Study On Energy Efficient Routing Algorithms For Wireless Sensor Networks

Wireless sensor networks (WSNs), is an energy-limited network, which is highly correlated with application. It often consists of a large amount of small-size, low-cost and multifunctional sensor nodes. These sensor nodes work cooperatively and instantly to monitor sense and collect data information on monitoring objects and then transfer them to the manager through sink node or base station. In recent years, the wireless sensor networks has become to be a hot research issue and attracted highly attention in various fields both at home and aboard.Due to the characteristics of the sensor node itself and the special application environment, it is often impossible to replace battery of sensor node. Therefore, in the design of routing algorithms in wireless sensor network, the primary consideration is to save energy consumption, and prolong the lifetime of the whole network.Wireless Sensor networks has many characteristics which is different from traditional networks, such as large number of nodes, big density, limited energy, topology changing frequently, etc. Therefore, the design of routing protocols is particularly important. The main aim of the design of routing protocols is lower energy consumption, load balancing and long lifetime.In traditional WSNs, sink and sensor nodes are statically deployed in the sensing area, and data packets are forwarded from the source node to the sink by multi-hops. Therefore, sensor nodes close to sink node have more traffic loads and will quickly deplete their limited energy. After these sensor nodes die, the connectivity of the network will be damaged so that it will have to stop working. This situation in WSNs is called hot spots problem. Adding sink mobility into sensor networks can bring in new opportunities to mitigate hot spots problem and improve energy efficiency for WSNs. This thesis mainly makes researches on energy efficient routing algorithms to prolong network lifetime. The major work is as follows:(1) Relative theories about wireless sensor network and routing algorithms are first reviewed. Then classifications of routing algorithms and typical algorithms are discussed. Based on LEACH, an energy-efficient routing algorithm is proposed to improve network performance. In this protocol, unequal clustering technique is utilized; also distance from base station and residual energy of each sensor node is taken into consideration when choosing cluster heads.(2) In order to alleviate the formation of hot spot, sink mobility technology is introduced into wireless sensor network and a multiple mobile sinks based routing algorithm for data dissemination is proposed. The whole network will be partitioned into different areas and multiple mobile sinks will be utilized to move back and forth along predetermined paths to collect data packets.(3) To further improve network performance, a novel routing algorithm, which combines clustering technique, sink mobility and Ant Colony Optimization, is proposed to mitigate hot spots problem, balance energy consumption and extend the network lifetime.