DefinePK

Abstract

A channel independent pre-coding for MIMO-OFDM systems with insufficient cyclic prefix (CP) is proposed by using the notion of interference nulling. The proposed pre-coding is more bandwidth efficient than the conventional zero-padded (ZP) or CP added MIMO systems, such as, ZP-only and CP-OFDM, when the number of receiver antennas is not more than the number of transmitting antennas. OFDM is an enticing modulation technique for transmitting large amounts of digital data over radio waves. Peak to Average Power Ratio (PAPR) for MIMO-OFDM system is still a demanding area and a difficult issue. A novel phase offset scheme to reduce PAPR in Alamouti coded OFDM systems without side information (SI) is by multiplying different phase rotation sequences by their corresponding phase offsets at the transmitter. Moreover, at the receiver, a MED decoder is also proposed, and the phase offset with the minimum Euclidian distance is selected as the sign of phase rotation sequence used at the transmitter. In this way, the SI can be obtained by estimating the phase offset, since they are one-to-one correspondence. Therefore, the proposed scheme does not need to reserve bits for the transmission of the SI, resulting in an increased data rate.