S. Subramaniam

• Professor (Full) at George Washington University

In this paper, we examine a multi-sensor system where each sensor monitors multiple dynamic information processes and transmits updates over a shared communication channel. These updates may include correlated information across the various processes. In this type of system, we analyze the impact of preemption, where ongoing transmissions are repla...

The implementation of 5G and the future deployment of 6G necessitate the utilization of optical networks that possess substantial capacity and exhibit minimal latency. The dynamic arrival and departure of connection requests in optical networks result in particular central links experiencing more traffic and congestion than non-central links. The o...

Space division multiplexed elastic optical networks (SDM-EONs) enhance service provisioning by offering increased fiber capacity through the use of flexible spectrum allocation, multiple spatial modes, and efficient modulations. In these networks, the problem of allocating resources for connections involves assigning routes, modulations, cores, and...

In the realms of the internet of vehicles (IoV) and intelligent transportation systems (ITS), software defined vehicular networks (SDVN) and edge computing (EC) have emerged as promising technologies for enhancing road traffic efficiency. However, the increasing number of connected autonomous vehicles (CAVs) and EC-based applications presents multi...

Elastic optical networks (EONs) operating in the C-band have been widely deployed worldwide. However, two major technologies—multiband elastic optical networks (MB-EONs) and space division multiplexed elastic optical networks (SDM-EONs)—can significantly increase network capacity beyond traditional EONs. A one-time greenfield deployment of these fl...

A fine-grained, flexible frequency grid of elastic optical transmission and space division multiplexing (SDM) in conjunction with spectrally efficient modulations is an ideal solution for the impending capacity crunch. The routing, modulation, core, and spectrum assignment (RMCSA) problem is an important lightpath resource assignment problem in SDM...

A novel and effective network capacity estimation method and an RSA algorithm suitable for elastic optical path networks are presented. The proposed algorithm successfully achieves the utilization penalty of just 5-16% from the bound.

The Tridental Resource Assignment algorithm (TRA) has been shown to effectively assign resources by bal- ancing the tradeoff between spectrum utilization and intercore crosstalk in multicore fiber networks. It calculates the Tridental Coefficient (TC) to capture the tradeoff. The TC is calculated for all the resource choices to establish a lightpat...

The use of various bands in optical transmission promises to expand the optical network capacity using existing Single-Core Fiber. Multi-band Optical Networks exploit the unused spectrum in the fiber for the accommodation of more traffic demands to keep pace with the surge in global Internet traffic. In this work, we propose and Routing, Modulation...

C-band enabled Elastic optical networks (EONs) have been one of the most deployed optical network solutions in the world. However, as traffic demands continue to increase, ca- pacity exhaustion is inevitable. There are two major technologies, namely, multiband elastic optical networks (MB-EONs) and space division multiplexed elastic optical network...

Space division multiplexed elastic optical networks (SDM-EONs) offer increased fiber capacity to enhance service provisioning with the help of fine-grained flexible spectrum, multiple spatial modes, and efficient modulation formats. The connection resource provisioning problem in SDM EONs is the route, modulation format (MF), core and spectrum assi...

Bayesian optimization (BO) is a popular global optimization scheme for sample-efficient optimization in domains with expensive function evaluations. The existing BO techniques are capable of finding a single global optimum solution. However, finding a set of global and local optimum solutions is crucial in a wide range of real-world problems, as im...

This special issue contains a collection of invitation-only extensions based on papers presented at the Optical Networks and Systems Symposium at IEEE GLOBECOM held 4–8 December 2022 in Rio de Janeiro, Brazil. We present a brief introduction followed by an overview of each of the papers.

A fine-grained, flexible frequency grid of elastic optical transmission and space division multiplexing (SDM) in conjunction with spectrally efficient modulations is an ideal solution for the impending capacity crunch. The routing, modulation, core, and spectrum assignment (RMCSA) problem is an important lightpath resource assignment problem in SDM...

