2011 IEEE Student Conference on Research and Development, 2011
Abstract In many applications it is desirable to have the maximum radiation of an array directed ... more Abstract In many applications it is desirable to have the maximum radiation of an array directed normal to the axis of the array (Broadside radiation). In this paper, the optimal broadside radiation patterns of three-ring Concentric Circular Antenna Arrays (CCAA) with and without central element feeding are reported. For each optimal synthesis, optimal current excitation weights and optimal radii of the rings are determined having the objective of maximum Sidelobe Level (SLL) reduction. A new class of Particle Swarm Optimization ...
End-to-end (E2E) quality of experience (QoE) for 6G applications depends on the synchronous alloc... more End-to-end (E2E) quality of experience (QoE) for 6G applications depends on the synchronous allocation of networking and computing resources, also known as slicing. However, the relationship between the resources and the E2E QoE outcomes is typically stochastic and non-stationary. Existing works consider known resource demands for slicing and formulate optimization problems for slice reconfiguration. In this work, we create and manage slices by learning the relationship between E2E QoE and resources. We develop a gradient-based online slice reconfiguration algorithm (OSRA) to reconfigure and manage slices in resource-constrained scenarios for radio access networks (RAN). We observe that our methodology meets the QoE requirements with high accuracy compared to existing approaches. It improves upon the existing approaches by approximately 98\% for bursty traffic variations. Our algorithm has fast convergence and achieves low E2E delay violations for lower priority slices.
Emerging applications such as Augmented Reality, the Internet of Vehicles and Remote Surgery requ... more Emerging applications such as Augmented Reality, the Internet of Vehicles and Remote Surgery require both computing and networking functions working in harmony. The End-to-end (E2E) quality of experience (QoE) for these applications depends on the synchronous allocation of networking and computing resources. However, the relationship between the resources and the E2E QoE outcomes is typically stochastic and non-linear. In order to make efficient resource allocation decisions, it is essential to model these relationships. This article presents a novel machine-learning based approach to learn these relationships and concurrently orchestrate both resources for this purpose. The machine learning models further help make robust allocation decisions regarding stochastic variations and simplify robust optimization to a conventional constrained optimization. When resources are insufficient to accommodate all application requirements, our framework supports executing some of the applications...
This paper presents an alternative approach for the design of linear phase digital low pass FIR f... more This paper presents an alternative approach for the design of linear phase digital low pass FIR filter using Particle Swarm Optimization with Constriction Factor and Inertia Weight Approach (PSO-CFIWA). FIR filter design is a multimodal optimization problem. The conventional gradient based optimization techniques are not efficient for digital filter design. Given the filter specification to be realized, PSO algorithm generates a set of filter coefficients and tries to meet the ideal frequency characteristic. In this paper, for the given problem, the realization of the FIR filters of different order has been performed. The simulation results have been compared with the well accepted evolutionary algorithm such as genetic algorithm (GA). The results justify that the proposed filter design approach using PSO-CFIWA outperforms to that of GA, not only in the accuracy of the designed filter but also in the convergence speed and solution quality.
Emerging real-time applications such as those classified under ultra-reliable low latency (uRLLC)... more Emerging real-time applications such as those classified under ultra-reliable low latency (uRLLC) generate bursty traffic and have strict Quality of Service (QoS) requirements. Passive Optical Network (PON) is a popular access network technology, which is envisioned to handle such applications at the access segment of the network. However, the existing standards cannot handle strict QoS constraints. The available solutions rely on instantaneous heuristic decisions and maintain QoS constraints (mostly bandwidth) in an average sense. Existing works with optimal strategies are computationally complex and are not suitable for uRLLC applications. This paper presents a novel computationally-efficient, far-sighted bandwidth allocation policy design for facilitating bursty traffic in a PON framework while satisfying strict QoS (age of information/delay and bandwidth) requirements of modern applications. To this purpose, first we design a delay-tracking mechanism which allows us to model the...
