Research On Load-balanced Routing Algorithms In Wireless Sensor Networks

Wireless sensor networks (WSN) are multi-hop self-organized network systems in which massive sensor nodes are randomly deployed to communicate with each other. Routing protocol is regarded as one of the crucial techniques in WSN, and its performance will straightly affect the efficiency of the entire network. In recent years, the researches about routing protocols in WSN have made a quite great progress, but there still remain a lot of awkward problems. Because of the energy limitation of sensor nodes,"hot spot" or "routing hole" problem may cause some nodes in the network overloaded, even the entire network die early. Thus, how to extend WSN’s lifetime and make the whole nodes load evenly is a very challenging and essential research issue.In this paper, we focus on the load-balanced routing techniques of wireless sensor networks, especially aim at addressing the problems caused by "hot spot" and "routing hole". Here, we proposed three load-balanced routing algorithms, which are listed as follows:(1) A clustering-based routing algorithm with nonuniform sensor distribution (CRND) is put forward to solve the "hot spot" problem during data transmission in WSN. Main innovation of CRND is its network topology, that nodes deployed unevenly in a ring circle network, a different number of clusters are formed in each ring based on both the distance from sink node and the node’s residual energy. Through theoretical analysis, article gives the ratios between the numbers of nodes of all loops when achieving energy balance. Based on such quantitative deployment, CRND realizes inter-and intra-cluster routes, efficiently extending the network lifetime. Simulation results show that CRND, compared with LEACH and nonuniform node distribution strategy without clustering, has more excellent network energy utilization and routing success rate.(2) Geographic routing is widely used in wireless sensor networks due to its great efficiency, good scalability and computed routing close to the best possible. However, geographic routing costs a lot to obtain nodes’geographic information and will be easy to encounter "routing hole". Aiming at this problem, we present a Landmark-based Virtual Geographic Routing Algorithm (LVGR), which depends only on node connectivity and not on any knowledge of node positions to discover the global topology of the sensor field. After topology discover, nodes can successfully communicate through local coordinate routing. Simulation shows that LVGR generates routes that are comparable to those generated by geographic routing algorithms, and even load-balanced. It has advantages in low cost, light routing overhead and high performance.(3) Geographic routing (Georouting) with greedy forwarding is attractive for WSN, but holes in networks often cause routing failures. Aiming at this situation, we propose a Greedy Georouting Algorithm with Conducted Void-bypass Paths (Conby). Most routing hole algorithms adopt strategies after encounter routing hole node during every data forwarding. Different with them, Conby tries to avoid holes in advance. The first time Conby reaches a routing hole node, it conducts one or two shortest paths which could get out of the hole. The subsequent packet forwardings will be aware of the void before reaching its routing hole node, consequently saving a lot of unnecessary energy consumption. To prevent the exhausting of nodes’ energy in the network, we introduce a threshold of the remaining energy. This will encourage more nodes to participate with routing activity, make balanced energy usage in the network and extend the network lifetime.