ORIGINAL RESEARCH Performance investigation of MLR optical WDM network based on ITU-T conforming fibers in the presence of SRS, XPM and FWM Rochak Bajpai 1 • Sujata Sengar 1 • Sridhar Iyer 2 • Shree Prakash Singh 1 Received: 16 May 2017 / Accepted: 10 July 2018 Ó Bharati Vidyapeeth’s Institute of Computer Applications and Management 2018 Abstract This article investigates the performance degra- dation of a mixed line rate (MLR) optical wavelength division multiplexing network in the presence of the combined FWM, XPM and SRS effects. For performance evaluation a novel mathematical model is developed which evaluates the results in terms of quality-factor. Further, the simulations are performed (i) based on the optical fre- quency grid defined by the ITU-T Recommendation G.692, and (ii) considering the ITU-T compliant optical fibers viz., G.652, G. 652D, G. 653, G. 654, G.655, and LEAF. The obtained results show that among the various considered fibers and modulation format configuration cases, irre- spective of spacing between the channels (i) SMF (G.652) and DSF (G.653) fibers provide the best and the worst performances, respectively, and (ii) a combination of the central channel transmitting at 40 Gbps using the duo-bi- nary modulation format with adjacent channels transmit- ting at 10 Gbps using OOK modulation format, provides the best performance. However, with increase in spacing between the channels, the performance is enhanced owing to mitigation of the deleterious non-linear effects. Overall, the results clearly show that choice of the data rate of both, the central channel and its adjacent channel has a major effect on the MLR network performance. Keywords Mixed line rate  Wavelength division multiplexing  Physical layer impairments  Cross phase modulation  Four wave mixing  Stimulated Raman scattering 1 Introduction Currently, optical communication based on wavelength division multiplexing (WDM) is the dominant technology to fulfill demands of the increasing capacity requirements. In order to satisfy the requirements of diverse traffic, in recent years, the concept of mixed line rate (MLR) optical WDM network has evolved in which, channels at 10, 40 Gbps, and/or 100 Gbps, are combined as sub-bands, and each of which consist of wavelengths that operate at the same bit rate [1]. However, in MLR networks, when the signal traverses for long distances, the effect of physical layer impairments (PLIs) become prominent which in turn results in the degradation of signal quality and hence, an increase in the bit error rate (BER) [2]. Further, in view of satisfying the rapidly increasing traffic demands, WDM networks with narrower channel spacings are being used [3], and as a result, the major linear [chromatic dispersion (CD)] and non-linear effects [cross phase modulation (XPM), four wave mixing (FWM) and stimulated Raman scattering (SRS)] become more pronounced which presents major design challenges for the system design engineers [4, 5]. Amongst all the existing studies on WDM and MLR optical network performance investigation, very few researchers have performed an in-depth analysis consider- ing the combined non-linear effects [6–8]. These analyses have been conducted to identify the impact of the com- bined non-linear effects on the system quality-factor (Q- factor). However, in these analysis, the nonlinearities and their interplay has been analysed from a generic dispersive & Shree Prakash Singh sps_nsit@yahoo.co.uk 1 Division of ECE, Netaji Subhas Institute of Technology, Sector-3, Dwarka, New Delhi 110078, India 2 Department of ECE, Jain College of Engineering, T S. Nagar Hunchanatti Cross, Belagavi, KA 590014, India 123 Int. j. inf. tecnol. https://doi.org/10.1007/s41870-018-0212-2