Soft-Guarantee-Based Call Admission Control for IEEE 802.11 Wireless LANs

IEEE 802.11 MAC protocol is a well-known method used in Wireless LANs (WLANs). However, it provides poor QoS guarantee for time sensitive traffic such as media streaming, or high priority traffic such as voice/video signaling requests. For improving the QoS guarantee of communications, call admission control (CAC) is important for access point’s (AP’s) point coordination function (PCF). In this paper, we combine the concepts of CAC and MAC to construct a comprehensive algorithm called Soft-Guarantee-Based Call Admission Control (SCAC) method, which focuses on providing soft QoS guarantee for media streaming traffic and high register speed for signaling requests. SCAC is composed of three major components: QoS-enabled Call Admission Control (Q-CAC) module, Efficient Contention Control Algorithm (ECCA) module, and Resource Management Database (RMDB) module. According to the demands of registered mobile terminals (MTs), Q-CAC limits the candidates of under-registering MTs with signaling requests. After looking up pre-constructed RMDB, ECCA adopts two-phase algorithm to provide optimal contending mechanism for signaling requests. Simulation results show that SCAC provides probabilistically soft QoS guarantee for media streaming traffics and increases the speed of contention process for signaling requests.