WSN is using of communicating. At the beginning of the next round, re-selecting the active grid, and moving the boundaries of each cluster to make the active grid is always in the center of the cluster. In the simulation, GAFHH compare with GAFDG and GAFH, and simulation results show that the load balancing and throughput of the former are superior to the latter two. Therefore, the proposing of GAFHH is a certain significance.GAFDG and GAFHH are proposed in the paper, respectively dividing monitoring area into the dislocated square girds and honeycomb grids and making the nodes construct a cluster by the corresponding rules, and respectively adopting "the principle of minimum energy consumption" and "the principle of maximum residual energy" to select cluster heads, and the backbone network of WSN is constructed by all cluster heads. Reasonably dispatching the energy resources from the space, extending the network lifetime, and achieving the purpose of load balancing. Finally, the paper describes the application of WSN in remote monitoring system of Coal-field Fires, whose routing had adopted a similar GAFHH to balance the load of each node. |
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