arXiv subjects

Saswati Sarkar

Publications and source records attributed to Saswati Sarkar.

28 records · Page 2Linked to original sources

arXiv2015

Optimal Energy-Aware Epidemic Routing in DTNs

In this work, we investigate the use of epidemic routing in energy constrained Delay Tolerant Networks (DTNs). In epidemic routing, messages are relayed by intermediate nodes at contact opportunities, i.e., when pairs of nodes come within the transmission range of each other. Each node needs to decide whether to forward its message upon contact with a new node based on its own residual energy level and the age of that message. We mathematically characterize the fundamental trade-off between energy conservation and a measure of Quality of Service as a dynamic energy-dependent optimal control problem. We prove that in the mean-field regime, the optimal dynamic forwarding decisions follow simple threshold-based structures in which the forwarding threshold for each node depends on its current remaining energy. We then characterize the nature of this dependence. Our simulations reveal that the optimal dynamic policy significantly outperforms heuristics.

eess.SY↗

arXiv2015

Quality Sensitive Price Competition in Spectrum Oligopoly:Part 1

We investigate a spectrum oligopoly market where primaries lease their channels to secondaries in lieu of financial remuneration. Transmission quality of a channel evolves randomly. Each primary has to select the price it would quote without knowing the transmission qualities of its competitors' channels. Each secondary buys a channel depending on the price and the transmission quality a channel offers. We formulate the price selection problem as a non co-operative game with primaries as players. In the one-shot game, we show that there exists a unique symmetric Nash Equilibrium(NE) strategy profile and explicitly compute it. Our analysis reveals that under the NE strategy profile a primary prices its channel to render high quality channel more preferable to the secondary; this negates the popular belief that prices ought to be selected to render channels equally preferable to the secondary regardless of their qualities. We show the loss of revenue in the asymptotic limit due to the non co-operation of primaries. In the repeated version of the game, we characterize a subgame perfect NE where a primary can attain a payoff arbitrarily close to the payoff it would obtain when primaries co-operate.

cs.GT↗

arXiv2014

Market-Based Power Allocation for a Differentially Priced FDMA System

In this paper, we study the problem of differential pricing and QoS assignment by a broadband data provider. In our model, the broadband data provider decides on the power allocated to an end-user not only based on parameters of the transmission medium, but also based on the price the user is willing to pay. In addition, end-users bid the price that they are willing to pay to the BTS based on their channel condition, the throughput they require, and their belief about other users' parameters. We will characterize the optimum power allocation by the BTS which turns out to be a modification of the solution to the well-known water-filling problem. We also characterize the optimum bidding strategy of end-users using the belief of each user about the cell condition.

cs.IT↗

arXiv2014

Quality Sensitive Price Competition in Spectrum Oligopoly

We investigate a spectrum oligopoly where primary users allow secondary access in lieu of financial remuneration. Transmission qualities of the licensed bands fluctuate randomly. Each primary needs to select the price of its channel with the knowledge of its own channel state but not that of its competitors. Secondaries choose among the channels available on sale based on their states and prices. We formulate the price selection as a non-cooperative game and prove that a symmetric Nash equilibrium (NE) strategy profile exists uniquely. We explicitly compute this strategy profile and analytically and numerically evaluate its efficiency. Our structural results provide certain key insights about the unique symmetric NE.

cs.GT↗

arXiv2014

Network Non-Neutrality on the Internet: Content Provision Under a Subscription Revenue Model

The goal of this paper is to provide an insight into the equilibrium of the Internet market, when the current balance of the market is disrupted, and one of the ISPs switches to a non-neutral regime. We consider a content provider with a subscription revenue model and a continuum of end-users. The CP is also non-neutral, in the sense that she can charge users of different ISPs different subscription fees, and use this "leverage" to control the equilibrium outcome. Results reveal that the CP is able to control the non-neutral ISP to some extend. However, switching to a non-neutral regime by an ISP tips the balance of the market in favor of this ISP.

