Estimating the ratio of traffic channel power to pilot power in a MIMO wireless communication system

A method in a wireless receiver for processing a received multi-stream multiple-input multiple-output (MIMO) signal, comprising:

• calculating an average symbol amplitude or average symbol power level from a plurality of de-spread traffic channel symbols received in a first transmission slot;
• estimating a corresponding pilot symbol amplitude or pilot symbol power level, based on an estimated propagation channel response and at least one of a plurality of precoding vectors used to generate the MIMO signal;
• computing a per-code traffic-channel-to-pilot power ratio for the first transmission slot by dividing the average symbol amplitude or average symbol power level by the corresponding pilot symbol amplitude or pilot symbol power level;
• wherein calculating an average symbol amplitude or average symbol power level from a plurality of de-spread traffic channel symbols received in a first transmission slot comprises:
• calculating stream-specific combining weights from the estimated propagation channel response, the precoding vectors used to generate the MIMO signal, and a previously calculated per-code power ratio computed for a prior transmission slot as a weighted average of per-code power ratios computed for two or more prior transmission slots;
• de-spreading samples of the received signal at each of multiple time delays and combining the de-spread samples using the stream-specific combining weights corresponding to a first stream of the MIMO signal, to obtain each of a plurality of combined traffic channel symbols;
• and
• calculating the average symbol amplitude or average symbol power level from the plurality of combined traffic channel symbols.