  This paper examines the uplink user capacity in a two-tier code division
multiple access (CDMA) system with hotspot microcells 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. First, a two-cell system composed of one macrocell
and one embedded microcell is studied and analytical methods are developed to
estimate the user capacity as a function of a dimensionless parameter that
depends on the transmit power constraint and cell radius. Next, novel
analytical methods are developed to study the effect of variable fading, both
with and without transmit power constraints. Finally, the analytical methods
are extended to estimate uplink user capacity for multicell CDMA systems,
composed of multiple macrocells and multiple embedded microcells. In all cases,
the analysis-based estimates are compared with and confirmed by simulation
results.
