Probabilistically shaped polar-coded MIMO-FSO communication systems with spatially correlated fading.

In this paper, the probabilistically shaped polar-coded multiple-input multiple-output free-space optical (MIMO-FSO) communication system with or without spatially correlated (SC) fading is investigated to improve transmission performance. The designed shaping-polar encoder can flexibly generate three typical shapes of distribution via shaping bits and be decoded in the conventional method. The achievable information rate (AIR) of MIMO-FSO systems with or without SC fading is evaluated to determine the number of shaping bits for the shaping-polar encoder.

Real-time IBFD transmission system based on adaptive optical self-interference cancellation using the hybrid criteria regular triangle algorithm.

In this Letter, we first propose and demonstrate a real-time in-band full duplex (IBFD) transmission system based on adaptive optical self-interference cancellation (OSIC). The field programmable gate array (FPGA) is used for high-speed and real-time orthogonal frequency-division multiplexing (OFDM) transmission. The hybrid criteria regular triangle (RT) algorithm is first proposed to combine signal power and the bit error rate (BER) together as the objective function to realize the adaptive control process.

Polar coded probabilistic amplitude shaping for the free space optical atmospheric turbulence channel.

In this paper, the polar coded probabilistic amplitude shaping (PC-PAS) is investigated in a free space optical (FSO) communication system to combat the fading induced by turbulence. The achievable rate of multiple level coding (MLC) and bit-interleaved coded modulation (BICM) schemes with different distributions are studied in turbulence channels, which proves that the non-uniform distribution can achieve larger achievable rates than the uniform distribution in the FSO turbulence channel. And the PC-PAS techniques based on MLC and BICM are both investigated.

Neural network decoder of polar codes with tanh-based modified LLR over FSO turbulence channel.

The deep learning-based decoder of polar codes is investigated over free space optical (FSO) turbulence channel for the first time. The feedforward neural networks (NN) are adopted to establish the decoder and some custom layers are designed to train the NN decoder over the turbulence channel. The tanh-based modified log-likelihood ratio (LLR) is proposed as the input of NN decoder, which has faster convergence and better bit error rate (BER) performance compared with the standard LLR input.

Adaptive over-the-air RF self-interference cancellation using a signal-of-interest driven regular triangle algorithm.

An optically-enabled radio frquency (RF) self-interference cancellation system is demonstrated for over-the-air in-band full duplex transmission, based on a signal-of-interest (SOI) driven regular triangle algorithm. Since the goal of a self-interference cancellation system is to retrieve the SOI that is masked by the in-band interference signal, using the SOI quality as the driven parameter for optimizing the self-interference cancellation performance is a natural and effective way to allow the system to adapt to changes and obtain the best cancellation performance. Since regular triangle algorithm has short iteration time, bursts of pseudo-random binary sequence would be used between real data transmission for optimizing the self-interference cancellation performance.

Adaptive optical self-interference cancellation for in-band full-duplex systems using regular triangle algorithm.

In this paper, we propose an adaptive optical self-interference cancellation using regular triangle algorithm for in-band full-duplex systems. By using this algorithm, the manual adjustment of the tunable optical time delay line and attenuator is replaced with the adaptive program to change the delay and attenuation for achieving optimal cancellation point. The adjustment process is simplified as a convex function problem.

Performance investigation of the polar coded FSO communication system over turbulence channel.

In this paper, for the first time, to the best of our knowledge, polar codes are introduced and experimentally implemented in a free space optical (FSO) communication system to combat atmospheric turbulence induced fading. By analyzing the characteristics of the turbulence channel, a method of evaluating the channel state information for polar decoding is proposed that can achieve good trade-off between the performance and the computational complexity of this polar coded system. To verify our scheme, an intensity modulation direct detection FSO communication experimental platform with a turbulence chamber is established.

High performance and cost effective CO-OFDM system aided by polar code.

A novel polar coded coherent optical orthogonal frequency division multiplexing (CO-OFDM) system is proposed and demonstrated through experiment for the first time. The principle of a polar coded CO-OFDM signal is illustrated theoretically and the suitable polar decoding method is discussed. Results show that the polar coded CO-OFDM signal achieves a net coding gain (NCG) of more than 10 dB at bit error rate (BER) of 10 over 25-Gb/s 480-km transmission in comparison with conventional CO-OFDM.