Adaptive multicarrier system with reduced feedback information in wideband radio channels

Abstract

OFDM (orthogonal frequency division multiplexing) is considered as a physical layer modulation scheme in wireless ATM/LAN standards. Generally, adaptive modulation requires precise channel estimation and channel state information feedback. In a wireless channel, a large portion of the total transmitting information is occupied by the feedback information due to the frequent adaptation to time-varying channel attenuation. In this paper, we propose an adaptive multicarrier system which adopts reduced feedback information for wireless application. This scheme is based on the general bit loading pouring algorithm, and suggests that the channel state information can be unified to the fractional number of loaded bits and it can be fed back differentially. In addition, we apply a linear predictor to reduce the degradation during the feedback interval.