Brendan C. Jones

Outage contours and cell size distributions in cellular and microcellular networks

The paper describes an interference model that provides a simplified description of cellular and microcellular outage contours. The model and computer simulations indicate that cell size variation increases as microcellular systems become more interference limited. Some cellular and microcellular systems are modelled.

An Integrated Propagation-Mobility Interference Model for Microcell Network Coverage Prediction

This paper presents a new interference model for microcellular networks which integrates radio propagation parameters and user terminal mobility. This model uses a parameter denoted the “interference to noise ratio” (INR) to obtain a simplified description of mobile link outage contours as a function of the location of the fixed and mobile radio ports. The INR is used to demonstrate that microcell networks are more interference limited than macrocell networks, and thus are more affected by user terminal mobility. Expressions are derived for the INR and user terminal cell radius distributions. It is shown that in microcell systems a significant proportion of terminals may not be able to meet a contiguous coverage criterion, and that closer microcell spacing can reduce rather than improve the coverage quality. Examination of cochannel and adjacent channel reuse ratios in DCA microcell systems suggest that the closer frequency reuse is primarily responsible for these coverage effects. Monte Carlo simulations are used to test the analytical theory. These results may form the basis of a design methodology for microcell systems.

Interference distributions in microcell ensembles

An interference model developed for arbitrary microcellular networks, based upon a parameter called the ‘Interference to Noise Ratio’ or INR, is used to derive interference and cell radius statistics for mobile stations in a microcellular network. The theoretical INR and cell radius statistics for simple interference environments show good agreement with numerical Monte Carlo simulations. For more complex environments, it is hypothesised that the Central Limit Theorem could be applied to approximate the behaviour of an interferer ensemble, enabling the cell radius statistics for a network to be expressed in terms of the system design parameters. Simulations of microcell ensembles that support this hypothesis are presented.

System design for contiguous cell coverage in high density microcellular networks

This paper examines whether microcellular networks can be designed to provide contiguous cell coverage for a given proportion of mobile terminals. Simulation results using a general microcellular interference model show that contiguous cell coverage may not be possible for an acceptable proportion of mobile terminals even if the call loss rate is low.

Influence of terminal distributions and channel spills on microcell coverage

The distribution functions of cell radii in a microcell system are derived in closed form for three portable terminal distributions and tested using a Monte Carlo simulation. These distributions provide information about the quality of the microcell coverage. The results suggest that cell size reduction from near-far or same-cell interference from terminals using well spaced channels can be as severe as that resulting from adjacent channel interference from terminals in nearby microcells.

Derivation of cochannel and adjacent channel reuse ratio distributions in DCA cellular systems

This paper presents the first closed-form analysis of cochannel and adjacent channel reuse ratio distributions in dynamic channel assignment (DCA) cellular systems and compares the results with conventional fixed channel assignment (FCA) cellular systems. Computer simulations show that DCA systems exhibit significantly closer cochannel and adjacent channel frequency reuse than FCA systems for a significant proportion of terminals. Mathematical analysis is used to show that this is a fundamental consequence of DCA channel pooling and that the resultant interference distributions cannot be obtained using conventional cellular engineering techniques. The closed-form expressions derived establish a theoretical lower limit to channel reuse in DCA cellular systems.

HIPERLAN system performance under DCA and FCA

HIPERLAN is a high speed wireless LAN standard adopted by the ETSI. It operates in 150 MHz of spectrum in the 5 GHz band, with up to five TDD channels provided for duplex data transmission at up to 23.5 Mb/s. This paper shows that in the presence of cochannel cells and full link utilisation, HIPERLAN performs poorly when using its DCA-type clear channel assessment (CCA) scheme, and that the target performance levels are only achievable under optimal FCA-type channel assignments. Two main factors contribute to this poor performance: HIPERLAN has insufficient channels to meet C/I constraints in the presence of cochannel cells; and the CCA scheme results in poor channel distributions.

Cochannel and adjacent channel reuse ratio distributions in dynamic channel assignment microcellular systems

This paper presents a novel analysis of cochannel and adjacent channel reuse ratio distributions in DCA microcell systems, and compares the results with conventional FCA macrocell systems. Computer simulations show that DCA systems exhibit significantly closer channel reuse than FCA systems for a significant proportion of terminals. Mathematical analysis is used to show that this is a fundamental consequence of the microcell architecture and that the resultant interference distributions cannot be obtained using conventional cellular engineering techniques. A closed form expression for the channel reuse ratio distribution in DCA microcell systems is derived, which in turn establishes a theoretical lower limit to the channel reuse ratio in DCA systems.

Cochannel Reuse Distributions in DCA Microcellular Systems with In-Cell Reuse Constraint

This paper presents a novel analysis of cochannel reuse in Dynamic Channel Assignment (DCA) microcellular systems with an in-cell channel reuse constraint. Mathematical analysis is used to show that DCA systems exhibit significantly closer cochannel reuse than Fixed Channel Assignment (FCA) systems despite the reuse constraint. Closed form expressions for the cochannel reuse ratio (CRR) distributions in DCA microcell systems are derived. It is shown that the DCA reuse distributions cannot be obtained using conventional cellular engineering techniques, and are a fundamental consequence of the microcell architecture.