宽带CDMA系统的自适应功率和速率控制性能分析

PERFORMANCE ANALYSIS OF ADAPTIVE POWER AND RATE CONTROL IN WIDEBAND CDMA SYSTEMS

该文研究一种新的自适应功率和速率控制方案,导出了采用这种方案的宽带CDMA系统的误比特率(BER)公式,并分别给出了系统在平坦衰落信道和多径衰落信道中性能分析的数值结果。在这种方案中,移动台根据衰落信道的变化自适应地调整其发射功率和传输速率,而衰落信道的变化通过一种新的远程预测算法进行预测。首先将预测的总平均信道功率的概率密度函数划分为若干个面积相同的区间,从而得出这些区间之间的门限值;然后通过与传统功率控制技术相似的方式,将这些门限值用于自适应功率和速率控制。数值结果表明,采用这种方案能够有效地提高宽带CDMA系统的理论BER性能。

In this paper, a novel adaptive power and rate control scheme is studied, the BER (Bit Error Rate) formula for the wideband CDMA system with this scheme is derived, and the numerical results of performance analysis in flat fading and frequency-selective channels are given respectively. In this scheme, the transmit power and rate are adapted by the mobile based on the variations of the fading channel. Firstly the predicted Probability Distribution Function (PDF) is divided into several regions equally, and the threshold values among these regions are got. Then the thresholds are used in adaptive power and rate control in a way similar to the traditional power control technique. The numerical results show that the theoretical BER performance of wideband CDMA system can be improved effectively by this scheme.