FPGA-based LDPC-coded APSK for optical communication systems

Abstract

Abstract:In this paper, with the aid of mutual information and generalized mutual information (GMI) capacity analyses, it is shown that the geometrically shaped APSK that mimics an optimal Gaussian distribution with equiprobable signaling together with the corresponding gray-mapping rules can approach the Shannon limit closer than conventional quadrature amplitude modulation (QAM) at certain range of FEC overhead for both 16-APSK and 64-APSK. The field programmable gate array (FPGA) based LDPC-coded APSK emulation is conducted on block interleaver-based and bit interleaver-based systems; the results verify a significant improvement in hardware efficient bit interleaver-based systems. In bit interleaver-based emulation, the LDPC-coded 64-APSK outperforms 64-QAM, in terms of symbol signal-to-noise ratio (SNR), by 0.1 dB, 0.2 dB, and 0.3 dB at spectral efficiencies of 4.8, 4.5, and 4.2 b/s/Hz, respectively. It is found by emulation that LDPC-coded 64-APSK for spectral efficiencies of 4.8, 4.5, and 4.2 b/s/Hz is 1.6 dB, 1.7 dB, and 2.2 dB away from the GMI capacity.

Optimized-Eight-State CV-QKD Protocol Outperforming Gaussian Modulation Based Protocols

“…An optimized-eight-state CV-QKD protocol has been proposed significantly outperforming both previously introduced DM protocols and GM-based CV-QKD protocols for practical reconciliation efficiencies in terms of the SKR for given channel attenuation and distance. As an illustration, high information reconciliation scheme proposed in [23] is directly applicable here, given that the proposed DM scheme belongs to the class of amplitude-phase-shift keying (APSK) modulation schemes. This information reconciliation scheme belongs to the class of low-complexity bit-interleaved coded modulation (BICM) and has already been implemented in FPGA.…”

Load Modulation for Backscatter Communication: Channel Capacity and Capacity-Approaching Finite Constellations

“…5 is naturally resembled by amplitude and phase-shift keying (APSK). This long-established scheme [30] has been used by optical [42] and satellite [43] communication systems. APSK constellation design comes with various degrees of freedom and there are different proposals for settling the details [38], [40], [44]- [46].…”