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On marton's inner bound for the general broadcast channel
, Article IEEE Transactions on Information Theory ; Volume 60, Issue 7 , 2014 , Pages 3748-3762 ; ISSN: 00189448 ; Gamal, A. E ; Anantharam, V ; Sharif University of Technology
2014
Abstract
We establish several new results on Marton's inner bound on the capacity region of the general broadcast channel. Inspired by the fact that Marton's coding scheme without superposition coding is optimal in the Gaussian case, we consider the class of binary input degraded broadcast channels with no common message that have the same property. We characterize this class. We also establish new properties of Marton's inner bound that help restrict the search space for computing the Marton sum rate. In particular, we establish an extension of the XOR case of the binary inequality of Nair, Wang, and Geng
Infeasibility proof and information state in network information theory
, Article IEEE Transactions on Information Theory ; Vol. 60, Issue. 10 , 2014 , Pages 5992-6004 ; ISSN: 00189448 ; Anantharam, V ; Sharif University of Technology
2014
Abstract
In this paper, we revisit the structure of infeasibility results in network information theory, based on a notion of information state. We also discuss ideas for generalizing a known outer bound for lossless transmission of independent sources over a network to one of lossy transmission of dependent sources over the same network. To concretely demonstrate this, we apply our ideas and prove new results for lossy transmission of dependent sources by generalizing: 1) the cut-set bound; 2) the best known outer bound on the capacity region of a general broadcast channel; and 3) the outer bound part of the result of Maric, Yates, and Kramer on strong interference channels with a common message
Comments on 'Information-Theoretic Key Agreement of Multiple Terminals - Part I'
, Article IEEE Transactions on Information Theory ; Volume 63, Issue 8 , 2017 , Pages 5440-5442 ; 00189448 (ISSN) ; Anantharam, V ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Theorem 5 of A. Gohari, V. Anantharam, IEEE Transactions on Information Theory, vol. 56, no. 8, pp. 3973-3996, 2010, states an upper bound on the secrecy capacity for the source model problem. It has a three page proof given in Appendix B of the paper. Unfortunately, we show that this bound does not provide any improvement over the simpler bound given in Corollary 1 of the paper. We also provide an example of a family of two agent source model problems where the one-way secrecy rate in each direction is zero, but the secrecy rate is nonzero and can be determined exactly as a conditional mutual information. © 1963-2012 IEEE
Generating dependent random variables over networks
, Article 2011 IEEE Information Theory Workshop, ITW 2011 ; 2011 , Pages 698-702 ; 9781457704376 (ISBN) ; Anantharam, V ; Sharif University of Technology
2011
Abstract
In this paper we study the problem of generation of dependent random variables, known as the coordination capacity [4], [5], in multiterminal networks. In this model m nodes of the network are observing i.i.d. repetitions of X (1), X (2),⋯, X (m) distributed according to q(x (1),⋯, x (m)). Given a joint distribution q(x (1),⋯,x (m), y (1), ⋯, y (m)), the final goal of the i th node is to construct the i.i.d. copies of Y (i) after the communication over the network where X (1), X (2),⋯, X (m), Y (1), Y (2),⋯, Y (m) are jointly distributed according to q(x (1), , x (m), y (1),⋯,y (m)). To do this, the nodes can exchange messages over the network at rates not exceeding the capacity constraints...
Critical graphs in index coding
, Article IEEE International Symposium on Information Theory - Proceedings ; 2014 , p. 281-285 ; Shahrasbi, A ; Gohari, A ; Sharif University of Technology
2014
Abstract
In this paper we define critical graphs as minimal graphs that support a given set of rates for the index coding problem, and study them for both the one-shot and asymptotic setups. For the case of equal rates, we find the critical graph with minimum number of edges for both one-shot and asymptotic cases. For the general case of possibly distinct rates, we show that for one-shot and asymptotic linear index coding, as well as asymptotic non-linear index coding, each critical graph is a union of disjoint strongly connected subgraphs (USCS). On the other hand, we identify a non-USCS critical graph for a one-shot non-linear index coding problem. In addition, we show that the capacity region of...
