Adaptive modulation and coding where the mapping from channel quality to modulation and coding scheme is adjusted depending upon ack/nack receipt

摘要

The invention relates to adaptive modulation and coding (AMC) in wireless networks, in particular third generation (3G) mobile phone networks. In the basic 3GPP high speed downlink packet access (HSDPA) proposal for AMC there is a fixed relationship between the measured channel quality (CQI) and the modulation and coding scheme (MCS) to be used (Fig. 5). In the proposed system the CQI (12) is mapped to an adjustable soft MCS value (14). The soft MCS value is adjusted up when a packet is successfully received (ack) and down on failed reception (nack). This soft MCS value is then used to select the appropriate MCS to be used. The system allows the appropriate MCS to be selected even when path and channel conditions vary.