Pilot power adjustment for saving transmit power in pilot channel assisted DS-CDMA mobile systems

In DS-CDMA systems coherent detection is usually adopted by adding or multiplexing redundant pilot signals with voice or data traffic. The pilot signals need additional transmit power but, at the same time, decrease the power used for traffic channel through facilitating channel estimation, which reduces the bit energy-to-noise density ratio (E_b/N_o) required for delivering the traffic signals. The interdependency between pilot and traffic channel powers has been analyzed in various studies, but has not yet been exploited in existing power control methods. In this letter, we provide a method of using the interdependency to adjuIn DS-CDMA systems coherent detection is usually adopted by adding or multiplexing redundant pilot signals with voice or data traffic. The pilot signals need additional transmit power but, at the same time, decrease the power used for traffic channel through facilitating channel estimation, which reduces the bit energy-to-noise density ratio (E_b/N_o) required for delivering the traffic signals. The interdependency between pilot and traffic channel powers has been analyzed in various studies, but has not yet been exploited in existing power control methods. In this letter, we provide a method of using the interdependency to adjust pilot power in the context of the existing power control algorithms, and prove its convergence and that it reduces the total transmit power.st pilot power in the context of the existing power control algorithms, and prove its convergence and that it reduces the total transmit power.