Power allocation and capacity analysis in multi-class DS-CDMA systems with power control error

We propose a power allocation (PA) scheme under imperfect power control (IPC) in the reverse link of direct sequence-code division multiple access (DS-CDMA) systems for supporting multi-class traffic, and analyze the effect of power control error on the system capacity. First, we present an optimum PA scheme under perfect power control (PPC), which can determine dynamically optimum reference power levels for power control under varying traffic and channel conditions. Second, we analyze the outage degradation due to power control error when the optimum levels under PPC are used. In order to mitigate the outage degradation, we introduce two strategies: (1) call dropping (CD) and (2) outage lowering (OL). Using the modified reference power levels, we analyze the reverse link capacity subject to an outage constraint on the total composite power at a cell-site receiver under IPC. Finally, numerical analyses over various traffic and channel conditions are done to compute the reference power levels under IPC and then the reverse link capacity is evaluated under both PPC and IPC