Department of Computer Science and Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

&nbsp;

IIT Palakkad

In this paper, we propose an intra-task dynamic voltage scaling (DVS) scheduling technique for energy reduction of hard real-time systems. Different from previous works, we incorporate the leakage-temperature dependency in our system model and proposes a novel intra-task DVS scheduling technique to reduce the overall energy consumption. The experimental result shows that significant energy reduction is achieved using the proposed approach in comparison to the existing approach. © 2015 IEEE.

World University root node

International Conference on Digital Signal Processing, DSP

Leakage-aware intra-task dynamic voltage scaling technique for energy reduction in real-time embedded systems

In this letter, we propose a scheme to improve the secrecy rate of cooperative networks using Analog Network Coding (ANC). ANC mixes the signals in the air; the desired signal is then separated out, from the mixed signals, at the legitimate receiver using techniques like self interference subtraction and signal nulling, thereby achieving better secrecy rates. Assuming global channel state information, memoryless adversaries and the decode-and-forward strategy, we seek to maximize the average secrecy rate between the source and the destination, subject to an overall power budget. Then, exploiting the structure of the optimization problem, we compute its optimal solution. Finally, we use numerical evaluations to compare our scheme with the conventional approaches. © 2015 IEEE.

IEEE Signal Processing Letters

Secure transmission in cooperative networks with weak eavesdroppers

In this paper, by augmenting beamforming with signal nulling, we present a scheme to improve the equivocation in wireless relay networks. Assuming global channel state information, memoryless adversaries, and the decode-and-forward relaying strategy, we seek to maximize the average achievable secrecy rate between the source and the legitimate destination, subject to an overall power budget per message. Then, exploiting the structure of the optimization problem, we present an online sequential approach to compute an achievable average rate. Finally, we use numerical evaluations to compare our method with the conventional schemes. © 2015 IFIP.

2015 13th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, WiOpt 2015

Beating resource constrained eavesdroppers: A physical layer security study

The separation dimension of a graph G is the smallest natural number k for which the vertices of G can be embedded in Rk such that any pair of disjoint edges in G can be separated by a hyperplane normal to one of the axes. Equivalently, it is the smallest possible cardinality of a family F of total orders of the vertices of G such that for any two disjoint edges of G, there exists at least one total order in F in which all the vertices in one edge precede those in the other. In general, the maximum separation dimension of a graph on n vertices is Θ(log n). In this article, we focus on bounded degree graphs and show that the separation dimension of a graph with maximum degree d is at most 29 log ∗ d d. We also demonstrate that the above bound is nearly tight by showing that, for every d, almost all d-regular graphs have separation dimension at least ⌈d/2⌉. © 2015 Society for Industrial and Applied Mathematics.

Fulltext

SIAM Journal on Discrete Mathematics

Separation dimension of bounded degree graphs

The structural properties of temporal networks often influence the dynamical processes that occur on these networks, e.g., bursty interaction patterns have been shown to slow down epidemics. In this paper, we investigate the effect of link lifetimes on the spread of history-dependent epidemics. We formulate an analytically tractable activity-driven temporal network model that explicitly incorporates link lifetimes. For Markovian link lifetimes, we use mean-field analysis for computing the epidemic threshold, while the effect of non-Markovian link lifetimes is studied using simulations. Furthermore, we also study the effect of negative correlation between the number of links spawned by an individual and the lifetimes of those links. Such negative correlations may arise due to the finite cognitive capacity of the individuals. Our investigations reveal that heavy-tailed link lifetimes slow down the epidemic, while negative correlations can reduce epidemic prevalence. We believe that our results help shed light on the role of link lifetimes in modulating diffusion processes on temporal networks. © 2015 American Physical Society.

Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

Dynamics of history-dependent epidemics in temporal networks

Interference management (RF management) remains one of the main challenges facing the design and deployment of large-scale WLAN. RF management involves the detection, estimation and control of power level, channel allocations and link schedules, to improve the performance of the wireless network. Among interfering links, one can find different types of dependencies. While some of these types can be predicted with relatively low overheads, observing and inferring other types can be a challenging task. In this paper, we ask the question - in WLANs, what is the probability of different types of pair-wise link dependencies? We answer this question by deriving analytical expressions for various types of link dependencies seen in IEEE 802.11 WLANs, numerically evaluating them, and comparing them against simulations. © 2015 IFIP.

