Call Admission Control with Adaptive Active Link Protection for Wireless Systems

In wireless communication systems, a call admission control mechanism is usually deployed to determine whether a new communication node can be admitted into the network system. In wireless systems that implement power control, the maximum achievable signal-to-interference plus noise ratio (SINR) for a new node depends on the link gains amongst all the co-channel interfering nodes involved and the white noise strength. Thus, one of the challenges in call admission control (CAC) in a wireless system with power control is the estimation of maximum achievable SINR when information about global link gains is not available. In this paper, by ignoring the white noise factor we present a predictor for the maximum achievable signal-to-interference ratio (SIR) of a new node trying to get admission into a wireless system. Using the SIR predictor we then calculate an optimal active link protection margin, which together with the SINR or SIR threshold would constitute an enhanced threshold value for the new node to attain. By doing so current active links would be protected from performance degradation should the maximum achievable SIR value common to all the nodes be lower than the SIR threshold. For each nodal topology ranging from low density to high density values, the accuracy of the predictor is evaluated by means of simulation in terms of mean error and root mean square error. Together with finding the corresponding optimal active link protection margin, efficient CAC mechanism to ensure stability of the feasible system can be maintained over a wide range of operating SIR values