Design of energy-efficient access networks has emerged as an important area of research, since ac... more Design of energy-efficient access networks has emerged as an important area of research, since access networks consume $80-90\%$ of the overall Internet power consumption. TWDM-PON is envisaged to be one of the widely accepted future access technologies. TWDM-PON offers an additional opportunity to save energy at the OLT along with the existing energy-efficient ONU design. In this paper, we focus on the energy-efficient OLT design in a TWDM-PON. While most of the conventional methods employ a minimization of the number of wavelengths, we propose a novel approach which aims at minimizing the number of voids created due to scheduling. In the process, for the first time, we present a low-complexity on-line scheduling algorithm for the upstream traffic considering delay constraints. Our extensive simulations demonstrate a significant improvement in energy efficiency of $\sim 25\%$ for high load at the OLT receivers. Furthermore, we provide an analytical upper-bound on the energy-efficie...
2018 International Conference on Optical Network Design and Modeling (ONDM), 2018
All-optical access-metro networks avoid costly OEO conversions which results in subsequent reduct... more All-optical access-metro networks avoid costly OEO conversions which results in subsequent reduction of infrastructure costs and improvement in energy-efficiency of the network. However, avoiding OEO conversions imply that OLTs are unable to route packets to the ONUs due to unavailability of processing provisions, which necessitates setting up of lightpaths between ONUs. Setting up lightpaths, require a control mechanism, which considers requests from all ONUs in the metro-ring and informs them about the lightpath to be set up. Owing to high data rate of optical networks, the lifetime of a lightpath may be minuscule (few microseconds), which enforces the control mechanism to perform these operations frequently, which incurs large control overhead and processing complexity. This turns out to be a major bottleneck in all existing proposals, which can be alleviated if lightpaths are set up between OLTs instead of ONUs. However, in this case, facilitating data transmission between sourc...
Economical and environmental concerns necessitate research on designing energy-efficient optical ... more Economical and environmental concerns necessitate research on designing energy-efficient optical access network especially Ethernet Passive Optical Network (EPON) which is one of the most widely accepted and deployed last-mile access network. In this paper, our primary focus is on designing a protocol for saving energy at Optical Network Units (ONUs) while satisfying the Service Label Agreement (SLA). The SLA of both Up-Stream (US) and Down-Stream (DS) traffic can be satisfied only if the EPON network can react to their instantaneous load change during sleep periods of ONUs and to the best of our knowledge, there doesn't exist any such proposal. Towards this target, we propose a mechanism that allows the Optical Line Terminal (OLT) to force ONUs to wake-up from sleep mode. Here, we demonstrate that if the OLT can distribute the active ONUs (transceivers are active) fairly among cycles then it provides a significant improvement in energy-efficiency. To achieve this, we formulate ...
Environmental and economic concerns promote research on designing energy-efficient Time and Wavel... more Environmental and economic concerns promote research on designing energy-efficient Time and Wavelength Division Multiplexed Ethernet Passive Optical Network (TWDM-EPON), which is the future extension to TDM-EPON. In TDM-EPON, a plethora of research is already present to achieve energy savings at Optical Network Units (ONUs) which can easily be applied for TWDM-EPON ONUs. However, TWDM-EPON provides an additional opportunity for saving energy at the Optical Line Terminal (OLT). All existing protocols have primarily been designed for saving energy at the OLT receivers. The protocols to save energy at the OLT receives depends only on the Up-Stream(US) traffic scheduling while its transmitter counterpart depends on both US and Down-Stream (DS) scheduling since the OLT transmits GATE message along with DS traffic. The US and DS scheduling have a basic difference. The MAC protocol doesn't allow scheduling of US traffic of an ONU after its REPORT arrival at multiple disjoint time slots...
IEEE Transactions on Green Communications and Networking
Owing to the Economic and Environmental concerns, energy-efficient Time and Wavelength Division M... more Owing to the Economic and Environmental concerns, energy-efficient Time and Wavelength Division Multiplexed Ethernet Passive Optical Network (TWDM-EPON) has already emerged as an important research area. TWDM-EPON allows saving energy at the Optical Line Terminal (OLT) along with Optical Network Units (ONUs), where existing protocols to save energy at ONUs of TDM-EPON can be employed. Moreover, a TWDM-EPON network is bound to support traffic with diverse delay bound to fulfil the recent need for supporting a variety of applications. Therefore, in this paper, for the first time to the best of our knowledge, we propose an online scheduling protocol to achieve energy efficiency at the OLT of a TWDM-EPON network that can support traffic with diverse delay bounds. Simulation results depict that the protocol provides a significant reduction in the probability of delay bound violation while maintaining a similar energy efficiency figure when compared with the most energy-efficient existing online protocol for a single traffic type. The performance of the protocol improves when the network is scaled up or the dimension of the network increases, and hence, suitable for both rural and urban scenarios.
