Demand for network bandwidth is growing at unprecedented rates, placing growing demands on switching and transmission technologies. Wavelength division multiplexing will soon make it possible to combine hundreds of gigabit channels on a single fiber. This paper presents an architecture for Burst Switching Systems designed to switch data among WDM links, treating each link as a shared resource rather than just a collection of independent channels. The proposed network architecture separates burst level data and control, allowing major simplifications in the data path in order to facilitate all-optical implementations. To handle short data bursts efficiently, the burst level control mechanisms in burst switching systems must keep track of future resource availability when assigning arriving data bursts to channels or storage locations. The resulting Lookahead Resource Management problems raise new issues and require the invention of completely new types of high speed control mechanisms. This paper introduces these problems and describes approaches to burst level resource management that attempt to strike an appropriate balance between high speed operation and efficiency of resource usage.

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Terabit burst switching

Fiber-optic communication systems form the high-capacity transport infrastructure that enables global broadband data services and advanced Internet applications. The desire for higher per-fiber transport capacities and, at the same time, the drive for lower costs per end-to-end transmitted information bit has led to optically routed networks with high spectral efficiencies. Among other enabling technologies, advanced optical modulation formats have become key to the design of modern wavelength division multiplexed (WDM) fiber systems. In this paper, we review optical modulation formats in the broader context of optically routed WDM networks. We discuss the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, multipath interference, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity

Advanced Optical Modulation Formats

We address the issue of how to provide basic quality of service (QoS) in optical burst-switched WDM networks with limited fiber delay lines (FDLs). Unlike existing buffer-based QoS schemes, the novel offset-time-based QoS scheme we study in this paper does not mandate any buffer for traffic isolation, but nevertheless can take advantage of FDLs to improve the QoS. This makes the proposed QoS scheme suitable for the next generation optical Internet. The offset times required for class isolation when making wavelength and FDL reservations are quantified, and the upper and lower bounds on the burst loss probability are analyzed. Simulations are also conducted to evaluate the QoS performance in terms of burst loss probability and queuing delay. We show that with limited FDLs, the offset-time-based QoS scheme can be very efficient in supporting basic QoS.

QoS performance of optical burst switching in IP-over-WDM networks

Since the first deployments of fiber-optic com- munication systems three decades ago, the capacity carried by a single-mode optical fiber has increased by a staggering 10 000 times. Most of the growth occurred in the first two decades with growth slowing to ten times in the last decade. Over the same three decades, network traffic has increased by a much smaller factor of 100, but with most of the growth occurring in the last few years, when data started dominating network traffic. At the current growth rate, the next factor of 100 in network traffic growth will occur within a decade. The large difference in growth rates between the delivered fiber capacity and the traffic demand is expected to create a capacity shortage within a decade. The first part of the paper recounts the history of traffic and capacity growth and extrapolations for the future. The second part looks into the technological chal- lenges of growing the capacity of single-mode fibers by pre- senting a capacity limit estimate of standard and advanced single-mode optical fibers. The third part presents elementary capacity considerations for transmission over multiple trans- mission modes and how it compares to a single-mode trans- mission. Finally, the last part of the paper discusses fibers supporting multiple spatial modes, including multimode and multicore fibers, and the role of digital processing techniques. Spatial multiplexing in fibers is expected to enable system capacity growth to match traffic growth in the next decades.

https://www.icg.isy.liu.se/courses/optical/Capacity_Trends.pdf

Capacity Trends and Limits of Optical Communication Networks Discussed in this paper are: optical communication network traffic evolution trends, required capacity and challenges to reaching it, and basic limits to capacity.

Celebrating the 20th anniversary of Optics Express, this paper reviews the evolution of optical fiber communication systems, and through a look at the previous 20 years attempts to extrapolate fiber-optic technology needs and potential solution paths over the coming 20 years. Well aware that 20-year extrapolations are inherently associated with great uncertainties, we still hope that taking a significantly longer-term view than most texts in this field will provide the reader with a broader perspective and will encourage the much needed out-of-the-box thinking to solve the very significant technology scaling problems ahead of us. Focusing on the optical transport and switching layer, we cover aspects of large-scale spatial multiplexing, massive opto-electronic arrays and holistic optics-electronics-DSP integration, as well as optical node architectures for switching and multiplexing of spatial and spectral superchannels.

Fiber-optic transmission and networking: the previous 20 and the next 20 years [Invited]

A significant part of signal-to-noise degradation in WDM optical fiber communications, due to Raman crosstalk, is found to be deterministic in nature. Shaping of amplifier output to offset depletion of high frequency channels improves signal capacity by an order of magnitude.

Multi-channel optical fiber communication system

One Tb/s aggregate capacity (50 channels each at 20 Gb/s) was transmitted through 55 km of non-zero-dispersion fiber. The fifty channels were generated by polarization multiplexing 25 wavelengths.

One Terabit/s Transmission Experiment

Link control, a new technique for protecting surviving channels on a per-link basis from fast power transients resulting from network reconfigurations or line failures, is demonstrated in a 560-km eight-amplifier wavelength division multiplexed link carrying seven 2.5-Gb/s channels plus the link control channel.

Fast-link control protection of surviving channels in multiwavelength optical networks

By optimising the detector threshold and using an optical reservoir channel, error-free transmission of 32/spl times/25 Gbit/s DWDM channels has been obtained over 125 km of AllWave/sup TM/ fibre using semiconductor optical amplifiers

Error-free transmission of 32 × 2.5 Gbit/s DWDM channels over 125 km using cascaded in-line semiconductor optical amplifiers

We experimentally investigate the optical noise induced by stimulated Brillouin scattering (SBS) in single-mode fibers. The noise, which is caused by the random nature of spontaneous Brillouin scattering, is induced in the transmitted wave as well as in the backward Brillouin wave. In fibers where the Brillouin gain spectra consist of several resonances, the induced intensity noise of the transmitted wave has a wide spectrum and it may be the dominant noise in the receiver for a broad radio frequency band (0-1 GHz). This unexpected result is explained by a multiple scattering process which is caused by stimulated and by thermally excited phonons. The SBS induced noise may cause a performance degradation in analog optical systems which require high optical powers and low noise. Using fibers with a single Brillouin resonance may limit the noise to lower frequencies.

Andrew Roman Chraplyvy

Papers

Multi-channel optical fiber communication system

One Terabit/s Transmission Experiment

Fast-link control protection of surviving channels in multiwavelength optical networks

Error-free transmission of 32 × 2.5 Gbit/s DWDM channels over 125 km using cascaded in-line semiconductor optical amplifiers

Broad-band transmitted intensity noise induced by Stokes and anti-Stokes Brillouin scattering in single-mode fibers