611 research outputs found
The Deterministic Capacity of Relay Networks with Relay Private Messages
We study the capacity region of a deterministic 4-node network, where 3 nodes
can only communicate via the fourth one. However, the fourth node is not merely
a relay since it can exchange private messages with all other nodes. This
situation resembles the case where a base station relays messages between users
and delivers messages between the backbone system and the users. We assume an
asymmetric scenario where the channel between any two nodes is not reciprocal.
First, an upper bound on the capacity region is obtained based on the notion of
single sided genie. Subsequently, we construct an achievable scheme that
achieves this upper bound using a superposition of broadcasting node 4 messages
and an achievable "detour" scheme for a reduced 3-user relay network.Comment: 3 figures, accepted at ITW 201
Using Network Coding to Achieve the Capacity of Deterministic Relay Networks with Relay Messages
In this paper, we derive the capacity of the deterministic relay networks
with relay messages. We consider a network which consists of five nodes, four
of which can only communicate via the fifth one. However, the fifth node is not
merely a relay as it may exchange private messages with the other network
nodes. First, we develop an upper bound on the capacity region based on the
notion of a single sided genie. In the course of the achievability proof, we
also derive the deterministic capacity of a 4-user relay network (without
private messages at the relay). The capacity achieving schemes use a
combination of two network coding techniques: the Simple Ordering Scheme (SOS)
and Detour Schemes (DS). In the SOS, we order the transmitted bits at each user
such that the bi-directional messages will be received at the same channel
level at the relay, while the basic idea behind the DS is that some parts of
the message follow an indirect path to their respective destinations. This
paper, therefore, serves to show that user cooperation and network coding can
enhance throughput, even when the users are not directly connected to each
other.Comment: 12 pages, 5 figures, submitted to IEEE JSAC Network codin
On the Capacity Region of the Deterministic Y-Channel with Common and Private Messages
In multi user Gaussian relay networks, it is desirable to transmit private
information to each user as well as common information to all of them. However,
the capacity region of such networks with both kinds of information is not easy
to characterize. The prior art used simple linear deterministic models in order
to approximate the capacities of these Gaussian networks. This paper discusses
the capacity region of the deterministic Y-channel with private and common
messages. In this channel, each user aims at delivering two private messages to
the other two users in addition to a common message directed towards both of
them. As there is no direct link between the users, all messages must pass
through an intermediate relay. We present outer-bounds on the rate region using
genie aided and cut-set bounds. Then, we develop a greedy scheme to define an
achievable region and show that at a certain number of levels at the relay, our
achievable region coincides with the upper bound. Finally, we argue that these
bounds for this setup are not sufficient to characterize the capacity region.Comment: 4 figures, 7 page
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