Abstract
In this paper, we investigate adaptive QAM in Coded OFDM using second moment adaptation of channel SNR. In this scheme the transmitted data is adaptively mapped to M-QAM constellation after a 1/4; rate channel coding, based on the channel state information. The second central moment of the channel impulse response SNR, or its variance, is used as switching thresholds for QAM modulation. With the assumption of perfect channel knowledge, variance of each subband is calculated and compared with the switching thresholds to determine the number of bits per symbol that can be transmitted The 512 subcarriers of this coded OFDM system is divided into 32 subbands so that adaptation is done on a subband basiss. Results show that for adaptation up to 4 bits per symbols, second moment adaptation is about 3 dB more superior than adaptation by mean channel SNR. Comparison has also been made between results of second moment adaptation with fixed 2-, 4- and 8-QAM modulation which shows that BER performance is better (eg. by as much as 10 db compared to 8QAM) with some compensation on throughput.
| Original language | English |
|---|---|
| Title of host publication | IEEE Region 10 Annual International Conference, Proceedings/TENCON |
| Volume | B |
| Publication status | Published - 2004 |
| Event | IEEE TENCON 2004 - 2004 IEEE Region 10 Conference: Analog and Digital Techniques in Electrical Engineering - Chiang Mai Duration: 21 Nov 2004 → 24 Nov 2004 |
Other
| Other | IEEE TENCON 2004 - 2004 IEEE Region 10 Conference: Analog and Digital Techniques in Electrical Engineering |
|---|---|
| City | Chiang Mai |
| Period | 21/11/04 → 24/11/04 |
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ASJC Scopus subject areas
- Engineering(all)
Cite this
Second moment adaptation of quadrature amplitude modulation in Coded OFDM over fading channel. / Noordin, Nor K.; Ali, Borhanuddin M.; Jamuar, S. S.; Rahman, Tharek A.; Ismail, Mahamod.
IEEE Region 10 Annual International Conference, Proceedings/TENCON. Vol. B 2004.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - Second moment adaptation of quadrature amplitude modulation in Coded OFDM over fading channel
AU - Noordin, Nor K.
AU - Ali, Borhanuddin M.
AU - Jamuar, S. S.
AU - Rahman, Tharek A.
AU - Ismail, Mahamod
PY - 2004
Y1 - 2004
N2 - In this paper, we investigate adaptive QAM in Coded OFDM using second moment adaptation of channel SNR. In this scheme the transmitted data is adaptively mapped to M-QAM constellation after a 1/4; rate channel coding, based on the channel state information. The second central moment of the channel impulse response SNR, or its variance, is used as switching thresholds for QAM modulation. With the assumption of perfect channel knowledge, variance of each subband is calculated and compared with the switching thresholds to determine the number of bits per symbol that can be transmitted The 512 subcarriers of this coded OFDM system is divided into 32 subbands so that adaptation is done on a subband basiss. Results show that for adaptation up to 4 bits per symbols, second moment adaptation is about 3 dB more superior than adaptation by mean channel SNR. Comparison has also been made between results of second moment adaptation with fixed 2-, 4- and 8-QAM modulation which shows that BER performance is better (eg. by as much as 10 db compared to 8QAM) with some compensation on throughput.
AB - In this paper, we investigate adaptive QAM in Coded OFDM using second moment adaptation of channel SNR. In this scheme the transmitted data is adaptively mapped to M-QAM constellation after a 1/4; rate channel coding, based on the channel state information. The second central moment of the channel impulse response SNR, or its variance, is used as switching thresholds for QAM modulation. With the assumption of perfect channel knowledge, variance of each subband is calculated and compared with the switching thresholds to determine the number of bits per symbol that can be transmitted The 512 subcarriers of this coded OFDM system is divided into 32 subbands so that adaptation is done on a subband basiss. Results show that for adaptation up to 4 bits per symbols, second moment adaptation is about 3 dB more superior than adaptation by mean channel SNR. Comparison has also been made between results of second moment adaptation with fixed 2-, 4- and 8-QAM modulation which shows that BER performance is better (eg. by as much as 10 db compared to 8QAM) with some compensation on throughput.
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M3 - Conference contribution
VL - B
BT - IEEE Region 10 Annual International Conference, Proceedings/TENCON
ER -