Showing papers by "Min Zhang published in 2014"

Experimental research and comparison of LDPC and RS channel coding in ultraviolet communication systems.

Abstract: We have implemented a modified Low-Density Parity-Check (LDPC) codec algorithm in ultraviolet (UV) communication system. Simulations are conducted with measured parameters to evaluate the LDPC-based UV system performance. Moreover, LDPC (960, 480) and RS (18, 10) are implemented and experimented via a non-line-of-sight (NLOS) UV test bed. The experimental results are in agreement with the simulation and suggest that based on the given power and 10(-3)bit error rate (BER), in comparison with an uncoded system, average communication distance increases 32% with RS code, while 78% with LDPC code.

Flexible Optical Cross-Connect Structures Supporting WDM Multicast With Multiple Pumps for Multiple Channels

Abstract: We not only propose three flexible optical cross-connect (OXC) structures, with the ability of wavelength-division multiplexing (WDM) multicast, but also experimentally demonstrate two WDM multicast schemes based on four-wave mixing in a semiconductor optical amplifier (SOA). One-to-ten WDM multicast of 25-Gb/s QPSK signals is achieved with three pumps, and the power penalties for all signals are less than 1.7 dB. For the first time, dual-channel WDM multicasts are simultaneously realized with only two pumps. One-to-six multicast for one input with the largest power penalty of 1.28 dB is obtained, whereas one-to-three multicast for the other input with the power penalty of 1.27 dB is also realized. The demonstrated schemes can be applied to the proposed OXC structures, according to the different requirements. The effect of bias current on conversion efficiency and optical signal-to-noise ratio is also discussed, and the optimal value is given.

Experimental demonstration of an indoor visible light communication positioning system using dual-tone multi-frequency technique

Abstract: In this paper, a visible light communication (VLC)-based indoor positioning system (IPS) employing a dedicated algorithm and using the dual-tone multi-frequency technique is proposed. Unlike the time-division multiplexing based VLC-IPS, the proposed positioning system doesn't require synchronization between the transmitter and receiver, which makes it a simple, robust and cost effective. To test the accuracy of the proposed method, an experimental test-bed using 3 white light-emitting diodes and a photomultiplier tube is developed. The results show that the proposed VLC-IPS is highly accurate with an average positioning error of about 1.6cm, which far lower than many existing indoor position systems.

Simultaneous multichannel wavelength multicasting and XOR logic gate multicasting for three DPSK signals based on four-wave mixing in quantum-dot semiconductor optical amplifier

Abstract: In this paper, we experimentally demonstrate simultaneous multichannel wavelength multicasting (MWM) and exclusive-OR logic gate multicasting (XOR-LGM) for three 10Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signals in quantum-dot semiconductor optical amplifier (QD-SOA) by exploiting the four-wave mixing (FWM) process. No additional pump is needed in the scheme. Through the interaction of the input three 10Gbps DPSK signal lights in QD-SOA, each channel is successfully multicasted to three wavelengths (1-to-3 for each), totally 3-to-9 MWM, and at the same time, three-output XOR–LGM is obtained at three different wavelengths. All the new generated channels are with a power penalty less than 1.2dB at a BER of 10−9. Degenerate and non-degenerate FWM components are fully used in the experiment for data and logic multicasting.

Design and experiment of FBG-based icing monitoring on overhead transmission lines with an improvement trial for windy weather.

Abstract: A scheme for monitoring icing on overhead transmission lines with fiber Bragg grating (FBG) strain sensors is designed and evaluated both theoretically and experimentally. The influences of temperature and wind are considered. The results of field experiments using simulated ice loading on windless days indicate that the scheme is capable of monitoring the icing thickness within 0–30 mm with an accuracy of ±1 mm, a load cell error of 0.0308v, a repeatability error of 0.3328v and a hysteresis error is 0.026%. To improve the measurement during windy weather, a correction factor is added to the effective gravity acceleration, and the absolute FBG strain is replaced by its statistical average.

Multifunctional switching unit for add/drop, wavelength conversion, format conversion, and WDM multicast based on bidirectional LCoS and SOA-loop architecture.