When is it possible to simulate a DMC channel from another?
, Article 2013 IEEE Information Theory Workshop, ITW 2013 ; Sept , 2013 , Page(s): 1 - 5 ; 9781479913237 (ISBN) ; Yassaee, M. H ; Aref, M. R ; Gohari, A
2013
Abstract
In this paper, we study the problem of simulating a DMC channel from another DMC channel. We assume that the input to the channel we are simulating is i.i.d. and that the transmitter and receivers are provided with common randomness at limited rates. We prove bounds for simulating point-to-point, MAC and broadcast channels. As a special case, we recover the achievability part of the result of Cuff for point-to-point channel simulation via a noiseless link and shared randomness
On Marton's inner bound for broadcast channels
, Article IEEE International Symposium on Information Theory - Proceedings, 1 July 2012 through 6 July 2012 ; July , 2012 , Pages 581-585 ; 9781467325790 (ISBN) ; Nair, C ; Anantharam, V ; Sharif University of Technology
2012
Abstract
Marton's inner bound is the best known achievable region for a general discrete memoryless broadcast channel. To compute Marton's inner bound one has to solve an optimization problem over a set of joint distributions on the input and auxiliary random variables. The optimizers turn out to be structured in many cases. Finding properties of optimizers not only results in efficient evaluation of the region, but it may also help one to prove factorization of Marton's inner bound (and thus its optimality). The first part of this paper formulates this factorization approach explicitly and states some conjectures and results along this line. The second part of this paper focuses primarily on the...
Deterministic randomness extraction from generalized and distributed santha-vazirani sources
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 6 July 2015 through 10 July 2015 ; Volume 9134 , 2015 , Pages 143-154 ; 03029743 (ISSN) ; 9783662476710 (ISBN) ; Etesami, O ; Gohari, A ; Sharif University of Technology
Springer Verlag
2015
Abstract
A Santha-Vazirani (SV) source is a sequence of random bits where the conditional distribution of each bit, given the previous bits, can be partially controlled by an adversary. Santha and Vazirani show that deterministic randomness extraction from these sources is impossible. In this paper, we study the generalization of SV sources for nonbinary sequences. We show that unlike the binary case, deterministic randomness extraction in the generalized case is sometimes possible. We present a necessary condition and a sufficient condition for the possibility of deterministic randomness extraction. These two conditions coincide in “non-degenerate” cases. Next, we turn to a distributed setting. In...
The value of information-theoretic content of help bits for computation
, Article IWCIT 2015 - Iran Workshop on Communication and Information Theory, 6 May 2015 through 7 May 2015 ; 2015 ; 9781479982356 (ISBN) ; Etesami, O ; Gohari, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
'Help bits' are some limited trusted information about an instance or instances of a computational problem that may reduce the computational complexity of solving that instance or instances. Assume that we can efficiently solve k instances of a decision problem using some help bits whose entropy is less than k when the k instances are drawn independently from a particular distribution. Then there is an upper bound on the average-case complexity of the problem, namely we can efficiently solve an instance drawn from that distribution correctly with probability better than 1/2
The value of help bits in randomized and average-case complexity
, Article Computational Complexity ; Volume 26, Issue 1 , 2017 , Pages 119-145 ; 10163328 (ISSN) ; Etesami, O ; Gohari, A ; Sharif University of Technology
Birkhauser Verlag AG
2017
Abstract
“Help bits" are some limited trusted information about an instance or instances of a computational problem that may reduce the computational complexity of solving that instance or instances. In this paper, we study the value of help bits in the settings of randomized and average-case complexity. If k instances of a decision problem can be efficiently solved using ℓ< k help bits, then without access to help bits one can efficiently compute a k-bit vector that is not equal to the k-bit vector of solutions to the k instances. A decision problem with this property is called k-membership comparable. Amir, Beigel, and Gasarch (1990) show that for constant k, all k-membership comparable languages...
