This study is supported in part by the BK21 program of the Ministry of Education

This paper is concerned with the reverse link signal power and interference of a spectrally overlaid macro/micro cellular CDMA system. Several narrowband subsystems are overlaid on the wideband subsystem in macrocells, while in a microcell a single narrowband subsystem is operated with the same spectrum as one of the macrocell narrowband subsystems. Using a typical propagation model, the relative user signal power and the cross-tier interference factors between the microcell and the macrocell are analyzed considering various system parameters. The analysis results show that dominant parameters affecting the signal power and the interference factors are the spectral overlay ratio and the distance between macrocell and microcell base stations. The results can be applied to a radio performance analysis of the CDMA overlay system