Research Article
Filterbank Multicarrier and Multicarrier CDMA for Cognitive Radio Systems
@INPROCEEDINGS{10.1109/CROWNCOM.2007.4549844, author={Ehsan Azarnasab and Roland Kempter and Neal Patwari and Behrouz Farhang-Boroujeny}, title={Filterbank Multicarrier and Multicarrier CDMA for Cognitive Radio Systems}, proceedings={2nd International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications}, publisher={IEEE}, proceedings_a={CROWNCOM}, year={2008}, month={6}, keywords={CDMA Cognitive Radio OFDM OFDM-OQAM multicarrier CDMA}, doi={10.1109/CROWNCOM.2007.4549844} }- Ehsan Azarnasab
Roland Kempter
Neal Patwari
Behrouz Farhang-Boroujeny
Year: 2008
Filterbank Multicarrier and Multicarrier CDMA for Cognitive Radio Systems
CROWNCOM
IEEE
DOI: 10.1109/CROWNCOM.2007.4549844
Abstract
Recent works in cognitive radio (CR) have suggested multicarrier communication based on orthogonal frequencydivision multiplexing (OFDM) for CR networks. In this paper, we propose two alternative multicarrier techniques. The first one, filterbank-based OFDM-OQAM (OFDM-offset quadrature amplitude modulation), allows to maximize the secondary users’ spectral efficiency by eliminating the need for guard bands. Also, OFDM-OQAM’s filterbank spectral estimator has greater dynamic range than the conventional fast fourier transform in OFDM, which further reduces the probability of undesirable collisions between the secondary users (SU) and primary users (PU). However, OFDM-OQAM still requires an SU base station for distributed sensing. For cases where such is not available, or when sensing information cannot be conveyed, we suggest another multicarrier technique, namely multicarrier code division multiple access (MC-CDMA). While MC-CDMA does not achieve comparably high spectral efficiency as OFDM-OQAM, the spreading gain of MC-CDMA results in graceful degradation in the case of collisions between PUs and SUs. Furthermore, compared to direct sequence (DS) CDMA, MC-CDMA allows to exclude narrowband PU interferers locally at the SU receiver, hence improving SU performance. We show that MC-CDMA makes it possible to operate the SU network without distributed sensing and hence no need for a base station infrastructure and/or a signaling channel.