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19
Degraded Compound Multireceiver Wiretap Channels
, 2009
"... In this paper, we study the degraded compound multireceiver wiretap channel. The degraded compound multireceiver wiretap channel consists of two groups of users and a group of eavesdroppers, where, if we pick an arbitrary user from each group of users and an arbitrary eavesdropper, they satisfy a ..."
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Cited by 22 (11 self)
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In this paper, we study the degraded compound multireceiver wiretap channel. The degraded compound multireceiver wiretap channel consists of two groups of users and a group of eavesdroppers, where, if we pick an arbitrary user from each group of users and an arbitrary eavesdropper, they satisfy a certain Markov chain. We study two different communication scenarios for this channel. In the first scenario, the transmitter wants to send a confidential message to users in the first (stronger) group and a different confidential message to users in the second (weaker) group, where both messages need to be kept confidential from the eavesdroppers. For this scenario, we assume that there is only one eavesdropper. We obtain the secrecy capacity region for the general discrete memoryless channel model, the parallel channel model, and the Gaussian parallel channel model. For the Gaussian multipleinput multipleoutput (MIMO) channel model, we obtain the secrecy capacity region when there is only one user in the second group. In the second scenario we study, the transmitter sends a confidential message to users in the first group which needs to be kept confidential from the second group of users and the eavesdroppers. Furthermore, the transmitter sends a different confidential message to users in the second group which needs to be kept confidential only from the eavesdroppers. For this scenario, we do not put any restriction on the number of eavesdroppers. As in the first scenario, we obtain the secrecy capacity region for the general discrete memoryless channel model, the parallel channel model, and the Gaussian parallel channel model. For the Gaussian MIMO channel model, we establish the secrecy capacity region when there is only one user in the second group.
Achievability proof via output statistics of random binning
 in Proc. IEEE Int. Symp. Inform. Theory (ISIT), 2012
"... This paper introduces a new and ubiquitous framework for establishing achievability results in network information theory (NIT) problems. The framework uses random binning arguments and is based on a duality between channel and source coding problems. Further, the framework uses pmf approximation ar ..."
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Cited by 18 (6 self)
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This paper introduces a new and ubiquitous framework for establishing achievability results in network information theory (NIT) problems. The framework uses random binning arguments and is based on a duality between channel and source coding problems. Further, the framework uses pmf approximation arguments instead of counting and typicality. This allows for proving coordination and strong secrecy problems where certain statistical conditions on the distribution of random variables need to be satisfied. These statistical conditions include independence between messages and eavesdropper’s observations in secrecy problems and closeness to a certain distribution (usually, i.i.d. distribution) in coordination problems. One important feature of the framework is to enable one to add an eavesdropper and obtain a result on the secrecy rates “for free.” We make a case for generality of the framework by studying examples in the variety of settings containing channel coding, lossy source coding, joint sourcechannel coding, coordination, strong secrecy, feedback and relaying. In particular, by investigating the framework for the lossy source coding problem over broadcast channel, it is shown that the new framework provides a simple alternative scheme to hybrid coding scheme. Also, new results on secrecy rate region (under strong secrecy criterion) of wiretap broadcast channel and wiretap relay channel are derived. In a set of accompanied papers, we have shown the usefulness of the framework to establish achievability results for coordination problems including interactive channel simulation, coordination via relay and channel simulation via another channel. Index terms — Random binning, achievability, network information theory, strong secrecy, duality. 1
Wiretap Channel with Causal State Information
"... Abstract—A lower bound on the secrecy capacity of the wiretap channel with state information available causally at both the encoder and decoder is established. The lower bound is shown to be strictly larger than that for the noncausal case by Liu and Chen. Achievability is proved using block Markov ..."
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Abstract—A lower bound on the secrecy capacity of the wiretap channel with state information available causally at both the encoder and decoder is established. The lower bound is shown to be strictly larger than that for the noncausal case by Liu and Chen. Achievability is proved using block Markov coding, Shannon strategy, and key generation from common state information. The state sequence available at the end of each block is used to generate a key, which is used to enhance the transmission rate of the confidential message in the following block. An upper bound on the secrecy capacity when the state is available noncausally at the encoder and decoder is established and is shown to coincide with the lower bound for several classes of wiretap channels with state. I.