Deterministic randomness extraction from generalized and distributed Santha-Vazirani sources
, Article SIAM Journal on Computing ; Volume 46, Issue 1 , 2017 , Pages 1-36 ; 00975397 (ISSN) ; Etesami, O ; Gohari, A ; Sharif University of Technology
Society for Industrial and Applied Mathematics Publications
2017
Abstract
A Santha-Vazirani (SV) source is a sequence of random bits where the conditional distribution of each bit, given the previous bits, can be partially controlled by an adversary. Santha and Vazirani show that deterministic randomness extraction from these sources is impossible. In this paper, we study the generalization of SV sources for nonbinary sequences. We show that unlike the binary setup of Santha and Vazirani, deterministic randomness extraction in the generalized case is sometimes possible. In particular, if the adversary has access to s "nondegenerate" dice that are c-sided and can choose one die to throw based on the previous realizations of the dice, then deterministic randomness...
How compressible are innovation processes?
, Article IEEE Transactions on Information Theory ; Volume 64, Issue 7 , 2018 , Pages 4843-4871 ; 00189448 (ISSN) ; Amini, A ; Gohari, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
The sparsity and compressibility of finite-dimensional signals are of great interest in fields, such as compressed sensing. The notion of compressibility is also extended to infinite sequences of independent identically distributed or ergodic random variables based on the observed error in their nonlinear $k$ -term approximation. In this paper, we use the entropy measure to study the compressibility of continuous-domain innovation processes (alternatively known as white noise). Specifically, we define such a measure as the entropy limit of the doubly quantized (time and amplitude) process. This provides a tool to compare the compressibility of various innovation processes. It also allows us...
Power control to enable QoS for indoor wireless infrared CDMA networks
, Article HUT-ICCE 2006 1st International Conference on Communications and Electronics, Hanoi, 10 October 2006 through 11 October 2006 ; Volume PART 1 , 2006 , Pages 246-252 ; 1424405688 (ISBN); 9781424405688 (ISBN) ; Pakravan, M. R ; Sharif University of Technology
2006
Abstract
Wireless infrared optical CDMA (W-OCDMA) is a new developing technique with some useful applications. Control and efficient use of optical power is a key issue in analysis and design of these systems. Also, multi user interference is a major source if impairment in these system. As a result, power control is a key issue in design and implementation of these systems. In this article we investigate a Dynamic Resource Management Algorithm (DRMA) as a framework, which employs power control to enable QoS in terms of reliability for multimedia traffic in W-OCDMA networks using Optical Orthogonal Codes (OOC's). A numerical method is also proposed to overcome computational difficulties of call...
Analysis of power control for indoor wireless infrared CDMA communication
, Article 25th IEEE International Performance, Computing, and Communications Conference, 2006, IPCCC 2006, Phoenix, AZ, 10 April 2006 through 12 April 2006 ; Volume 2006 , 2006 , Pages 297-302 ; 1424401976 (ISBN); 9781424401970 (ISBN) ; Pakravan, M. R ; Sharif University of Technology
2006
Abstract
we study the uplink performance of wireless infrared code-division multiple access (CDMA) networks using OOK with optical orthogonal codes (OOC's). The analysis is performed in two cases assuming a cellular network architecture, in which all users are uniformly distributed in the cell's area. The first case is when all users transmit with the same power and no power control mechanism is used. Then, the system that deploys power control mechanism is analyzed and the performance improvements are demonstrated. The impact of imperfect power control which is caused by errors in channel estimation is also analyzed and the analytical and numerical results for all cases are included. The results...
Synthesis and Study of Catalytic Activity of[Ru(oxazine)2(EtOH)2]Cl complex in epoxidation of Olefins and Oxidation of Alkanes, Alcohol and Sulfide with TBHP and UHP
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
Ruthenium complexes with their wide range of stable but chemically accessible oxidation states have been extensively studied as catalyst of hydrocarbon oxidation. In recent years, these complexes with various ligands have been reported as new catalysts with better selectivity and several co-oxidations. Ruthenium complexes act as oxidation catalyst, often via ruthenium-oxo species as active intermediates in the oxygen transfer process, oxidizing alcohols or alkanes and epoxidizing alkane. Here, we reported the synthesis and catalytic activity of a ruthenium(III) complex with bidentate oxazine ligand. The new synthesized Ru(III)-oxazine complex was characterized by IR and UV-Vis spectra and...
