Optimizing Link Efficiency for Gated DPCCH Transmission on HSUPA

To minimize the terminal's transmission power in bursty uplink traffic conditions, the evolved high-speed uplink packet access (HSUPA) concept in 3GPP WCDMA includes a feature known as dedicated physical control channel (DPCCH) gating. We present here a detailed link level study of gating from a link efficiency (LE) perspective; LE being expressed in bits per second per Watt. While the overall gain mechanisms of gating are well known, we show how special challenges related to discontinuous enhanced dedicated channel (E-DCH) transmission can be addressed for high link and system performance. We consider the E-DCH performance degradation caused by gating on other radio procedures relying on the DPCCH, such as inner and outer loop power control. Our studies show that gating is beneficial for both for 2 and 10 ms transmission time intervals. The gains in terms of LE with a vehicular A 30 kmph channel are in the range of 4-5 dB for a bit rate of 32 kbps and an E-DCH activity factor of 0.1. For bit rates higher than 1 Mbps and an activity factor of 0.25, the gains are close to zero or even negative.