Abstract: We propose a multifunctional optical switching unit based on the bidirectional liquid crystal on silicon (LCoS) and semiconductor optical amplifier (SOA) architecture. Add/drop, wavelength conversion, format conversion, and WDM multicast are experimentally demonstrated. Due to the bidirectional characteristic, the LCoS device cannot only multiplex the input signals, but also de-multiplex the converted signals. Dual-channel wavelength conversion and format conversion from 2 × 25Gbps differential quadrature phase-shift-keying (DQPSK) to 2 × 12.5Gbps differential phase-shift-keying (DPSK) based on four-wave mixing (FWM) in SOA is obtained with only one pump. One-to-six WDM multicast of 25Gbps DQPSK signals with two pumps is also achieved. All of the multicast channels are with a power penalty less than 1.1 dB at FEC threshold of 3.8 × 10−3.

Optical Network Node Supporting One-to-Six WDM Multicasting of QPSK Signals

Abstract: The capability of multicast directly in the optical domain at the routing nodes is a target for energy saving, fast service provisioning, and effective network resource utilization. An optical network node architecture supporting wavelength conversion, unicast, and multicast is presented and a shared multicast/wavelength conversion module is designed in the intermediate node. Wavelength conversion and one-to-six WDM multicast of 25-Gb/s QPSK signals based on four-wave mixing are experimentally demonstrated using a semiconductor optical amplifier with only two pumps. All six multicast signals achieve error-free performance with a power penalty <;4.3 dB.

Spread spectrum-based ultraviolet communication with experiments

Abstract: We report experiments of ultraviolet (UV) communication based on spread-spectrum technique. Field mea­surements via online UV communication are conducted to compare the system performances with and with­out spectrum spreading. The results indicate that the spread-spectrum technique is capable of suppressing noise in UV atmospheric scattering channel and therefore improve the system performance evidently. Details of implementation are also provided to make the results useful for similar system design in research on optical wireless communications.

On the performance of a scalable optical switching architecture for flat intercluster data center network with centralized control

Abstract: Data centers have to sustain the rapid growth of data traffic due to the increasing demand of bandwidth-hungry Internet services. The current fat tree topology causes communication bottlenecks in the server interaction process, resulting in power-hungry O-E-O conversions that limit the minimum latency and the power efficiency of these systems. As a result, recent efforts have advocated that all optical data center networks (DCNs) have the capability to adapt to traffic requirements on demand. We present the design, implementation, and evaluation of a cascaded microelectromechanical systems switches-based DCN architecture which dynamically changes its topology and link capacities, thereby achieving unprecedented flexibility to adapt to dynamic traffic patterns. We analyze it under a data center traffic model to determine its suitability for this type of environment. The proposed architecture can be scaled to 3300 input/output ports by available experimental components with low blocking probability and latency. The blocking probability and latency are about 0.03 and 72 ms at a moderate traffic load for 32 input/output ports based on our numerical results, which are much smaller than the results for 4 input/output ports which are 0.13 and 235 ms, respectively.

Enhancement of practically deployable indoor VLC system with LDPC code

Abstract: The enhanced visible light communications (VLC) system with transmission distance of 6m is demonstrated using transmission path design and forward error correction code in this paper. The experimental results suggest that based on the given power and 10−3 bit error rate, in comparison with uncoded system, average communication distance increases 45%, communication area increases 236% with LDPC code.

Combination of distributed and centralized control architecture based on PCE protocol for large scale multi-domain elastic optical networks

Abstract: For large scale multi-domain elastic optical networks, we propose a combination of distributed and centralized control architecture (DC-CA) based on stateful hierarchical PCE. Experiment results are presented from DC-CA testbed and automated provisioning and recovery time of multi-fault are reported.

QPSK wavelength multicasting based on four-wave mixing in semiconductor optical amplifier

Abstract: We experimentally demonstrate one-to-five quadrature phase-shift keying (QPSK) wavelength multicasting based on four-wave mixing in bulk semiconductor optical amplifier. The input 25 Gb/s nonreturn-to-zero QPSK signal is successfully multicast to five new wavelengths with all information preserved. All the multicast channels are with a power penalty less than 1.1 dB at a bit error rate (BER) of 10-3. A characterization of the conversion efficiency in terms of pump and signal powers using the BER as figure of merit is also presented, the results indicate that the pump and signal powers should be optimized to eliminate the introduced deleterious nonlinear components.

40-Gb/s downstream and 10-Gb/s upstream long-reach WDM-PON employing remotely pumped EDFA and self wavelength managed tunable transmitter

Abstract: We propose a remotely pumped EDFA and tunable transmitter-based 40-Gb/s/λ downstream and 10-Gb/s/λ upstream transmissions long-reach WDM-PON scheme and an optical beat noise-based novel automatic wavelength control method for tunable transmitter. Transmissions of 40-Gb/s DQPSK downstream using MZ Modulator and 10-Gb/s OOK upstream using optical beat noise-based self wavelength managed tunable transmitter are demonstrated with 40-km fiber.

