Research Of A TDMA/CSMA MAC Protocols For Wireless Sensor Networks

The Wireless sensor network(WSN) is a new Cross Research area,which includes modern sensor technology,Microelectronic technology, Embedded computing technology and Distributed information processing technology. WSN is a Real-time monitor network,it can collect various information of enviroment or objects being monitored, these information can be well processed for detailing and accurate knowledge.An efficient MAC protocol is one of the keys for long-time working and high-performance communication of WSN. There are several mechanisms for wireless channel allocation, such as Contention-based Random Access, TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access) and CDMA (Code Division Multiple Access). According to WSN, the CSMA-based MAC protocol which is a typical Contention-based Random Access mechanism has disadvantages like idle listening and collision ; the TDMA-based MAC protocol could not perform well in the time synchronization and has low scalability problem; the FDMA-based and CDMA-based MAC protocol is complex for the resource-limited nodes to implement. So to design a hybird MAC protocol for the wireless sensor works, which makes up of the advantages of several mechanisms, is now becoming one development trend in research of MAC protocol for WSN.This thesis presents a cluster-based hybrid MAC protocol for WSN, called MAC (Clustering TDMA/CSMA MAC Procotol). MAC proposes the cluster nodes use TDMA and the cluster heads use CSMA. MAC could achieve collision avoidance and low latency in clusters, and do not have to ensure high accuracy synchronization between each cluster, so that the scalability of the sensor network would be enhanced. Furthermore MAC puts forword an-early-warning algorithm to identify the attacks and ensure the security on the the bottom-layer.As the hardware platform is lacked, we choose the J-Sim simulator which is built upon the notion of the autonomous component programming model to test the performance of MAC. As the energy efficiency is considered as the most important attribute of one MAC protocol, we have made some experiments on the attribute. In addition, we simulate some attacks on the bottom-layer, and then test the effect of the early-warning algorithm. In view of the comparison with MAC energy consumption and the attack simulation results, MAC achieves a good energy efficient and bottom-layer attack responsibility.