2 research outputs found
The DoF of the Asymmetric MIMO Interference Channel with Square Direct Link Channel Matrices
This paper studies the sum Degrees of Freedom (DoF) of -user {\em
asymmetric} MIMO Interference Channel (IC) with square direct link channel
matrices, that is, the -th transmitter and its intended receiver have
antennas each, where need not be the same for all
.
Starting from a -user example, it is shown that existing cooperation-based
outer bounds are insufficient to characterize the DoF. Moreover, it is shown
that two distinct operating regimes exist. With a {\it dominant} user, i.e., a
user that has more antennas than the other two users combined, %(say ), it is DoF optimal to let that user transmit alone on the IC.
Otherwise, it is DoF optimal to {\em decompose} and operate the 3-user MIMO IC
as an -user SISO IC. This indicates that MIMO operations are
useless from a DoF perspective in systems without a dominant user.
The main contribution of the paper is the derivation of a novel outer bound
for the general -user case that is tight in the regime where a dominant user
is not present; this is done by generalizing the insights from the 3-user
example to an arbitrary number of users.Comment: Presented at 52nd Allerton Conference, 201