Search

In radio systems, quality of service is achieved by assigning channels with reference to a set of protection ratios, which in a simplified setting may be replaced with frequency-distance bounds. This paper considers the assignment problem on a lattice of hexagonal cells, with the allowed assignments generated by regular tilings of a single polyhex. The main aim is to investigate the interplay between the cochannel and adjacent channel separations without restricting the assignments unnecessarily. The outcome is a unified framework in which all previous results appear as particular cases. The possible cochannel lattices are carefully classified, and then an algorithm is developed, which assigns channels on any cochannel lattice so that the adjacent channel separation is maximized. In this way, a library of the best assignments can be compiled. The results are of relevance to a range of applications, including both broadcast and mobile systems. Index Terms - Radio channel assignment, regular networks, spectrum planning.

An innovative hierarchical microcell/macrocell architecture is presented. By applying the concept of cluster planning, the proposed sectoring arrangement can provide good shielding between microcells and macrocells. As a result, underlaid microcells can reuse the same frequencies as overlaying macrocells without decreasing the macrocell system capacity. With the proposed method, microcells not only can be gradually deployed, but they can be extensively installed to provide complete coverage and increase capacity throughout the service area. With these flexibilities, the proposed method allows existing macrocellular systems to evolve smoothly into a hierarchical microcell/macrocell architecture. Index Terms - Cluster planning, hierarchical cellular architecture, macrocell/microcell overlaying system.

This paper deals with an efficient Dynamic Channel Allocation (DCA) technique applicable to terrestrial mobile cellular networks. A channel (or resource) is a fixed frequency bandwidth (FDMA), a specific time-slot within a frame (TDMA), or a particular code (CDMA), depending on the multiple access technique used. A cost function has been defined by which the optimum channel to be assigned on demand can be selected. In addition, a suitable mobility model has been derived to determine the effects of handovers on network performance. The performance of the proposed DCA technique has been derived by computer simulations in terms of call blocking and handover failure probabilities. Comparisons with the classical Fixed Channel Allocation (FCA) technique and other dynamic allocation algorithms recently proposed in the literature have been carried out to validate the proposed technique.

Channel allocation is one of the fundamental problems faced by designers of the portable communication systems. A Distributed Dynamic Channel Allocation (DDCA) algorithm is proposed. The DDCA combines the advantages of both the fixed and the dynamic channel allocation algorithms in an effective way. Initialization is easy and it is adaptive to slowly changing environments. It is flexible. A port can utilize all the channels available to the system. It is adaptive to slowly changing environments so that the port can adjust the channel allocation automatically when ports are added or removed from the system. It is stable, simple and fully distributed. Simulation shows that it has 25% improvement over the U.K. DECT testbed DCA and 16% improvement over the Channel Segregation DCA, in terms of system capacity with one percent of grade of service.