Call admission control in mobile cellular CDMA systems using fuzzy associative memory

Abstract

In a mobile cellular system quality of service (QoS) to mobile terminals (MTs) is measured by the probability of forced termination P/sub ft/ and/or probability of new call blocking (P/sub b/). Since, both cannot be reduced simultaneously, usually keeping the P/sub ft/ below a designated level DP/sub ft/ is considered as QoS guarantee to the users of the system. However, P/sub ft/ is related to system parameters namely, maximum capacity of the cell C, the average new call arrival rate /spl lambda/, the average call holding time 1//spl mu/, and the average cell dwell time 1//spl eta/ by complex nonlinear equations. Therefore, call admission control (CAC) for maintaining P/sub ft/ at DP/sub ft/ is a very challenging task. A fuzzy controller is proposed to dynamically maintain P/sub ft/ at DP/sub ft/ with changes in system parameters. Also, current cellular networks are employing CDMA as the multiple access technique since it provides much more capacity than other techniques. Interference received at the base station (BS) of a cell is considered in the decision making process of whether to admit a call or not. We describe the CAC criteria used in CDMA cellular networks in this paper. Also, through simulation we show that fuzzy controller can be integrated with other CAC schemes to guarantee QoS to the users.