1 research outputs found
Degrees of Freedom of the Bursty MIMO X Channel with Instantaneous Topological Information
We study the effects of instantaneous feedback of channel topology on the
degrees of freedom (DoF) of the bursty MIMO X channel, where the four
transmitter-receiver links are intermittently on-and-off, governed by four
independent Bernoulli random sequences, and each transmitter and receiver
are equipped with and antennas, respectively. We partially characterize
this channel: The sum DoF is characterized when or when
. In the remaining regime, the
lower bound is within of the upper bound. Strictly higher DoF is
achieved by coding across channel topologies. In particular, codes over as many
as topologies are proposed to achieve the sum DoF of the channel when . A transfer function view of the network is employed to simplify
the code design and to elucidate the fact that these are space-time codes,
obtained by interference alignment over space and time.Comment: This is the full version of the paper accepted by IEEE International
Symposium on Information Theory (ISIT) 201