Comparative study of frequency agile data transmission schemes for cognitive radio transceivers

摘要

In this paper, we present a comparative study of two frequency agile data transmission schemes employed by cognitive radio transceivers for use in dynamic spectrum access (DSA) networks. The transmission schemes under study, non-contiguous orthogonal frequency division multiplexing (NC-OFDM) and a modified form of multicarrier code division multiple access (MC-CDMA), are based on conventional OFDM and MC-CDMA schemes. Besides providing a degree of error robustness while yielding large data throughputs, the schemes under study are designed to avoid interference with incumbent user transmissions via subcarrier deactivation, i.e., nulling, in order to operate within a DSA network. Although several studies comparing conventional OFDM and MC-CDMA have been conducted in the literature, and the relative performance of NC-OFDM and the variant of MC-CDMA schemes is intuitive, there has not been a quantitative performance evaluation of these schemes when used within a DSA network. The quantitative evaluation corroborates with the intuitive assessment that NC-OFDM exhibits a greater degree of error robustness when avoiding incumbent transmissions relative to the variant of MC-CDMA.