Development of a Novel Random Matrix Spreading Code Generator for WCDMA Rake Receiver

Abstract

This paper describes a proposed spreading method to improve the bit error rate (BER) and user capacity in WCDMA system. The method is applied to the system up-link. The spreading process includes a new proposed random matrix constructed using the Walsh code generator, called randmat spreading code generator. Conventionally, the selection of the Walsh seed is highly dependable on the spreading factor (SF) of the system. This spreading factor has to be in the power of 2. However, by carefully selecting a variable n, to result in SF-h for the input seed to the Walsh code, our simulation results show that the BER can improve dramatically. The proposed multilevel modulation method could also increase the data rate and user capacity of the WCDMA system. To test the functionality of our proposed spreading method, we use a simulation model using MATLAB that is close to the behavior of a mobile station as specified in the WCDMA standards, specifically ETSI TS 125.211 and ETSI TS 125.213.