Lightwave system using microwave subcarrier multiplexing

We present a demonstration of subcarrier multiplexing in a lightwave multiple-access network. Three 44 Mbit/s digital signals are transmitted along a single-mode fibre bus by intensity-modulating two 1.3 ?-wavelength, multimode laser diodes with FSK subcarriers, at frequencics between 3.5 and 4.0 GHz. Intermodulation distotion, generated when two or more subcarriers are transmitted by the same laser, does not degrade the tranmission quality.     

Subcarrier multiplexed coherent lightwave systems for videodistribution

The application of subcarrier multiplexing techniques to coherent lightwave systems designed for video transmission is described. The theory of the intrinsic receiver sensitivity of multichannel coherent SCM (subcarrier multiplexing) systems is presented. Specific implementations of SCM coherent systems transmitting 60 FM video channels and 20 100 Mb/s FSK (frequency shift keying) channels are described. It is shown that a simple phase noise canceling circuit can be implemented, which allows these systems to be built with wide-linewidth DFB (distributed feedback) lasers. Several applications of multichannel coherent SCM systems to video distribution networks are proposed     

Tuned optical receivers for microwave subcarrier multiplexedlightwave systems

An analysis of tuned optical-receiver noise performance for microwave subcarrier multiplexed lightwave systems is presented. The effect of correlation between the gate and the drain HEMT noise sources and the design of tuning networks to obtain partial noise cancellation were investigated. Anoptimization algorithm is used to determine the tuning elements values for minimizing noise of 16 dB for a 60-video-channel subcarrier multiplexing (SCM) system, and 12 dB for a 120-channel system, which allows a significant increase in passive optical network distribution capacity. Design results for tuned front-end receivers encompassing the effects of p-i-n, HEMT, and SCM band parameters are presented     

Performance improvement of hybrid subcarrier multiplexing optical spectrum code division multiplexing system using spectral direct decoding detection technique

This paper proposes a hybrid subcarrier multiplexing/optical spectrum code division multiplexing (SCM/OSCDM) system for the purpose of combining the advantages of both techniques. Optical spectrum code division multiple-access (OSCDMA) is one of the multiplexing techniques that is becoming popular because of the flexibility in the allocation of channels, ability to operate asynchronously, enhanced privacy and increased capacity in bursty nature networks. On the other hand, subcarrier multiplexing (SCM) technique is able to enhance the channel data rate of OSCDMA systems. In this paper, a newly developed detection technique for the OSCDM called spectral direct decoding (SDD) detection technique is compared mathematically with the AND subtraction detection technique. The system utilizes a new unified code construction named KS (Khazani–Syed) code. The results characterizing the bit-error-rate (BER) show that SDD offers a significant improved performance at BER of 10^?9.     

Subcarrier multiplexing for lightwave networks and videodistribution systems

Applications for subcarrier multiplexing include a variety of analog and digital lightwave transmission systems. An overview of the requirements and capabilities of these systems is presented by describing specific examples of the most popular system types. These examples include multiuser interactive local area networks and multichannel digital, FM, and AM-VSB (vestigal sideband) video distribution systems. Limitations imposed on each by the linearity of directly or externally modulated sources, receiver noise, and relative-intensity noise are discussed     

Bidirectional multichannel 1.44 Gbit/s lightwave distributionsystem using subcarrier multiplexing

Demonstrates a bidirectional lightwave distribution system that uses subcarrier multiplexing to transmit data to eight nodes from a single head-end laser. Data for each node (180 Mbit/s) and return date (45 Mbit/s digital video) are transmitted as FSK subcarrier, between 2.5 and 5.0 GHz. Penalties from laser nonlinearities, interchannel interference or bidirectional transmission are negligible     

Multidestination communication over tunable-receiver single-hop WDMnetworks

We address the issue of providing efficient mechanisms for multidestination communication over one class of lightwave wavelength division multiplexing (WDM) architectures, namely, single-hop networks with tunability provided only at the receiving side. We distinguish a number of multicast traffic types, we present a number of alternative broadcast/multicast time-division multiple-access (TDMA) schedules for each type, and we develop heuristics to obtain schedules that result in low average packet delay. One of our major contributions is the development of a suite of adaptive multicast protocols which are simple to implement, and have good performance under changing multicast traffic conditions     

