Implementation of Channel Estimation and Multiuser Detection Algorithms for W-CDMA on Digital Signal Processors
Rajagopal, Sridhar; Xu, Gang; Cavallaro, Joseph R.
Proposed algorithms for Third Generation W-CDMA communication systems have extremely high performance requirements. In this paper, we study the implementation issues involved for one of the proposed multiuser channel estimation and detection algorithms for base-stations in the uplink using TI's TMS320C6x DSP Evaluation Modules(EVM). It was found that these proposed algorithms for multiuser channel estimation and detection have different processing and precision requirements. While the detector can be implemented using the C6201 16-bit fixed point DSP, the proposed channel estimation algorithm may be more suitable for a oating point implementation using the C6701 floating point DSP. We study the effects of the specialized approximate instructions available on the C6701 DSP on channel estimation. Then, the advantage of multistep optimizations and use of assembly code is studied for both the algorithms. Memory issues involved in the implementation of these algorithms is also investigated. It was found that the data memory requirements for channel estimation for the chosen system parameters necessitates the use of external memory while the multistage detection algorithm could be placed in the available internal data memory. We finally discuss the current and future trends of DSPs and their utilization for such wireless communication applications.