Ahmad Jalali

Optimal forward link power allocation for data transmission in CDMA systems

The paper considers optimal forward link power allocation for data transmission in DS-CDMA systems. Acceptable quality voice communications in DS-CDMA can be achieved through the application of the forward error correction (FEC). Due to stringent requirements on signal delay, no retransmission is allowed in voice only systems. Highly reliable data transmission over wireless channels, however, can be achieved with hybrid automatic-repeat-request (ARQ) schemes. The average power allocated to data users then needs to be calculated as the actual link transmitted power times the average number of times that a data packet must be transmitted before it is accepted. Since a base stations total power available to mobiles is limited, there is an optimum power allocated to every data user in the cell, which maximizes the system capacity. The optimal power allocation can be described as the stochastic nonlinear programming optimization problem. Numerical results are presented to illustrate the problem. The powers allocated to data users are location dependent, but the numerical results demonstrate that the mean signal-to-interference ratio (SIR) is location independent when the optimal power allocation is achieved.

Performance of fast forward link power control for CDMA systems

Fast power control is being considered on the forward link for the third generation CDMA systems. This paper simulates fast power control on the forward link for a 9600 bps data rate and discusses potential capacity gains. Performance of the fast power control scheme for 800 and 1600 Hz power control update rates are given to determine the potential capacity improvements as the update rate is increased. The paper also discusses some of the issues that need to be considered in designing fast power control for the forward link.