Subcarrier multiplexed lightwave systems for broad-banddistribution

Microwave subcarrier multiplexing (SCM) is an important approach to the design of lightwave systems for broadband distribution. Recent progress in the design and performance of both analog and digital multichannel SCM systems is reviewed. The application of broadband SCM systems to both passive and optically amplified distribution networks is discussed. The discussion covers the general features of SCM systems; the electrooptic components that have been used in the system experiments described here, including laser intensity noise and noise due to intermodulation products; the carrier-to-noise ratio requirements; some multichannel FM systems experiments; and a 20-channel digital systems experiment; and a hybrid system carrying 60 FM SCM channels plus a 100-Mb/s baseband digital channel. Several approaches to broadband subscriber distribution networks are analyzed     

Microwave/millimeter-wave frequency subcarrier lightwavemodulations based on self-sustained pulsation of laser diode

A method of subcarrier lightwave modulation based on the self-sustained pulsation (SSP) of laser diodes is presented. The tunable microwave/millimeter-wave frequency subcarrier is generated by the laser diode itself under proper DC biases. The subcarrier is frequency-modulated when the DC bias is superimposed with a small AC signal. No external modulation is needed. A theoretical analysis based on a double-section laser diode reveals that Hopf bifurcation is the origin of SSP. Theoretical calculations also show that the modulator has the potential of generating subcarriers up to 100 GHz by proper control of the device parameters V-channeled substrate inner-stripe (VSIS) GaAlAs laser diodes were used to generate 1-7-GHz SSP subcarriers. A preliminary subcarrier multiplexing (SCM) experiment demonstrated the transmission of 1-GHz modulation and video signals on a readily FM-modulated 6.3-GHz SSP subcarrier     

Performance impact of partial reconfiguration on multihop lightwavenetworks

Rearrangeable multihop lightwave networks can be dynamically reconfigured to adapt the connectivity among network stations to prevailing traffic conditions. With no limitations on the tunability range of the transmitters and/or receivers allocated to each network station, all connection diagrams can be realized among network stations, within the constraints of the number of transmitters and receivers at each station. Since the number of wavelengths in use may be very large, the tunability range of transmitters/receivers will be restricted, in practice, to some limited set of contiguous wavelengths, or waveband. As a result, all connection diagrams might not be achievable and the network may loose some of its ability to adapt to traffic changes through reconfiguration. We derive bounds on the performance degradation experienced by the network as a function of the tunability restrictions. We then propose and analyze a waveband decomposition, illustrating how networks with good performance can be designed with tunability constraints on the transceivers. We also describe other architectures (subcarrier division multiplexing, multi-fiber physical topology) to which our model and analysis readily apply     

An overview of lightwave packet networks

The unique systems opportunities offered by, and the unique systems constraints imposed by, lightwave technology as it applies to the field of distributed packet networks are examined. Single-channel and star topology approaches are first considered. Terabit-capacity lightwave networks are discussed, covering both wavelength-division and time-division multiplexing. Multichannel multihop lightwave networks are then considered, and a particular implementation, the ShuffleNet, is described, and its performance, as well as some simple addressing and routing schemes, is discussed     

A chunk and power allocation algorithm for proportional fairness in OFDMA relay networks

Wireless Networks - Applying amplify-and-forward (AF) protocol to orthogonal frequency division multiple-access (OFDMA) relay networks opens questions regarding subcarrier matching and resource...     