The Effect of Shock and Vibration Loads on Disconnection and Fluctuations of Electrical Current in Connectors
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mehdi (Supervisor)
Abstract
Electrical connectors that used in high speed systems interrupt the connection at the effect of Inertia. Also connectors should be able to work in high vibration conditions without any problems. Vibration of the connector pins can reduce the contact area or even remove it at very short time intervals, which lead to increase connector resistance or disconnection of instantaneous current. These current fluctuations will result in unpredictable performance disturbanceof the electrical system in very sensitive systems and therefore it should be avoided. In this Project, impacts of shock and vibration loads on the connectors is modeled by using FEM and with consideration of this model, connection...
Thermal Management in Fault-Tolerant Mixed-Criticality Multicore Systems
, M.Sc. Thesis Sharif University of Technology ; Hessabi, Shahin (Supervisor)
Abstract
The increasing complexity of embedded systems has led to the integration of tasks with various degrees of criticality on a common hardware platform called a mixed-criticality system. These systems typically exploit the inherent redundancy of multicore systems to employ the fault-tolerant techniques to satisfy the required target reliability. On the other hand, the use of fault-tolerant techniques increases the time that cores are simultaneously active with maximum power, which can violate the thermal design power (TDP) and exceed the safe temperature of the chip. This activates the dynamic thermal manage- ment (DTM) technique. Some of the most well-known methods to reduce the chip surface...
Beyond the cut-set bound: Uncertainty computations in network coding with correlated sources
, Article IEEE Transactions on Information Theory ; Volume 59, Issue 9 , 2013 , Pages 5708-5722 ; 00189448 (ISSN) ; Yang, S ; Jaggi, S ; Sharif University of Technology
2013
Abstract
Cut-set bounds are not, in general, tight for all classes of network communication problems. In this paper, we introduce a new technique for proving converses for the problem of transmission of correlated sources in networks, which results in bounds that are tighter than the corresponding cut-set bounds. We also define the concept of 'uncertainty region' which might be of independent interest. We provide a full characterization of this region for the case of two correlated random variables. The bounding technique works as follows: on one hand, we show that if the communication problem is solvable, the uncertainty of certain random variables in the network with respect to imaginary parties...
Beyond the cut-set bound: Uncertainty computations in network coding with correlated sources
, Article IEEE International Symposium on Information Theory - Proceedings, 31 July 2011 through 5 August 2011 ; July , 2011 , Pages 598-602 ; 21578104 (ISSN) ; 9781457705953 (ISBN) ; Yang, S ; Jaggi, S ; Sharif University of Technology
2011
Abstract
Cut-set bounds on achievable rates for network communication protocols are not in general tight. In this paper we introduce a new technique for proving converses for the problem of transmission of correlated sources in networks, that results in bounds that are tighter than the corresponding cut-set bounds. We also define the concept of "uncertainty region" which might be of independent interest. We provide a full characterization of this region for the case of two correlated random variables. The bounding technique works as follows: on one hand we show that if the communication problem is solvable, the uncertainty of certain random variables in the network with respect to imaginary parties...
Family of interleaved high step-up DC-DC converters utilizing multi-winding coupled inductors
, Article 13th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2022, 1 February 2022 through 3 February 2022 ; 2022 , Pages 555-560 ; 9781665420433 (ISBN) ; Tarzamni, H ; Sabahi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This paper proposes a family of interleaved DC-DC converters for high step-up applications based on multi-winding coupled inductors, which utilize inductive and capacitive approaches to transfer the input energy to the output load. The wide output load voltage level of the proposed converter depends on the switches duty cycle and the coupled inductor (CI) turns ratio. As some features, interleaving and cascading help the converters achieve high output voltage gain, low input current ripple, low-volume input inductor, and high reliability. Moreover, employing multi-winding coupled inductors improves output voltage gain, recycles the magnetic components stored energy, cancels circulating...