Biblio

In this work, we implement a complete probabilistic amplitude shaping (PAS) architecture on a field-programmable gate array (FPGA) platform to study the interplay between probabilistic shaping (PS) and forward error correction (FEC). Due to the fully parallelized input–output interfaces based on look up table (LUT) and low computational complexity without high-precision multiplication, hierarchical distribution matching (HiDM) is chosen as the solution for real time probabilistic shaping. In terms of FEC, we select two kinds of the mainstream soft decision-forward error correction (SD-FEC) algorithms currently used in optical communication system, namely Open FEC (OFEC) and soft-decision quasi-cyclic low-density parity-check (SD-QC-LDPC) codes. Through FPGA experimental investigation, we studied the impact of probabilistic shaping on OFEC and LDPC, respectively, based on PS-16QAM under moderate shaping, and also the impact of probabilistic shaping on LDPC code based on PS-64QAM under weak/strong shaping. The FPGA experimental results show that if pre-FEC bit error rate (BER) is used as the predictor, moderate shaping induces no degradation on the OFEC performance, while strong shaping slightly degrades the error correction performance of LDPC. Nevertheless, there is no error floor when the output BER is around 10-15. However, if normalized generalized mutual information (NGMI) is selected as the predictor, the performance degradation of LDPC will become insignificant, which means pre-FEC BER may not a good predictor for LDPC in probabilistic shaping scenario. We also studied the impact of residual errors after FEC decoding on HiDM. The FPGA experimental results show that the increased BER after HiDM decoding is within 10 times compared to post-FEC BER.

With a record 400Gbps 100-piece-FPGA implementation, we investigate performance of the potential FEC schemes for OIF-800GZR. By comparing the power dissipation and correction threshold at 10−15 BER, we proposed the simplified OFEC for the 800G-ZR FEC.

Physical layer secret key exploits the random but reciprocal channel features between legitimate users to encrypt their data against fiber-tapping. We propose a novel tapping-based eavesdropper scheme, leveraging its tapped signals from legitimate users to reconstruct their common features and the secret key.

In this paper, the malicious code is run in the sandbox in a safe and controllable environment, the API sequence is deduplicated by the idea of the longest common subsequence, and the CNN and Bi-LSTM are integrated to process and analyze the API sequence. Compared with the method, the method using deep learning can have higher accuracy and work efficiency.

In this paper, we propose a numerical simulation investigation of the wavelength division multiplexing mechanism between a chaotic secure channel and a traditional fiber channel using the advanced modulation method DP-16QAM at the bitrate of 80Gbps, the fiber length of 80 km and 100 GHz channel spacing in C-band. Our paper investigates correlation coefficients between the transmitter and also the receiver for two forms of communication channels. Our simulation results demonstrate that, in all cases, BER is always below 2.10-4 even when we have not used the forward-error-correction method. Besides, cross-interaction between the chaotic channel and also the non-chaotic channel is negligible showing a highly independent level between two channels.

Optical time domain reflectometry (OTDR) plays an important role in optical fiber communications. To improve the performance of OTDR, we propose a method based on the Variational Mode Decomposition (VMD) and Hilbert transform (HT) for fiber events detection. Firstly, the variational mode decomposition is applied to decompose OTDR data into some intrinsic mode functions (imfs). To determine the decomposition mode number in VMD, an adaptive estimation method is introduced. Secondly, the Hilbert transform is utilized to obtain the instantaneous amplitude of the imf for events localization. Finally, the Dynamic Time Warping (DTW) is used for identifying the type of event. Experimental results show that the proposed method can locate events accurately. Compared with the Short-Time Fourier Transform (STFT) method, the VMD-HT method presents a higher accuracy in events localization, which indicates that the method is effective and applicable.

With the rapid development of mobile communication technology, the reconnaissance on terminal capability and identity information is not only an important guarantee to maintain the normal order of mobile communication, but also an essential means to ensure the electromagnetic space security. According to the characteristics of 5G mobile communication terminal's transporting capability and identity information, the smart jamming is first used to make the target terminal away from the 5G network, and then the jamming is turned off at once. Next the terminal will return to the 5G network. Through the time-frequency matching detection method, interactive signals of random access process and network registration between the terminal and the base station are quickly captured in this process, and the scheduling information in Physical Downlink Control Channel (PDCCH) and the capability and identity information in Physical Uplink Shared Channel (PUSCH) are demodulated and decoded under non-cooperative conditions. Finally, the experiment is carried out on the actual 5G communication terminal of China Telecom. The capability and identity information of this terminal are extracted successfully in the Stand Alone (SA) mode, which verifies the effectiveness and correctness of the method. This is a significant technical foundation for the subsequent development on the 5G terminal control equipment.

We re-use a polarization-multiplexed I/Q modulator to acquire the quantum randomness of its seed laser light for the purpose of quantum random number generation. We obtain 9×104 256-bit AES keys/second after randomness extraction. Time-interleaved random number generation is demonstrated for PM-QPSK transmission.

In this paper, a hybrid optical frequency hopping system based on OAM multiplexing is proposed, which is mainly applied to the security of free space optical communication. In the proposed scheme, the segmented users' data goes through two stages of hopping successively to realize data hiding. And the security performance is also analyzed in this paper. © 2020 The Author(s).

