Title :
Degrees of freedom in vector interference channels
Author :
Stotz, David ; Bolcskei, Helmut
Author_Institution :
Dept. of IT &EE, ETH Zurich, Zurich, Switzerland
Abstract :
This paper continues the Wu-Shamai-Verdú program [1] on characterizing the degrees of freedom (DoF) of interference channels (ICs) through Rényi information dimension. Concretely, we find a general formula for the DoF of vector ICs, encompassing multiple-input multiple-output (MIMO) ICs, time- and/or frequency-selective ICs, and combinations thereof, as well as constant single-antenna ICs considered in [1]. As in the case of constant single-antenna ICs, achieving full DoF requires the use of singular input distributions. Strikingly, in the vector case it suffices to enforce singularity on the joint distribution of individual transmit vectors. This can be realized through signaling in subspaces of the ambient signal space, which is in accordance with the idea of interference alignment, and, most importantly, allows the scalar components of the transmit vectors to have non-singular distributions. We recover the result by Cadambe and Jafar on the non-separability of parallel ICs [2] and we show that almost all parallel ICs are separable. Finally, our results extend the main finding in [1] to the complex case.
Keywords :
MIMO communication; antennas; radiofrequency interference; wireless channels; DoF; MIMO IC; Renyi information dimension; Wu-Shamai-Verdu program; constant single-antenna IC; degrees of freedom; frequency-selective IC; interference alignment; multiple-input multiple-output IC; nonsingular distributions; parallel IC; scalar components; singular input distributions; time-selective IC; transmit vectors; vector interference channels; Integrated circuits; Interference; Joints; MIMO; Probability distribution; Time-frequency analysis; Vectors;
Conference_Titel :
Communication, Control, and Computing (Allerton), 2012 50th Annual Allerton Conference on
Conference_Location :
Monticello, IL
Print_ISBN :
978-1-4673-4537-8
DOI :
10.1109/Allerton.2012.6483434