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Introduction
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July 2007 - present
September 2001 - September 2005
Publications
Publications (136)
We investigate the problem of maximizing the sum of the weighted rates of user equipment (UE) by finding a UE and a beam for each access point (AP) for concurrent transmission in millimeter wave (mmWave) networks. We prove that this problem is NP-complete. We propose two algorithms– Markov Chain Monte Carlo (MCMC) based and local interaction game (...
The escalating demand for high-quality video streaming poses a major challenge for communication networks today. Catering to these bandwidth-hungry video streaming services places a huge burden on the limited spectral resources of communication networks, limiting the resources available for other services as well. Large volumes of video traffic can...
Integrated access and backhaul (IAB) is an innovative wireless backhaul solution to provide cost-efficient deployment of small cells for successful 5G adoption. Besides, IAB can utilize the same spectrum for access and backhaul purposes. The 3GPP has standardized IAB in Release 16 and may incorporate a few enhancements in the upcoming releases. The...
In video streaming applications, especially during live streaming events, video traffic can account for a significant portion of the network traffic and can lead to severe network congestion. For such applications, multicast provides an efficient means to deliver the same content to a large number of users simultaneously. However, in multicast, if...
In video streaming applications especially during live streaming events (such as the Super Bowl), video traffic can account for a significant portion of network traffic and can lead to severe network congestion. During such events, multicast transmission can be used to avoid network congestion since the same video content is being streamed to multi...
The 3GPP has envisioned Integrated Access and Backhaul (IAB) as a key enabler to support the flexible and ultra-dense deployment of 5G cells with significantly reduced deployment costs. However, IAB introduces new research challenges, especially when studying multihop topology. This paper presents a QoS-based downlink scheduler designed explicitly...
Multi-connectivity has emerged as a key enabler for providing seamless connectivity in cellular mobile networks. However, its potential for improving the quality of multicast transmissions has remained unexplored. In this paper, we investigate the use of multi-connectivity in wireless multicast streaming. Multi-connectivity can significantly improv...
Linear Non-Linear(LN) models are widely used to characterize the receptive fields of early-stage auditory processing. We apply the principle of efficient coding to the LN model of Spectro-Temporal Receptive Fields(STRFs) of the neurons in primary auditory cortex. The Efficient Coding Principle has been previously used to understand early visual rec...
To overcome the
curses of dimensionality and modeling
of dynamic programming methods to solve Markov decision process problems, reinforcement learning (RL) methods are adopted in practice. Contrary to traditional RL algorithms, which do not consider the structural properties of the optimal policy, we propose a structure-aware learning algorithm t...
In todays wireless networks, a variety of Radio Access Technologies (RATs) are present. However, each RAT being controlled individually leads to suboptimal utilization of network resources. Due to the remarkable growth of data traffic, interworking among different RATs is becoming necessary to overcome the problem of suboptimal resource utilization...
<<Accepted for publication in IEEE WCNC 2021>>
The Third Generation Partnership Project (3GPP) Fifth Generation (5G) network employs Software Defined Networking (SDN) paradigm allowing for a clear separation of control and data plane functionalities in the 5G network. However, the control plane in a 5G network not only performs network control ta...
This paper addresses the robustness of large-scale closed-loop structured systems in the sense of arbitrary pole placement when subject to failure of feedback links. Given a structured system with input, output, and feedback matrices, we first aim to verify whether the closed-loop structured system is robust to the simultaneous failure of any subse...
Fifth Generation (5G) mobile networks utilize network slicing for providing diverse services over a shared infrastructure. User Equipments (UEs) can access multiple slices concurrently to avail services requiring different Quality of Service (QoS). Third Generation Partnership Project (3GPP) 5G stipulates that all slices supported for a given UE sh...
The upcoming Fifth Generation (5G) mobile network aims to support a wide variety of services. In addition to the four standardized service use cases, network operators are also looking for the ability to deploy newer services in shorter timescales to quickly monetize the 5G network. This has resulted in the emergence of Software-Defined Networking...
Our aim is to maximize throughput of a transmitter–receiver pair assisted by amplify-and-forward relay. We consider a case in which the relay is powered solely by a renewable energy source, and the transmitter has average power constraint. The receiver employs optimal combining. Instantaneous CSI is assumed to be available. Our aim is to design a t...
Mobile Networks today comprise of multiple Radio Access Technologies (RATs), e.g., 4G LTE, Wireless Local Area Network (WLAN), and the upcoming 5G-New Radio (5G-NR). The access networks of these RATs are controlled by RAT-specific entities, e.g., the resource management function located inside an individual LTE eNB is used for the eNB control, or a...
