403 research outputs found
Optimal Order of Decoding for Max-Min Fairness in -User Memoryless Interference Channels
A -user memoryless interference channel is considered where each receiver
sequentially decodes the data of a subset of transmitters before it decodes the
data of the designated transmitter. Therefore, the data rate of each
transmitter depends on (i) the subset of receivers which decode the data of
that transmitter, (ii) the decoding order, employed at each of these receivers.
In this paper, a greedy algorithm is developed to find the users which are
decoded at each receiver and the corresponding decoding order such that the
minimum rate of the users is maximized. It is proven that the proposed
algorithm is optimal.Comment: 11 Pages, Submitted to IEEE International Symposium on Information
Theory(ISIT 2007
Achievable Rates for K-user Gaussian Interference Channels
The aim of this paper is to study the achievable rates for a user
Gaussian interference channels for any SNR using a combination of lattice and
algebraic codes. Lattice codes are first used to transform the Gaussian
interference channel (G-IFC) into a discrete input-output noiseless channel,
and subsequently algebraic codes are developed to achieve good rates over this
new alphabet. In this context, a quantity called efficiency is introduced which
reflects the effectiveness of the algebraic coding strategy. The paper first
addresses the problem of finding high efficiency algebraic codes. A combination
of these codes with Construction-A lattices is then used to achieve non trivial
rates for the original Gaussian interference channel.Comment: IEEE Transactions on Information Theory, 201
On Discrete Alphabets for the Two-user Gaussian Interference Channel with One Receiver Lacking Knowledge of the Interfering Codebook
In multi-user information theory it is often assumed that every node in the
network possesses all codebooks used in the network. This assumption is however
impractical in distributed ad-hoc and cognitive networks. This work considers
the two- user Gaussian Interference Channel with one Oblivious Receiver
(G-IC-OR), i.e., one receiver lacks knowledge of the interfering cookbook while
the other receiver knows both codebooks. We ask whether, and if so how much,
the channel capacity of the G-IC- OR is reduced compared to that of the
classical G-IC where both receivers know all codebooks. Intuitively, the
oblivious receiver should not be able to jointly decode its intended message
along with the unintended interfering message whose codebook is unavailable. We
demonstrate that in strong and very strong interference, where joint decoding
is capacity achieving for the classical G-IC, lack of codebook knowledge does
not reduce performance in terms of generalized degrees of freedom (gDoF).
Moreover, we show that the sum-capacity of the symmetric G-IC- OR is to within
O(log(log(SNR))) of that of the classical G-IC. The key novelty of the proposed
achievable scheme is the use of a discrete input alphabet for the non-oblivious
transmitter, whose cardinality is appropriately chosen as a function of SNR
A New Capacity Result for the Z-Gaussian Cognitive Interference Channel
This work proposes a novel outer bound for the Gaussian cognitive
interference channel in strong interference at the primary receiver based on
the capacity of a multi-antenna broadcast channel with degraded message set. It
then shows that for the Z-channel, i.e., when the secondary receiver
experiences no interference and the primary receiver experiences strong
interference, the proposed outer bound not only is the tightest among known
bounds but is actually achievable for sufficiently strong interference. The
latter is a novel capacity result that from numerical evaluations appears to be
generalizable to a larger (i.e., non-Z) class of Gaussian channels
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