Channel Sounding with Partial Channel Information in the Uplink of OFDM-Based Wireless Systems

In this paper, we consider a new channel sounding scheme for opportunistic scheduling with the use of reduced channel information in the uplink of orthogonal frequency division multiplexing (OFDM)-based wireless systems. To reduce signaling overhead for the sounding, we propose a two step channel sounding process considering the correlation characteristic in the time and frequency domain; called pre-sounding and mainsounding. Signal-to-noise power ratio (SNR) of each subchannel is first estimated through the pre-sounding process. Then, a main-sounding signal is sent over subchannels having high SNR but not highly correlated to each other. Since it is possible to extract the whole channel information from partial one by exploiting the channel correlation, the proposed scheme can significantly reduce the sounding signaling overhead without noticeable performance degradation compared to the full sounding scheme. Simulation results show that the proposed scheme provides significant performance improvement over conventional schemes especially when the channel is highly correlated in the time and frequency domain.