28 research outputs found
Cooperative Relaying with State Available Non-Causally at the Relay
We consider a three-terminal state-dependent relay channel with the channel
state noncausally available at only the relay. Such a model may be useful for
designing cooperative wireless networks with some terminals equipped with
cognition capabilities, i.e., the relay in our setup. In the discrete
memoryless (DM) case, we establish lower and upper bounds on channel capacity.
The lower bound is obtained by a coding scheme at the relay that uses a
combination of codeword splitting, Gel'fand-Pinsker binning, and
decode-and-forward relaying. The upper bound improves upon that obtained by
assuming that the channel state is available at the source, the relay, and the
destination. For the Gaussian case, we also derive lower and upper bounds on
the capacity. The lower bound is obtained by a coding scheme at the relay that
uses a combination of codeword splitting, generalized dirty paper coding, and
decode-and-forward relaying; the upper bound is also better than that obtained
by assuming that the channel state is available at the source, the relay, and
the destination. In the case of degraded Gaussian channels, the lower bound
meets with the upper bound for some special cases, and, so, the capacity is
obtained for these cases. Furthermore, in the Gaussian case, we also extend the
results to the case in which the relay operates in a half-duplex mode.Comment: 62 pages. To appear in IEEE Transactions on Information Theor
Bounds on the Capacity of the Relay Channel with Noncausal State at Source
We consider a three-terminal state-dependent relay channel with the channel
state available non-causally at only the source. Such a model may be of
interest for node cooperation in the framework of cognition, i.e.,
collaborative signal transmission involving cognitive and non-cognitive radios.
We study the capacity of this communication model. One principal problem is
caused by the relay's not knowing the channel state. For the discrete
memoryless (DM) model, we establish two lower bounds and an upper bound on
channel capacity. The first lower bound is obtained by a coding scheme in which
the source describes the state of the channel to the relay and destination,
which then exploit the gained description for a better communication of the
source's information message. The coding scheme for the second lower bound
remedies the relay's not knowing the states of the channel by first computing,
at the source, the appropriate input that the relay would send had the relay
known the states of the channel, and then transmitting this appropriate input
to the relay. The relay simply guesses the sent input and sends it in the next
block. The upper bound is non trivial and it accounts for not knowing the state
at the relay and destination. For the general Gaussian model, we derive lower
bounds on the channel capacity by exploiting ideas in the spirit of those we
use for the DM model; and we show that these bounds are optimal for small and
large noise at the relay irrespective to the strength of the interference.
Furthermore, we also consider a special case model in which the source input
has two components one of which is independent of the state. We establish a
better upper bound for both DM and Gaussian cases and we also characterize the
capacity in a number of special cases.Comment: Submitted to the IEEE Transactions on Information Theory, 54 pages, 6
figure
State-Dependent Relay Channel with Private Messages with Partial Causal and Non-Causal Channel State Information
In this paper, we introduce a discrete memoryless State-Dependent Relay
Channel with Private Messages (SD-RCPM) as a generalization of the
state-dependent relay channel. We investigate two main cases: SD-RCPM with
non-causal Channel State Information (CSI), and SD-RCPM with causal CSI. In
each case, it is assumed that partial CSI is available at the source and relay.
For non-causal case, we establish an achievable rate region using
Gel'fand-Pinsker type coding scheme at the nodes informed of CSI, and
Compress-and-Forward (CF) scheme at the relay. Using Shannon's strategy and CF
scheme, an achievable rate region for causal case is obtained. As an example,
the Gaussian version of SD-RCPM is considered, and an achievable rate region
for Gaussian SD-RCPM with non-causal perfect CSI only at the source, is
derived. Providing numerical examples, we illustrate the comparison between
achievable rate regions derived using CF and Decode-and-Forward (DF) schemes.Comment: 5 pages, 2 figures, to be presented at the IEEE International
Symposium on Information Theory (ISIT 2010), Austin, Texas, June 201
Channel with States at the Source
We consider a state-dependent three-terminal full-duplex relay channel with the channel states noncausally available at only the source, that is, neither at the relay nor at the destination. This model has application to cooperation over certain wireless channels with asymmetric cognition capabilities and cognitive interference relay channels. We establish lower bounds on the channel capacity for both discrete memoryless (DM) and Gaussian cases. For the DM case, the coding scheme for the lower bound uses techniques of rate-splitting at the source, decode-and-forward (DF) relaying, and a Gel'fand-Pinsker-like binning scheme. In this coding scheme, the relay decodes only partially the information sent by the source. Due to the rate-splitting, this lower bound is better than the one obtained by assuming that the relay decodes all the information from the source, that is, full-DF. For the Gaussian case, we consider channel models in which each of the relay node and the destination node experiences on its link an additive Gaussian outside interference. We first focus on the case in which the links to the relay and to the destination are corrupted by the same interference; and then we focus on the case of independent interferences. We also discuss a model with correlated interferences. For each of the first two models, we establish a lower bound on the channel capacity. The coding schemes for the lower bounds use techniques of dirty paper coding or carbon copying onto dirty paper, interference reduction at the source and decode-and-forward relaying. The results reveal that, by opposition to carbon copying onto dirty paper and its root Costa's initial dirty paper coding (DPC), it may be beneficial in our setup that the informed source uses a part of its power to partially cancel the effect of the interference so that the uninformed relay benefits from this cancellation, and so the source benefits in turn
Bounds on the Capacity of the Relay Channel with Noncausal State Information at Source
We consider a three-terminal state-dependent relay channel with the channel
state available non-causally at only the source. Such a model may be of
interest for node cooperation in the framework of cognition, i.e.,
collaborative signal transmission involving cognitive and non-cognitive radios.
