Power Control Study For WCDMA Mobile Communications System

There is an in-depth study of power control in WCDMA system in this paper. It puts power control as one of key techniques based on the detailed analysis of the character in WCDMA system. After the study of the domestic and international latest investigation technology, the power control arithmetic is deeply researched by theoretical analysis and simulation. The application methods as well as a practical example are also given in this paper. All these study and research is benefit for improving the sampling precision of power control.Currently, the third generation standards that International Telecommunication Union has accepted are mainly three kinds the following standards: WCDMA, CDMA2000 and TD-SCDMA, which based on the technology of CDMA. In CDMA system, "multi-access interference", "near and far problem" and "shading effect" deteriorate the quality of communication, which leading to the system capacity decrease. Power control is introduced to solve these problems effectively. Power control technology is introduced to weak the influence of interference and to make the transmit power maintain the lowest level satisfying SIR requirement. Power control technology both helps transmission and reduces the interference to other users. Thus system capacity can be improved. Based on the analysis of the character of system capacity in WCDMA system, some improving processing methods are put forward so that the effect of simulated this data latter.The high altitude platform stations (HAPS) is a new information system that has been developed at an early stage in recent years. By using the stable weather conditions and good radio wave transmission behavior of the stratosphere, this new system can realize communications connections between the platform and its terrestrial users, between two platforms as well as between a platform and a communications satellite, therefore, it possesses advantages of flexible arrangement, vast-range, cost-effective, safe and reliable communicating, etc. Since CDMA is an interrupted and restricted system, its capacities and the function are restricted by multiple access interrupt, while multi-user detection (MUD) algorithm can reduce significantly the interrupts of multiple access and multiple paths, which can entirely reduce every user's error code function. Therefore, adopting multi-user detection algorithm in WCDMA system can be effective improving the systematic function's index. In this paper, we examine the impact of both power control and multi-user detection on the uplink of a WCDMA HAPS system and analyze the principle of their operation. We further discuss the feasibility and method to unite power control and multi-user detection in a WCDMA system.