Proportional Fair (PF) is a scheduling technique to maintain a balance between maximizing throughput and ensuring fairness to users. Dual Connectivity (DC) technique was introduced by the 3rd Generation Partnership Project (3GPP) to improve the mobility robustness and system capacity in heterogeneous networks. In this paper, we demonstrate the util...
This paper deals with structural controllability of a Linear Time Invariant (LTI) composite system consisting of several circuits/subsystems. We consider subsystems with structurally similar state matrices, i.e., the zero/non-zero pattern of the state matrices of the subsystems are the same, but dynamics can be different due to different numerical...
Markov Decision Process (MDP) problems can be solved using Dynamic Programming (DP) methods which suffer from the curse of dimensionality and the curse of modeling. To overcome these issues, Reinforcement Learning (RL) methods are adopted in practice. In this paper, we aim to obtain the optimal admission control policy in a system where different c...
Multimedia traffic is predicted to account for
$\mathbf {82}$
% of the total data traffic by the year 2020. With the increasing popularity of video streaming applications like YouTube, Netflix, Amazon Prime Video, popular video content is often required to be delivered to a large audience simultaneously. Multicast transmission can be used to cate...
The Third Generation Partnership Project (3GPP) Fifth Generation (5G) networks employ network slicing in order to implement multiple service types corresponding to different business needs. Network slicing results in the creation of multiple end-to-end logical networks over shared physical infrastructure. User Equipments (UEs) can use multiple netw...
Today’s wireless networks consist of a multitude of
Radio Access Technologies (RATs), each being controlled indi-
vidually, leading to suboptimal utilization of network resources.
However, the unprecedented growth of data traffic is creating the
need for an efficient inter-working of various RATs to circumvent
the problem of suboptimal utilization...
In this paper, we propose a low latency, robust and scalable neural net based decoder for convolutional and low-density parity-check (LPDC) coding schemes. The proposed decoders are demonstrated to have bit error rate (BER) and block error rate (BLER) performances at par with the state-of-the-art neural net based decoders while achieving more than...
Bandwidth hungry video content has become the dominant contributor to the data traffic world over. Cellular networks are constantly evolving to meet the growing traffic demands. Over the past few years, wireless multicast has been garnering a lot of attention as a means of efficient resource utilization. Multicast transmission lets spectral resourc...
We consider allocation of a resource to multiple interested users with a constraint that if the resource is allocated to user i, then it cannot be allocated simultaneously to a predefined set of users si. This scenario arises in many practical systems that include wireless networks and constrained queuing systems. It is known that the socially opti...
To overcome the curse of dimensionality and curse of modeling in Dynamic Programming (DP) methods for solving classical Markov Decision Process (MDP) problems, Reinforcement Learning (RL) algorithms are popular. In this paper, we consider an infinite-horizon average reward MDP problem and prove the optimality of the threshold policy under certain c...
This paper deals with structural controllability of a linear time-invariant composite system consisting of several heterogeneous subsystems. The interaction links through which the subsystems interact with other subsystems are referred to as interconnections. We assume the composite system to be structurally controllable if all possible interconnec...
Multicast transmission has been gaining importance as an efficient means of delivering bandwidth hungry video content and is expected to become an integral part of cellular networks worldwide. This has resulted in the need for generalized allocation algorithms that are capable of handling multiple multicast and unicast services with different Quali...
Multi-armed bandit(MAB) problem is a reinforcement learning framework where an agent tries to maximise her profit by proper selection of actions through absolute feedback for each action. The dueling bandits problem is a variation of MAB problem in which an agent chooses a pair of actions and receives relative feedback for the chosen action pair. T...
In an offload-capable Long Term Evolution(LTE)- Wireless Fidelity(WiFi) Heterogeneous Network(HetNet), we consider the problem of maximization of the total system throughput under voice user blocking probability constraint. The optimal policy is threshold in nature. However, computation of optimal policy requires the knowledge of the statistics of...
To overcome the curse of dimensionality and curse of modeling in Dynamic Programming (DP) methods for solving classical Markov Decision Process (MDP) problems, Reinforcement Learning (RL) algorithms are popular. In this paper, we consider an infinite-horizon average reward MDP problem and prove the optimality of the threshold policy under certain c...
We consider allocation of a resource to multiple interested users with a constraint that if the resource is allocated to user $i$ then it can not be allocated simultaneously to a predefined set of users $\cS_i$ . This scenario arises in many practical systems that include wireless networks and constrained queuing systems. It is known that socially...
Composite systems are large complex systems con- sisting of interconnected agents (subsystems). Agents in a com- posite system interact with each other towards performing an in- tended goal. Controllability is essential to achieve desired system performance in linear time-invariant composite systems. Agents in a composite system are often uncontrol...
