Application of the Residue Number System to Digital Communication Systems
Hunter, Todd R.
Digital signal processors (DSP) are beginning to dominate the communications industry. The demand of the industry is to provide smaller, lighter, lower powered communication technology without sacrificing performance. This study investigates the application of an alternative method of implementation for a digital frequency modulation receiver, the cross-correlator. Instead of using a traditional fixed point DSP based platform, residue number systems (RNS) are applied to the application. The main focus of this work iey to evaluate the performance of an RlNS based cross-correlator receiver and compare it to the same receiver using traditional fixed point DSP techniques. Theoretical calculations are performed on the receiver and a model is developed. The model is developedto allow for the analysis of both the fixed point DSP based receiver as well as the RNS based receiver. This model is used to analyze the bit error rate (BER) performance of the receiver for various input signal to noise ratios. Comparison of the model's BER results indicates that an RNS based receiver using 6-bits for quantization of all receiver inputs and 6-bits at the output of the receiver performs as well as an 8-bit fixed point DSP based receiver. The cross-correlator receiver is also simulated to determine the accuracy of the model. Both the RNS and DSP based methods of implementation are simulated. The BER results from the simulation show that the RNS based receiver using 6-bits for quantization and output does not perform as well as the 8-bit DSP based system. However by using 8-bits for the quantization of the low pass filter coefficients, the BER performance of the RNS based system significantly improves. The model and simulation provide similar performance ratings, however the model is not as affected by the characteristics of the low pass filters.