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.

Radio-over-fiber systems

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.

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)

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.

Fiber impairments mitigation in OFDM based cognitive optical networks

In medical environments, a wireless body sensor network (WBSN) is used to operate remotely, and sensor nodes are employed. It consists of sensor nodes installed on a human body to monitor a patient’s condition, such as heartbeat, temperature, and blood sugar level, and are functionalized and controlled by remote devices. A WBSN consists of nodes that are actually sensors in nature and are operated with a short range of communication. These sensor nodes are fixed with limited computation power and the main concern is energy consumption and path loss. In this paper, we propose a new protocol named energy-efficient distance- and link-aware body area (EEDLABA) with a clustering mechanism and compare it with the current link-aware and energy-efficient body area (LAEEBA) and distance-aware relaying energy-efficient (DARE) routing protocols in a WBSN. The proposed protocol is an extended type of LAEEBA and DARE in which the positive features have been deployed. The clustering mechanism has been presented and deployed in EEDLABA for better performance. To solve these issues in LAEEBA and DARE, the EEDLABA protocol has been proposed to overcome these. Path loss and energy consumption are the major concerns in this network. For that purpose, the path loss and distance models are proposed in which the cluster head (CH) node, coordinator (C) node, and other nodes, for a total of nine nodes, are deployed on a human body. The results have been derived from MATLAB simulations in which the performance of the suggested EEDLABA has been observed in assessment with the LAEEBA and DARE. From the results, it has been concluded that the proposed protocol can perform well in the considered situations for WBSNs.

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EEDLABA: Energy-Efficient Distance- and Link-Aware Body Area Routing Protocol Based on Clustering Mechanism for Wireless Body Sensor Network

In the real world of wireless communication systems, one solution to the practical limitation of interference alignment in terms of global channel state information at the transmitter (CSIT) requirement is to consider a linear precoding approach that only uses delayed CSIT known as retrospective interference alignment (RIA). Therefore, in the proposed work, a novel RIA scheme for the cooperative cell edge (CE) users that are more vulnerable to inter-cell interference in a multi-cellular multiple-input multiple-output (MIMO) interference multiple access channels (IMAC) is presented. The core idea of the proposed RIA is characterized by interference refining at the end of the first two stages and interference redirecting at the third stage. The initial stage 1 involves feeding the base station (BS) in cell-1 with the data streams from the cooperative CE users. During stage 2, the BS in cell-2 is fed with data streams from the cooperative CE users in cell-2. In the final stage 3, the overheard equation redirecting is performed. Based on the proposed method, we showed that for a three CE user cooperative multi-cellular MIMO IMAC channel, the achievable degrees of freedom (DoF) is 24/7 and later extended to a general L CE user cooperative multi-cellular MIMO IMAC channel and obtained the desired DoF as 2L(L+1)/2L+1. The simulation result shows that in comparison with the other benchmark schemes considered, the proposed scheme provides a greater DoF and thereby enhances the performance of cooperative CE users. 

/pdf/a-novel-tri-staged-ria-scheme-for-cooperative-cell-edge-198pv9ar.pdf

A Novel Tri-Staged RIA Scheme for Cooperative Cell Edge Users in a Multi-Cellular MIMO IMAC

With the emergence of new viral infections and the rapid spread of chronic diseases in recent years, the demand for integrated short-range wireless technologies is becoming a major bottleneck. Implementation of advanced medical telemonitoring and telecare systems for on-body sensors needs frequent recharging or battery replacement. This paper discusses a priority-based resource allocation scheme and smart channel assignment in a wireless body area network capable of energy harvesting. We investigate our transmission scheme in regular communication, where the access point transmits energy and command while the sensor simultaneously sends the information to the access point. A priority scheduling nonpreemptive algorithm to keep the process running for all the users to achieve the maximum reliability of access by the decision-maker or hub during critical situations of users has been proposed. During an emergency or critical situation, the process does not stop until the decision-maker or the hub takes a final decision. The objective of the proposed scheme is to get all the user processes executed with minimum average waiting time and no starvation. By allocating a higher priority to emergency and on data traffic signals such as critical and high-level signals, the proposed transmission scheme avoids inconsistent collisions. The results demonstrate that the proposed scheme significantly improves the quality of the network service in terms of data transmission for higher priority users.

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Priority-Based Resource Allocation and Energy Harvesting for WBAN Smart Health

Improved fiber nonlinearity mitigation in dispersion managed optical OFDM links

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.

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

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.

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

Abstract In this paper, an efficient cognitive algorithm is proposed to support multiple users, more number of services, and devices under any channel conditions. However, the factors like attenuation, signal penetration loss, received power, fading effects, coverage area, bandwidth, and link quality still remains a significant challenge in the real-world applications. A hybrid FSO/RoF with a cognitive algorithm is proposed to overcome the limitations of existing methods. The proposed algorithm assesses the channel conditions based on various parameters and selects the optimum one for transmission. The simulation results confirm that the proposed method can be reliable under any channel conditions and its performance is compared with the existing methods.

Ilavarasan Tamilarasan

Papers

Priority-Based Resource Allocation and Energy Harvesting for WBAN Smart Health

Improved fiber nonlinearity mitigation in dispersion managed optical OFDM links

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

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

Deployment of hybrid FSO/RoF links for 5G heterogeneous networks