User capacity in a CDMA macrocell with a hotspot microcell: effects of transmit power constraints and finite dispersion

This paper examines the uplink user capacity in a CDMA system composed of one macrocell and one microcell when user terminal power is limited and the wireless channel is finitely-dispersive. A finitely-dispersive channel causes variable fading of the signal power at the output of the RAKE receiver. Analytical methods are developed to compute the user capacity as a function of a dimensionless parameter that depends on the transmit power constraint and cell radius. Additionally, a novel analytical method is developed to study the effect of variable fading due to a finite number of multipaths. This technique derives the user capacity for any delay profile using the results for the uniform multipath channel. Simulation results confirm the accuracy of these simple analytical solutions.