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#### On the transmission strategies for the two-user state-dependent gaussian interference channel

, Article Proceedings of the International Symposium on Wireless Communication Systems ; Aug , 2013 , Pages 224-228 ; 21540217 (ISSN) ; 9783800735297 (ISBN) ; Behroozi, H ; Sharif University of Technology
IEEE Computer Society
2013

Abstract

In this paper, we study a general additive state-dependent Gaussian interference channel (ASD-GIC) where we consider two-user interference channel with two independent states known non-causally at both transmitters, but unknown to either of the receivers. A special case, where there is a common additive state is studied in [1], [2], where it is shown that the gap between the achievable symmetric rate and the upper bound is less than 1 /4 bits for the strong interference case. Here, we also consider the case where interference link gains satisfy a12 ≥ N1/ N2 and a 21 ≥ N2/ N1 (Ni is the channel noise variance) and each channel state has an unbounded variance [3], which is referred to as the...

#### Cooperative relay cognitive interference channel

, Article Proceedings 2010 IEEE International Conference on Information Theory and Information Security, ICITIS 2010, 17 December 2010 through 19 December 2010, Beijing ; 2010 , Pages 1064-1069 ; 9781424469406 (ISBN) ; Aref, M. R ; Ahmadian Attari, M ; Sharif University of Technology
2010

Abstract

The cooperative relay cognitive interference channel (RCIC) is a four-node network with two source nodes (primary source and cognitive source) and two destination nodes, in which sources try to communicate at certain rates with their corresponding destinations simultaneously through a common medium and each destination can act as a relay to assist the other one. For the partially cooperative RCIC (PC-RCIC), in which only one of the destinations (corresponding to the cognitive source) acts as a relay, we derive an achievable rate region based on using rate splitting and superposition coding at the cognitive source, and using decode-and-forward scheme at the relay. For the degraded PC-RCIC, we...

#### Multiple access channel with common message and secrecy constraint

, Article IET Communications ; Volume 10, Issue 1 , 2016 , Pages 98-110 ; 17518628 (ISSN) ; Akhbari, B ; Ahmadian Attari, M ; Aref, M. R ; Sharif University of Technology
Institution of Engineering and Technology

Abstract

The authors study the problem of secret communication over a multiple-access channel with a common message. Here, the authors assume that two transmitters have confidential messages, which must be kept secret from the wiretapper (the second receiver), and both of them have access to a common message which can be decoded by the two receivers. The authors call this setting as multiple-access wiretap channel with common message (MAWC-CM). For this setting, the authors derive general inner and outer bounds on the secrecy capacity region for the discrete memoryless case and show that these bounds meet each other for a special case called the switch channel. As well, for a Gaussian version of...

#### Pairwise secret key agreement using the source common randomness

, Article Proceedings of the International Symposium on Wireless Communication Systems, 28 August 2012 through 31 August 2012 ; Aug , 2012 , Pages 751-755 ; 21540217 (ISSN) ; 9781467307604 (ISBN) ; Skoglund, M ; Salmasizadeh, M ; Aref, M. R ; Sharif University of Technology
2012

Abstract

A secret key agreement setup between three users is considered in which each pair of them wishes to agree on a secret key hidden from the remaining user. The three users observe i.i.d. outputs of correlated sources and there is a noiseless public channel from each user for communication to the others. In this setup, inner and outer bounds of the secret key capacity region is derived. Moreover, some special cases are obtained in which the inner bound coincides the explicit outer bound. Also a binary-erasure example is presented through which the results are examined

#### Coordination via a relay

, Article IEEE International Symposium on Information Theory - Proceedings ; 2012 , Pages 3048-3052 ; 9781467325790 (ISBN) ; Yassaee, M. H ; Gohari, A ; Aref, M. R ; Sharif University of Technology
IEEE
2012

