Design for increasing spectral efficiency of PSAM-OFDM system based on segmented effective transmission rate

This paper presents a design for increasing spectral efficiency of Pilot Symbol Assisted Modulation (PSAM)-Orthogonal Frequency Division Multiplexing (OFDM) system by the use of segmented data rate transmission in the frequency-selective block fading channel model. In the proposed scheme, the transmitter divides the information-bearing tones of a block into several segments, each of which uses the data rate limited by its lower bound of the mutual information. The receiver detects current segments and uses the detected symbols as the addition pilots for next segment. With the number of the pilot symbols increases, quality of each channel estimate is improved and, consequently, the spectral efficiency of the system can be increased. It is reasonable to assume that the limit of symbol error rate is zero when each segment contains large number of symbols. Under this assumption, we derived the lower bound of the spectral efficiency. The numerical results show the spectral efficiency gain over the conventional design.