A temporal averaging technique for direction of arrival estimation in a multipath environment

A new procedure is proposed for estimating directions of arrival (DOA) of multipaths in multipath channels. Assuming finite support, a finite matrix description of the channel is derived. A sufficient condition for computing the DOAs is that the rank of this matrix be at least equal to the number of multipaths. This condition need not hold at all times, especially when the channel length in number of symbols is smaller than the number of multipaths. Usually this problem is solved via a so called spatial smoothing approach. But spatial smoothing requires a large array of antennas as it needs averaging over a number of subarrays (each subarray being larger than the number of significant multipaths). The new technique does not require extra antennas and computes the DOAs as long as the path delays are distinct