On the spectral efficiency of amplify-and-forward relay systems with adaptive M-QAM

Jae Woo Kwon, Young-Chai Ko, Hong Chuan Yang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In wireless networks, cooperative diversity transmission can considerably improve the reliability of the wireless links with the introduction of a relay node forwarding the source information to the destination. Generally, cooperative system with multiple L relays suffers from a spectral efficiency loss with the factor 1/(L+1), because the transmission process takes place in (L+1) orthogonal channels by using time-division multiple access. To overcome such a spectral efficiency loss, the incremental relaying (IR) scheme for one relay environment was proposed in [1]. In [2], the incremental opportunistic relaying (IOR) scheme was proposed to extend the IR scheme in conjunction with the best relay selection scheme over multiple relays environment. An alternative approach to improve a spectral efficiency is that all the relays simultaneously transmit on the same subchannel. The relays can share the same bandwidth, and the destination can coherently combine the signals by co-phasing. In addition, adaptive modulation can achieve high spectral efficiency over fading channels while satisfying a certain bit error rate (BER) requirement. The IR with adaptive modulation (IR-AM) scheme was proposed and studied for three-node cooperative transmission system [3]. However, the IR-AM scheme may suffer from some loss of the overall spectral efficiency as it will still use the direct transmission even though the relaying transmission may achieve much higher spectral efficiency. In this paper, we propose a new cooperative transmission scheme for amplify-and-forward (AF) relaying system with multiple relays, termed as maximum spectral efficiency with adaptive modulation (MSE-AM) scheme as its objective is to maximize the spectral efficiency. To accurately quantify the performance gain of the proposed scheme, we carry out accurate analysis on the average spectral efficiency of the MSE-AM scheme based on an upper bound of the combined output signal-to-noise ratio (SNR) with AF relaying. We obtain some useful closed-form expression for some interest cases. Our numerical results show the proposed scheme can offer significant performance gain over the conventional schemes.

Original languageEnglish
Title of host publication2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010
DOIs
Publication statusPublished - 2010 Dec 6
Event2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010 - Honolulu, HI, United States
Duration: 2010 Aug 282010 Sep 3

Other

Other2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010
CountryUnited States
CityHonolulu, HI
Period10/8/2810/9/3

Fingerprint

Quadrature amplitude modulation
Adaptive modulation
Time division multiple access
Fading channels
Bit error rate
Telecommunication links
Wireless networks
Signal to noise ratio
Bandwidth

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Information Systems

Cite this

Kwon, J. W., Ko, Y-C., & Yang, H. C. (2010). On the spectral efficiency of amplify-and-forward relay systems with adaptive M-QAM. In 2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010 [5612253] https://doi.org/10.1109/ICWITS.2010.5612253

On the spectral efficiency of amplify-and-forward relay systems with adaptive M-QAM. / Kwon, Jae Woo; Ko, Young-Chai; Yang, Hong Chuan.

2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010. 2010. 5612253.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Kwon, JW, Ko, Y-C & Yang, HC 2010, On the spectral efficiency of amplify-and-forward relay systems with adaptive M-QAM. in 2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010., 5612253, 2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010, Honolulu, HI, United States, 10/8/28. https://doi.org/10.1109/ICWITS.2010.5612253
Kwon JW, Ko Y-C, Yang HC. On the spectral efficiency of amplify-and-forward relay systems with adaptive M-QAM. In 2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010. 2010. 5612253 https://doi.org/10.1109/ICWITS.2010.5612253
Kwon, Jae Woo ; Ko, Young-Chai ; Yang, Hong Chuan. / On the spectral efficiency of amplify-and-forward relay systems with adaptive M-QAM. 2010 IEEE International Conference on Wireless Information Technology and Systems, ICWITS 2010. 2010.
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