The Research On Power Control Strategy For DS-CDMA Mobile Communication Systems

Due to increasing requests on the mobile communication systems, it has arrived in a brand-new stage. Many papers in communication field have focused on the key technologies of Code Division Multiple Access (CDMA), while the third generation (3G) communication systems based on CDMA is implemented gradually. Power control technology, one of them, is what this paper studied by proposing new power control methods aimed to improve the key performances, including mean power, convergence speed and capacity, as much as possible.This paper is organized as follows:1. This paper has studied power control for Wide-band Code Division Multiple Access (WCDMA), which is a practical example of CDMA. Though it is an excellent method, Dynamic Resource Scheduling (DRS) still has a shortcoming. This paper proposes a method named Probability-Dynamic Resource Scheduling (P-DRS). The problem that DRS makes users launch much larger transmitting power will be resolved by P-DRS.2. This paper proposes two multi-status distributed power control methods, based on the theory of iteration accelerating, for DS-CDMA systems. By taking advantage of more states, the convergence speed of Signal-to-interference (SIR) of proposed methods for DS-CDMA has been speeded up. As a result, the capacity of system has been increased.3. There is a kind of phenomena called positive feedback in SIR based power control process of CDMA systems. It does harm to CDMA systems. In fact, the positive feedback equals to the so-called non-cooperative game. Based on the analysis, this paper proposes a game-theory-based distributed power control method whose core is the newly proposed cost function/utility function. The positive feedback can be resolved well by that. The SIR of mobile users, therefore, is able to converge in a less value taking less transmitting power.By analyzing and simulating, this paper has proved that the proposed methods are more rational as well as preferable.