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 TDMA/CSMA/FDMA-based hybrid MAC protocol for industry application real time moniroring WSN, called Reliable-MAC which Using the capacity of multi-frequency listening availabled in WSN hardware such as MICAZ to take full advantage of free collision parallel transmission , thereby reducing delay of end-to-end data transmission , improve network throughput. For the needs of Air Compensation System, the data which is sensitive to threshold can be deliveried by faster and more reliable transmission through the super-frame CSMA,to ensure no missed capture requirements for all abnormal events to the system. It is easily to adapt to The network topology changes and enhance the network scalability.In order to verify Reliable-MAC protocol performance, we have nodes on the experimental platform data acquisition module further improvement, which can obtain data on Monitoring and control. In the cases of no interference, we have coducted a series of test experiments aimed at end to end delay, packet loss rate, throughput, and reliability on sensitive data transmission. In Reliable-Mac testing, the delay of the data downs to 20ms, it reaches the requirement of industry monitoring (such as the air Compensation System), the rate of the lost also come down. It remains the reliability of the data transmission, especially the important data. So it reaches the requirement of the air Compensation System.