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110
Broadcast Channels with Cooperating Decoders
, 2006
"... We consider the problem of communicating over the general discrete memoryless broadcast channel (BC) with partially cooperating receivers. In our setup, receivers are able to exchange messages over noiseless conference links of finite capacities, prior to decoding the messages sent from the transmi ..."
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Cited by 60 (4 self)
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We consider the problem of communicating over the general discrete memoryless broadcast channel (BC) with partially cooperating receivers. In our setup, receivers are able to exchange messages over noiseless conference links of finite capacities, prior to decoding the messages sent from the transmitter. In this paper we formulate the general problem of broadcast with cooperation. We first find the capacity region for the case where the BC is physically degraded. Then, we give achievability results for the general broadcast channel, for both the two independent messages case and the single common message case.
On interference channels with generalized feedback
- In Proceedings of IEEE Int. Symp. on Inform. Theory, ISIT2007
, 2007
"... An Interference Channel with Generalized Feedback (IFC-GF) is a model for a wireless network where several source-destination pairs compete for the same channel resources, and where the sources have the ability to sense the current channel activity. The signal overheard from the channel provides inf ..."
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Cited by 48 (9 self)
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An Interference Channel with Generalized Feedback (IFC-GF) is a model for a wireless network where several source-destination pairs compete for the same channel resources, and where the sources have the ability to sense the current channel activity. The signal overheard from the channel provides information about the activity of the other users, and thus furnishes the basis for cooperation. In this two-part paper we study achievable strategies and outer bounds for a general IFC-GF with two source-destination pairs. We then evaluate the proposed regions for the Gaussian channel. Part I: Achievable Region. We propose that the generalized feedback is used to gain knowledge about the message sent by the other user and then exploited in two ways: (a) to relay the messages that can be decoded at both destinations–thus realizing the gains of beam-forming of a distributed multi-antenna system–and (b) to hide the messages that can not be decoded at the non-intended destination–thus leveraging the interference “pre-cancellation” property of dirty-paper-type coding. We show that our achievable region generalizes several known achievable regions for IFC-GF and that it reduces
Capacity of cognitive interference channels with and without secrecy,” submitted for publication
"... Abstract—Like the conventional two-user interference channel, the cognitive interference channel consists of two transmitters whose signals interfere at two receivers. It is assumed that there is a common message (message 1) known to both transmitters, and an additional independent message (message ..."
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Cited by 39 (6 self)
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Abstract—Like the conventional two-user interference channel, the cognitive interference channel consists of two transmitters whose signals interfere at two receivers. It is assumed that there is a common message (message 1) known to both transmitters, and an additional independent message (message 2) known only to the cognitive transmitter (transmitter 2). The cognitive receiver (receiver 2) needs to decode messages 1 and 2, while the noncognitive receiver (receiver 1) should decode only message 1. Furthermore, message 2 is assumed to be a confidential message which needs to be kept as secret as possible from receiver 1, which is viewed as an eavesdropper with regard to message 2. The level of secrecy is measured by the equivocation rate. In this paper, a single-letter expression for the capacity-equivocation region of the discrete memoryless cognitive interference channel is obtained. The capacity-equivocation region for the Gaussian cognitive interference channel is also obtained explicitly. Moreover, particularizing the capacity-equivocation region to the case without a secrecy constraint, the capacity region for the two-user cognitive interference channel is obtained, by providing a converse theorem. Index Terms—Capacity-equivocation region, cognitive communication, confidential messages, interference channel, rate splitting, secrecy capacity region. I.
About Priority Encoding Transmission
, 2000
"... Recently, Albanese et al. introduced Priority Encoding Transmission (pet) for sending hierarchically organized messages over lossy packet-based computer networks [1]. In a pet system, each symbol in the message is assigned a priority which determines the minimal number of codeword symbols that is re ..."
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Cited by 31 (0 self)
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Recently, Albanese et al. introduced Priority Encoding Transmission (pet) for sending hierarchically organized messages over lossy packet-based computer networks [1]. In a pet system, each symbol in the message is assigned a priority which determines the minimal number of codeword symbols that is required to recover that symbol. This note revisits the pet approach using tools from Network Information Theory. We rst outline that Priority Encoding Transmission is intimately related with the Broadcast Erasure Channel with Degraded Message Set. Using the information spectrum approach, we provide an informational characterization of the capacity region of general Broadcast Channels with Degraded Message Set. We show that the pet inequality has an information-theoretical counterpart: the inequality de ning the capacity region of the broadcast erasure channel with degraded message sets. Hence the pet approach which consists in timesharing and interleaving classical erasure resilient codes achieves the capacity region of this channel. Moreover, we show that the PET approach may achieve the sphere packing exponents. Finally we observe that on some simple non-stationary broadcast channels, time-sharing may be outperformed. The impact of memory on the optimality of the PET approach remains elusive.
Inner and outer bounds for the Gaussian cognitive interference channel and new capacity results
- IEEE Trans. Inf. Theory
"... Abstract—The capacity of the Gaussian cognitive interference channel, a variation of the classical two-user interference channel where one of the transmitters (referred to as cognitive) has knowl-edge of both messages, is known in several parameter regimes but remains unknown in general. This paper ..."
