van den Hpa Henrie Boom

High-speed transmission over multimode fiber using discrete multitone modulation

Focus Issue: Orthogonal-Frequency-Division Multiplexed Communications Systems and Networks Discrete multitone (DMT) modulation is a subclass of the more general orthogonal-frequency-division multiplexing, where the output of the inverse fast Fourier transform modulator is real instead of complex-valued. Therefore, no in-phase and quadrature modulation onto an RF carrier is required. As a result, broadband, high-frequency, analog RF components are omitted, reducing system complexity and costs. We give an overview of important issues such as synchronization and peak-to-average power that should be considered when DMT is employed in an intensity-modulated direct-detection multimode fiber (MMF) link. Experimental results showing 24Gbits/s transmission over silica MMF and 8Gbits/s transmission over the standard step-index polymer optical fiber (SI-POF) are presented, demonstrating the potential of DMT to enable high-speed transmission over MMF using only low-bandwidth transceivers.

47.4 Gb/s Transmission Over 100 m Graded-Index Plastic Optical Fiber Based on Rate-Adaptive Discrete Multitone Modulation

We experimentally demonstrate a bit-rate of 47.4 Gb/s over 100 m of perfluorinated multimode graded-index plastic optical fiber (GI-POF) by exploiting discrete multitone (DMT) modulation with rate-adaptive bit-loading. The maximum achieved aggregate bit rate is 51.8 Gb/s including DMT transmission overhead (cyclic prefix and preambles) and the standard of 7% of forward-error-correction (FEC) overhead. This is achieved over an intensity-modulated direct-detection (IM-DD) link using a directly-modulated DFB laser (1300-nm) and a multimode fiber-coupled photodetector with a large diameter of 25-¿m. The bandwidth requirement is only 12 GHz due to the use of spectral-efficient modulation formats of up to 64-QAM.

Cost optimization of optical in-building networks

We compare the CapEx and OpEx of in-building networks for fibre and Cat-5E solutions. For residential homes, our analysis shows that total network costs during economic lifetime are lowest for a point-to-point duplex POF topology.

Discrete multitone modulation for high-speed data transmission over multimode fibers using 850-nm VCSEL

30-Gb/s transmission over 500 m and 28-Gb/s over 1 km of multimode fiber (with 850-nm multimode VCSEL and large-area photodetector) is experimentally demonstrated by use of discrete multitone modulation (DMT) combined with bit-loading algorithm.

30-Gb/s 3

This letter investigates a 30-Gb/s 3 × 3 optical mode group-division-multiplexing (MGDM) system over graded index multimode fiber (GI-MMF). With mode-selective spatial filtering (MSSF), the optimized joint detection has been realized, which de creases the complexity of the signal processing to recover received signals.

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We demonstrate a proof of concept real time HD video stream delivery over 50m 1mm core diameter plastic optical fiber and 3m wireless link employing MB-OFDM UWB technology for in-home networks.

3 Optical Mode Group-Division-Multiplexing System With Optimized Joint Detection

A 30Gbit/s 3 × 3 optical Mode Group Division Multiplexing system with Mode-Selective Spatial Filtering (MSSF) using single-mode fiber is demonstrated over 20m graded-index multimode fiber. Crosstalk among the mode groups is minimized through MSSF.

First demonstration of HD video distribution over large-core POF employing UWB for in-home networks

Hybrid fiber-coax CATV networks are considered a promising infrastructure for the implementation of future interactive services. Efficient utilization of the available CATV spectrum requires a communication system which is dedicated to the specific properties of these networks. This paper presents the physical layer of a bidirectional communication system for HFC CATV networks which is based on CDMA, a technique that has a certain robustness to the ingress noise found in the CATV bandwidth. Because the application of asynchronous CDMA results in a poor spectral efficiency, a transmission scheme based on synchronous CDMA is adopted. Using synchronous CDMA and QPSK modulation, a capacity of 64 channels of 64 kbit/s each can be achieved in a bandwidth of 6 MHz. It is found that small synchronization errors can be tolerated without significant performance degradation. Next, a description is given of the cable modems responsible for the communication between subscribers and a CATV headend. The design exploits the typical CATV network configuration to enable a cost-effective hardware realization. Sensitivity of system performance to linear distortion is investigated by computer simulation. Especially linearly varying group delay and uneven amplitude response are shown to be potential causes of performance degradation.

30Gbit/s 3 × 3 optical Mode Group Division Multiplexing system with Mode-Selective Spatial Filtering

The family of 3 × 2N quadrature amplitude modulation (QAM) constellations in combination with discrete multitone modulation is employed to maximize the throughput of 1-mm core diameter plastic optical fibers. Using this scheme together with a bit and power loading algorithm, a bit-rate improvement of 12% is achieved compared with using only 2N-QAM scheme. A bit rate of 5.6 Gb/s is demonstrated over 50 m of 1-mm core diameter graded-index plastic optical fiber (POF).

A CDMA based bidirectional communication system for hybrid fiber-coax CATV networks

Optical true time delay (OTTD) is an attractive way to realize microwave beam steering (MBS) due to its inherent features of broadband, low-loss, and compactness. In this Letter, we propose a novel OTTD approach named cyclic additional optical true time delay (CAO-TTD). It applies additional integer delays of the microwave carrier frequency to achieve spectral filtering but without disturbing the spatial filtering (beam steering). Based on such concept, a broadband MBS scheme for high-capacity wireless communication is proposed, which allows the tuning of both spectral filtering and spatial filtering. The experimental results match well with the theoretical analysis.