Dynamic SIR based admission control algorithm for 3G wireless networks

Next generation wireless systems, as Universal Mobile Telecommunications System (UMTS), aim at revolutionizing the actual wireless communication paradigm offering real time multimedia services now available on fixed terminals whose quality of service (QoS) requirements could be satisfied by network resources adaptation to traffic conditions. Since radio interface is based on CDMA technology, this system suffers form mutual interference among active connections. Approximately, the communication quality decreases at the increasing of active users number. As a consequence, there exists an active user threshold below which an intolerable QoS degradation is produces, especially for those applications named in 3GPP standard as interactive or background. Therefore, proper admission control (AC) algorithm that mitigates mutual interference by keeping active users under a dynamic threshold, is a crucial topic in UMTS system optimization. This paper deals with an advanced AC scheme proposal that estimates the requesting connections signal to noise plus interference ratio (SINR) by means of accurate multiple access interference (MAI) analysis results. Basically, this algorithm verifies the possibility of a new call admission by valuating if an overall power configuration there exists, whose predicted SINR values satisfy each QoS constraints. Whenever a new connection is accepted, a further optimization is performed in order to allow a QoS higher than the requested value under a maximum radiated power constraint. This value is delivered to power control (PC) algorithm jointly with the associated SINR value. Numerical simulations, closely related to an UMTS system, underline a remarkable number of active users increase up to four times traditional AC policies, together with the maximization of QoS requirements.