cs.NI↗

arXiv2014

Optimal Patching in Clustered Malware Epidemics

Studies on the propagation of malware in mobile networks have revealed that the spread of malware can be highly inhomogeneous. Platform diversity, contact list utilization by the malware, clustering in the network structure, etc. can also lead to differing spreading rates. In this paper, a general formal framework is proposed for leveraging such heterogeneity to derive optimal patching policies that attain the minimum aggregate cost due to the spread of malware and the surcharge of patching. Using Pontryagin's Maximum Principle for a stratified epidemic model, it is analytically proven that in the mean-field deterministic regime, optimal patch disseminations are simple single-threshold policies. Through numerical simulations, the behavior of optimal patching policies is investigated in sample topologies and their advantages are demonstrated.

cs.CR↗

arXiv2008

Information Acquisition and Exploitation in Multichannel Wireless Networks

A wireless system with multiple channels is considered, where each channel has several transmission states. A user learns about the instantaneous state of an available channel by transmitting a control packet in it. Since probing all channels consumes significant energy and time, a user needs to determine what and how much information it needs to acquire about the instantaneous states of the available channels so that it can maximize its transmission rate. This motivates the study of the trade-off between the cost of information acquisition and its value towards improving the transmission rate. A simple model is presented for studying this information acquisition and exploitation trade-off when the channels are multi-state, with different distributions and information acquisition costs. The objective is to maximize a utility function which depends on both the cost and value of information. Solution techniques are presented for computing near-optimal policies with succinct representation in polynomial time. These policies provably achieve at least a fixed constant factor of the optimal utility on any problem instance, and in addition, have natural characterizations. The techniques are based on exploiting the structure of the optimal policy, and use of Lagrangean relaxations which simplify the space of approximately optimal solutions.

cs.DS↗

arXiv2006

Using Invisible Graviton Radiation to Detect Heavy Electroweak Resonances at a 500 GeV e+e- Collider

The process e+e- --> mu+ mu- + missing E_T, where the missing energy is due to the production of a tower of invisible graviton states in a model with large extra dimensions, is considered. We focus on the scenario when this process is used to detect a heavy dileptonic resonance in the electroweak sector of the model, taking as example some models with an extra Z' boson. It turns out that at a 500 GeV machine with 1000 inverse fb of luminosity, it may be possible to use this process to such detect resonances if there are two large extra dimensions and the string scale is not too far above a TeV.

hep-ph↗

arXiv2000

HERA Constraint on Warped Quantum Gravity

We study recent data on deep inelastic e^+ p scattering at HERA to constrain the parameters of a Randall-Sundrum-type scenario of quantum gravity with a small extra dimension and a non-factorable geometry.

hep-ph↗

arXiv1999

An $SU(2)_{L}\times U(1)_{Y} \times S_{3} \times D$ model for atmospheric and solar neutrino deficits

Motivated by the recent Super-Kamiokande experiment on atmospheric and solar neutrino oscillation we propose a see-saw model of three generations of neutrinos based on the gauge group $SU(2)_{L}\times U(1)_{Y}$ with discrete symmetries $(S_{3} \times D)$ and three right handed singlet neutrinos so that this model can accommodate the recent Super-Kamiokande data on atmospheric and solar neutrino oscillations. The model predicts maximal mixing between $ν_μ$ and $ν_τ$ with $sin^{2}2{θ_{μτ}}$ = 1 as required by the atmospheric neutrino data and small mixing between $ν_{e}$ and $ν_μ$ with $sin^{2}2{θ_{eμ}} \sim (10^{-2}-10^{-3})$ as a possible explanation of the solar neutrino deficit through the MSW mechanism. The model admits two mass scales of which one breaks the electroweak symmetry and the other is responsible for the breaking of the lepton number symmetry at GUT scale leading to small Majorana mass of the left handed doublet neutrinos.

hep-ph↗