Gamal, “Threereceiver broadcast channels with common and confidential messages
 IEEE Transactions on Information Theory
, 2012
"... Abstract—This paper establishes inner bounds on the secrecy capacity regions for the general threereceiver broadcast channel with one common and one confidential message sets. We consider two setups. The first is when the confidential message is to be sent to two receivers and kept secret from the ..."
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Cited by 11 (0 self)
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Abstract—This paper establishes inner bounds on the secrecy capacity regions for the general threereceiver broadcast channel with one common and one confidential message sets. We consider two setups. The first is when the confidential message is to be sent to two receivers and kept secret from the third receiver. Achievability is established using indirect decoding, Wyner wiretap channel coding, and the new idea of generating secrecy from a publicly available superposition codebook. The inner bound is shown to be tight for a class of reversely degraded broadcast channels and when both legitimate receivers are less noisy than the third receiver. The second setup investigated in this paper is when the confidential message is to be sent to one receiver and kept secret from the other two receivers. Achievability in this case follows from Wyner wiretap channel coding and indirect decoding. This inner bound is also shown to be tight for several special cases. Index Terms—Secrecy capacity regions, threereceiver broadcast channels, wiretap channels. I.
SecretKey Agreement With Channel State Information at the Transmitter
"... Abstract We study the capacity of secretkey agreement over a wiretap channel with state parameters. The transmitter, the legitimate receiver, and the eavesdropper are connected by a discrete memoryless wiretap channel with a memoryless statesequence. The transmitter and the legitimate receiver gene ..."
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Cited by 9 (1 self)
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Abstract We study the capacity of secretkey agreement over a wiretap channel with state parameters. The transmitter, the legitimate receiver, and the eavesdropper are connected by a discrete memoryless wiretap channel with a memoryless statesequence. The transmitter and the legitimate receiver generate a secretkey that must be concealed from the eavesdropper. We assume that the state sequence is known noncausally to the transmitter and no public discussion channel is available.Wederivelowerand upper bounds on the secretkey capacity. The lower bound involves a sourcechannel codebook for constructing a common reconstruction sequence at the legitimate terminals and then mapping this sequence to a secretkey using a secretkey codebook. For the special case of Gaussian channels with additive interference (secretkeys from dirty paper channel) ourboundsdiffer by 0.5 bit/symbol and coincide in the high signaltonoiseratio and high interferencetonoiseratio regimes. In another special case symmetric channel state information (CSI) when the legitimate receiver is also revealed the state sequence, we establish optimality of our lower bound. In addition, only causal side information at the transmitter and the receiver suf�ces to attain the secretkey capacity in the case of symmetric CSI. Index Terms Channel reciprocity, channels with state parameters, fading channels, informationtheoretic security, secretkey generation, secret sharing, wireless channels, wiretap channels. I.
Is NonUnique Decoding Necessary?
"... Abstract—In mutiterminal communication systems, signals carrying messages meant for different destinations are often observed together at any given destination receiver. Han and Kobayashi (1981) proposed a receiving strategy which performs a joint unique decoding of messages of interest along with a ..."
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Abstract—In mutiterminal communication systems, signals carrying messages meant for different destinations are often observed together at any given destination receiver. Han and Kobayashi (1981) proposed a receiving strategy which performs a joint unique decoding of messages of interest along with a subset of messages which are not of interest. It is now wellknown that this provides an achievable region which is, in general, larger than if the receiver treats all messages not of interest as noise. Nair and El Gamal (2009) and Chong, Motani, Garg, and El Gamal (2008) independently proposed a generalization called indirect or nonunique decoding where the receiver uses the codebook structure of the messages to only uniquely decode its messages of interest. Indirect (nonunique) decoding has since been used in various scenarios. The main result in this paper is to provide an interpretation and a systematic proof technique for why indirect decoding, in all known cases where it has been employed, can be replaced by a particularly designed joint unique decoding strategy, without any penalty from a rate region viewpoint 1. I.
Secure Broadcasting Using Multiple Antennas
"... Abstract: We consider three different secure broadcasting scenarios: i) Broadcast channels with common and confidential messages (BCC), ii) multireceiver wiretap channels with public and confidential messages, and iii) compound wiretap channels. The BCC is a broadcast channel with two users, where ..."
