359 research outputs found
Capacity Theorems for the AWGN Multi-Way Relay Channel
The L-user additive white Gaussian noise multi-way relay channel is
considered, where multiple users exchange information through a single relay at
a common rate. Existing coding strategies, i.e., complete-decode-forward and
compress-forward are shown to be bounded away from the cut-set upper bound at
high signal-to-noise ratios (SNR). It is known that the gap between the
compress-forward rate and the capacity upper bound is a constant at high SNR,
and that between the complete-decode-forward rate and the upper bound increases
with SNR at high SNR. In this paper, a functional-decode-forward coding
strategy is proposed. It is shown that for L >= 3, complete-decode-forward
achieves the capacity when SNR <= 0 dB, and functional-decode-forward achieves
the capacity when SNR >= 0 dB. For L=$, functional-decode-forward achieves the
capacity asymptotically as SNR increases.Comment: accepted and to be presented at ISIT 201
Partial decode-forward for quantum relay channels
A relay channel is one in which a Source and Destination use an intermediate
Relay station in order to improve communication rates. We propose the study of
relay channels with classical inputs and quantum outputs and prove that a
"partial decode and forward" strategy is achievable. We divide the channel uses
into many blocks and build codes in a randomized, block-Markov manner within
each block. The Relay performs a standard Holevo-Schumacher-Westmoreland
quantum measurement on each block in order to decode part of the Source's
message and then forwards this partial message in the next block. The
Destination performs a novel "sliding-window" quantum measurement on two
adjacent blocks in order to decode the Source's message. This strategy achieves
non-trivial rates for classical communication over a quantum relay channel.Comment: 7 pages, submission to the 2012 International Symposium on
Information Theory (ISIT 2012), Boston, MA, US
Functional-Decode-Forward for the General Discrete Memoryless Two-Way Relay Channel
We consider the general discrete memoryless two-way relay channel, where two
users exchange messages via a relay, and propose two functional-decode-forward
coding strategies for this channel. Functional-decode-forward involves the
relay decoding a function of the users' messages rather than the individual
messages themselves. This function is then broadcast back to the users, which
can be used in conjunction with the user's own message to decode the other
user's message. Via a numerical example, we show that functional-decode-forward
with linear codes is capable of achieving strictly larger sum rates than those
achievable by other strategies
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