Construction and blind estimation of phase sequences for subcarrier-phase control based PAPR reduction in LDPC coded OFDM systems

As described in this paper, construction and blind estimation methods of phase sequences are proposed for subcarrier-phase control based peak-to-average power ratio (PAPR) reduction in low-density paritycheck (LDPC)-coded orthogonal frequency division multiplexing (OFDM) systems. On the transmitter side, phase sequence patterns are constructed based on a given parity-check matrix. The PAPR of the OFDM signal is reduced by multiplying the constructed phase sequence selected from the same number of candidates as the number of weighting factor (WF) combinations in a partial transmit sequence (PTS) method. On the receiver side, the phase sequence is estimated blindly using the decoding function, i.e., the most likely phase sequence among a limited number of possible phase sequence candidates is inferred by comparing the sum-product calculation results of each candidate. Computer simulation results show that PAPR of QPSK-OFDM and 16QAM-OFDM signals can be reduced respectively by about 3.7 dB and 4.0 dB without marked degradation of the block error rate (BLER) performance as compared to perfect estimation in an attenuated 12-path Rayleigh fading condition.