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Cited by 7 (6 self)
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Abstract: We consider three different secure broadcasting scenarios: i) Broadcast channels with common and confidential messages (BCC), ii) multireceiver wiretap channels with public and confidential messages, and iii) compound wiretap channels. The BCC is a broadcast channel with two users, where in addition to the common message sent to both users, a private message, which needs to be kept hidden as much as possible from the other user, is sent to each user. In this model, each user treats the other user as an eavesdropper. The multireceiver wiretap channel is a broadcast channel with two legitimate users and an external eavesdropper, where the transmitter sends a pair of public and confidential messages to each legitimate user. Although there is no secrecy concern about the public messages, the confidential messages need to be kept perfectly secret from the eavesdropper. The compound wiretap channel is a compound broadcast channel with a group of legitimate users and a group of eavesdroppers. In this model, the transmitter sends a common confidential message to the legitimate users, and this confidential message needs to be kept perfectly secret from all eavesdroppers. In this paper, we provide a survey of the existing informationtheoretic results for these three forms of secure broadcasting problems, with a closer look at the Gaussian multipleinput multipleoutput (MIMO) channel models. We also present the existing results for the more general discrete memoryless channel models, as they are often the first step in obtaining the capacity results for the corresponding Gaussian MIMO channel models. Index Terms: Broadcast channels, information theoretic security, multiple antennas.
Capacity of compound statedependent channels with states known at the transmitter
 in Proc. IEEE International Symposium on Information Theory, Seoul, Korea
, 2009
"... Abstract—The problem of sending information over compound statedependent channels with noncausal state information available at only the transmitter is investigated. We prove a coding theorem and its strong converse establishing the capacity of this scenario for the case of discrete memoryless cha ..."
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Cited by 5 (1 self)
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Abstract—The problem of sending information over compound statedependent channels with noncausal state information available at only the transmitter is investigated. We prove a coding theorem and its strong converse establishing the capacity of this scenario for the case of discrete memoryless channels. Specific results are derived for additive white Gaussian noise channels corrupted by an additive Gaussian interference which is available at the transmitter only. We focus on the case where such interference may be absent on the channel, but the transmitter is unaware of this. Applications of the compound channels with noncausal state information arise in the context of multicast and cognitive radio channels, broadcast channels with imperfect channel knowledge and robust dirtypaper coding. I.
On Gaussian MIMO Compound Wiretap Channels
"... Abstract — We study the twouser oneeavesdropper discrete memoryless compound wiretap channel, where the transmitter sends a common confidential message to both users, which needs to be kept perfectly secret from the eavesdropper. We provide a new achievable secrecy rate which is shown to be potent ..."
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Abstract — We study the twouser oneeavesdropper discrete memoryless compound wiretap channel, where the transmitter sends a common confidential message to both users, which needs to be kept perfectly secret from the eavesdropper. We provide a new achievable secrecy rate which is shown to be potentially better than the best known lower bound for the secrecy capacity of this compound wiretap channel. We next consider the twouser oneeavesdropper Gaussian multipleinput multipleoutput (MIMO) compound wiretap channel. We obtain an achievable secrecy rate for the Gaussian MIMO compound wiretap channel by using dirtypaper coding (DPC) in the achievable scheme we provided for the discrete memoryless case. We show that the corresponding achievable secrecy rate achieves at least half of the secrecy capacity of the twouser oneeavesdropper Gaussian MIMO wiretap channel. We also obtain the secrecy capacity of the twouser oneeavesdropper Gaussian MIMO compound wiretap channel when the eavesdropper is degraded with respect to one of the two users. I.
A comparison of superposition coding schemes
 in Proc. IEEE Int. Symp. Inf. Theory
, 2013
"... Abstract—There are two variants of superposition coding schemes. Cover’s original superposition coding scheme has code clouds of identical shape, while Bergmans’s superposition coding scheme has code clouds of independently generated shapes. These two schemes yield identical achievable rate regions ..."
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Abstract—There are two variants of superposition coding schemes. Cover’s original superposition coding scheme has code clouds of identical shape, while Bergmans’s superposition coding scheme has code clouds of independently generated shapes. These two schemes yield identical achievable rate regions in several scenarios, such as the capacity region for degraded broadcast channels. This paper shows that under optimal decoding, these two superposition coding schemes can result in different rate regions. In particular, it is shown that for the tworeceiver broadcast channel, Cover’s scheme achieves a larger rate region than Bergmans’s scheme in general. I.