Hyun-Seung Joo

A New Blind SLM Scheme With Low Decoding Complexity for OFDM Systems

In this paper, a new blind selected mapping (BSLM) scheme is proposed for orthogonal frequency division multiplexing systems. The proposed BSLM scheme embeds the side information identifying a phase sequence into itself by giving the optimal phase offset to the elements of each phase sequence, which are determined by the biorthogonal vectors for the partitioned subblocks. When U phase sequences and maximum likelihood decoder are used, the proposed BSLM scheme reduces the decoding complexity by (U-2)/U compared with the conventional BSLM scheme. Also, pairwise error probability (PEP) analysis for the proposed BSLM scheme is performed over the fading channel. Based on the PEP analysis, the bit error rate (BER) performance of the proposed BSLM scheme is shown to be determined by the subblock partitioning and phase offset. Finally, it is shown that for QPSK and 16-QAM, the detection failure probability and the BER of the proposed BSLM scheme are almost the same as those of the conventional BSLM scheme through numerical analysis.

Analysis of PAPR reduction performance of SLM schemes with correlated phase vectors

The peak to average power ratio (PAPR) reduction performance depends on the phase vectors of selected mapping (SLM) scheme where the alternative input symbol vectors are generated by multiplying an input symbol vector by phase vectors. Thus, the symbol powers of alternative orthogonal frequency division multiplexing (OFDM) signals obtained by inverse Fourier transforming the alternative input symbol vectors become correlated. In this paper, the relationship between the correlations of component powers of alternative OFDM signal vector and the correlations of phase vectors are evaluated. Then, the complementary cumulative distribution function (CCDF) of PAPR in SLM scheme is derived using multivariate gamma distribution. The derived CCDF coincides exactly with the simulation result for peak reduced OFDM system with SLM.

A New Blind SLM Scheme with Low Complexity of OFDM Signals

In this paper, we propose a new blind SLM scheme with low complexity using m-sequence as a phase sequence in OFDM. The proposed scheme significantly reduces the compu- tational complexity for searching the side information of the phase sequence and decoding the alternative symbol sequence at the receiver. After generating alternative symbol sequences using a set of phase sequences, the side information for each alternative symbol sequence is embedded in it through block partitioning and phase rotation. The proposed method does not need additional inverse fast Fourier transform (IFFT) and has the same PAPR reduction performance compared to the conventional SLM scheme. In order to find the side information, a maximum likelihood (ML) decoder with lower complexity is derived, which guarantees lower detection failure probability of side information compared to the conventional blind SLM scheme.

A blind SLM PAPR reduction scheme using cyclic shift in STBC MIMO-OFDM system

In this paper, we propose a blind SLM scheme using cyclic shift (BSLM-CS) in STBC MIMO-OFDM. After an OFDM signal sequence in each transmit antenna is cyclically shifted, alternative signal sequences in the proposed scheme are generated by linearly combining OFDM signal sequences using addition and subtraction without the need of the additional IFFT. Therefore, the proposed BSLM-CS scheme has low computational complexity for transmitting the alternative signal sequence with the lowest PAPR. In oder to recover the data at the receiver without side information, the ML decoder for the BSLM-CS scheme can be derived similar to the conventional BSLM scheme. The BER performance of the proposed scheme is not degraded com pared to the conventional SLM scheme with the perfect side information.

New PTS Schemes for PAPR Reduction of OFDM Signals Without Side Information

In this paper, two partial transmit sequence (PTS) schemes without side information (SI) are proposed for reducing peak-to-average power ratio of orthogonal frequency division multiplexing signals. The proposed schemes do not transmit SI identifying a rotating vector because identifiable phase offset is applied to the elements of each rotating vector. To extract SI from the received signal and recover the data sequence, the maximum likelihood (ML) detector is used. This ML detector exploits the Euclidean distance between the given signal constellation and the signal constellation rotated by the phase offset. By doing pairwise error probability (PEP) analysis, it is investigated how to choose good phase offsets for embedding SI. Also, the performance degradation caused by SI detection failure is analyzed based on PEP. Finally, through numerical analysis, it is shown that the BER performance of the proposed PTS schemes is not degraded compared with the conventional PTS with perfect SI.

A new subblock partitioning scheme using subblock partition matrix for PTS

In this paper, we propose a new subblock partitioning scheme using the subblock partition matrix for the partial transmit sequence. Based on the convolution property of the inverse fast Fourier transform (IFFT), the subblock partition matrix can be derived. The signal subsequences for the PTS scheme are generated from the circular convolution of the signal sequence and the subblock partition matrix. Since several IFFT operations of the signal subsequences are replaced by the convolution of the signal sequence with the proposed subblock partition matrix, only one IFFT operation is required. The interleaved subblock partitioning scheme is suitable for the proposed subblock partition matrix in terms of complexity.