CoS guarantee control for wireless LAN

The demand for multimedia service is increasing in wireless communication under the environment of wireless LANs. Many organizations research QoS (quality of service), and many protocols are proposed. In many proposed QoS control, classification of throughput, delay time and packet loss related to quality level is performed. The concept of QoS is CoS (class of service). However, these protocols are applied to a centralized network which is built by a central coordinator (ex. access point), and are not applied to ad hoc network. We investigate CoS in an ad hoc network. Since the mobile station sends a packet randomly in a wireless environment, it is necessary to avoid a packet collision in order to increase the channel throughput. IEEE 802.11 is a standard for wireless LANs. The basic access mechanism in its media access control (MAC) protocol is the distributed coordination function (DCF) based on carrier sense multiple access with collision avoidance (CSMA/CA) in an ad hoc network. However, this mechanism does not have CoS control, and a packet collision may occur by increasing the number of mobile stations. We propose a novel media access control using weight for CoS in an ad hoc network. Our scheme consists of carrier sense, packet scheduling for access timing related to CoS amid collision avoidance. Simulations are conducted to analyze our scheme. The simulation results show that our scheme is of high performance compared with conventional methods, and is able to perform CoS control.