In signal separation and channel equalisation, a short delay spread channel can result in high complexity receiver filters. The computational complexity of estimating these filters can be reduced by using multi-rate technique. In multi-rate processing, a problem is divided into a number of low complexity problems by means of a subband filterbank. Simulation results show up to 93%reduction in computational load compared to a fullband implementation at the expense of a small degradation in separation performance. The results also show that by properly optimizing the filterbank, the performance degradation can significantly be reduced.