Interference alignment and the degrees of freedom of wireless X networks

Viveck R. Cadambe, Syed A. Jafar

Research output: Contribution to journalArticle

300 Citations (Scopus)

Abstract

We explore the degrees of freedom of M, × N user wireless X networks, i.e., networks of M transmitters and N receivers where every transmitter has an independent message for every receiver. We derive a general outer bound on the degrees of freedom region of these networks. When all nodes have a single antenna and all channel coefficients vary in time or frequency, we show that the total number of degrees of freedom of the X network is equal to MN/M + N - 1 per orthogonal time and frequency dimension. Achievability is proved by constructing interference alignment schemes for X networks that can come arbitrarily close to the outer bound on degrees of freedom. For the case where either M = 2 or N = 2 we find that the degrees of freedom characterization also provides a capacity approximation that is accurate to within O(1). For these cases the degrees of freedom outer bound is exactly achievable.

Original languageEnglish (US)
Pages (from-to)3893-3908
Number of pages16
JournalIEEE Transactions on Information Theory
Volume55
Issue number9
DOIs
StatePublished - Sep 4 2009

Fingerprint

Transmitters
interference
Antennas
recipient
time

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Computer Science Applications
  • Library and Information Sciences

Cite this

@article{21e13c2f84a3486b81a7e49e834ca68b,
title = "Interference alignment and the degrees of freedom of wireless X networks",
abstract = "We explore the degrees of freedom of M, × N user wireless X networks, i.e., networks of M transmitters and N receivers where every transmitter has an independent message for every receiver. We derive a general outer bound on the degrees of freedom region of these networks. When all nodes have a single antenna and all channel coefficients vary in time or frequency, we show that the total number of degrees of freedom of the X network is equal to MN/M + N - 1 per orthogonal time and frequency dimension. Achievability is proved by constructing interference alignment schemes for X networks that can come arbitrarily close to the outer bound on degrees of freedom. For the case where either M = 2 or N = 2 we find that the degrees of freedom characterization also provides a capacity approximation that is accurate to within O(1). For these cases the degrees of freedom outer bound is exactly achievable.",
author = "Cadambe, {Viveck R.} and Jafar, {Syed A.}",
year = "2009",
month = "9",
day = "4",
doi = "10.1109/TIT.2009.2025541",
language = "English (US)",
volume = "55",
pages = "3893--3908",
journal = "IEEE Transactions on Information Theory",
issn = "0018-9448",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "9",

}

Interference alignment and the degrees of freedom of wireless X networks. / Cadambe, Viveck R.; Jafar, Syed A.

In: IEEE Transactions on Information Theory, Vol. 55, No. 9, 04.09.2009, p. 3893-3908.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Interference alignment and the degrees of freedom of wireless X networks

AU - Cadambe, Viveck R.

AU - Jafar, Syed A.

PY - 2009/9/4

Y1 - 2009/9/4

N2 - We explore the degrees of freedom of M, × N user wireless X networks, i.e., networks of M transmitters and N receivers where every transmitter has an independent message for every receiver. We derive a general outer bound on the degrees of freedom region of these networks. When all nodes have a single antenna and all channel coefficients vary in time or frequency, we show that the total number of degrees of freedom of the X network is equal to MN/M + N - 1 per orthogonal time and frequency dimension. Achievability is proved by constructing interference alignment schemes for X networks that can come arbitrarily close to the outer bound on degrees of freedom. For the case where either M = 2 or N = 2 we find that the degrees of freedom characterization also provides a capacity approximation that is accurate to within O(1). For these cases the degrees of freedom outer bound is exactly achievable.

AB - We explore the degrees of freedom of M, × N user wireless X networks, i.e., networks of M transmitters and N receivers where every transmitter has an independent message for every receiver. We derive a general outer bound on the degrees of freedom region of these networks. When all nodes have a single antenna and all channel coefficients vary in time or frequency, we show that the total number of degrees of freedom of the X network is equal to MN/M + N - 1 per orthogonal time and frequency dimension. Achievability is proved by constructing interference alignment schemes for X networks that can come arbitrarily close to the outer bound on degrees of freedom. For the case where either M = 2 or N = 2 we find that the degrees of freedom characterization also provides a capacity approximation that is accurate to within O(1). For these cases the degrees of freedom outer bound is exactly achievable.

UR - http://www.scopus.com/inward/record.url?scp=69449104840&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=69449104840&partnerID=8YFLogxK

U2 - 10.1109/TIT.2009.2025541

DO - 10.1109/TIT.2009.2025541

M3 - Article

AN - SCOPUS:69449104840

VL - 55

SP - 3893

EP - 3908

JO - IEEE Transactions on Information Theory

JF - IEEE Transactions on Information Theory

SN - 0018-9448

IS - 9

ER -