Spectral Efficiency Analysis in OFDM and OFDM/OQAM Based Cognitive Radio Networks

The future wireless communication is expected to be able to improve the efficiency of spectrum usage. To solve the challenge of spectrum shortage, an innovative opportunistic spectrum access strategy, called cognitive radio (CR) has been proposed. Conventional orthogonal frequency division multiplexing (OFDM) has already been suggested as a physical layer candidate for CR system. Herein another potential candidate for CR, OFDM offset quadrature amplitude modulation (OFDM/OQAM) is introduced, and its spectral efficiency for coded multicarrier transmission is compared with cyclic prefix based OFDM (CP-OFDM) and raised cosine windowed OFDM (RC-OFDM) in CR context. Simulated results of spectral efficiency comparison (SEC) for different multicarrier systems are interpreted by theoretically analyzing the out-of-band radiation of their prototype pulses shaping. Both theoretic analysis and experimental results can show that OFDM/OQAM is a more natural candidate than CP-OFDM and RC-OFDM for CR networks application.