Unmanned aerial vehicle (UAV)-empowered edge computing has been widely investigated in obstacle-free scenarios, where a moving UAV is in charge of handling offloaded singleton tasks from mobile devices on the ground. However, little attention has been paid to the scenario, in which the UAV serves a complex area with multiple obstacles and depend...

In the presence of intercore crosstalk (XT), the Tridental Resource Assignment (TRA) algorithm, which is a route, modulation, core, and spectrum assignment (RMCSA) algorithm, has shown to best assign resources in multicore fiber-based optical networks. In TRA, the tridental coefficient (TC) is used to balance the trade-off between spectrum utilizat...

Industry 4.0-enabled smart factories are expected to realize the next revolution for manufacturers. Although artificial intelligence (AI) technologies have improved productivity, current use cases belong mainly to small-scale and single-task operations.A zero-touch network platform is developed for intelligent manufacturing, which unbound the poten...

In this paper, we introduce a new metric, named Penalty upon Decision (PuD), for measuring the impact of communication delays and state changes at the source on a remote decision maker. Specifically, the metric quantifies the performance degradation at the decision maker's side due to delayed, erroneous, and (possibly) missed decisions. We clarify...

A fine-grained flexible frequency grid for elastic optical transmission and space division multiplexing in conjunction with spectrally efficient modulations is an excellent solution to the coming capacity crunch. In space division multiplexed elastic optical networks (SDM-EONs), the routing, modulation, core, and spectrum assignment (RMCSA) problem...

We propose a novel bundled-path-routing node architecture for multi-band optical networks and a network design algorithm based on graph degeneration. Feasibility is demonstrated through experiments on a prototype with 300.8 Tbps throughput.

The Tridental Resource Assignment algorithm (TRA) has proven to optimally assign the resources in multicore fiber networks in the presence of intercore crosstalk (XT). It balances the trade-off between spectrum utilization and XT with the help of the tridental coefficient (TC). The TC is calculated for all the resource choices which makes it comput...

Bayesian optimization (BO) is a popular global optimization scheme for sample-efficient optimization in domains with expensive function evaluations. The existing BO techniques are capable of finding a single global optimum solution. However, finding a set of global and local optimum solutions is crucial in a wide range of real-world problems, as im...

Elastic optical networks (EONs) have emerged as attractive candidates to satisfy the dramatic growth of demand in 5G and cloud applications. EONs promise to provide high spectrum utilization due to flexibility in resource assignment. In translucent EONs, the spectrum efficiency can be further improved by deploying regenerators. Because of their ext...

Data-intensive computing frameworks typically split job workload into fixed-size chunks, allowing them to be processed as parallel tasks on distributed machines. Ideally, when the machines are homogeneous and have identical speed, chunks of equal size would finish processing at the same time. However, such determinism in processing time cannot be g...

Service provisioning can be enhanced with spectrally spatially flexible optical networks (SS-FONs) with multicore fibers; however, intercore crosstalk (XT) is a dominant impairment that complicates the problem of maintaining the quality of transmission (QoT) and resource allocation. The selection of modulation formats (MFs), due to their unique XT...

The age of information (AoI) is now well established as a metric that measures the freshness of information delivered to a receiver from a source that generates status updates. This paper is motivated by the inherent value of packets arising in many cyber-physical applications (e.g., due to precision of the information content or an alarm message)....

Space-division multiplexing (SDM) is expected to increase the capacity of photonic networks. Reconfigurable optical add-drop multiplexers (ROADMs) for SDM-based networks must have high scalability in terms of port count. However, the ROADM architecture adopted in present networks cannot support large numbers of ports due to the limited port count o...

It is critical but challenging to provide efficient information services to support disaster-response operations in disaster-hit areas. A UAVFog-assisted data-driven disaster-response architecture, which combines unmanned aerial vehicles (UAVs) and fog computing paradigm, showed many advantages in response latency and on-the-fly deployment. This pa...

