Cross-Layer Approaches for Planning and Operating Impairment-Aware Optical Networks

Abstract

This paper presents some recent developments in cross-layer approaches for planning and operating impairment-aware optical networks; included are associated challenges, comparative analysis with some solutions, and future research.

Estimation Uncertainties in the Optical Signal-to-Noise Ratio Network Optimization

“…The evolution of optical network layer equipment has provided flexibility with respect to the adjustment of the network link conditions and traffic demands, however optical networks are mostly static yet owing to potential impairments that are hard to forecast or model [2] [5]. These impairments are composed by the linear and nonlinear physical effects [6].…”

“…Besides, the nonlinear impairments include self-phase modulation (SPM), cross-phase modulation (XPM) and four-wave mixing (FWM) [6]. In this scenario, the lightpaths are exceptionally modified, as soon as assigned due to these impairments [2] [5]. Furthermore, algorithms of resource allocation such as routing and wavelength allocation (RWA) and power allocation (PA) are done mainly at the planning step, with significant over-provisioning.…”

“…Furthermore, algorithms of resource allocation such as routing and wavelength allocation (RWA) and power allocation (PA) are done mainly at the planning step, with significant over-provisioning. In the RWA, given a set of connection requests that represents a traffic matrix, the problem consists of selecting a lightpath, that is, an appropriate path and a wavelength on the links of that path, for each requested connection [3] [5]. On the other hand, the PA consists in the determination of the appropriated value of the transmitted power for each lightpath according to the adequate optical signal-to-noise ratio (OSNR) level [2].…”

“…Furthermore, different lightpaths can travel via different routes and presents different requirements of quality of service (QoS). The QoS is related to the OSNR, dispersion, and nonlinear effects those are represented by the quality-of-transmission (QoT) [5] [7]. Therefore, it is desirable to adjust network parameters such as optical transmitted power, amplifier gain, OADMs/OXCs power losses in an optimal way, based on online decentralized iterative algorithms, to accomplish such adjustment [7]- [9] [10].…”

“…The estimation process is based on combinations and 3 interpolations of optical performance monitors (OPM) measurements, as well as in analytical models and numerical simulations [11]- [13]. The main figures of merit of QoT are the OSNR and the bit error rate (BER) [5]. The estimation of QoT at each node is affected directly by the transmitted pulse shape, filter types and bandwidth.…”