11,526 research outputs found
Capacity and Rate Regions of A Class of Broadcast Interference Channels
In this paper, a class of broadcast interference channels (BIC) is
investigated, where one of the two broadcast receivers is subject to
interference coming from a point-to-point transmission. For a general discrete
memoryless broadcast interference channel (DM-BIC), an achievable scheme based
on message splitting, superposition and binning is proposed and a concise
representation of the corresponding achievable rate region R is obtained. Two
partial-order broadcast conditions interference-oblivious less noisy and
interference-cognizant less noisy are defined, thereby extending the usual less
noisy condition for a regular broadcast channel by taking interference into
account. Under these conditions, a reduced form of R is shown to be equivalent
to a rate region based on a simpler scheme, where the broadcast transmitter
uses only superposition. Furthermore, if interference is strong for the
interference-oblivious less noisy DM-BIC, the capacity region is given by the
aforementioned two equivalent rate regions. For a Gaussian broadcast
interference channel (GBIC), channel parameters are categorized into three
regimes. For the first two regimes, which are closely related to the two
partial-order broadcast conditions, achievable rate regions are derived by
specializing the corresponding achievable schemes of DM-BICs with Gaussian
input distributions. The entropy power inequality (EPI) based outer bounds are
obtained by combining bounding techniques for a Gaussian broadcast channel
(GBC) and a Gaussian interference channel (GIC). These inner and outer bounds
lead to either exact or approximate characterizations of capacity regions and
sum capacity under various conditions. For the remaining complementing regime,
inner and outer bounds are also provided
Capacity Bounds and Sum Rate Capacities of a CLass of Discrete Memoryless Interference Channels
This paper studies the capacity of a class of discrete memoryless
interference channels where interference is defined analogous to that of
Gaussian interference channel with one-sided weak interference. The sum-rate
capacity of this class of channels is determined. As with the Gaussian case,
the sum-rate capacity is achieved by letting the transceiver pair subject to
interference communicate at a rate such that its message can be decoded at the
unintended receiver using single user detection. It is also established that
this class of discrete memoryless interference channels is equivalent in
capacity region to certain degraded interference channels. This allows the
construction of capacity outer-bounds using the capacity regions of associated
degraded broadcast channels. The same technique is then used to determine the
sum-rate capacity of discrete memoryless interference channels with mixed
interference as defined in the paper. The obtained capacity bounds and sum-rate
capacities are used to resolve the capacities of several new discrete
memoryless interference channels.Comment: submitted to IEEE Trans. Inf. Theory. arXiv admin note: substantial
text overlap with arXiv:1207.332
Duality, Polite Water-filling, and Optimization for MIMO B-MAC Interference Networks and iTree Networks
This paper gives the long sought network version of water-filling named as
polite water-filling. Unlike in single-user MIMO channels, where no one uses
general purpose optimization algorithms in place of the simple and optimal
water-filling for transmitter optimization, the traditional water-filling is
generally far from optimal in networks as simple as MIMO multiaccess channels
(MAC) and broadcast channels (BC), where steepest ascent algorithms have been
used except for the sum-rate optimization. This is changed by the polite
water-filling that is optimal for all boundary points of the capacity regions
of MAC and BC and for all boundary points of a set of achievable regions of a
more general class of MIMO B-MAC interference networks, which is a combination
of multiple interfering broadcast channels, from the transmitter point of view,
and multiaccess channels, from the receiver point of view, including MAC, BC,
interference channels, X networks, and most practical wireless networks as
special case. It is polite because it strikes an optimal balance between
reducing interference to others and maximizing a link's own rate. Employing it,
the related optimizations can be vastly simplified by taking advantage of the
structure of the problems. Deeply connected to the polite water-filling, the
rate duality is extended to the forward and reverse links of the B-MAC
networks. As a demonstration, weighted sum-rate maximization algorithms based
on polite water-filling and duality with superior performance and low
complexity are designed for B-MAC networks and are analyzed for Interference
Tree (iTree) Networks, a sub-class of the B-MAC networks that possesses
promising properties for further information theoretic study.Comment: 63 pages, 12 figure
New inner and outer bounds for the discrete memoryless cognitive interference channel and some capacity results
The cognitive interference channel is an interference channel in which one
transmitter is non-causally provided with the message of the other transmitter.
This channel model has been extensively studied in the past years and capacity
results for certain classes of channels have been proved. In this paper we
present new inner and outer bounds for the capacity region of the cognitive
interference channel as well as new capacity results. Previously proposed outer
bounds are expressed in terms of auxiliary random variables for which no
cardinality constraint is known. Consequently it is not possible to evaluate
such outer bounds explicitly for a given channel model. The outer bound we
derive is based on an idea originally devised by Sato for the broadcast channel
and does not contain auxiliary random variables, allowing it to be more easily
evaluated. The inner bound we derive is the largest known to date and is
explicitly shown to include all previously proposed achievable rate regions.
