Capacity analysis of spectrally overlaid macro/microcellular CDMA systems supporting multiple types of traffic

Abstract

The reverse link capacity of a spectrally overlaid macrocell/microcell cellular code-division multiple-access system supporting various types of traffic is analyzed. Several narrow-band subsystems are overlaid with a wide-band subsystem in macrocells, while in a microcell a single narrow-band subsystem is operated with the same spectrum as one of the macrocell narrow-band subsystems. Using a typical propagation model, the reverse link signal power and interference are characterized as the relative user signal power and the cross-tier interference factors between the macrocell and the microcell, considering various system parameters. The reverse link capacity of the overlay system is then analyzed. Results show that the dominant parameters affecting the system performance are the spectral overlay ratio and the distance between the microcell and macrocell base stations. In particular, when the distance equals half of the macrocell radius, optimum performance can be achieved by minimizing the cross-tier interference factors. These results can be applied to network planning for future wireless communication services.