Research Of Bottom-Layer Security TDMA/CSMA MAC Protocols For Wireless Sensor Networks

As a high and new technique and the next generation sensor network the wireless sensor network (WSN) is now developing more and more quickly. WSN has been used for various application areas, such as military, industry supervision, safety monitoring and environment monitoring. It also shows vast application perspective in precise agriculture, smart home, medical treatment and so on. So far as it goes, WSN which gives a new principle of data acquisition and processing is becoming a hot spot not only in academy but also in industry.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 the idle listening and collision problems; the TDMA-based MAC protocol has the time synchronization and 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 STC-MAC (bottom-layer Security TDMA/CSMA MAC Procotol). STC-MAC proposes the cluster nodes use TDMA and the cluster heads use CSMA. STC-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 STC-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 STC-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 802.11 MAC energy consumption and the attack simulation results, STC-MAC achieves a good energy efficient and bottom-layer attack responsibility.