Practical Feedback Design based OFDM Link Adaptive Communications over Frequency Selective Channels

LANGUAGE
English
SOURCE
IEEE International Conference on Communications (ICC 2006), Istanbul, Turkey
Published Date:2006-06-11
ABSTRACT
OFDM is an effective multicarrier technique for wireless transmissions over frequency selective fading channels. Adaptive techniques can be used to further enhance the transmission ability. For ideal OFDM adaptive transmissions, each subcarrier can get an independent adaptive mode according to the Channel State Information (CSI) of the corresponding subcarrier. The awfully large amount of CSI feedback and signalling transmissions will be a serious problem in adaptive OFDM systems, which make ideal adaptive OFDM systems impossible to be implemented. This paper focuses on the practical feedback and adaptive signalling designs of OFDM systems. Based on the characteristics of frequency selective channels, a Dynamic Neighboring Subcarrier Grouping Scheme (DNSGS) is proposed to cut down the feedback and adaptive signalling overhead, and to simplify the implementation of adaptive OFDM systems. Then the capacity of DNSGS based OFDM systems is also given. The simulation results powerfully show that the scheme designed in this paper is flexible enough for different kinds of communication environments, and can effectively cut down the feedback and signalling overhead with rather limited performance penalty as compared with the ideal subcarrier-to-subcarrier adaptive techniques. Besides, DNSGS outperforms the existing grouping schemes greatly. The schemes designed in this paper can be a highly recommendable candidate of future 4G/5G communications.