Data centers have become a popular computing platform for various applications, and they account for nearly 2% of total US energy consumption. Therefore, it has become important to optimize data center power, and reduce their energy footprint. Most existing work optimizes power in servers and networks independently and does not address them togethe...

Status update systems consist of sensors that take measurements of a physical parameter and transmit them to a remote receiver. Age of Information (AoI) has been studied extensively as a metric for the freshness of information in such systems with and without an enforced hard or soft deadline. In this paper, we propose three metrics for status upda...

A spatial channel network (SCN) was recently proposed toward the forthcoming spatial division multiplexing (SDM) era, in which the optical layer is explicitly evolved to the hierarchical SDM and wavelength division multiplexing layers, and an optical node is decoupled into a spatial cross-connect (SXC) and wavelength cross-connect to achieve an ult...

Coping with diverse channel access attacks (CAAs) has been a major obstacle to realize the full potential of wireless networks as a basic building block of smart applications. Identifying and classifying different types of CAAs in a timely manner is a great challenge because of the inherently shared nature and randomness of the wireless medium. To...

Distributed computing systems often need to consider the scheduling problem involving a collection of highly dependent data-processing tasks that must work in concert to achieve mission-critical objectives. This paper considers the unrelated machine scheduling problem for minimizing weighted sum completion time under arbitrary precedence constraint...

Edge computing applications typically require generated data to be preprocessed at the source and then transmitted to an edge server. In such cases, transmission time and preprocessing time are coupled, yielding a tradeoff between them to achieve the targeted objective. This paper presents analysis of such a system with the objective of optimizing...

We experimentally evaluate the transmission performance of OXC structures based on flexible-waveband routing. 1600 km, 700 km, and 600 km transmission is demonstrated using 32 Gbaud DP-QPSK, DP-8QAM, and DP-16QAM on 37.5 GHz grid, respectively.

Emerging inter-datacenter applications involving data transferred, processed, and analyzed at multiple datacenters, such as virtual machine migrations, real-time data backup, remote desktop, and virtual datacenters, can be modeled as virtual network requests that share computing and spectrum resources of a common substrate physical inter-datacenter...

The Internet gateway selection problem is becoming very important as the number of Internet-connected devices increases and stresses the limited number of Internet gateway nodes. The gateway nodes often experience frequent performance fluctuations, and the best gateway selection candidate changes frequently with growing network dynamics. We propose...

It is a critical but difficult task to provide information transmission and computation services to first responders or rescue teams in disaster-hit areas as catastrophes may cause casualties and massive damage to human-made facilities. Unmanned aerial vehicles (UAVs) are a great choice to provide these services in such areas due to their inherent...

A datacenter that consists of hundreds or thousands of servers can provide virtualized environments to a large number of cloud applications and jobs that value the requirement of reliability very differently. Checkpointing a virtual machine (VM) is a proven technique to improve reliability. However, existing checkpoint scheduling techniques for enh...

Elastic optical networks (EONs) are able to provide high spectrum utilization efficiency due to flexibility in resource assignment. In translucent EONs, by employing regenerators and using advanced modulation formats for transmission, spectrum efficiency can be further improved. Survivability is regarded as an important aspect of EONs, and p-cycle...

With the growing deadline-sensitivity of cloud applications, adherence to specific deadlines is becoming increasingly crucial, particularly in shared clusters. A few slow tasks called stragglers can potentially adversely affect job execution times. Equally, inadequate slotting of data analytics applications could result in inappropriate resource de...

Motivated by the inherent value of packets arising in many cyber-physical applications (e.g., due to precision of the information content or an alarm message), we consider status update systems with update packets carrying values as well as their generation time stamps. Once generated, a status update packet has a random initial value and a determi...

This paper is motivated by emerging edge computing systems which consist of sensor nodes that acquire and process information and then transmit status updates to an edge receiver for possible further processing. As power is a scarce resource at the sensor nodes, the system is modeled as a tandem computation-transmission queue with power-efficient c...