We study the capacity of this communication model. One principal problem in
this setup is caused by the relay's not knowing the channel state. In the
discrete memoryless (DM) case, we establish lower bounds on channel capacity.
For the Gaussian case, we derive lower and upper bounds on the channel
capacity. The upper bound is strictly better than the cut-set upper bound. We
show that one of the developed lower bounds comes close to the upper bound,
asymptotically, for certain ranges of rates.Comment: 5 pages, submitted to 2010 IEEE International Symposium on
Information Theor
On Cooperative Multiple Access Channels with Delayed CSI at Transmitters
We consider a cooperative two-user multiaccess channel in which the
transmission is controlled by a random state. Both encoders transmit a common
message and, one of the encoders also transmits an individual message. We study
the capacity region of this communication model for different degrees of
availability of the states at the encoders, causally or strictly causally. In
the case in which the states are revealed causally to both encoders but not to
the decoder we find an explicit characterization of the capacity region in the
discrete memoryless case. In the case in which the states are revealed only
strictly causally to both encoders, we establish inner and outer bounds on the
capacity region. The outer bound is non-trivial, and has a relatively simple
form. It has the advantage of incorporating only one auxiliary random variable.
We then introduce a class of cooperative multiaccess channels with states known
strictly causally at both encoders for which the inner and outer bounds agree;
and so we characterize the capacity region for this class. In this class of
channels, the state can be obtained as a deterministic function of the channel
inputs and output. We also study the model in which the states are revealed,
strictly causally, in an asymmetric manner, to only one encoder. Throughout the
paper, we discuss a number of examples; and compute the capacity region of some
of these examples. The results shed more light on the utility of delayed
channel state information for increasing the capacity region of state-dependent
cooperative multiaccess channels; and tie with recent progress in this
framework.Comment: 54 pages. To appear in IEEE Transactions on Information Theory. arXiv
admin note: substantial text overlap with arXiv:1201.327
Lecture Notes on Network Information Theory
These lecture notes have been converted to a book titled Network Information
Theory published recently by Cambridge University Press. This book provides a
significantly expanded exposition of the material in the lecture notes as well
as problems and bibliographic notes at the end of each chapter. The authors are
currently preparing a set of slides based on the book that will be posted in
the second half of 2012. More information about the book can be found at
http://www.cambridge.org/9781107008731/. The previous (and obsolete) version of
the lecture notes can be found at http://arxiv.org/abs/1001.3404v4/
Information Theoretic Limits of State-dependent Networks
We investigate the information theoretic limits of two types of state-dependent models in this dissertation. These models capture a wide range of wireless communication scenarios where there are interference cognition among transmitters. Hence, information theoretic studies of these models provide useful guidelines for designing new interference cancellation schemes in practical wireless networks.
In particular, we first study the two-user state-dependent Gaussian multiple access channel (MAC) with a helper. The channel is corrupted by an additive Gaussian state sequence known to neither the transmitters nor the receiver, but to a helper noncausally, which assists state cancellation at the receiver. Inner and outer bounds on the capacity region are first derived, which improve the state-of-the-art bounds given in the literature. Further comparison of these bounds yields either segments on the capacity region boundary or the full capacity region by considering various regimes of channel parameters.
We then study the two-user Gaussian state-dependent Z-interference channel (Z-IC), in which two receivers are corrupted respectively by two correlated states that are noncausally known to transmitters, but unknown to receivers. Three interference regimes are studied, and the capacity region or the sum capacity boundary is characterized either fully or partially under various channel parameters. The impact of the correlation between the states on the cancellation of state and interference as well as the achievability of the capacity is demonstrated via numerical analysis.
Finally, we extend our results on the state-dependent Z-IC to the state-dependent regular IC. As both receivers in the regular IC are interfered, more sophisticated achievable schemes are designed. For the very strong regime, the capacity region is achieved by a scheme where the two transmitters implement a cooperative dirty paper coding. For the strong but not very strong regime, the sum-rate capacity is characterized by rate splitting, layered dirty paper coding and successive cancellation. For the weak regime, the sum-rate capacity is achieved via dirty paper coding individually at two receivers as well as treating interference as noise. Numerical investigation indicates that for the regular IC, the correlation between states impacts the achievability of the channel capacity in a different way from that of the Z-IC