TWDM PON is an emerging access architecture that is capable of offering different categories of s... more TWDM PON is an emerging access architecture that is capable of offering different categories of services. For example, the operator can provide high-priced failure-proof services to the business users by deploying redundant elements in this network, along with low-priced unprotected service to the residential users. In this article, we analyze the economics of optical networks with a provision of such hybrid services. Specifically, we describe the operator as an economic entity that targets to maximize its earned profit by judiciously choosing the subscribers, the data rate price, the primary and redundant components that need to be deployed in the network to serve both business and residential users. The operator's profit maximization appears to be an MINLP (a mixed integer non-linear problem) that is hard to solve via polynomially complex algorithms. Interestingly, we show that, if users’ demand functions crossover at most finitely many points, one can develop an efficient algorithm to solve this optimization. For homogeneous user demand, we obtain a set of inequations that depicts economic viability of the optical network. Alongside, we also investigate how the system parameters impact different economic outcomes. Our model reveals several insightful results. For example, we exhibit that, by deploying optical fibers and leasing it to the operator at high prices, the government can earn a large revenue. However, this depreciates the number of served consumers. Similar trade-off is also observed between the user number and their welfare. Most part of our article considers a full protection scheme where the operator guarantees $\text{100}\%$ protection against service failures to the corporate users. Later we also extend our analysis to the case where the protection is guaranteed with a certain availability, $\alpha < 1$. In this context, we show how the availability requirements of the corporate users affect the sustainability and economics of the network.
IEEE Transactions on Green Communications and Networking
Edge and fog networks call for high speed and energy-efficient networking platforms. Passive Opti... more Edge and fog networks call for high speed and energy-efficient networking platforms. Passive Optical Networks (PON) have been identified as a promising candidate for such platforms. In conventional dynamic bandwidth allocation (DBA) schemes for PON, the transmitter of an optical network unit (ONU) remains idle until the completion of upstream transmission of all other ONUs which indicates poor utilization of the transmitter. Scheduling fog services during these free intervals of time would lead to improved transmitter utilization. In this work, we exploit this opportunity and present a DBA protocol and its architecture, for enabling fog services. Our architecture employs a single line card at the ONUs providing considerable savings in terms of cost and energy. The results show that the cost per ONU could be reduced by 87$ and power savings of 5W per ONU could be achieved compared to proposals using separate transceivers at the ONU. The proposed DBA improves the load tolerance by ~300% towards maintaining delay bound of 10 ms and an improvement in throughput by ~20% at high loads when compared to existing philosophies, which is highly desirable for a delay-sensitive fog network. Placing fog node at remote node allows the fog node to operate at higher loads while maintaining delay bound when compared to its placement at OLT.
The design of energy-efficient optical network units (ONUs) in passive optical networks (PONs) ha... more The design of energy-efficient optical network units (ONUs) in passive optical networks (PONs) has been studied extensively in the literature. Time- and wavelength- division multiplexed PONs, a widely accepted future access technology, offer an additional opportunity to save energy at the OLT along with the existing energyefficient ONU design due to the idle periods (voids) created by scheduling. Existing proposals utilize few of the available wavelengths (active wavelengths) for scheduling, and energy efficiency is achieved by switching off the OLT receivers associated with the remaining wavelengths. In this paper we reason that, subject to a delay bound of the upstream data, the voids created due to scheduling in the active wavelengths remain unutilized and thus create ample opportunity for saving energy at the OLT. Further, we show that modifications of the conventional method provide a limited scope of utilizing these voids for energy efficiency. Thus, we deviate from the conventional methodology and propose a novel online scheduling protocol which aims at minimizing the number of voids in all wavelengths. Our results demonstrate a significant improvement in energy efficiency, as compared to existing proposals, without affecting the algorithmic complexity.
