Fast transmit power control using 2-step outer loop control with variable step size in inter-cell site diversity for W-CDMA reverse link

摘要

This paper proposed the fast transmit power control (TPC) method using 2-step outer loop control with variable step size in inter-cell site diversity for W-CDMA reverse link and evaluated its effect by laboratory experiments. In the proposed method, 1st Outer loop compensates the target E{sub}b/N{sub}0 in order to track the change of the propagation channel such as the number of multipaths, and 2nd outer loop compensates the standard threshold for FER detection of the 1 outer loop for offsetting the difference of the measured FER values before and after selection combining. The experimental results showed that the variable step size method can decrease the convergence time of FER and BER measurements to approximately 1/4 of that with fixed step size method, which is equal to two outer loop updating periods. Since control bit through back haul required for outer loop control is used only for the users in the inter-cell Site diversity mode for 2-step outer loop method, back haul load is significantly decreased compared to the conventional outer loop method at RNC.