Personal communication systems using multiple hierarchical cellular overlays

Abstract

A personal communication system with multiple hierarchical cellular overlays is considered. The system can include a terrestrial segment and a space segment. The terrestrial segment, consisting of microcells and macrocells, provides high channel capacity by covering service areas with microcells. Overlaying macrocells cover spots that are difficult in radio propagation for microcells and provide overflow groups of channels for clusters of microcells. At the highest hierarchical level, communications satellites comprise a space segment. The satellite beams overlay clusters of terrestrial macrocells and provide primary access for satellite-only subscribers. Call attempts from ceUular/satellite dual subscribers are first directed to the terrestrial cellular network, with satellites providing necessary overlay. At each level of the hierarchy, hand-off calls are given priority access to the channels.The mathematicd structure is that of a multi-layer hierarchical overflow system. An analytical model for teletraffic performance (including hand-off) is developed. Theoretical performance measures are calculated for users having different mobility characteristics. These show the carried trafRc, traffic distribution, blocking, and forced termination probabilities. by the larger cells, i.e. cells that are higher in system hierarchy. This traffic distribution is achieved without any other mechanism for mobility management, such as those based on speed measurements for initial cell assignment.

Performance Analysis of Cellular Networks

“…micro-cellular networks that accommodate larger subscriber populations [7,8), hierarchical cellular networks that accommodate subscribers with varied mobilities [7,9,10,11], and GPRS (General Packet Radio Service) for packet based data transfers (email and web• browsing) [12].…”

“…The trend in existing literature has been to assume that the unencumbered call holding time distribution!M(t) is negative exponentially distributed [2. 7,9,15,16,21,27):…”

“…• Similar to existing studies [7,9,15,27,28,29.30], we assume a homogeneous network where each cell is identical to its neighbours in every aspect such as traffic statistics, user mobility, cell coverage etc.…”

Overflows in Multiservice Systems

“…Other notable multiservice models of overflow systems include, for example, [52], [53] which propose concepts for modelling traffic offered to SR on the basis of processes of the type: Markov-Modulated Poisson Process (MMPP). Then, in [54], [55], to describe such traffic the Batched Poisson Process (BPP) is used.…”

Blocking analysis and simulation studies in satellite-augmented cellular networks

“…In such models, all layers are assumed to have the same propagation characteristics and re-use constraints. A recent study [3] computes the Performance of one such hierarchical scheme in terms of call blocking probability and handover blocking.…”