A Novel Rake Receiver Design for Wideband Wireless Communications

Abstract

In this paper a novel RAKE receiver design is proposed. Its main characteristic is its non-uniform taps distribution. A wide-sense stationary uncorrelated scattering (WSSUS) frequency-selective Rayleigh fading channel is assumed. Uniform and exponential power delay profiles (PDPs) are considered. Taps positions optimization is done according to the Maximum Power Minimum Correlation (MPMC) criterion. This implies the simultaneous maximization of the sum of squares of total average signal power received in each finger and minimization of the sum of squares of autocorrelation between each pair of fingers. Robustness of the technique with respect to errors in channel estimation or in the optimum taps placement is also studied.Several simulation examples of the proposed receiver show its superior performance comparing with other implementations. Finally analytical expressions for the correlation coefficients at the branches outputs of a RAKE receiver for rectangular chip waveforms are derived.

Suboptimal Rake Finger Allocation: Performance and Complexity Tradeoffs

“…Then, we present the proposed receiver architecture. In practice, the proposal extends the MPMC RAKE proposed in [16], [18], considering that only a subset of the total finger positions is optimized. In the rest of the paper, we refer to the proposed receiver as aRC MPMC RAKE (notation RC stands for reduced complexity; parameter a is the ratio of the optimized fingers M to the total available fingers L ).…”

“…Energy maximization and correlation minimization at the fingers outputs of a RAKE receiver improve its performance. However, it has been found, [16], [18], that optimal performance is obtained when a simultaneous maximization of the sum of squares of average received signal power in each finger and minimization of the sum of squares of autocorrelation between each pair of fingers takes place. This rule is known as Maximum Power Minimum Correlation (MPMC) criterion and it is translated into a multi-objective optimization problem, [27][28].…”

“…In [8], a combining rule based on maximum likelihood (ML) principles, [5][6], improved system performance by setting finger spacing below the chip duration. Similar principles were applied and evaluated in [9][10][11][12][13][14][15][16][17][18], for the estimation of optimum finger settings.…”

“…For example, in the Maximum Power Minimum Correlation (MPMC) RAKE receiver, [16], [18], finger placement is determined by the simultaneous maximization of the sum of squares of average received signal power in each finger and minimization of the sum of squares of the cross-correlation between them. In this case, the solution of a multi-objective optimization problem gives the optimal finger settings.…”

“…Here, we discuss a suboptimal RAKE finger allocation method. In this proposal, only a subset of the fingers is optimally positioned using the MPMC criterion, [16], [18]. Determination of their delays is a multi-objective optimization problem based on the correlation properties of the signal components in each finger.…”