Basic issues on dynamic allocation of PRMA carriers

The growing development of the personal communication networks (PCN) entails a strong demand for increasing spectrum efficiency. Therefore, a large number of new techniques are being proposed in the view of the third generation of mobile systems. A major requirement of these new techniques is that they result a natural evolution of the already developed second generation techniques, so that it is possible to take advantage of the already existing software and hardware and to gradually introduce the new techniques. One of the most successful second generation standard is the Global System for Mobile communications (GSM) which is based on a frequency division multiplex/time division multiple access (FDM/TDMA) technique. Two very promising ways of enhancing such a technique in order to improve spectrum efficiency, are dynamic channel allocation (DCA) strategies and packet reservation multiple access (PRMA) techniques. This paper deals with some basic problems of DCA and PRMA. The following problems are tackled: (i) the coordination among base stations (BSs) in order to avoid, in the framework of a DCA strategy, conflicting acquisitions of a same carrier from two BSs located at a distance lower than the reuse distance; in that respect, a new asynchronous technique is proposed; (ii) the strategy to be followed by the BSs in order to select the carrier to be acquired (or the carrier to be released); and (iii) the determination of a short-term parameter for determining the link quality of a PRMA carrier: as such a quality goes down a given threshold the DCA mechanism starts