Enhancement of wireless ultraviolet communication system using FEC codes

Abstract: We present theoretical and experimentally study on performance of typical FEC codes in wireless ultraviolet communication system. The results show that, the communication distance increases about 116% with LDPC and 41% with RS code by comparison with that without FEC.

An optimal independent sets based greedy spectral defragmentation algorithm in elastic optical network

Abstract: We quantify the fragmentation in elastic optical networks and propose a defragmentation algorithm which takes network's existing condition of spectrum allocation into consideration for the first time, we simulate the blocking probability (BP) together with spectrum continuous degree of networks after using three different algorithms. The results show our defragmentation algorithm has better performance compared to the existing strategies.

Simultaneous format conversion of parallel multichannel based on FWM in symmetric highly nonlinear fiber loop

Abstract: A parallel multichannel format conversion scheme for elastic optical networking based on four wave mixing (FWM) in symmetric highly nonlinear fiber loop (S-HNLF-L) is proposed and the performance is evaluated and discussed. Parallel four channels format conversion from quadrature phase shift keying (QPSK) to binary phase shift keying (BPSK) signals at 40 Gb/s is theoretically analyzed and simulated. The results are helpful for the format-adaptive elastic optical networks.

Enhancement of indoor VLC communication system with optical path design and FEC code

Abstract: The enhanced visible light communications (VLC) system with transmission distance of 7m is demonstrated using transmission path design and forward error correction code in this paper. Moreover, RS (160, 128) and LDPC (960, 480) code are implemented and experimented via VLC test-bed. The results suggest that based on the given power, 5Mbps transmission bit rate and 10-3 bit error rate (BER), in comparison with uncoded system, average communication distance increases 18% with RS code and 39% with LDPC code, effective communication area increases 154% with RS code and 236% with LDPC code.

A distributed and scalable optical packet switch architecture for data centers

Abstract: We propose an AWGR and SOA based scalable optical packet switch architecture with modular structure and highly distributed control scheme for data center networks. Numerical results show this architecture can achieve high throughput with low blocking probability and latency.

A Novel Virtual Network Embedding Algorithm with Load Balancing in Elastic Optical Networks

Abstract: This paper proposes a novel load balancing algorithm for virtual network embedding problem in elastic optical networks. Simulation results show the algorithm achieves a better tradeoff between balancing spectrum resource load and reducing spectrum usage.

Dual-Channel Format Conversion from DQPSK to DPSK Based on FWM in a Single SOA

Abstract: We experimentally demonstrate the dual-channel wavelength conversion and format conversion from 2×25 Gbps DQPSK signals to 2 × 12.5 Gbps DPSK based on FWM in SOA using only one pump. About 0.5-dB sensitivity improvement at FEC threshold for DPSK1 is achieved and 0.4-dB power penalty is paid for DPSK2.

Rayleigh Noise Mitigation in Channel-Reuse 10Gb/s/λ DWDM-PON Employing Optical Beat Noise-based Self Wavelength Managed Tunable Laser

Abstract: We propose an optical beat noise-based wavelength difference detection method and a RB noise mitigation method relying on wavelength shift between upstream and downstream used in tunable laser-based channel-reuse DWDM-PON system. The feasibility is also experimentally verified.

Demonstration of 54.8-GHz radio-over-fiber system with wavelength reuse based on distributed intensity conversion

Abstract: We have proposed and successfully demonstrated a new architecture of MMW RoF system with wavelength reuse to deliver VHT data/video services. Based on PolM-to-IM conversion, frequency multiplied MMW (54.8-GHz) and intensity-free OC with slight phase fluctuation were received by adjusting PCs. 1.0-Gb/s OOK DS signal has been transmitted over 25-km SMF and air links. Meanwhile, successful transmission of the rate-symmetric US signals is implemented by reusing the light-wave. Additionally, in order to strengthen the stability of the device, a commercial automatic polarization tracker could be employed to replace PC we used in BS.

Scalable and Low-Latency Optical Interconnect Architecture based on WMS and AWGR for Data Center Networks

Abstract: We present an intra-data center optical network based-on wavelength multiplexing switch (WMS) and a self-routing and non-blocking AWGR-based switch. The proposed architecture is highly scalable, traffic adaptive and suitable for dynamic and diverse topology requirement.