The notion of strong structural controllability (s-controllability) allows for determining controllability properties of large linear time-invariant systems even when numerical values of the system parameters are not known a priori. The s-controllability guarantees controllability for all numerical realizations of the system parameters. We address...
Multimedia traffic is predicted to account for 82% of the total data traffic by the year 2020. With the increasing popularity of video streaming applications like YouTube, Netflix, Amazon Prime Video, popular video content is often required to be delivered to a large number of users simultaneously. Multicast transmission can be used for catering to...
Modulation recognition is a challenging task while performing spectrum sensing in a cognitive radio setup. Recently, the use of deep convolutional neural networks (CNNs) has shown to achieve state-of-the-art accuracy for modulation recognition \cite{survey}. However, a wireless channel distorts the signal and CNNs are not explicitly designed to und...
Modulation recognition is a challenging task while performing spectrum sensing in a cognitive radio setup. Recently, the use of deep convolutional neural networks (CNNs) has shown to achieve state-of-the-art accuracy for modulation recognition \cite{survey}. However, a wireless channel distorts the signal and CNNs are not explicitly designed to und...
In this paper, we study static output feedback selection in linear time invariant structured systems. We assume that the inputs and the outputs are dedicated, i.e., each input actuates a single state and each output senses a single state. Given a structured system with dedicated inputs and outputs and a cost matrix that denotes the cost of each fee...
This paper deals with the analysis of robustness of closed-loop structured system. Specifically, given a structured system and a structured feedback matrix, our aim is to verify whether the closed-loop system is robust to failure of any k feedback links, where k is an integer. We refer to this problem as the feedback resilience problem. Firstly, we...
In this paper, we study output feedback selection in linear time-invariant structured systems. We assume that the inputs and the outputs are dedicated, i.e., each input directly actuates a single state and each output directly senses a single state. Given a structured system with dedicated inputs and outputs and a cost matrix that denotes the cost...
In this paper, we study structural controllability of a linear time invariant (LTI) composite system consisting of several subsystems. We assume that the neighbourhood of each subsystem is unconstrained, i.e., any subsystem can interact with any other subsystem. The interaction links between subsystems are referred as interconnections. We assume th...
Enhancement of system capacity is one of the objectives of the fifth generation (5G) networks in which device-to-device (D2D) communications is anticipated to play a crucial role. This can be achieved by devising efficient resource allocation strategies for the D2D users. While most of the works in resource allocation assume full knowledge of the c...
This paper deals with a complete bipartite matching problem with the objective of finding an optimal matching that maximizes a certain generic predefined utility function on the set of all matchings. After proving the NP-hardness of the problem using reduction from the 3-SAT problem, we propose a randomized algorithm based on Markov Chain Monte Car...
A significant barrier in providing affordable rural broadband is to connect the rural and remote places to the optical Point of Presence (PoP) over distances of few kilometers. A lot of work has been done in the area of long distance Wi-Fi networks. However, these networks require tall towers and high gain (directional) antennas. Also, they work in...
Rural areas in the developing countries are predominantly devoid of Internet access as it is not viable for operators to provide broadband service in these areas. To solve this problem, we propose a middle mile Long erm Evolution Advanced (LTE-A) network operating in TV white space to connect villages to an optical Point of Presence (PoP) located i...
It is well known that IEEE 802.11 based MAC provides max–min fairness to all nodes even in a multi-rate WLAN. However, the max–min fairness may not always be the preferred fairness criteria as it significantly reduces overall system throughput. In this paper, we explore the proportional fairness and the time fairness. First, we obtain a condition t...
This paper deals with optimal feedback selection problem in linear time-invariant (LTI) structured systems, an important open problem in structured systems. Specifically, we solve the sparsest feedback selection problem for LTI structured systems. In this paper, we consider structurally cyclic systems with dedicated inputs and outputs. For this cla...
This paper solves the sparsest feedback selection problem for linear time invariant structured systems, a long-standing open problem in structured systems. We consider structurally cyclic systems with dedicated inputs and outputs. We prove that finding a sparsest feedback selection is of linear complexity for the case of structurally cyclic systems...
This paper addresses optimal feedback selection for generic arbitrary pole placement of structured systems when each feedback edge is associated with a cost. Given a structured system and a feedback cost matrix, our aim is to find a feasible feedback matrix of minimum cost that guarantees arbitrary pole placement of the closed-loop structured syste...
This paper addresses optimal feedback selection for generic arbitrary pole placement of structured systems when each feedback edge is associated with a cost. Given a structured system and a feedback cost matrix, our aim is to find a feasible feedback matrix of minimum cost that guarantees arbitrary pole placement of the closed-loop structured syste...