This comparison highlights which features of the transmission scheme - which
includes rate-splitting, superposition coding, a broadcast channel-like binning
scheme, and Gel'fand Pinsker coding - are most effective in approaching
capacity. We next present new capacity results for a class of discrete
memoryless channels that we term the "better cognitive decoding regime" which
includes all previously known regimes in which capacity results have been
derived as special cases. Finally, we determine the capacity region of the
semi-deterministic cognitive interference channel, in which the signal at the
cognitive receiver is a deterministic function of the channel inputs
On the Capacity of Interference Channels with Degraded Message sets
This paper is motivated by a sensor network on a correlated field where
nearby sensors share information, and can thus assist rather than interfere
with one another. A special class of two-user Gaussian interference channels
(IFCs) is considered where one of the two transmitters knows both the messages
to be conveyed to the two receivers (called the IFC with degraded message
sets). Both achievability and converse arguments are provided for this scenario
for a class of discrete memoryless channels with weak interference. For the
case of the Gaussian weak interference channel with degraded message sets,
optimality of Gaussian inputs is also shown, resulting in the capacity region
of this channel
Discrete Memoryless Interference and Broadcast Channels with Confidential Messages: Secrecy Rate Regions
We study information-theoretic security for discrete memoryless interference
and broadcast channels with independent confidential messages sent to two
receivers. Confidential messages are transmitted to their respective receivers
with information-theoretic secrecy. That is, each receiver is kept in total
ignorance with respect to the message intended for the other receiver. The
secrecy level is measured by the equivocation rate at the eavesdropping
receiver. In this paper, we present inner and outer bounds on secrecy capacity
regions for these two communication systems. The derived outer bounds have an
identical mutual information expression that applies to both channel models.
The difference is in the input distributions over which the expression is
optimized. The inner bound rate regions are achieved by random binning
techniques. For the broadcast channel, a double-binning coding scheme allows
for both joint encoding and preserving of confidentiality. Furthermore, we show
that, for a special case of the interference channel, referred to as the switch
channel, the two bound bounds meet. Finally, we describe several transmission
schemes for Gaussian interference channels and derive their achievable rate
regions while ensuring mutual information-theoretic secrecy. An encoding scheme
in which transmitters dedicate some of their power to create artificial noise
is proposed and shown to outperform both time-sharing and simple multiplexed
transmission of the confidential messages.Comment: to appear Special Issue of IEEE Transactions on Information Theory on
Information Theoretic Securit
Improvement of the Han-Kobayashi Rate Region for General Interference Channel
Allowing the input auxiliary random variables to be correlated and using the
binning scheme, the Han- Kobayashi (HK) rate region for general interference
channel is improved. The obtained new achievable rate region (i) is shown to
encompass the HK region and its simplified description, i.e., Chong-Motani-Garg
(CMG) region,considering a detailed and favorable comparison between different
versions of the regions, and (ii) has an interesting and easy interpretation:
as expected, any rate in our region has generally two additional terms in
comparison with the HK region (one due to the input correlation and the other
as a result of the binning scheme).Comment: submitted to IEEE Trans.on Information theory, on June 2
Cooperative Strategies for Simultaneous and Broadcast Relay Channels
Consider the \emph{simultaneous relay channel} (SRC) which consists of a set
of relay channels where the source wishes to transmit common and private
information to each of the destinations. This problem is recognized as being
equivalent to that of sending common and private information to several
destinations in presence of helper relays where each channel outcome becomes a
branch of the \emph{broadcast relay channel} (BRC). Cooperative schemes and
capacity region for a set with two memoryless relay channels are investigated.
The proposed coding schemes, based on \emph{Decode-and-Forward} (DF) and
\emph{Compress-and-Forward} (CF) must be capable of transmitting information
simultaneously to all destinations in such set.
Depending on the quality of source-to-relay and relay-to-destination
channels, inner bounds on the capacity of the general BRC are derived. Three
cases of particular interest are considered: cooperation is based on DF
strategy for both users --referred to as DF-DF region--, cooperation is based
on CF strategy for both users --referred to as CF-CF region--, and cooperation
is based on DF strategy for one destination and CF for the other --referred to
as DF-CF region--. These results can be seen as a generalization and hence
unification of previous works. An outer-bound on the capacity of the general
BRC is also derived. Capacity results are obtained for the specific cases of
semi-degraded and degraded Gaussian simultaneous relay channels. Rates are
evaluated for Gaussian models where the source must guarantee a minimum amount
of information to both users while additional information is sent to each of
them.Comment: 32 pages, 7 figures, To appear in IEEE Trans. on Information Theor
On the Capacity Region of the Cognitive Interference Channel with Unidirectional Destination Cooperation
The cognitive interference channel with unidirectional destination
cooperation (CIFC-UDC) is a variant of the cognitive interference channel
(CIFC) where the cognitive (secondary) destination not only decodes the
information sent from its sending dual but also helps enhance the communication
of the primary user. This channel is an extension of the original CIFC to
achieve a win-win solution under the coexistence condition. The CIFC-UDC
comprises a broadcast channel (BC), a relay channel (RC), as well as a
partially cooperative relay broadcast channel (PCRBC), and can be degraded to
any one of them. In this paper, we propose a new achievable rate region for the
dis-crete memoryless CIFC-UDC which improves the previous re-sults and includes
the largest known rate regions of the BC, the RC, the PCRBC and the CIFC. A new
outer bound is presented and proved to be tight for two classes of the
CIFC-UDCs, result-ing in the characterization of the capacity region.Comment: submitted to ISIT 201
Cognitive Interference Channels with Confidential Messages
The cognitive interference channel with confidential messages is studied.
Similarly to the classical two-user interference channel, the cognitive
interference channel consists of two transmitters whose signals interfere at
the two receivers. It is assumed that there is a common message source (message
1) known to both transmitters, and an additional independent message source
(message 2) known only to the cognitive transmitter (transmitter 2). The
cognitive receiver (receiver 2) needs to decode both messages, while the
non-cognitive receiver (receiver 1) should decode only the common message.
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. A single-letter expression for the capacity-equivocation
region of the discrete memoryless cognitive interference channel is established
and is further explicitly derived for the Gaussian case. Moreover,
particularizing the capacity-equivocation region to the case without a secrecy
constraint, establishes a new capacity theorem for a class of interference
channels, by providing a converse theorem.Comment: To appear in Proc. of forty-fifth annual Allerton conference on
communication, control, and computing, Allerton house, Monticello, IL, US
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