2 research outputs found
Network Coherence Time Matters - Aligned Image Sets and the Degrees of Freedom of Interference Networks with Finite Precision CSIT and Perfect CSIR
This work obtains the first bound that is provably sensitive to network
coherence time, i.e., coherence time in an interference network where all
channels experience the same coherence patterns. This is accomplished by a
novel adaptation of the aligned image sets bound, and settles various open
problems noted previously by Naderi and Avestimehr and by Gou et al. For
example, a necessary and sufficient condition is obtained for the optimality of
1/2 DoF per user in a partially connected interference network where the
channel state information at the receivers (CSIR) is perfect, the channel state
information at the transmitters (CSIT) is instantaneous but limited to finite
precision, and the network coherence time is T_c= 1. The surprising insight
that emerges is that even with perfect CSIR and instantaneous finite precision
CSIT, network coherence time matters, i.e., it has a DoF impact.Comment: 19 pages, 4 figure
Sum-set inequalities from aligned image sets: Instruments for robust GDoF bounds
We present sum-set inequalities specialized to the generalized degrees of freedom (GDoF) framework. These are information theoretic lower bounds on the entropy of bounded density linear combinations of discrete, power-limited dependent random variables in terms of the joint entropies of arbitrary linear combinations of new random variables that are obtained by power level partitioning of the original random variables. The bounds are useful instruments to obtain GDoF characterizations for wireless interference networks, especially with multiple antenna nodes, subject to arbitrary channel strength and channel uncertainty levels