Research On Key Technologies For Energy-efficient Construction Of Wireless Sensor Network

A wireless sensor network is a wireless network consisted of a great deal of sensor nodes which are deployed densely in the sensing region. The establishment of wireless sensor network does not depend on any network infrastructure. It is a non-central, distributed, multi-hop transmission, self-organizing wireless communication networks. Owing to its features, such as rapid deployment, survivability, high accuracy surveillance and large coverage, wireless sensor network technology has become a research hotspot of IT field. Sensor node is battery-powered, and its energy is very limited. Consequently, how to efficiently use the limited energy of sensor nodes and extend wireless sensor network lifetime as long as possible has become its basic research goal. Aim at this goal, this article studies some key technologies which are used to build sensor networks, including address allocation strategy, density control technology, topology control technology and access technology. By putting energy-saving technology in these technologies, the wireless sensor network improves energy efficiency and extends its lifetime.The auto assignment of IP address is the premise and foundation to form wireless sensor networks. It also has an effect on energy consumption of sensor nodes. In order to communicate with the Internet easily, in this paper, we present SNMAAP (Sensor Networks Multi-agents Address Assignment Protocol), an IPv6 address assignment protocol based on multi-agents for sensor networks, utilizing the IPv6 to meet the wireless sensor network requirement of considerable network addresses. By using agent nodes in the network, not only each node can get an IP address in a short period of time, but also the probability of the address collision and overhead is low. The simulation results demonstrate that under the same condition, SNMAAP guarantees a unique IP address assignment and has lower latency, communication and duplicate address detection overhead.There are often a large number of sensor nodes in wireless sensor network. If all sensor nodes worked together, not only there would be a lot of redundant information, but also they would have great adverse impact on network throughput, bandwidth, latency, and energy. So we use density control technology to reduce the number of active sensor nodes under the precondition of ensuring network coverage and network connectivity. We propose SNDC (Sensor Network Density Control), a density control algorithm for wireless sensor network to keep as few as possible sensors in active state to achieve a complete connected coverage of a specific monitored area. Inactive sensors can turn off sensing modules to save energy. Unlike other algorithms, the proposed one does not rely on position information or ranging information of sensors. It just requires each active sensor to periodically send three beacons of different transmission ranges. Sensors can decide to stay active or inactive state according to received beacons. The proposed algorithm is fault-tolerant in the sense that one or more inactive sensors can switch to the active state to take over the surveillance responsibility when any active sensor runs out of energy or fails. Under the assumption of RC≥2RS, the algorithm can approximate the optimal connected coverage, where RC and RC are the radio communication radius and the sensing radius of sensors, respectively.Topology control technology of wireless sensor network has a direct impact on network performance. This article proposes EBTCA (Energy Balance Topology Control Algorithm) based on LMST algorithm. The algorithm takes not only the communication but also the remaining node energy into account. It will be able to minimize total energy consumption, achieve energy balance, and solve the problem that bottlenecks nodes die rapidly because of high load. It can also extend the working time of the sensor nodes, and then extend the network lifetime. The simulation results show that EBTCA effectively extends the lifetime of the network under the premise of guaranteeing low end-to-end latency, high throughput and delivery rate.The internet connectivity is required in order that the wireless sensor network can be applied effectively. Traditional wireless sensor network connectivity strategy doesn't take the load balance of sinks and sensor nodes within the one hop range of sinks into account. It will lead to the increase of connection latency, the consumption of node energy and the decrease of connection time. In this paper, we present ELSIC (Energy-aware Load-balanced Strategy for Internet Connectivity of wireless sensor network). We make the sensor node that in the one hop range of sink the agent node. By using the load balance strategy which takes energy, latency, distance and other factors into account, we distribute the connection load to every sink and agent node. This will decrease the latency, prolong the connection time. The simulation results demonstrate that under the same condition, ELSIC guarantees the internet connectivity and has lower latency, longer node life and connection time, and the higher throughput.In order to evaluate the network performance and energy performance when building wireless sensor network with the algorithm proposed by this paper, we analysis and design architecture of wireless sensor network and simulate search strategy on the OPNET Modeler. We design four scenes for studying sensor network performance in different node density and network load. The number of alive nodes, network energy, avergy node energy, delivery ratio, end-to-end latency, and throughput are considered and compared in the simulation. The simulation results demonstrate that proposed algorithms not only can ensure good delivery rate, end-to-end latency and throughput, but also can greatly increase the number of alive nodes in the network, improved energy efficiency and prolong the lifetime of network.