Downlink User Capacity in a CDMA Macrocell with a Hotspot Microcell

This paper examines the downlink user capacity in a CDMA system composed of a macrocell and a microcell, where both cells use the same frequency channel. The effect of channel dispersion on the number of simultaneous users supported is studied for three different downlink power control methods. Channel dispersion produces in-cell interference and variable fading of the received signal power. Novel analytical methods are developed to account for both effects; these techniques derive user capacity for any delay profile using the results for the uniform delay profile. The downlink user capacities for the three power control methods are compared to the uplink user capacity under the same channel conditions. The results point to the need for fast power control to obtain uplink-limited performance.