DocumentCode :
849213
Title :
Slow Adaptive M -QAM With Diversity in Fast Fading and Shadowing
Author :
Conti, Andrea ; Win, Moe Z. ; Chiani, Marco
Author_Institution :
Bologna Univ.
Volume :
55
Issue :
5
fYear :
2007
fDate :
5/1/2007 12:00:00 AM
Firstpage :
895
Lastpage :
905
Abstract :
This paper investigates the performance of adaptive M-ary quadrature amplitude modulation (QAM) with antenna subset diversity. We consider a slow adaptive modulation (SAM) technique that adapts the constellation size to the slow variation of the channel due, for example, to shadowing. The proposed SAM technique is more practical than conventional fast adaptive modulation (FAM) techniques that require adaptation to fast-fading variations. Our results show that the SAM technique can provide a substantial increase in throughput with respect to fixed schemes while maintaining an acceptable low bit-error outage. We also compare SAM and FAM techniques, showing that the throughput of SAM can be, in many practical cases, close to that of FAM, despite the fact that SAM is less complex and requires a lower feedback rate. For example, using a set of possible modulations {4,16,64}-QAM with dual-branch maximal ratio combining reception, 5% outage at a bit-error probability of 10-2 and a median signal-to-noise ratio of 22 dB, SAM is capable of improving the mean spectral efficiency of fixed schemes from about 1.9 to 4.7 b/s/Hz, which is close to the 5.5 b/s/Hz achieved by FAM
Keywords :
adaptive modulation; diversity reception; error statistics; fading channels; mobile antennas; mobile communication; quadrature amplitude modulation; antenna subset diversity; bit-error probability; fading channels; fast adaptive modulation; quadrature amplitude modulation; slow adaptive M-QAM; slow adaptive modulation; Adaptive arrays; Amplitude modulation; Diversity reception; Fading; Feedback; Laboratories; Quadrature amplitude modulation; Quality of service; Shadow mapping; Throughput; Adaptive modulation; fading channels; mobile communication; quadrature amplitude modulation (QAM);
fLanguage :
English
Journal_Title :
Communications, IEEE Transactions on
Publisher :
ieee
ISSN :
0090-6778
Type :
jour
DOI :
10.1109/TCOMM.2007.892453
Filename :
4200937
Link To Document :
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