A QPSK-assisted MIMO equalization is investigated to compensate bandwidth limitation for 800-Gb/s/λ DP-256QAM systems with only 25G-class optics. Compared with conventional MIMO equalization, the proposed equalization scheme exhibits 1.8-dB OSNR improvement at 15% FEC limit.

Negative curvature hollow core fibers (NC-HCFs) realize great research attention due to their comparatively low losses with simplified design and fabrication simplicity. Recently, revolver type fibers that combine the NC-HCF and conventional lattice structured photonic crystal fiber (PCF) have opened up a new era in communications due to their low loss, power confinement capacity, and multi-bandwidth applications. In this study, we present a customized optical fiber design that comprises the PCF with the NC-HCF to get lowest confinement loss. Extensive numerical simulations are performed and a noteworthy low loss of 4.47×10-05dB/m at a wavelength of 0.85 μm has been recorded for the designed fiber, which is almost 4600 times lower than annular revolver type fibers. In addition, a conspicuous low loss transmission bandwidth ranging from 0.6 μm to 1.8 μm has found in this study. This may have potential applications in spectroscopy, material processing, chemical and bio-molecular sensing, security, and industry applications.

We propose a photonic compressive sampling scheme based on multimode fiber for radio spectrum sensing, which shows high accuracy and stability, and low complexity and cost. Pulse overlapping is utilized for a fast detection. © 2020 The Author(s).

We propose a multipartite quantum communication network (QCN) based on surface codes (SCs). We describe how simultaneously to entangle multiple nodes in an arbitrary network topology by employing the SCs. We further describe how to extend the transmission distance between arbitrary two nodes by using the SCs as well. Finally, we describe how to operate the proposed QCN by employing the SDN concept.

This paper investigates the secrecy outage performance of a dual-hop decode-and-forward (DF) mixed radio-frequency/underwater optical wireless communication (RF/UOWC) system. We consider a one-antenna source node ( S), communicating with one legitimate destination node (D) via a multi-antenna DF relay (R) node. In this context, the relay node receives the incoming signal from S via an RF link, which is subject to Rayleigh fading, then performes selection-combining (SC) followed by decoding and then re-encoding for transmission to the destination over a UOWC link, subject to mixture Exponential-Gamma fading. Under the assumption of eavesdroppers attempting to intercept the S-R (RF side), a closed-form expression for the secrecy outage probability is derived. Our analytical results are corroborated through computer simulations, which verifies their validity.

This paper investigates the secrecy outage performance of an energy harvesting-based dual-hop amplify-and-forward (AF) mixed radio-frequency/underwater optical wireless communication (RF/UOWC) system. A single-antenna source node (S) is considered, communicating with one legitimate destination node (D) with the aid of a multi-antenna AF relay (R) device. In this setup, the relay node receives the incoming signal from S via an RF link, which is subject to Nakagami-m fading, then performs maximal-ratio-combining (MRC) followed by a fixed-gain amplification, before transmitting it to the destination via a UOWC link, subject to mixture Exponential-Gamma fading. Assuming the presence of a malicious eavesdropper attempting to intercept the S- R hop, a tight approximate expression for the secrecy outage probability is retrieved. The derived results provide useful insights into the influence of key system parameters on the secrecy outage performance. Our analytical results are corroborated through computer simulations, which verifies their validity.

This paper focuses on how to provide virtual network (VN) with the survivability of node failure. In the SVNE that responds to node failures, the backup mechanism provided by the VN initial mapping method should be as flexible as possible, so that backup resources can be shared among the VNs, thereby providing survivability support for the most VNs with the least backup overhead, which can improve The utilization of backup resources can also improve the survivability of VN to deal with multi-node failures. For the remapping method of virtual networks, it needs to be higher because it involves both remapping of virtual nodes and remapping of related virtual links. The remapping efficiency, so as to restore the affected VN to a normal state as soon as possible, to avoid affecting the user's business experience. Considering that the SVNE method that actively responds to node failures always has a certain degree of backup resource-specific phenomenon, this section provides a SVNE method that passively responds to node failures. This paper mainly introduces the survivability virtual network initial mapping method based on physical node recoverability in this method.

We evaluate the use of LEDs intended for illumination as low-cost filtered optical detectors. An optical wireless system that is exclusively based on commercial off-the-shelf 5-mm R/G/B LEDs is experimentally demonstrated for Gb/s close-proximity transmission.

In multicarrier direct modulation direct detection systems, interaction between laser chirp and fiber group velocity dispersion induces subcarrier-to-subcarrier intermixing interferences (SSII) after detection. Such SSII become a major impairment in orthogonal frequency division multiplexing-based access systems, where a high modulation index, leading to large chirp, is required to maximize the system power budget. In this letter, we present and experimentally verify an analytical formulation to predict the level of signal and SSII and estimate the signal to noise ratio of each subcarrier, enabling improved bit-and-power loading and subcarrier attribution. The reported model is compact, and only requires the knowledge of basic link characteristics and laser parameters that can easily be measured.