Bit-interleaved coded modulation with iterative decoding (BICM-ID) is suitable for correlated Rayleigh fading channels. Additionally, BICM-ID using differential encoding can avoid the pilot overhead. In this paper, we consider BICM-ID using 16-DAPSK (differential amplitude and phase-shift keying). We first derive the probability of receiving signals conditioned on the transmission of input bits for general differential encoding; then we propose two new 16-DAPSK bit labeling methods. In addition, convolutional codes for the new bit labeling are developed. Both the minimum distance and the simulation results show that the proposed labeling has better error performance than that of the original differential encoding, and the searched new codes can further improve the error performance.

Amplitude phase shift keying (APSK) constellation with Gray mapping was proposed recently. Inspired by the simplified soft demapping for regular Gray-QAM, a simplified soft demapping algorithm for Gray-APSK is proposed in this paper. Compared with conventional soft demapping schemes, its complexity is greatly reduced with only a little SNR loss, which is validated by the complexity analysis and FPGA compilation results.

This paper presents comprehensive comparisons of the achievable throughput between the 32-/64-ary amplitude and phase shift keying (APSK) and cross 32QAM/square 64QAM schemes based on mutual information (MI) considering the peak-to-average power ratio (PAPR) of the modulated signal. As a PAPR criterion, we use a cubic metric (CM) that directly corresponds to the transmission back-off of a power amplifier. In the analysis, we present the best ring ratio for the 32 or 64APSK scheme from the viewpoint of minimizing the required received signal-to-noise power ratio (SNR) considering the CM that achieves the peak throughput, i.e., maximum error-free transmission rate. We show that the required received SNR considering the CM at the peak throughput is minimized with the number of rings of M = 3 and 4 for 32-ary APSK and 64-asry APSK, respectively. Then, we show with the best ring ratios that the (4, 12, 16) 32APSK scheme with M = 3 achieves a lower required received SNR considering the CM compared to that for the cross 32QAM scheme. Similarly, we show that the (4, 12, 20, 28) 64APSK scheme with M = 4 achieves almost the same required received SNR considering the CM as that for the square 64QAM scheme.

A low complexity log-likelihood ratio (LLR) calculation for high-order amplitude phase shift keying (APSK) signals is proposed. Using proper constellation partitioning together with a look-up table, the number of terms for the comparison of Euclidean distances can be significantly reduced. Compared with the log-sum LLR approximation, the proposed method reduces the computational complexity by more than 65% and 75% for 16-APSK and 32-APSK signals, respectively, with very small bit error rate performance degradation.

This paper proposes an adaptive algorithm for adaptive arrays that minimizes the bit error rate (BER) of the array output signals in radio communication systems with the use of multilevel modulation signals. In particular, amplitude phase shift keying (APSK) is used as one type of multilevel modulations in this paper. Simultaneous non-linear equations that are satisfied by the optimum weight vector of the proposed algorithm are derived and used for theoretical analyze of the performance of the adaptive array based on the proposed algorithm. As a result of the theoretical analysis, it can be shown that the proposed adaptive array improves the carrier to interference ratio of the array output signal without taking advantage of the nulls. Furthermore, it is confirmed that the result of the theoretical analysis agrees with that of computer simulation. When the number of the received antenna is less than that of the received signals, the adaptive array based on the proposed algorithm is verified to achieve much better performance then that based on the least mean square (LMS) algorithm.

A method to construct bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) is developed that approaches the Shannon limit very closely at high spectrum efficiency, where amplitude-phase shift keying (APSK) constellations are designed and chosen. For 1/2-rate 64APSK, the Es/N0 threshold derived through extrinsic information transfer (EXIT) charts is less than 0.55 dB away from the Shannon limit of the continuous-input additive white Gaussian noise (AWGN) channel, and exceeds the theoretical limit constrained by standard 64QAM-input.

In this letter, the effect of distorted constellation shapes of 16-ary modulation due to the power saturation channel is analyzed. In particular, error bounds for 16-QAM and 16-APSK with distorted constellations are derived, and optimal operating points in terms of Es/N0 are presented. The result can be used to accurately predict the performance of these modulation schemes with a given level of the constellation distortion, as well as to determine the amount of input power to the saturation channel which minimizes the probability of modulation symbol error.

The performance of a new APSK receiver is analyzed using numerical simulation. The proposed receiver eliminates the penalty caused by SPM-induced phase-shift of optical pulses by employing three sub-modules and an amplitude-pattern controlled switch for each DPSK tributary. The interplay between SPM, IXPM, and XPM determines the performance of the proposed receiver for single-channel and WDM transmission.

In this paper, the bit error rate (BER) of 16 differential amplitude phase shift keying (16DAPSK) modems in future mobile communication system is derived analytically. The channel employed in this paper is the frequency-selective and fast Rayleigh fading channel, corrupted by cochannel interference (CCI) and additive white Gaussian noise (AWGN). Exact expressions for the probability distributions of the differential phase and amplitude ratio are derived for the BER calculation. The BER and optimum boundary are obtained for various channel conditions. In addition, the results for the BER in the presence of CCI are provided.