Research On Mechanism Of QoS On MAC Layer Of Wireless Image Sensor Networks

The technology of wireless communications is one of the most important parts of Wireless Sensor Networks (WSN). Wireless communications are the foundation to realize data transmission between the motes of WSNs. Because of the limited power supply, limited ability of communications, limited computability and memory on the mote, it is always a research emphasis to design a more efficient and power saving protocol for wireless data transmission. Along with the extense of the WSN applications, it is a new research area to provide Quality of Service (QoS) on data transmission, and the applications in this area have very wide foregrounds. Thereby, it is meaningful to realize QoS in protocols for wireless communications.The content of this article is the research on the protocols for wireless communications on the media access control (MAC) layer, which is a sublayer of the link layer, one of the five layers (the physics layer, the link layer, the network layer, the transmission layer and the application layer) which construct the stack of protocols for wireless communications. The emphasis of the research is on the applicability and superiority of two protocols on the MAC layer. The protocol of IEEE 802.11 on the MAC layer is a basic MAC protocol, whose excellence and maturity are worldwide acknowledged. The protocol of IEEE 802.11e on the MAC layer, which is derived from IEEE 802.11 and integrates the control of QoS, is more applicable in the area of WSNs.The article analyses and compares the two protocols roundly from both theoretics and simulations. The quantificational comparison between the two protocols is based on the definitions of throughput, end-to-end delay, jitter and packet drop rate. From a large amount of experiment data, we get the conclusion that compared with IEEE 802.11, the protocol of IEEE 802.11e on the MAC layer has the characteristics that are more suitable for WSNs. Based on it, the article also puts forward a pertinent improvement on IEEE 802.11e, which makes the protocol more efficient in WSNs for image collection and transmission.The environment for simulation in this article is NS2. The languages for modeling include C++ and tcl. The languages for testing include awk and gnuplot.