2011 IEEE Student Conference on Research and Development, 2011
Abstract In many applications it is desirable to have the maximum radiation of an array directed ... more Abstract In many applications it is desirable to have the maximum radiation of an array directed normal to the axis of the array (Broadside radiation). In this paper, the optimal broadside radiation patterns of three-ring Concentric Circular Antenna Arrays (CCAA) with and without central element feeding are reported. For each optimal synthesis, optimal current excitation weights and optimal radii of the rings are determined having the objective of maximum Sidelobe Level (SLL) reduction. A new class of Particle Swarm Optimization ...
End-to-end (E2E) quality of experience (QoE) for 6G applications depends on the synchronous alloc... more End-to-end (E2E) quality of experience (QoE) for 6G applications depends on the synchronous allocation of networking and computing resources, also known as slicing. However, the relationship between the resources and the E2E QoE outcomes is typically stochastic and non-stationary. Existing works consider known resource demands for slicing and formulate optimization problems for slice reconfiguration. In this work, we create and manage slices by learning the relationship between E2E QoE and resources. We develop a gradient-based online slice reconfiguration algorithm (OSRA) to reconfigure and manage slices in resource-constrained scenarios for radio access networks (RAN). We observe that our methodology meets the QoE requirements with high accuracy compared to existing approaches. It improves upon the existing approaches by approximately 98\% for bursty traffic variations. Our algorithm has fast convergence and achieves low E2E delay violations for lower priority slices.
Emerging applications such as Augmented Reality, the Internet of Vehicles and Remote Surgery requ... more Emerging applications such as Augmented Reality, the Internet of Vehicles and Remote Surgery require both computing and networking functions working in harmony. The End-to-end (E2E) quality of experience (QoE) for these applications depends on the synchronous allocation of networking and computing resources. However, the relationship between the resources and the E2E QoE outcomes is typically stochastic and non-linear. In order to make efficient resource allocation decisions, it is essential to model these relationships. This article presents a novel machine-learning based approach to learn these relationships and concurrently orchestrate both resources for this purpose. The machine learning models further help make robust allocation decisions regarding stochastic variations and simplify robust optimization to a conventional constrained optimization. When resources are insufficient to accommodate all application requirements, our framework supports executing some of the applications...
This paper presents an alternative approach for the design of linear phase digital low pass FIR f... more This paper presents an alternative approach for the design of linear phase digital low pass FIR filter using Particle Swarm Optimization with Constriction Factor and Inertia Weight Approach (PSO-CFIWA). FIR filter design is a multimodal optimization problem. The conventional gradient based optimization techniques are not efficient for digital filter design. Given the filter specification to be realized, PSO algorithm generates a set of filter coefficients and tries to meet the ideal frequency characteristic. In this paper, for the given problem, the realization of the FIR filters of different order has been performed. The simulation results have been compared with the well accepted evolutionary algorithm such as genetic algorithm (GA). The results justify that the proposed filter design approach using PSO-CFIWA outperforms to that of GA, not only in the accuracy of the designed filter but also in the convergence speed and solution quality.
Emerging real-time applications such as those classified under ultra-reliable low latency (uRLLC)... more Emerging real-time applications such as those classified under ultra-reliable low latency (uRLLC) generate bursty traffic and have strict Quality of Service (QoS) requirements. Passive Optical Network (PON) is a popular access network technology, which is envisioned to handle such applications at the access segment of the network. However, the existing standards cannot handle strict QoS constraints. The available solutions rely on instantaneous heuristic decisions and maintain QoS constraints (mostly bandwidth) in an average sense. Existing works with optimal strategies are computationally complex and are not suitable for uRLLC applications. This paper presents a novel computationally-efficient, far-sighted bandwidth allocation policy design for facilitating bursty traffic in a PON framework while satisfying strict QoS (age of information/delay and bandwidth) requirements of modern applications. To this purpose, first we design a delay-tracking mechanism which allows us to model the...
