73 research outputs found
Optimal Coding Functions for Pairwise Message Sharing on Finite-Field Multi-Way Relay Channels
This paper considers the finite-field multi-way relay channel with pairwise
message sharing, where multiple users exchange messages through a single relay
and where the users may share parts of their source messages (meaning that some
message parts are known/common to more than one user). In this paper, we design
an optimal functional-decode-forward coding scheme that takes the shared
messages into account. More specifically, we design an optimal function for the
relay to decode (from the users on the uplink) and forward (back to the users
on the downlink). We then show that this proposed function-decode-forward
coding scheme can achieve the capacity region of the finite-field multi-way
relay channel with pairwise message sharing. This paper generalizes our
previous result for the case of three users to any number of users.Comment: Author's final version (accepted for presentation at the 2014 IEEE
International Conference on Communications [ICC 2014]
The Three-User Finite-Field Multi-Way Relay Channel with Correlated Sources
This paper studies the three-user finite-field multi-way relay channel, where
the users exchange messages via a relay. The messages are arbitrarily
correlated, and the finite-field channel is linear and is subject to additive
noise of arbitrary distribution. The problem is to determine the minimum
achievable source-channel rate, defined as channel uses per source symbol
needed for reliable communication. We combine Slepian-Wolf source coding and
functional-decode-forward channel coding to obtain the solution for two classes
of source and channel combinations. Furthermore, for correlated sources that
have their common information equal their mutual information, we propose a new
coding scheme to achieve the minimum source-channel rate.Comment: Author's final version (accepted and to appear in IEEE Transactions
on Communications
A Novel User Pairing Scheme for Functional Decode-and-Forward Multi-way Relay Network
In this paper, we consider a functional decode and forward (FDF) multi-way
relay network (MWRN) where a common user facilitates each user in the network
to obtain messages from all other users. We propose a novel user pairing
scheme, which is based on the principle of selecting a common user with the
best average channel gain. This allows the user with the best channel
conditions to contribute to the overall system performance. Assuming lattice
code based transmissions, we derive upper bounds on the average common rate and
the average sum rate with the proposed pairing scheme. Considering M-ary
quadrature amplitude modulation with square constellation as a special case of
lattice code transmission, we derive asymptotic average symbol error rate (SER)
of the MWRN. We show that in terms of the achievable rates, the proposed
pairing scheme outperforms the existing pairing schemes under a wide range of
channel scenarios. The proposed pairing scheme also has lower average SER
compared to existing schemes. We show that overall, the MWRN performance with
the proposed pairing scheme is more robust, compared to existing pairing
schemes, especially under worst case channel conditions when majority of users
have poor average channel gains.Comment: 30 pages, 6 figures, submitted for journal publicatio
MIMO Multiway Relaying with Pairwise Data Exchange: A Degrees of Freedom Perspective
In this paper, we study achievable degrees of freedom (DoF) of a
multiple-input multiple-output (MIMO) multiway relay channel (mRC) where
users, each equipped with antennas, exchange messages in a pairwise manner
via a common -antenna relay node. % A novel and systematic way of joint
beamforming design at the users and at the relay is proposed to align signals
for efficient implementation of physical-layer network coding (PNC). It is
shown that, when the user number , the proposed beamforming design can
achieve the DoF capacity of the considered mRC for any setups. % For
the scenarios with , we show that the proposed signaling scheme can be
improved by disabling a portion of relay antennas so as to align signals more
efficiently. Our analysis reveals that the obtained achievable DoF is always
piecewise linear, and is bounded either by the number of user antennas or
by the number of relay antennas . Further, we show that the DoF capacity can
be achieved for and
, which
provides a broader range of the DoF capacity than the existing results.
Asymptotic DoF as is also derived based on the proposed
signaling scheme.Comment: 13 pages, 7 figure
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