Effect of error in channel state information on the channel capacity with QAM signalling and the design of robust signal constellations

• Published in: IET communications Vol. 1; no. 6; pp. 1118 - 1125
• Main Authors: AL-ASKARY, O, SLIMANE, S. B
• Format: Journal Article
• Language: English
• Published: Stevenage Institution of Engineering and Technology 01.12.2007; John Wiley & Sons, Inc
• Subjects: Applied sciences; Channel capacity; Channels; Constellations; Detection, estimation, filtering, equalization, prediction; Error analysis; Errors; Exact sciences and technology; Genetic algorithms; Information, signal and communications theory; Modulation; Modulation, demodulation; Phase shift keying; Signal and communications theory; Signal, noise; Switching and signalling; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Fading channels; Performance evaluation; Estimation error; Parameter estimation; Channel capacity; Quadrature amplitude modulation; Probabilistic approach; Error estimation; Rayleigh channels; Amplitude modulation; Probability distribution; Signalling; Phase shift keying; Genetic algorithm; Channel estimation; Discrete time
• ISSN: 1751-8628; 1751-8636
• DOI: 10.1049/iet-com:20060185

The effects of channel estimation errors on the channel capacity of a discrete time, discrete input and infinite output Rayleigh fading channel are investigated. The case of conventional modulation methods such as phase shift keying and quatrature amplitude modulation (QAM) is investigated at first where it was observed that the capacity degrades rapidly with increasing channel estimation errors. The effect of error in the channel estimation is similar to the effect of higher noise in the channel that depends on the transmitted signal. A genetic algorithm is used to optimise the signal constellation in order to maximise the capacity for a given finite number of signal points. The aim of trying to maximise the capacity is to estimate the remaining gap in performance between a traditional modulation scheme such as QAM and the best possible constellation that is optimised for the channel. The constellations obtained from the genetic algorithm are, in general, not directly implementable.