Design of energy-efficient access networks has emerged as an important area of research, since ac... more Design of energy-efficient access networks has emerged as an important area of research, since access networks consume $80-90\%$ of the overall Internet power consumption. TWDM-PON is envisaged to be one of the widely accepted future access technologies. TWDM-PON offers an additional opportunity to save energy at the OLT along with the existing energy-efficient ONU design. In this paper, we focus on the energy-efficient OLT design in a TWDM-PON. While most of the conventional methods employ a minimization of the number of wavelengths, we propose a novel approach which aims at minimizing the number of voids created due to scheduling. In the process, for the first time, we present a low-complexity on-line scheduling algorithm for the upstream traffic considering delay constraints. Our extensive simulations demonstrate a significant improvement in energy efficiency of $\sim 25\%$ for high load at the OLT receivers. Furthermore, we provide an analytical upper-bound on the energy-efficie...
2018 International Conference on Optical Network Design and Modeling (ONDM), 2018
All-optical access-metro networks avoid costly OEO conversions which results in subsequent reduct... more All-optical access-metro networks avoid costly OEO conversions which results in subsequent reduction of infrastructure costs and improvement in energy-efficiency of the network. However, avoiding OEO conversions imply that OLTs are unable to route packets to the ONUs due to unavailability of processing provisions, which necessitates setting up of lightpaths between ONUs. Setting up lightpaths, require a control mechanism, which considers requests from all ONUs in the metro-ring and informs them about the lightpath to be set up. Owing to high data rate of optical networks, the lifetime of a lightpath may be minuscule (few microseconds), which enforces the control mechanism to perform these operations frequently, which incurs large control overhead and processing complexity. This turns out to be a major bottleneck in all existing proposals, which can be alleviated if lightpaths are set up between OLTs instead of ONUs. However, in this case, facilitating data transmission between sourc...
Economical and environmental concerns necessitate research on designing energy-efficient optical ... more Economical and environmental concerns necessitate research on designing energy-efficient optical access network especially Ethernet Passive Optical Network (EPON) which is one of the most widely accepted and deployed last-mile access network. In this paper, our primary focus is on designing a protocol for saving energy at Optical Network Units (ONUs) while satisfying the Service Label Agreement (SLA). The SLA of both Up-Stream (US) and Down-Stream (DS) traffic can be satisfied only if the EPON network can react to their instantaneous load change during sleep periods of ONUs and to the best of our knowledge, there doesn't exist any such proposal. Towards this target, we propose a mechanism that allows the Optical Line Terminal (OLT) to force ONUs to wake-up from sleep mode. Here, we demonstrate that if the OLT can distribute the active ONUs (transceivers are active) fairly among cycles then it provides a significant improvement in energy-efficiency. To achieve this, we formulate ...
Environmental and economic concerns promote research on designing energy-efficient Time and Wavel... more Environmental and economic concerns promote research on designing energy-efficient Time and Wavelength Division Multiplexed Ethernet Passive Optical Network (TWDM-EPON), which is the future extension to TDM-EPON. In TDM-EPON, a plethora of research is already present to achieve energy savings at Optical Network Units (ONUs) which can easily be applied for TWDM-EPON ONUs. However, TWDM-EPON provides an additional opportunity for saving energy at the Optical Line Terminal (OLT). All existing protocols have primarily been designed for saving energy at the OLT receivers. The protocols to save energy at the OLT receives depends only on the Up-Stream(US) traffic scheduling while its transmitter counterpart depends on both US and Down-Stream (DS) scheduling since the OLT transmits GATE message along with DS traffic. The US and DS scheduling have a basic difference. The MAC protocol doesn't allow scheduling of US traffic of an ONU after its REPORT arrival at multiple disjoint time slots...
IEEE Transactions on Green Communications and Networking
Owing to the Economic and Environmental concerns, energy-efficient Time and Wavelength Division M... more Owing to the Economic and Environmental concerns, energy-efficient Time and Wavelength Division Multiplexed Ethernet Passive Optical Network (TWDM-EPON) has already emerged as an important research area. TWDM-EPON allows saving energy at the Optical Line Terminal (OLT) along with Optical Network Units (ONUs), where existing protocols to save energy at ONUs of TDM-EPON can be employed. Moreover, a TWDM-EPON network is bound to support traffic with diverse delay bound to fulfil the recent need for supporting a variety of applications. Therefore, in this paper, for the first time to the best of our knowledge, we propose an online scheduling protocol to achieve energy efficiency at the OLT of a TWDM-EPON network that can support traffic with diverse delay bounds. Simulation results depict that the protocol provides a significant reduction in the probability of delay bound violation while maintaining a similar energy efficiency figure when compared with the most energy-efficient existing online protocol for a single traffic type. The performance of the protocol improves when the network is scaled up or the dimension of the network increases, and hence, suitable for both rural and urban scenarios.
