INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS Int. J. Commun. Syst. 2008; 21:25–50 Published online 7 March 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/dac.878 On multi-cell admission control in CDMA networks G´ abor Fodor ∗, † and Magnus Lindstr¨ om Ericsson Research, SE-164 80 Stockholm, Sweden SUMMARY We consider a multi-cell (MC) code division multiple access (CDMA) system that supports multiple service classes, including peak rate allocated and elastic ones. Peak rate allocated sessions—when admitted into the system—transmit at a constant bit rate, while elastic sessions can be slowed down at the expense of increasing their residency time. Admitted sessions cause an instantaneous bit rate-dependent interference in neighbour cells. In this rather general setting, we propose a method to calculate the class-wise blocking probabilities as the functions of the estimated so-called inter-cell coupling factors. In the paper this coupling factor is the ratio between the uplink path gains to different Node-B:s (that can be easily obtained in a CDMA system from pilot measurement reports), but our model could include other coupling measures as well. We find that when these coupling factors are underestimated, the system may get into false states (FSs) or false rate states (FRSs) that lead to violating the noise rise threshold. As traffic becomes increasingly elastic, the probability of FSs decreases, but the probability of FRSs increases. Based on numerical results, we make the point that as the traffic becomes more elastic, avoiding the underestimation of these coupling factors as well as exercising MC admission control plays an increasingly important role in guaranteeing proper service quality. Copyright 2007 John Wiley & Sons, Ltd. Received 2 June 2006; Revised 30 November 2006; Accepted 4 January 2007 KEY WORDS: CDMA networks; radio resource management; admission control 1. INTRODUCTION Code division multiple access (CDMA) networks are designed to provide a variety of services including peak rate allocated and elastic ones. One of the key performance measures of such multi-service CDMA networks is their Erlang capacity under some class-wise blocking probability constraints. Elastic service classes are associated with a minimum bit rate requirement (sometimes referred to as the guaranteed bit rate (GBR)) that is less than their peak bit rate (PBR) requirement. The elasticity of such service classes can be characterized by the ˆ a = PBR/GBR ratio which is referred to as the slowdown factor in [1]. A recent key result has shown that the blocking probabilities decrease (the Erlang capacity increases) when the ‘elasticity’ ( ˆ a) of the carried traffic ∗ Correspondence to: G´ abor Fodor, Ericsson Research, SE-164 80 Stockholm, Sweden. † E-mail: Gabor.Fodor@ericsson.com Copyright 2007 John Wiley & Sons, Ltd.