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Cited by 30 (13 self)
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Abstract—The capacity of the Gaussian cognitive interference channel, a variation of the classical two-user interference channel where one of the transmitters (referred to as cognitive) has knowl-edge of both messages, is known in several parameter regimes but remains unknown in general. This paper provides a comparative overview of this channel model as it proceeds through the following contributions. First, several outer bounds are presented: a) a new outer bound based on the idea of a broadcast channel with de-graded message sets, and b) an outer bound obtained by trans-forming the channel into channels with known capacity. Next, a compact Fourier–Motzkin eliminated version of the largest known inner bound derived for the discrete memoryless cognitive inter-ference channel is presented and specialized to the Gaussian noise case, where several simplified schemes with jointly Gaussian input are evaluated in closed form and later used to prove a number of results. These include a new set of capacity results for: a) the “pri-mary decodes cognitive ” regime, a subset of the “strong interfer-ence ” regime that is not included in the “very strong interference” regime for which capacity was known, and b) the “S-channel in strong interference ” in which the primary transmitter does not in-terfere with the cognitive receiver and the primary receiver expe-riences strong interference. Next, for a general Gaussian channel the capacity is determined to within one bit/s/Hz and to within a factor two regardless of the channel parameters, thus establishing rate performance guarantees at high and low SNR, respectively. The paper concludes with numerical evaluations and comparisons of the various simplified achievable rate regions and outer bounds in parameter regimes where capacity is unknown, leading to fur-ther insight on the capacity region. Index Terms—Broadcast channel with degraded message sets, capacity in the primary decodes cognitive regime, capacity for the Z-channel in strong interference, capacity to within one bit, ca-pacity to within a factor of two, cognitive interference channel, inner bound, outer bound. I.
Evaluation of Marton’s Inner Bound for the General Broadcast Channel
"... Abstract—The best known inner bound on the two-receiver general broadcast channel without a common message is due to Marton [3]. This result was subsequently generalized in [2, p. 391, Problem 10(c)] and [4] to broadcast channels with a common message. However the latter region is not computable (ex ..."
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Cited by 27 (12 self)
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Abstract—The best known inner bound on the two-receiver general broadcast channel without a common message is due to Marton [3]. This result was subsequently generalized in [2, p. 391, Problem 10(c)] and [4] to broadcast channels with a common message. However the latter region is not computable (except in certain special cases) as no bounds on the cardinality of its auxiliary random variables exist. Nor is it even clear that the inner bound is a closed set. The main obstacle in proving cardinality bounds is the fact that the Carathéodory theorem, the main known tool for proving cardinality bounds, does not yield a finite cardinality result. Our new tool is based on an identity that relates the second derivative of the Shannon entropy of a discrete random variable (under a certain perturbation) to the corresponding Fisher information. In order to go beyond the traditional Carathéodory type arguments, we identify certain properties that the auxiliary random variables corresponding to the extreme points of the inner bound satisfy. These properties are then used to establish cardinality bounds on the auxiliary random variables of the inner bound, thereby proving the computability of the region, and its closedness. Although existence of cardinality bounds renders Marton’s inner bound computable, it is still hard to evaluate the region. It is however shown that the computation can be significantly simplified if we further assume that Marton’s inner bound and the recent outer bound of Nair and El Gamal match at the given particular channel. In order to demonstrate this, we consider a large class of binary input broadcast channels and compute maximum of the sum rate of private messages assuming that the inner and the outer bound match at the given broadcast channel. We also show that the inner and the outer bound do not match for some broadcast channels, thus establishing a conjecture of [15]. I.
On the capacity of 1-to-k broadcast packet erasure channels with channel output feedback
- IEEE Transactions on Information Theory
, 2012
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The Capacity Region of a Class of 3-Receiver Broadcast Channels with Degraded Message Sets
"... Körner and Marton established the capacity region for the 2-receiver broadcast channel with degraded message sets. Recent results and conjectures suggest that a straightforward extension of the Körner-Marton region to more than 2 receivers is optimal. This paper shows that this is not the case. We e ..."
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Cited by 24 (1 self)
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Körner and Marton established the capacity region for the 2-receiver broadcast channel with degraded message sets. Recent results and conjectures suggest that a straightforward extension of the Körner-Marton region to more than 2 receivers is optimal. This paper shows that this is not the case. We establish the capacity region for a class of 3-receiver broadcast channels with 2-degraded message sets and show that it can be strictly larger than the straightforward extension of the Körner-Marton region. The idea is to split the private message into two parts, superimpose one part onto the “cloud center ” representing the common message, and superimpose the second part onto the resulting “satellite codeword”. One of the receivers finds the common message directly by decoding the “cloud center, ” a second receiver finds it indirectly by decoding a satellite codeword, and a third receiver by jointly decoding the transmitted codeword. This idea is then used to establish new inner and outer bounds on the capacity region of the general 3-receiver broadcast channel with two and three degraded message sets. We show that these bounds are tight for some nontrivial cases. The results suggest that finding the capacity region of the 3-receiver broadcast channel with degraded message sets is as at least as hard finding as the capacity region of the general 2-receiver broadcast channel with common and private message.
A graph-based framework for transmission of correlated sources over broadcast channels
- IEEE TRANS. INFORM. THEORY
, 2006
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The capacity region of multiway relay channels over finite fields with full data exchange
- IEEE Trans. Inf. Theory
, 2011
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