The increasing demand for higher system capacity and better quality of service in wireless mobile communication systems such as Code Division Multiple Access (CDMA) systems motivates the need for new techniques in order to fulfill this ever growing demand. The capacity of CDMA technologies used in wireless mobile networks relies on efficient power control algorithms due to near-far effect. In this work, a new Modified Adaptive Power Control (MAPC) algorithm for CDMA mobile networks is proposed. This proposed algorithm is able to significantly decrease the variance of the power control maladjustment without any increase in power control signalling; and only one bit is still needed for the power control feedback command. Moreover, it is able to minimize mobile station total transmission power which the conventional fixed step power control algorithms fail to handle. In this work, simulation carried out in MATLAB platform is used to verify that the proposed algorithm—the MAPC algorithm—reduces drastically the mobile stations’ transmit power, which in turn improves the capacity of CDMA mobile network, thanks to its tunable parameters.

The need for high performance and better service quality in wireless mobile communication system such as Code Division Multiple Access (CDMA) has been increasing exponentially in the last decade. This is because of the user mobility and flexibility, particularly on the communication link between the mobile terminals and the base stations (otherwise known as the uplink), which cannot be provided in wired line communication system. Unfortunately, this communication link serves as a bottleneck which limits system capacity as a result of some impeding problems experienced in the CDMA mobile communication system. One critical problem with CDMA mobile communication system is the near-far problem. This problem occurs in the absence of power control—if all mobiles are to transmit at the same power level, the mobile closest to the Base Station (BS) will overpower all others (since the signal power drops exponentially with the distance). And also both co-channel and adjacent channel interferences have been a major setback in CDMA systems whereby users share a single frequency and are only separated by different spreading codes, and this interference typically limits the system capacity. The requirement of Power Control (PC) in the uplink CDMA system is a critical limitation (Gilhousen et al., 1991). Power control is needed because all users share the same bandwidth and thus intrauser interference is bound to occur. Without power control, a signal received by the BS from a nearby Mobile Station (MS) will dominate the signal from a faraway MS, thus resulting in the so-called near–far effect. The objective of power control is to control the transmitted power by the mobile users so that the average power received from each user is generally constant. The goal is more precisely stated as to achieve a certain Signal-to-Interference Ratio (SIR) regardless of channel conditions while minimizing the interference and hence improving the overall performance. Many schemes have been suggested for power control in uplink channel which generally offer a strategy for transmit power of users to reduce interference and enhance battery life while maintaining data rates required for quality of service.

Telecommunications Journal, Power control, Modified Adaptive Power Control Algorithm (MAPC), Transmission power, Capacity enhancement.