1,391 research outputs found
Capacity Region of the Broadcast Channel with Two Deterministic Channel State Components
This paper establishes the capacity region of a class of broadcast channels
with random state in which each channel component is selected from two possible
functions and each receiver knows its state sequence. This channel model does
not fit into any class of broadcast channels for which the capacity region was
previously known and is useful in studying wireless communication channels when
the fading state is known only at the receivers. The capacity region is shown
to coincide with the UV outer bound and is achieved via Marton coding.Comment: 5 pages, 3 figures. Submitted to ISIT 201
On X-Channels with Feedback and Delayed CSI
The sum degrees of freedom (DoF) of the two-user MIMO X-channel is
characterized in the presence of output feedback and delayed channel state
information (CSI). The number of antennas at each transmitters is assumed to be
M and the number of antennas at each of the receivers is assumed to be N. It is
shown that the sum DoF of the two-user MIMO X-channel is the same as the sum
DoF of a two-user MIMO broadcast channel with 2M transmit antennas, and N
antennas at each receiver. Hence, for this symmetric antenna configuration,
there is no performance loss in the sum degrees of freedom due to the
distributed nature of the transmitters. This result highlights the usefulness
of feedback and delayed CSI for the MIMO X-channel.
The K-user X-channel with single antenna at each transmitter and each
receiver is also studied. In this network, each transmitter has a message
intended for each receiver. For this network, it is shown that the sum DoF with
partial output feedback alone is at least 2K/(K+1). This lower bound is
strictly better than the best lower bound known for the case of delayed CSI
assumption for all values of K.Comment: Submitted to IEEE ISIT 2012 on Jan 22, 201
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