Research For Wireless Sensor Networks MAC Protocol

Sensor network is a novel technology about information acquiring and processing, and consists of a large number of sensor nodes which have wireless communication capability. The availability of low-cost sensors and communication networks makes it have applications in fields such as military monitoring and environment sensing. Wireless sensor network is a data-centric network, and different strategies must be considered to prolong the lifetime of it when designing. Such strategies include in-network processing, multi-hop routing, and so on. Meanwhile, it is also a resource-limited network, which includes two aspects. First, resource in nodes is very limited such as battery energy, computation ability, and memory size. Second, wireless transmission is a bottleneck for sensor network. Wireless channel is limited in bandwidth, latency, and packet size. Such requirements and limitations bring many new technical problems to wireless sensor network researches.In this paper, we first introduce the basic concepts of wireless senor network, including sensor node, network architecture, communication protocol stack, security goals and limitations of wireless sensor network. This paper first introduces the basic wireless sensor networks, including the composition of the sensor nodes, sensor network architecture and communication protocol stack, and then sums up the sensor network routing protocols, analysis the classic DD (Directed Diffusion) agreement in detail, and then analyzed problems to support the QoS faced and the existing number of QoS routing protocols. Due to the existing QoS agreement does not mature, this paper re-designed new routing algorithm based on the DD agreement–QSBCG- to support QoS routing protocol. Yet the general, we have divided into two types of QoS operations. One is data services, require reliable transmission, packet loss rate as low as possible; one is real-time services, on the transmission very sensitive to delay and jitter. DD algorithm choose the shortest path from the source node to the sink nodes, easy to run out of energy in the node path to form a network of islands.Further more, the path may change frequently, resulting in that packets can not arrive in the order, do not apply to real-time services. QSBCG routing protocol takes parameter of the cost of the delay into account in gradient function, and to a certain probability to choose the main path, and ensure the stability and shortage of the main path; Outside of the main path, QSBCG routing protocols also include a sub-optimal winding path to ensure the reliability . For data services, in order to save network energy consumption, QSBCG routing protocol chooses the path of large energy bottleneck and small energy path to ensure that the overall network energy demotion.Finally, we briefly introduce the simulation tool NS2, describes the realization of the simulation process of the routing protocol QSBCG, and analysis of simulation results to compare before and after the improvement of network performance parameters, namely, delay and reliability of networks, such as survival. The experimental results show that QSBCG routing protocols supports QoS in wireless sensor network with energy efficiency.