In this dissertation, we are concerned with capacity estimation, soft handoff modeling, and its management in multi-code (MC) CDMA systems.
First, we analytically estimate the reverse-link capacity of a signal-to-interference ratio (SIR)-based power-controlled direct sequence (DS) CDMA system supporting ON-OFF traffic. Since, in an SIR-based power control system, the power level is a function of the number of active home users and the amount of total other cell interference, power level and total other cell interference can be calculated by a recursive method. SIR-based power control systems yield a higher system capacity than strength-based power control systems, which mainly results from smaller other cell interference. System capacity is largely affected by the activity factor, propagation parameters, the maximum received power, and the required $E_b/I_o$.
Second, we extend the analysis of an SIR-based power-controlled DS-CDMA system for an MC-CDMA system supporting heterogeneous CBR and ON-OFF traffic by adopting a Gaussian model for other cell interference. System capacity is derived in terms of admissible regions satisfying the maximum allowable outage probability.
Third, we characterize soft handoff in CDMA systems. Handoff call attempt rate and channel holding time are derived based on soft handoff. An overlap region is used in soft handoff analysis in addition to an inner cell, an outer cell, and a soft handoff region. An SR is divided into a number of overlap regions according to cell structure, and some new parameters are developed. The performance of soft handoff systems is numerically evaluated to investigate the effects of the above parameters and is compared with hard handoff systems.
Finally, we propose a traffic management scheme in an MC-CDMA system supporting soft handoff, which uses guard channels and a queue for realtime traffic. Reservation-on-Demand queue control is suggested to give a priority to queued handoff calls. Handoff traffic...