Abstract

In this paper, we study the problem of coordinating two nodes which can only exchange information via a relay at limited rates. The nodes are allowed to do a two-round interactive two-way communication with the relay, after which they should be able to generate i.i.d. copies of two random variables with a given joint distribution within a vanishing total variation distance. We prove inner and outer bounds on the coordination capacity region for this problem. Our inner bound is proved using the technique of "output statistics of random binning" that has recently been developed by Yassaee, et al

#### The capacity region of a class of 3-receiver broadcast channels with two eavesdroppers

, Article IEEE International Symposium on Information Theory - Proceedings, 31 July 2011 through 5 August 2011 ; August , 2011 , Pages 968-972 ; 21578104 (ISSN) ; 9781457705953 (ISBN) ; Aref, M. R ; Sharif University of Technology
2011

Abstract

In this paper, we consider the 3-receiver broadcast channel with one common and two confidential messages. One of the confidential messages is sent to the first and second receivers and kept secret from the third receiver (eavesdropper). The other confidential message is sent to the first receiver and kept secret from the second and third receivers (eavesdroppers). The common message is decoded by all receivers. We study some special cases of the model and determine their secrecy capacity regions

#### On the capacity region of the degraded Z channel

, Article ; 2010 IEEE Information Theory Workshop, ITW 2010 - Proceedings, 30 August 2010 through 3 September 2010 , 2010 ; 9781424482641 (ISBN) ; Aref, M. R ; Sharif University of Technology
Abstract

In this paper, we consider the two-user Z Channel (ZC). There are two senders and two receivers in the model. One of the senders transmits information to its intended receiver, while the other sender transmits information to both receivers. We establish a new achievable rate region for the ZC, using Marton's binning technique. At the receivers, we use joint decoding strategy. To illustrate the tightness of the proposed inner bound, we consider the degraded ZC which was first introduced by Chong et. al. We then characterize the capacity region of this type of degraded ZC

#### An outer bound on the capacity region of Broadcast-Relay-Channel

, Article IEEE International Symposium on Information Theory - Proceedings, 13 June 2010 through 18 June 2010, Austin, TX ; 2010 , Pages 599-603 ; 21578103 (ISSN) ; 9781424469604 (ISBN) ; Ghabeli, L ; Aref, M. R ; Sharif University of Technology
2010

Abstract

In this paper, we obtain an outer bound on the capacity region of the Broadcast-Relay-Channel (BRC). BRC is a four node network with one source, one relay and two destinations. To the best of our knowledge, this work represents the first effort to find an outer bound on the capacity region of the BRC. In the proof, we jointly utilize the ideas of the outer bounds on the Broadcast Channel (BC) and also the cut-set bound. The proposed outer bound looks like the inner bound obtained by Kramer et. al for BRC

#### The capacity region of the parallel partially cooperative relay broadcast channel with unmatched degraded subchannels

, Article 2009 IEEE International Symposium on Information Theory, ISIT 2009, Seoul, 28 June 2009 through 3 July 2009 ; 2009 , Pages 189-193 ; 21578102 (ISSN); 9781424443130 (ISBN) ; Mirmohseni, M ; Akhbari, B ; Firouzi, H ; Aref, M. R ; Sharif University of Technology
2009

Abstract

We investigate the parallel partially cooperative relay broadcast channel with unmatched degraded subchannels. We characterize the capacity region of this channel in the general setting that, transmitter sends a common message for both users and a private message for each of them. Our achievability result is based on the choosing appropriate parameters for the general achievable rate region of partially cooperative relay broadcast channel. We provide a converse proof for this achievable region as well, which establishes the capacity region.© 2009 IEEE

#### Key agreement over multiple access channel using feedback channel

, Article IEEE International Symposium on Information Theory - Proceedings, 31 July 2011 through 5 August 2011 ; August , 2011 , Pages 1970-1974 ; 21578104 (ISSN) ; 9781457705953 (ISBN) ; Salmasizadeh, M ; Aref, M. R ; Sharif University of Technology
2011

Abstract

In this paper, the effect of using an insecure and noiseless feedback channel in increasing secret key rates is investigated. There is a generalized discrete memoryless multiple access channel (GDMMAC) between two transmitters and a receiver where, in addition to the receiver, both of the transmitters receive noisy channel outputs. Furthermore, an insecure and noiseless feedback channel exists from the receiver to the transmitters. Each of the transmitters intends to share a secret key with the receiver while keeping it concealed from the other transmitter. For this setup, an inner bound of the secret key capacity region is derived. For some special cases, the secret key capacity region is...

