Bartlomiej Kozicki

Spectrum-efficient and scalable elastic optical path network: architecture, benefits, and enabling technologies

The sustained growth of data traffic volume calls for an introduction of an efficient and scalable transport platform for links of 100 Gb/s and beyond in the future optical network. In this article, after briefly reviewing the existing major technology options, we propose a novel, spectrum- efficient, and scalable optical transport network architecture called SLICE. The SLICE architecture enables sub-wavelength, superwavelength, and multiple-rate data traffic accommodation in a highly spectrum-efficient manner, thereby providing a fractional bandwidth service. Dynamic bandwidth variation of elastic optical paths provides network operators with new business opportunities offering cost-effective and highly available connectivity services through time-dependent bandwidth sharing, energy-efficient network operation, and highly survivable restoration with bandwidth squeezing. We also discuss an optical orthogonal frequency-division multiplexing-based flexible-rate transponder and a bandwidth-variable wavelength cross-connect as the enabling technologies of SLICE concept. Finally, we present the performance evaluation and technical challenges that arise in this new network architecture.

Distance-adaptive spectrum resource allocation in spectrum-sliced elastic optical path network [Topics in Optical Communications]

The rigid nature of current wavelength-routed optical networks brings limitations on network utilization efficiency. One limitation originates from mismatch of granularities between the client layer and the wavelength layer. The recently proposed spectrum-sliced elastic optical path network (SLICE) is expected to mitigate this problem by adaptively allocating spectral resources according to client traffic demands. This article discusses another limitation of the current optical networks associated with worst case design in terms of transmission performance. In order to address this problem, we present a concept of a novel adaptation scheme in SLICE called distance-adaptive spectrum resource allocation. In the presented scheme the minimum necessary spectral resource is adaptively allocated according to the end-to-end physical condition of an optical path. Modulation format and optical filter width are used as parameters to determine the necessary spectral resources to be allocated for an optical path. Evaluation of network utilization efficiency shows that distance-adaptive SLICE can save more than 45 percent of required spectrum resources for a 12-node ring network. Finally, we introduce the concept of a frequency slot to extend the current frequency grid standard, and discuss possible spectral resource designation schemes.

Demonstration of novel spectrum-efficient elastic optical path network with per-channel variable capacity of 40 Gb/s to over 400 Gb/s

We demonstrated, for the first time, a novel spectrum-efficient elastic optical path network for 100 Gb/s services and beyond, based on flexible rate transceivers and variable-bandwidth wavelength crossconnects.

Bandwidth Squeezed Restoration in Spectrum-Sliced Elastic Optical Path Networks (SLICE)

With the continuing growth in the amount of backbone traffic, improving the cost-effectiveness and ensuring survivability of the underlying optical networks are very important problems facing network service providers today. In this paper, we propose a bandwidth squeezed restoration (BSR) scheme in our recently proposed spectrum-sliced elastic optical path network (SLICE). The proposed BSR takes advantage of elastic bandwidth variation in the optical paths of SLICE. It enables spectrally efficient and highly survivable network recovery for best-effort traffic as well as bandwidth guaranteed traffic, while satisfying the service level specifications required from the client layer networks. We discuss the necessary interworking architectures between the optical path layer and client layer in the BSR in SLICE. We also present a control framework that achieves flexible bandwidth assignment as well as BSR of optical paths in SLICE. Finally, we describe an implementation example of a control plane using generalized multi-protocol label switching (GMPLS).

Algorithms for maximizing spectrum efficiency in elastic optical path networks that adopt distance adaptive modulation

We propose optical path routing and frequency slot assignment algorithms that suit elastic optical paths and the distance adaptive modulation scheme. The algorithms are proven to yield high spectrum efficiency for the distant-adaptive frequency allocation scheme.

Experimental demonstration of optical performance monitoring for RZ-DPSK signals using delay-tap sampling method

The emerging transparent optical networks, employing spectrally-efficient modulation formats require new methods for supervision of signal quality in the optical domain. In this paper we demonstrate the optical performance monitoring (OPM) of optical signal-to-noise ratio (OSNR) and chromatic dispersion (CD) in return-to-zero differential phase-shift keying (RZ-DPSK) signals using asynchronous delay-tap sampling and pattern recognition algorithms. We experimentally show noise measurement of OSNR from 8.7 dB to 32 dB with low optical input power requirement. Moreover, residual CD can be evaluated in the range from -600 to +600 ps/nm. The results indicate that careful adjustment of delay is necessary in order to ensure accurate measurement.

Filtering characteristics of highly-spectrum efficient spectrum-sliced elastic optical path (SLICE) network

We investigate the performance of OFDM-modulated signals in spectrum-sliced elastic optical path network. We analyze the filtering characteristics and the guard band for multi-node transmission. The architecture increases spectral efficiency over the current WDM systems.

Distance-adaptive super-wavelength routing in elastic optical path network (SLICE) with optical OFDM

We propose a spectrally-efficient super-wavelength-path routing in SLICE by selecting a set of subcarrier numbers and modulation levels according to path distances. We demonstrate 420 Gb/s path routing using short-reach 14-subcarrier 8-APSK and long-reach 21-subcarrier QPSK.

Distance-adaptive spectrum allocation in elastic optical path network (SLICE) with bit per symbol adjustment

We present a concept of spectrally-efficient optical networking with distance-adaptive spectral allocation by adjusting the number of modulation levels. We demonstrate it by routing 40 Gb/s optical paths using short-reach, narrow-spectrum 16APSK and long-reach QPSK.

Optical Path Aggregation for 1-Tb/s Transmission in Spectrum-Sliced Elastic Optical Path Network

We propose and experimentally demonstrate optical path aggregation in a spectrum-sliced elastic optical path network (SLICE). Multiple optical orthogonal frequency-division-multiplexed (OFDM) 100-Gb/s optical paths are aggregated in the optical domain to form a spectrally continuous 1-Tb/s super-wavelength optical path and transmitted over a network of bandwidth-variable wavelength cross-connects. We evaluate the potential implementation issues and conclude that the OFDM paths can be optically aggregated with optical signal-to-noise ratio penalty of less than 1 dB.