A new CAC scheme based on adaptive SINR threshold using fuzzy logic for CDMA system

Shixun Wu,Jiping Li,Shouyin Liu

doi:10.1109/iscit.2011.6089718

Abstract

Signal to interference plus noise ratio (SINR) based call admission control (CAC) scheme admits incoming calls as long as the measured SINR is higher than threshold value (SINR th ). If a high value of SINR th is chosen, the signal quality will improve but this will increase the blocking probability (p b ), and as a result, will decrease the network utilization. On the other hand, a low value of SINR th will reduce p b , however degrades the signal quality and increases outage probability (p out ). Hence, how to choose appropriate SINR th is very important. In this paper, we focus on the following aspects. Firstly, an accurate upper bound of SINR th is derived. Secondly, based on the upper bound of SINR th and a lower bound from other literature, we design a fuzzy logic controller (FLC), which can adaptively adjust SINR th according to the number of active users (AUs) in a cell and average arriving traffic intensity (AATI) in Erlang per cell. Finally, network performance based on FLC is compared with that based on optimal fixed SINR th . Numerical results show that the proposed scheme based on FLC has better performance than the optimal fixed threshold CAC scheme.

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