Fixed and adaptive blocking thresholds in CDMA cellular networks

Recent papers have shown that, in a code division multiple access (CDMA) cellular network a bursty user mobility entails remarkable negative effects on link availability, and hence on cellular network capacity. A possible provision for contrasting such negative effects is the introduction of a blocking threshold: whenever a given base station realizes (via proper measurements) that the received E_b/N₀ is lower than the blocking threshold, it no longer sets-up calls (i.e. the BS blocks new call set-up attempts). So doing, the link availability is increased at the expenses of the appearance of a non-null blocking probability. In order to maximize the capacity of the cellular network, the blocking threshold has to be selected so that a proper balancing of the blocking probability and of the link availability is achieved. This paper presents a new self-adaptive mechanism in which each BS, on the basis of the monitored system performance, continuously adjusts the blocking threshold in order to obtain the above-mentioned balancing. The paper shows that this mechanism, on the one hand achieves very good performance and, on the other hand, does not require any a priori knowledge of the system parameters and, in particular, of the mobility parameters