Brindha Saminathan

Bio: Brindha Saminathan is an academic researcher. The author has contributed to research in topics: Backhaul (telecommunications) & Radio over fiber. The author has an hindex of 2, co-authored 6 publications receiving 6 citations.

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.

Impairment assessment of orthogonal frequency division multiplexing over dispersion-managed links in backbone and backhaul networks

Abstract: The past decade has seen the phenomenal usage of orthogonal frequency division multiplexing (OFDM) in the wired as well as wireless communication domains, and it is also proposed in the literature as a future proof technique for the implementation of flexible resource allocation in cognitive optical networks. Fiber impairment assessment and adaptive compensation becomes critical in such implementations. A comprehensive analytical model for impairments in OFDM-based fiber links is developed. The proposed model includes the combined impact of laser phase fluctuations, fiber dispersion, self phase modulation, cross phase modulation, four-wave mixing, the nonlinear phase noise due to the interaction of amplified spontaneous emission with fiber nonlinearities, and the photodetector noises. The bit error rate expression for the proposed model is derived based on error vector magnitude estimation. The performance analysis of the proposed model is presented and compared for dispersion compensated and uncompensated backbone/backhaul links. The results suggest that OFDM would perform better for uncompensated links than the compensated links due to the negligible FWM effects and there is a need for flexible compensation. The proposed model can be employed in cognitive optical networks for accurate assessment of fiber-related impairments.

Energy and electromagnetic pollution considerations in ARoF-based multi-operator multi-service systems

Abstract: Energy-efficient system design with controlled levels of electromagnetic pollution, without compromising on the user quality of experience and operator revenue, are essential considerations in the design of next-generation wireless communication networks. Integration of multiple services and multiple operator transmissions onto a common shared infrastructure is the solution forward to satisfy the contradictory subscriber and operator requirements and also to derive a future-proof fronthaul to support new techniques like opportunistic, co-operative and cognitive communications. This paper reports the link budget analysis, energy efficiency estimation and electromagnetic radiation calculation for a Multi-Operator Multi-Service Analog Radio over Fiber fronthaul for a small cell configuration. The BER analysis and the link budget analysis are presented for the central base station to remote antenna unit (RAU) link as well as the RAU to user equipment link. The estimated minimum transmission power sufficient to establish and maintain a quality connection suggests the possibility of eliminating the energy consuming power amplifiers in the transceivers and also achieve a reduced electromagnetic pollution in the environment.

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 systems

Abstract: Radio-over-Fiber (RoF) systems have been actively researched to provide future broadband services. In this paper we review the schemes and strategies that have been carried out in Radio-over-Fiber (RoF) networks over the years to realize high-performance RoF links. © 2009 Optical Society of America.

Performance analysis and optimization of wavelength routed (WR) and wavelength selected (WS) hybrid optical distributed network (ODN) for next generation passive optical network stage 2 (NG-PON2)

Abstract: Next-generation passive optical network stage 2 (NG-PON2) supports the wavelength routed optical distributed network (WR-ODN), power splitter optical distributed network or wavelength-selected optical distributed network (WS-ODN) and hybrid of both the architecture configuration. NG-PON2 is world’s first multi-wavelength passive optical network (PON) standard. The fiber dispersion and nonlinearity degrades the performance of NG-PON2 severely. Fiber nonlinearity depends on the optical launch power and fiber reach. This paper focuses on maximizing the network performance and maximizing the number of simultaneous users with error-free performance by optimizing the optical launch power respectively at dynamic reach and differential reach. The optical launch power is optimized to abate the fiber nonlinearity and significantly enhances the performance of NG-PON2 at dynamic fiber reach for Alcatel 6912 Teralight Ultra 1625 commercial fiber specification. Furthermore, precise values of the optimum launch power for the dynamic fiber reach, for different NG-PON2 architecture, under industrial fiber specification is meticulously obtained. It is identified that irrespective of both, WR-ODN and WS-ODN architecture configuration, optimum launch power remains constant. Power budget is calculated for both, maximizing the performance and maximizing the simultaneous number of users at differential reach and dynamic reach of the NG-PON2.

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.

An Effective Combining Transformer to RelieveFiber Nonlinearity in CO-OFDM System

Abstract: This paper mainly concerns on reducing the impact of chromatic dispersion (CD) and the nonlinear(NL) impairments in coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. In effect, the system suffers from a severe problem due to a high peak to average power ratio (PAPR); and this consequently degrades the system performance. In this paper, a new method is proposed to mitigate the PAPR problem and thereby reduce the impact of nonlinearity on the performance of the CO-OFDM system with quadrature amplitude modulation QAM mapping. The recommended new technique is based on combining two effective ways of clipping method integrated with the L2-by3 method. The simulation results indicate that the proposed method was effectively able to improve system performance by enhancing system performance via bit error rate (BER), quality factor (QF), error vector magnitude (EVM) beside the Optical Signal-to-Noise Ratio (OSNR) without the need to add any digital processing at the receiver; and eventually decrease the receiver complexity. The proposed method reduced the peak to average power ratio (PAPR) about 3.8 dB and helped to increase transmission distance by approximately 200 km.

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.