Using Unclaimed Sub-carriers in Opportunistic OFDMA Systems
2006 (English)In: 2008 IEEE INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE, IEEE , 2006, 1-5 p.Conference paper (Refereed)
In this paper, we consider the unclaimed sub-carriers that no user feeds back in an opportunistic OFDMA system with a per sub-carrier power constraint. Unclaimed sub-carriers appear in OFDMA systems with reduced feedback, where the users concentrate the feedback on the sub-carriers with good channel quality. Here we propose and evaluate two ways to use these sub-carriers to improve the system performance. One approach is to transmit pilots symbols on the unclaimed sub-carriers. A second approach is to schedule users based on their feedback about adjacent sub-carriers. Simulation results show that for low to moderate channel rms delay spread, it is more advantageous to transmit data on unclaimed sub-carriers, even at a low rate, than to use them for additional pilot symbols. For high delay spreads however, transmitting pilots on the unclaimed sub-carriers gives higher system throughput.
Place, publisher, year, edition, pages
IEEE , 2006. 1-5 p.
, IEEE VTS Vehicular Technology Conference Proceedings, ISSN 1090-3038
OFDM modulation, frequency division multiple access, wireless channels, channel RMS delay, opportunistic OFDMA system, subcarrier power constraint
IdentifiersURN: urn:nbn:se:kth:diva-34907DOI: 10.1109/VTCF.2006.371ISI: 000260569401053ScopusID: 2-s2.0-34548832769OAI: oai:DiVA.org:kth-34907DiVA: diva2:428699
25th IEEE Instrumentation and Measurement Technology Conference Victoria, CANADA, MAY 12-15, 2008
QC 201107012011-07-012011-06-172012-01-23Bibliographically approved