Suboptimal Rake Finger Allocation: Performance and Complexity Tradeoffs

Optimal finger placement improves significantly the performance of RAKE receivers. However, due to its high complexity, it is rarely applied in mobile systems with large channel spread. In this paper, we evaluate the merits of suboptimal finger allocation in terms of performance and complexity. A subset of the RAKE fingers is optimally positioned based on the received signal correlation properties while the rest of them are uniformly distributed within the channel spread. The tradeoffs between performance and complexity of the method are discussed. Results show that optimizing half finger positions lead to similar performance with the full optimization scheme. Finally, comparisons with conventional and optimal receivers exhibit the advantages of the method.