100 channel optical FDM technology and its applications to opticalFDM channel-based networks

Optical frequency division multiplexing (optical FDM) technology, which allows the use of an extremely broad lightwave bandwidth (10-200 THz and over) and can realize transport systems that could replace the current digital (time division multiplexing based) transport networks, is described. The future outlook for communication networks based on optical FDM technology is assessed. Based on the technical results obtained from a 100-channel optical FDM experiment, of an optical FDM channel concept is proposed and a viable architecture for optical FDM-channel-based networks is developed     

Synchronous quantized subcarrier multiplexing for transport ofvideo, voice, and data

A quantized subcarrier multiplexing approach for the transmission of video, voice, and data information over optical fiber networks is explored. The basis of this technique is to utilize a single high-speed analog-to-digital converter to digitize a composite analog signal. Conventional subcarrier multiplexing methods are used to form the composite from multiple NTSC video, voice, and data signals. The process of synchronous multiplexing, quantization, serialization, transmission, and waveform recovery is explored for an experimental prototype system. Noise performance and the impact on laser linearity requirements are discussed     

Computer-aided analysis of distortions in SCM systems with EDFAs including chirping effect

In this paper, we have applied an equivalent electrical circuit model of erbium-doped fiber amplifier (EDFA) including chirping effect to analyze the distortions in subcarrier multiplexing (SCM) systems. The model is simple and convenient for analyzing the distortions and performance of lightwave transmission systems using EDFAs, through the aid of a SPICE circuit simulator. The performance evaluation is shown of a 42-channel SCM EDFA system, including the composite second-order distortions (CSO), the allowable modulation index, and the limit on the number of channels.     

Monolithically integrated semiconductor LED-amplifier for applications as transceivers in fiber access systems

We have fabricated a monolithically integrated LED-amplifier chip for application as a high-power broad-band transmitter. Amplified LED output of 10 mW and fiber-coupled power of 4 mW was demonstrated. The device can be used as a spectrally-sliced transmitter for wavelength-division-multiplexed networks or as a broad-band transmitter in subcarrier multiple-access systems to eliminate optical beat interference. The amplifier section in the integrated device can also be used as a photodetector. The performance of the device as a transceiver in a WDM multiple-access system operating at a typically proposed local-access data rate of 10 Mb/s was successfully demonstrated.     

Allowable received OTDR light power for in-service measurement inlightwave SCM systems

To measure in-service optical transmission lines in optical video distribution systems using subcarrier multiplexing (SCM) techniques, we clarify how measurement light from an optical time domain reflectometer (OTDR) affects the signal transmission performance when the light enters an optical network unit (ONU). We describe the additional noises induced when OTDR light is injected into the ONU and analyze the relationship between received OTDR light power and carrier-to-noise ratio. Moreover, we use the analysis to provide a technique for estimating the allowable received light power in lightwave SCM systems and show the dominant factors determining this allowable power. Finally, by using the estimation technique, we clarify the required rejection ratio for a filter designed to prevent OTDR light from entering ONU's in wavelength division multiplexing systems     

副载波多路复用模拟光传输系统中激光器非线性畸变的分析

本文主要分析副载波多路复用模拟光传输系统中激光器的非线性畸变，提出一个激光器非线性失真分析的完整的数学模型，特别考虑了多路副载波情况下激光器的削波影响。认真分析了ＱｕｎＳｈｉ等人的论文，对他们提出的传输系统中ＣＳＯ和ＣＴＢ的计算公式进行了改进，考虑了高阶失真项的影响。理论推导已为实验所得多路光纤ＣＡＴＶ链路中的ＣＳＯ和ＣＴＢ结果所证实。     

Simultaneous optical amplification, detection, and transmissionusing in-line semiconductor laser amplifiers

It is demonstrated that in broadband networks inline semiconductor laser amplifiers (SLAs) that provide system gain can also be used as simultaneous transceivers for additional channels at higher frequencies. In the experiment, an SLA in a 622-Mb/s baseband system provided a 6.5-dB fiber-to-fiber gain and served simultaneously as a receiver and a transmitter for two frequency-shift-keying (FSK) channels (each carrying 10 Mb/s) at 755 and 1075 MHz, respectively. Such optical amplifiers/transceivers are potentially useful in broadband digital networks with out-of-band signaling channels or in subcarrier multiple-access networks