Ilavarasan Tamilarasan

Bio: Ilavarasan Tamilarasan is an academic researcher from VIT University. The author has contributed to research in topics: Backhaul (telecommunications) & Signal. The author has co-authored 3 publications.

Fiber impairments mitigation in OFDM based cognitive optical networks

Abstract: An adaptive impairments assessment is necessary to evaluate the impact of various linear and nonlinear effects in future generation cognitive optical transport links. In this paper, an Adaptive Fiber Impairment Mitigation (AFIM) algorithm is proposed to identify a suitable mitigation scheme for the cognitive environment. The AFIM algorithm will assess fiber impairments and adaptively select a suitable mitigation scheme with minimum complexity based on the present network conditions and user performance target. The performance of AFIM algorithm is compared with Fixed Fiber Impairment Mitigation approach in terms of outage probability and outage capacity analysis. An Orthogonal Frequency Division Multiplexing based Mode Division Multiplexing system with Few Mode Fiber (FMF) is suggested as a solution to increase the nonlinearity threshold limit of the system. The $$\hbox {L}_2$$ -by-3 nonlinear transform based Peak to Average Power Ratio reduction technique is implemented to mitigate fiber nonlinear effects in FMF based backbone and backhaul links. The performance analysis of the FMF system has been evaluated and compared with that of Single Mode Fiber system. The proposed analytical model and mitigation schemes are integrated with the AFIM algorithm to realize the cognitive optical network. Further, the result shows that AFIM algorithm enhances the system capacity by more than 6-folds at an outage probability of 0.5 and reduces the outage probability to 0.6 at the capacity range of 20 Gbps.

Analysis of Laser Linewidth on the Performance of Direct Detection OFDM Based Backhaul and Backbone Networks

Abstract: Orthogonal frequency division multiplexing (OFDM) is a special form of multicarrier (MC) modulation technique which is adopted in 4G mobile communication systems. The combination of OFDM with passive optical network (PON) architecture is highly desirable for design of flexible and energy efficient backhaul and backbone networks for 5G systems. An intensive mathematical model for linewidth analysis in OFDM based backhaul (BH) and backbone (BB) systems is proposed. The proposed mathematical model includes fiber dispersion, fiber nonlinear effects, amplified spontaneous emission (ASE) noise, transmitter and receiver noises. The impact of laser linewidth in the developed analytical model is analysed in terms phase rotation term (PRT) and inter-carrier interference (ICI) power. Further, the BER performance of the DD-OFDM system as a function of laser linewidth is also presented. The results of the analytical model solved using MATLAB is compared with virtual photonics integrated (VPI) based simulation results. The results of our proposed model suggest that DD-OFDM would perform better for lower linewidth in dispersion uncompensated (DUC) links and it has no impact on the dispersion compensated (DC) links for BB networks. In BH networks, the system performs better for lower linewidth in both DUC and DC links.

Radio over fiber based signal transport schemes for emerging mobile fronthaul networks – a review

Abstract: Radio over fiber plays a prominent role in the realization of next generation integrated Optical -Wireless Networks to distribute mobile broadband signals effectively to meet the increasing demand of multimedia services with guaranteed quality of services. In this paper the signal transport schemes of analog and digitized Radio over fiber systems with relevance to cellular communication and the comparison of different Radio over fiber systems with their merits and demerits is explored. Further, review of existing different types of multioperator multiservice architectures to realize high performance Radio over fiber based fronthaul architectures also presented in detail.

A Dynamic Spectrum Allocation Scheme to limit the FWM Effects in Elastic Optical Networks

Abstract: Nonlinear impairments especially Four-Wave Mixing (FWM) affect the overall optical signal-to-noise ratio (OSNR) by introducing additional crosstalks into the system. FWM is a fiber nonlinearity, in which the interaction of three frequencies generates a fourth frequency known as the FWM component that produces crosstalk with the channel frequencies having the same frequencies as the generated ones. The impact of FWM crosstalk is severe in the case of Elastic Optical Networks (EONs) because a considerable amount of FWM crosstalk is created by inter and intra-channel interferences due to the small channel spacings. Therefore, it is necessary to reduce the FWM crosstalk effect in EONs to improve the OSNR for the established optical connections. The relevant research works on this field take into account the overall nonlinear effect on EONs; however, depreciation of FWM components in EONs is not considered explicitly. Therefore, in this paper, we propose a unique approach to suppress the FWM crosstalk, which we understand, has not been considered for EONs till now. The simulation results show that the number of FWM components has been reduced significantly using the proposed approach.

A Dynamic Spectrum Allocation Scheme to limit the FWM Effects in Elastic Optical Networks

Abstract: Nonlinear impairments especially Four-Wave Mixing (FWM) affect the overall optical signal-to-noise ratio (OSNR) by introducing additional crosstalks into the system. FWM is a fiber nonlinearity, in which the interaction of three frequencies generates a fourth frequency known as the FWM component that produces crosstalk with the channel frequencies having the same frequencies as the generated ones. The impact of FWM crosstalk is severe in the case of Elastic Optical Networks (EONs) because a considerable amount of FWM crosstalk is created by inter and intra-channel interferences due to the small channel spacings. Therefore, it is necessary to reduce the FWM crosstalk effect in EONs to improve the OSNR for the established optical connections. The relevant research works on this field take into account the overall nonlinear effect on EONs; however, depreciation of FWM components in EONs is not considered explicitly. Therefore, in this paper, we propose a unique approach to suppress the FWM crosstalk, which we understand, has not been considered for EONs till now. The simulation results show that the number of FWM components has been reduced significantly using the proposed approach.