#### A new secret key agreement scheme in a four-terminal network

, Article 12th Canadian Workshop on Information Theory, CWIT 2011, 17 May 2011 through 20 May 2011 ; May , 2011 , Pages 151-154 ; 9781457707438 (ISBN) ; Salimi, S ; Aref, M. R ; IEEE; Canadian Society of Information Theory (CSIT); UBC; Faculty of Applied Science; RIM ; Sharif University of Technology
2011

Abstract

A new scenario for simultaneously generating a secret key and two private keys among three Terminals in the presence of an external eavesdropper is considered. Terminals 1, 2 and 3 intend to share a common secret key concealed from the external eavesdropper (Terminal 4) and simultaneously, each of Terminals 1 and 2 intends to share a private key with Terminal 3 while keeping it concealed from each other and from Terminal 4. All four Terminals observe i.i.d. outputs of correlated sources and there is a public channel from Terminal 3 to Terminals 1 and 2. An inner bound of the secret key-private keys capacity region is derived and the single letter capacity regions are obtained for some...

#### Dynamic index coding gain over a complete bi-directional side information graph

, Article IWCIT 2016 - Iran Workshop on Communication and Information Theory, 3 May 2016 through 4 May 2016 ; 2016 ; 9781509019229 (ISBN) ; Mojahedian, M. M ; Aref, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016

Abstract

Dynamic Index coding as a generalization of the traditional index coding problem, deals with transmission of some dynamic data flows in the presence of side information. For a dynamic index coding system, the set of average flow rates for which the system can be stable is named Code-Constraint Capacity region. In this paper, we identify the code-constraint capacity region for a dynamic index coding problem with complete bi-directional side information graph. Furthermore, we introduce the concept of Dynamic Index Coding Gain to quantify the improvement resulted from the dynamic index coding with respect to uncoded transmissions. We also provide some corollaries about system performance...

#### 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
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...

#### Empirical coordination in a triangular multiterminal network

, Article IEEE International Symposium on Information Theory - Proceedings ; 2013 , Pages 2149-2153 ; ISSN: 21578095 ; ISBN: 9781479904464 ; Bahrami, M ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
2013

Abstract

In this paper, we investigate the problem of the empirical coordination in a triangular multiterminal network. A triangular multiterminal network consists of three terminals where two terminals observe two external i.i.d correlated sequences. The third terminal wishes to generate a sequence with desired empirical joint distribution. For this problem, we derive inner and outer bounds on the empirical coordination capacity region. It is shown that the capacity region of the degraded source network and the inner and outer bounds on the capacity region of the cascade multiterminal network can be directly obtained from our inner and outer bounds. For a cipher system, we establish key distribution...

#### On the secrecy capacity of 3-receiver Broadcast Channel with causal states and conferencing

, Article IEEE International Symposium on Information Theory - Proceedings ; 2012 , Pages 1167-1171 ; 9781467325790 (ISBN) ; Aref, M. R ; Sharif University of Technology
IEEE
2012

Abstract

We investigate the secrecy capacity region of 2-receiver, 1-eavesdropper Broadcast Channel (BC) with two causal states and conferencing decoders. The encoder sends two messages, one of them for both legitimate receivers and the other one for the first legitimate receiver. It keeps these messages secret from the eavesdropper. Each state is causally available at the corresponding receiver, while both states are known causally at the encoder. Each receiver wishes to send the state which is not available at the other receiver, through a noiseless link with limited capacity. We find an inner bound on the secrecy capacity region of this channel. The achievability scheme employs block Markov coding...

