Research On Backoff And Power Control Algorithms For Wireless Sensor Networks MAC Layer

As the result of properties of wireless sensor networks (WSNs) that fast deployment and robustness, WSNs have recently received a lot of attention in the international research man. And WSNs'nature makes it more attractive for military applications and other wide range of applications, such as environmental monitoring, climate forecasting and space exploring. It is revolution of information sensing and collection method and one of the important technologies in 21 century. Research on medium access control (MAC) protocol for WSNs is a challenge and the main task of MAC protocol is to efficiently saving energy.The tiny sensor nodes have limited low cost, power, computational capacity, bandwidth and memory. And WSNs must possess self-organizing capabilities and centreless architecture to ensure a wide range of applications. Conventional MAC mechanism can hardly provide good performance in such complex environment of distributed networks. Consequently it is meaningful to develop MAC techniques with adaptive ability for wireless sensor networks. Based on performance analysis and optimization of system, this dissertation focused on adaptive backoff algorithm and adaptive power control algorithm for WSNs.This paper proposes a new AASC backoff algorithm within CSMA for wireless sensor networks MAC layer, which can automatically adapt to network flow and effectively avoid second-collision.To analyze the performance of CSMA-CA's backoff algorithm specification in the IEEE802.15.4 standard, the network model, node model and protocol model are built in the OPNET simulation system. Energy limitation and multihop is the main character of wireless sensor networks. The simulation result shows that the CSMA-CA's backoff algorithm specification in the IEEE802.15.4 standard has shortcoming. In this paper a strategy which relay data has higher priority is proposed. This strategy guarantees that remote node's packets are transmitted reliably to destination node, whether network is burst flow or non-burst flow. Then the AASC backoff algorithm that can adapt to flow and avoid second-collision is proposed and analyzed for wireless sensor networks. Theory of discrete time Markov chains and OPNET simulation show that AASC backoff algorithm can...