Elastic optical networks (EONs) promise to provide high spectrum utilization efficiency due to flexibility in resource allocation. Survivability is regarded as an important aspect of EONs. P-cycle protection is very attractive for EONs due to fast restoration and high protection efficiency. P-cycles have been extensively studied for conventional fi...

The rapid growth of data center traffic requires data center networks (DCNs) to be scalable, energy-efficient, and provide low latencies. Optical Wavelength Division Multiplexing (WDM) is a promising technique to build data centers comprising millions of servers. In [24], a WDM-based Reconfigurable Hierarchical Optical DCN Architecture (RHODA) was...

Emerging inter-datacenter applications involving data transferred, processed, and analyzed at multiple data centers, such as virtual machine migrations, real-time data backup, remote desktop, and virtual data centers, can be modeled as virtual network requests that share computing and spectrum resources of a common substrate physical inter-datacent...

In this paper, we explore the potential of server waiting before packet transmission in improving the Age of Information (AoI) in status update systems. We consider a non-preemptive queue with Poisson arrivals and independent general service distribution and we incorporate waiting before serving in two packet management schemes: M/GI/1/1 and M/GI/1...

Edge computing applications typically require generated data to be preprocessed at the source and then transmitted to an edge server. In such cases, transmission time and preprocessing time are coupled, yielding a tradeoff between them to achieve the targeted objective. This paper presents analysis of such a system with the objective of optimizing...

Cloud computing based systems, that span data centers, are commonly deployed to offer high performance for user service requests. As data centers continue to expand, computer architects and system designers are facing many challenges on how to balance resource utilization efficiency, server and network performance, energy consumption and quality-of...

Cloud-as-the-center computing paradigms face multiple challenges in the 5G and Internet of Things scenarios, where the service requests are usually initiated by the end-user devices located at network edge and have rigid time constraints. Therefore, Fog computing, or mobile edge computing, is introduced as a promising solution to the service provis...

This paper is motivated by emerging edge computing applications in which generated data are pre-processed at the source and then transmitted to an edge server. In such a scenario, there is typically a tradeoff between the amount of pre-processing and the amount of data to be transmitted. We model such a system by considering two non-preemptive queu...

Elastic optical networks are seen as a promising solution to improve spectrum utilization efficiency by utilizing flex-grid optical orthogonal frequency division multiplexing technology and facilitating flexible bandwidth allocation to services with heterogeneous demands. With dramatic growth of Internet traffic and imminent fiber capacity exhausti...

Unmanned Aerial Vehicles (UAVs) are considered a promising solution for carrying communications and computational facilities to increase the flexibility of cloud-to-thing continuum, where short-range and long-range wireless links are adopted to connect mobile devices to the fog node and the fog node to the remote data center, respectively. Most exi...

Optical data center network architectures are becoming attractive because of their low energy consumption, large bandwidth, and low cabling complexity. In\cite{Xu1605:PODCA}, an AWGR-based passive optical data center architecture (PODCA) is presented. Compared with other optical data center architectures, e.g., DOS \cite{ye2010scalable}, Proteus \c...

Massive data centers are at the heart of the Internet. The rapid growth of Internet traffic and the abundance of rich data-driven applications have raised the need for enormous network bandwidth. Towards meeting this growing traffic demand, optical interconnects have gained significant attention, as they can provide high throughput, low latency, an...

In this paper, we introduce a new data freshness metric, relative Age of Information (rAoI), and examine it in a single server system with various packet management schemes. The (classical) AoI metric was introduced to measure the staleness of status updates at the receiving end with respect to their generation at the source. This metric addresses...

This paper explores the potential of waiting before packet transmission in improving the Age of Information (AoI) in status update systems. We consider a non-preemptive queue with Poisson arrivals and independent general service distribution, which we term M/GI/1/2*. There is a single unit buffer that captures the latest arriving status update pack...