Spectral efficiency comparison between OFDM/OQAM- and OFDM-based CR 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. In the concept of CR, secondary users or CR users, are allowed to transmit and receive date by detecting the portions of spectra where/when primary users are inactive provided that secondary transmissions cause no harmful interference to the licensed systems. Conventional orthogonal frequency division multiplexing (OFDM) has also been suggested as a physical layer candidate for CR system. In this paper, another potential candidate for CR, OFDM/offset quadrature amplitude modulation (OQAM) is introduced and compared with cyclic prefix based-OFDM (CP-OFDM) and raised cosine windowed-OFDM (RC-OFDM) in CR context, in which including spectral efficiency comparison (SEC) for uncoded transmission and coded transmission. SEC is investigated by balancing the tradeoff between the interference level caused by CR user to licensed user (LU) and the throughput of CR user. Simulated results of 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. Copyright (C) 2008 John Wiley & Sons, Ltd.
spectral efficiency ofdm/oqam ofdm cognitive radio out-of-band radiation