In this paper, a novel code based channel shortening (CCS) algorithm for faster-than-Nyquist (FTN) signaling is proposed, where a special type of convolutional codes is used to absorb the channel memory. In contrast to conventional schemes, the proposed CCS algorithm performs joint detection and decoding (JDD) based only on the code trellis by exploiting the code structure. Therefore, the proposed CCS algorithm provides a new view for channel shortening (CS) techniques, i.e., absorbing the channel memory by using channel codes. According to the code structure, we derive the path metric of the proposed CCS algorithm. Furthermore, we introduce a design of self-concatenated convolutional codes (SECCCs) for FTN signaling based on the CCS algorithm. Simulation results show that with a 16-states BCJR algorithm for JDD, the bit error rate (BER) performance of the designed SECCC incorporated with FTN signaling is only around 0.75 dB away from the Shannon limit of the shaping pulse, and the required signal-to-noise ratio (SNR) is below the BPSK capacity limit of Nyquist signaling.
© 2020 IEEE.

A novel low-density parity-check (LDPC) coded Gaussian minimum shift keying (GMSK) scheme is proposed for wireless communications subject to low SNRs, limited power and spectrum resources. We first design a non-recursive GMSK modulator to alleviate the impact of error propagation. Then, a pilot-aided quasi-coherent demodulation algorithm (PA-QCDA) is derived, where a modified BCJR-based detection is used to produce the soft-output with initial and ending trellis-states being determined using the overhead-limited pilot. We choose proper parameters for the non-recursive GMSK signaling according to the trade-off of the power and spectral efficiency. Simulation results show that the proposed non-recursive GMSK system with the PA-QCDA can achieve performance similar to the LDPC coded BPSK system and can also work well in the presence of large frequency and phase offsets or burst errors. © 2020 IEEE.

In this paper, a novel code based channel shortening (CCS) algorithm for faster-than-Nyquist (FTN) signaling is proposed, where a special type of convolutional codes is used to absorb the channel memory. In contrast to conventional schemes, the proposed CCS algorithm performs joint detection and decoding (JDD) based only on the code trellis by exploiting the code structure. Therefore, the proposed CCS algorithm provides a new view for channel shortening (CS) techniques, i.e., absorbing the channel memory by using channel codes. According to the code structure, we derive the path metric of the proposed CCS algorithm. Furthermore, we introduce a design of self-concatenated convolutional codes (SECCCs) for FTN signaling based on the CCS algorithm. Simulation results show that with a 16-states BCJR algorithm for JDD, the bit error rate (BER) performance of the designed SECCC incorporated with FTN signaling is only around 0.75 dB away from the Shannon limit of the shaping pulse, and the required signal-to-noise ratio (SNR) is below the BPSK capacity limit of Nyquist signaling. © 2020 IEEE.

In this paper, we present an improved belief propagation list (BPL) decoding algorithm for polar codes. Rather than getting L factor graphs (FGs) at random and cyclic shift permutation, we use the upper bounds on the block error propability of polar codes with different FGs as the metric to choose the best L FGs. By observing the bounds of different FGs, we propose a heuristic method to reduce search complexity. Simulation results show that there is only a gap of 0.2 dB between the frame error rate (FER) performance of the improved BPL decoder using RM16-GA construction and that of length-1024 5G polar code decoded by SCL with the same list size of 32 at FER =10^-4. Moreover, with the proposed FG selection method, BPL decoding can reduce clock cycles by 97.74% compared with the SCL decoding.
© 2020 IEEE.

In this paper, we propose a reliability-based adaptive incremental redundancy hybrid automatic repeat request (IR-HARQ) scheme for rate-compatible polar codes, where the size of retransmissions is determined by the current decoding reliability. Simulation results indicate that the proposed scheme can perform better than the existing schemes based on turbo codes, low-density parity-check (LDPC) codes and raptor codes in terms of both the throughput and latency. Furthermore, with the proposed scheme, rate-compatible polar codes can achieve the performance of about 0.5 dB away from the channel capacity with the information block length of 1024 bits. © 2020 IEEE.

In this paper, we study sliding window decoding of braided convolutional codes (BCCs) in the context of a streaming application, where decoder error propagation can be a serious problem. A window extension algorithm and a resynchronization mechanism are introduced to mitigate the effect of error propagation. In addition, we introduce a soft bit-error-rate stopping rule to reduce computational complexity, and the tradeoff between performance and complexity is examined. Simulation results show that, using the proposed window extension algorithm and resynchronization mechanism, the error performance of BCCs can be improved by up to three orders of magnitude with reduced computational complexity. © 2018 IEEE.

This paper presents a nonbinary low-density parity-check (LDPC) coded spatial modulation (CSM) for multiple-input multiple-output communication systems, in which the information bits for choosing active transmit antennas and the bits for choosing constellation signals are protected by a nonbinary LDPC code. We apply a many-to-one mapping known as Gallager mapping to signal constellation, resulting in an improved constellation design for the CSM system. Furthermore, we propose a Gallager mapping-based scheme to solve the design problem of the CSM system with arbitrary transmit antennas, in which Gallager mapping is used to map the index information bits to the active antenna, thus an integer-bit transmission can be achieved for any number of transmit antennas. With the use of nonbinary LDPC codes, a non-iterative receiver is able to recover the undistinguished information caused by the many-to-one mapping. Several communication scenarios are studied and simulation results show that the proposed scheme can offer substantial performance gains with design flexibility over the Rayleigh fading channel.
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