#### Multiple access channel with correlated channel states and cooperating encoders

, Article 2011 IEEE Information Theory Workshop, ITW 2011 ; 2011 , Pages 628-632 ; 9781457704376 (ISBN) ; Emadi, M. J ; Chaharsooghi, F. S ; Aref, M. R ; Sharif University of Technology
Abstract

In this paper, a two-user discrete memoryless multiple-access channel (DM-MAC) with correlated channel states, each known at one of the encoders is considered, in which each encoder transmits independent messages and tries to cooperate with the other one. To consider cooperating encoders, it is assumed that each encoder strictly-causally receives and learns the other encoder's transmitted symbols and tries to cooperate with the other encoder by transmitting its message. Next, we study this channel in a special case; we assume that the common part of both states is known at both, hence encoders use this opportunity to get better rate region. For these scenarios, an achievable rate region is...

#### Cooperative relay cognitive interference channels with causal channel state information

, Article Proceedings 2010 IEEE International Conference on Information Theory and Information Security, ICITIS 2010, 17 December 2010 through 19 December 2010 ; December , 2010 , Pages 1070-1075 ; 9781424469406 (ISBN) ; Mirmohseni, M ; Aref, M. R ; Sharif University of Technology
2010

Abstract

The cooperative relay cognitive interference channel (RCIC) is a four-node network with two source nodes (primary source and cognitive source) and two destination nodes, in which sources try to communicate at certain rates with their corresponding destinations simultaneously through a common medium and each destination can act as a relay to assist the other one. In this paper, we study partially and fully cooperative state-dependent relay cognitive interference channels (RCICs) with perfect causal channel state information (CSI). For each of these channels, we investigate three different cases. For the first case, perfect causal CSI is available at both the source and relay nodes; for the...

#### On the capacity region of a class of Z channels with cooperation

, Article ISITA/ISSSTA 2010 - 2010 International Symposium on Information Theory and Its Applications, 17 October 2010 through 20 October 2010 ; October , 2010 , Pages 464-468 ; 9781424460175 (ISBN) ; Aref, M. R ; Sharif University of Technology
2010

Abstract

In this paper, we consider Z Channel (ZC) with cooperation, where there are two senders and two receivers. The first sender transmits information to both receivers and also to the second sender. The first receiver and the second sender cooperate with the first sender in sending messages to the second receiver. The second sender transmits information only to its intended receiver. We first establish an achievable rate region for the general cooperative ZC. The coding scheme is based on rate splitting technique. At the receivers, we use joint decoding strategy. To illustrate the tightness of the proposed inner bound, we define degraded cooperative ZC. We derive an outer bound to the capacity...

#### On the Capacity of Information Networks Utilizing Cognition and Cooperative Strategies

, Ph.D. Dissertation Sharif University of Technology ; Aref, Mohammad Reza (Supervisor)
Abstract

Interference management is one of the key issues in wireless networks wherein multiple source-destination pairs share the same medium and frequency band and interfere with each other. The exponentially growth in the number of wireless systems and services results in the spectrum shortage which has emerged the technologies that increase the spectral eﬃciency. Providing the users with cognition equipments in these networks enables them to sense the medium and use the obtained data to adapt their transmissions to cooperate with other users and improve their own rates as well as the others which results in the cognitive radio technology. In order to access the full potential of this technology,...

#### Analysis of Secret Key Agreement in The Channel Model with Side Information

, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor)
Abstract

In this thesis, the problem of secret key agreement in the channel model with side information is studiedx. In order to investigate the problem, we consider three models according to the different ways of side information availability which are the state-dependent broadcast channel; the state-dependent broadcast channel in presence of public channel and the state-dependent wiretap channel with degraded versions of the channel state information.For the problem of secret key agreement in broadcast channels, two models, the state-dependent wiretap channel and state-dependent three receivers broadcast channel, are considered. We obtain inner and outer bounds of the secret key capacity region for...