Adjustment loop transmit power control during soft handover in CDMA cellular systems

In the downlink of CDMA cellular systems, the traffic capacity is increased with fast closed-loop transmit power control (TPC) and soft handover. However, during soft handover, the balance of transmit power in the downlink is not maintained between base stations due to the reception errors of fast closed-loop TPC commands. The imbalance of transmit power results in the loss of traffic capacity. In order to recover the balance, adjustment loop TPC is proposed, in which the base stations gradually change the transmit power so that the difference of transmit power between base stations is reduced without disturbing fast closed-loop TPC. Computer simulations show that average transmit power in the downlink is reduced by 0.7 dB per mobile station by recovering the balance with adjustment loop TPC.