TWDM PON is an emerging access architecture that is capable of offering different categories of s... more TWDM PON is an emerging access architecture that is capable of offering different categories of services. For example, the operator can provide high-priced failure-proof services to the business users by deploying redundant elements in this network, along with low-priced unprotected service to the residential users. In this article, we analyze the economics of optical networks with a provision of such hybrid services. Specifically, we describe the operator as an economic entity that targets to maximize its earned profit by judiciously choosing the subscribers, the data rate price, the primary and redundant components that need to be deployed in the network to serve both business and residential users. The operator's profit maximization appears to be an MINLP (a mixed integer non-linear problem) that is hard to solve via polynomially complex algorithms. Interestingly, we show that, if users’ demand functions crossover at most finitely many points, one can develop an efficient algorithm to solve this optimization. For homogeneous user demand, we obtain a set of inequations that depicts economic viability of the optical network. Alongside, we also investigate how the system parameters impact different economic outcomes. Our model reveals several insightful results. For example, we exhibit that, by deploying optical fibers and leasing it to the operator at high prices, the government can earn a large revenue. However, this depreciates the number of served consumers. Similar trade-off is also observed between the user number and their welfare. Most part of our article considers a full protection scheme where the operator guarantees $\text{100}\%$ protection against service failures to the corporate users. Later we also extend our analysis to the case where the protection is guaranteed with a certain availability, $\alpha < 1$. In this context, we show how the availability requirements of the corporate users affect the sustainability and economics of the network.
IEEE Transactions on Green Communications and Networking
Edge and fog networks call for high speed and energy-efficient networking platforms. Passive Opti... more Edge and fog networks call for high speed and energy-efficient networking platforms. Passive Optical Networks (PON) have been identified as a promising candidate for such platforms. In conventional dynamic bandwidth allocation (DBA) schemes for PON, the transmitter of an optical network unit (ONU) remains idle until the completion of upstream transmission of all other ONUs which indicates poor utilization of the transmitter. Scheduling fog services during these free intervals of time would lead to improved transmitter utilization. In this work, we exploit this opportunity and present a DBA protocol and its architecture, for enabling fog services. Our architecture employs a single line card at the ONUs providing considerable savings in terms of cost and energy. The results show that the cost per ONU could be reduced by 87$ and power savings of 5W per ONU could be achieved compared to proposals using separate transceivers at the ONU. The proposed DBA improves the load tolerance by ~300% towards maintaining delay bound of 10 ms and an improvement in throughput by ~20% at high loads when compared to existing philosophies, which is highly desirable for a delay-sensitive fog network. Placing fog node at remote node allows the fog node to operate at higher loads while maintaining delay bound when compared to its placement at OLT.
The design of energy-efficient optical network units (ONUs) in passive optical networks (PONs) ha... more The design of energy-efficient optical network units (ONUs) in passive optical networks (PONs) has been studied extensively in the literature. Time- and wavelength- division multiplexed PONs, a widely accepted future access technology, offer an additional opportunity to save energy at the OLT along with the existing energyefficient ONU design due to the idle periods (voids) created by scheduling. Existing proposals utilize few of the available wavelengths (active wavelengths) for scheduling, and energy efficiency is achieved by switching off the OLT receivers associated with the remaining wavelengths. In this paper we reason that, subject to a delay bound of the upstream data, the voids created due to scheduling in the active wavelengths remain unutilized and thus create ample opportunity for saving energy at the OLT. Further, we show that modifications of the conventional method provide a limited scope of utilizing these voids for energy efficiency. Thus, we deviate from the conventional methodology and propose a novel online scheduling protocol which aims at minimizing the number of voids in all wavelengths. Our results demonstrate a significant improvement in energy efficiency, as compared to existing proposals, without affecting the algorithmic complexity.
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