Since IEEE has standardized 802.11 protocol for WLANs [1], significant work has been done in developing rate adaptation algorithms. Most of the rate adaptation algorithms proposed till now are heuristic, sub-optimal and are competitive in nature. Even though these algorithms have advantage of implementing in distributed fashion, their throughput pe...
This paper is about minimum cost constrained selection of inputs and outputs for generic arbitrary pole placement. The input-output set is constrained in the sense that the set of states that each input can influence and the set of states that each output can sense is pre-specified. Our goal is to optimally select an input-output set that the syste...
This paper is about minimum cost constrained selection of inputs and outputs for generic arbitrary pole placement. The input-output set is constrained in the sense that the set of states that each input can influence and the set of states that each output can sense is pre-specified. Our goal is to optimally select an input-output set that the syste...
A Heterogeneous Network (HetNet) comprises of multiple Radio Access Technologies (RATs) allowing a user to associate with a specific RAT and steer to other RATs in a seamless manner. To cope up with the unprecedented growth of data traffic, mobile data can be offloaded to Wireless Fidelity (WiFi) in a Long Term Evolution (LTE) based HetNet. In this...
This paper deals with minimum cost constrained input selection for state space structured systems. The input matrix is constrained in the sense that the set of states that each input can influence is pre-specified and each input has a cost associated with it. Our goal is to optimally select an input set from the set of inputs given that the system...
This paper looks at two problems, minimum constrained input selection and minimum cost constrained input selection for state space structured systems. The input matrix is constrained in the sense that the set of states that each input can influence is pre-specified and each input has a cost associated with it. Our goal is to optimally select an inp...
In recent years, the computerised adaptive test (CAT) has gained popularity over conventional exams in evaluating student capabilities with desired accuracy. However, the key limitation of CAT is that it requires a large pool of pre-calibrated questions. In the absence of such a pre-calibrated question bank, offline exams with uncalibrated question...
Allotting Teaching Assistants (TAs) to courses is a common task at university centers which typically demands a good amount of human effort. We propose a method to allocate using computer algorithm. The presence of conflicting constraints, posed by requirements which determine tradeoff among them tend to make this problem difficult to solve. This i...
Throughput improvement of the wireless LANs has been a constant area of research. Most of the work in this area focuses on designing throughput optimal schemes for fully connected networks (no hidden nodes). The schemes are optimal in a sense that they maximize the sum throughput subject to giving equal channel access opportunity to each user. But,...
Optimizing energy consumption is paramount to sustain the growth of cellular networks. One of the approaches to reduce energy consumption is traffic dependent operation of networks. The traffic demand experienced by the network fluctuates over the duration of a day. Therefore, during the periods of low traffic, we may re-configure the network to tr...
A transmitter powered by a renewable energy source becomes self sustainable. In this paper, we consider the broadcast channel with a transmitter and N receivers. The transmitter is powered by a renewable energy source and has finite battery capacity. Transmitter requires power Pi to transmit a packet to ith user. In this setting, our objective is t...
Recent proliferation of mobile devices and high market demand have pushed power consumption of cellular networks to high levels in India. At the same time, the marginal gains to telecom operators for providing services have dwindled. Thus, a gap is slowly building up in the demand and supply of telecom services. The effect is adverse in urban areas...
Energy optimization is a concern not only for environmental impact but also for reducing the operational costs of the cellular network. In cellular networks, traffic load is time varying and asymmetric. Due to which, some base stations (BSs) are over-loaded and some are underutilized. However load is shown to be cyclostationary, i.e, it varies peri...
We address an issue of scheduling for uplink realtime flows in WiMAX networks. Real-time flows require hard delay and throughput guarantees. Thus, each packet has a strict deadline and the packets delayed beyond their respective deadlines are dropped. Real-time applications can sustain some loss gracefully. Alternatively, they require some minimum...
Radio resource sharing mechanisms are key to ensuring good performance in
wireless networks. In their seminal paper \cite{tassiulas1}, Tassiulas and
Ephremides introduced the Maximum Weighted Scheduling algorithm, and proved its
throughput-optimality. Since then, there have been extensive research efforts
to devise distributed implementations of th...
Wireless networks have emerged as the most popu-lar access technologies. Multiple technologies like WiFi, WiMAX, LTE, along with traditional cellular networks augmented with pico and femto base stations, are available for a user to access the Internet. Many emerging user devices, e.g. smart phones, allow for Internet connectivity using most of the...
Supporting real-time applications is paramount to sustaining the growth of wireless networks. Real time applications require strict delay guarantee, i.e., a packet delayed beyond certain predefined value is dropped. Fortunately, depending on the codec used, real-time applications can sustain some loss gracefully. Aim of an admission control algorit...