QRD-RLS Adaptive Equalizer and its CORDIC-Based Implementation for CDMA Systems

To combat the performance deterioration brought by the time-varying propagation conditions and multiuser/intersymbol interference in the CDMA system, this paper proposes a novel means of adaptive equalizer based on QR Decomposition-based Recursive Least Square (QRD-RLS) algorithm to replace the conventional RAKE receiver. The RLS algorithm has been exploited due to its relatively superior convergence property in comparison with other adaptive filtering algorithms. However, the high quality brings about high computational complexity as well. With regards to such a side-effect, the CORDIC algorithm has been exploited and it plays an essential role in the hardware implementation of the new approach. The proposed RLS structure is simulated extensively under different channel parameters and performance is compared against traditional RAKE structure.