Link dependence probabilities in IEEE 802.11 infrastructure WLANs

Cubicity of a graph G is the smallest dimension d, for which G is a unit disc graph in Rd, under the l∞ metric, i.e. G can be represented as an intersection graph of d-dimensional (axis-parallel) unit hypercubes. We call such an intersection representation a d-dimensional cube representation of G. Computing cubicity is known to be inapproximable in polynomial time, within an O(n1−ϵ) factor for any ϵ&gt;0, unless NP=ZPP. In this paper, we present a randomized algorithm that runs in polynomial time and computes cube representations of trees, of dimension within a constant factor of the optimum. It is also shown that the cubicity of trees can be approximated within a constant factor in deterministic polynomial time, if the cube representation is not required to be computed. As far as we know, this is the first constant factor approximation algorithm for computing the cubicity of trees. It is not yet clear whether computing the cubicity of trees is NP-hard or not.

Approximating the Cubicity of Trees

The rainbow connection number, rc(G), of a connected graph G is the minimum number of colours needed to colour its edges, so that every pair of its vertices is connected by at least one path in which no two edges are coloured the same. In this note we show that for every bridgeless graph G with radius r, rc(G) ≤ r(r + 2). We demonstrate that this bound is the best possible for rc(G) as a function of r, not just for bridgeless graphs, but also for graphs of any stronger connectivity. It may be noted that for a general 1-connected graph G, rc(G) can be arbitrarily larger than its radius (K 1,n for instance). We further show that for every bridgeless graph G with radius r and chordality (size of a largest induced cycle) k, rc(G) ≤ rk. Hitherto, the only reported upper bound on the rainbow connection number of bridgeless graphs is 4n/5 - 1, where n is order of the graph (Caro et al. in Electron J Comb 15(1):Research paper 57, 13, 2008). It is known that computing rc(G) is NP-Hard (Chakraborty and fischer in J Comb Optim 1-18, 2009). Here, we present a (r + 3)-factor approximation algorithm which runs in O(nm) time and a (d + 3)-factor approximation algorithm which runs in O(dm) time to rainbow colour any connected graph G on n vertices, with m edges, diameter d and radius r. © 2012 Springer Japan.

Graphs and Combinatorics

Rainbow Connection Number and Radius

With an increasing number of cores per chip, it is becoming harder to guarantee optimal performance for parallel shared memory applications due to interference caused by kernel threads, interrupts, bus contention, and temperature management schemes (referred to as jitter). We demonstrate that the performance of parallel programs gets reduced (up to 35.22 percent) in large CMP based systems. In this paper, we characterize the jitter for large multi-core processors, and evaluate the loss in performance. We propose a novel jitter measurement unit that uses a distributed protocol to keep track of the number of wasted cycles. Subsequently, we try to compensate for jitter by using DVFS across a region of timing critical instructions called a frame. Additionally, we propose an OS cache that intelligently manages the OS cache lines to reduce memory interference. By performing detailed cycle accurate simulations, we show that we are able to execute a suite of Splash2 and Parsec benchmarks with a deterministic timing overhead limited to 2 percent for 14 out of 17 benchmarks with modest DVFS factors. We reduce the overall jitter by an average 13.5 percent for Splash2 and 6.4 percent for Parsec. The area overhead of our scheme is limited to 1 percent. © 2013 IEEE.

IEEE Transactions on Parallel and Distributed Systems

Architectural support for handling jitterin shared memory based parallel applications

3D-MPSoC offer great performance and scalability benefits. However, due to strong vertical thermal correlation and increased power density, thermal challenges in 3D-MPSoC are critical. In this paper, we propose a novel thermal aware task scheduling technique that combine intelligent task mapping with DVFS to minimize the peak temperature of the system. Particularly, our approach leverages on the fundamental thermal characteristics of 3D architecture when mapping tasks to processing cores and employing DVFS at design time followed by a simple thermal optimization step at run time. Our experiments validate the efficiency of our approach in peak temperature minimization up to 14°C compared to other existing methods. © 2014 IEEE.