Degrees of freedom for mutually interfering broadcast channels

Seok Hwan Park, Inkyu Lee

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

In this paper, we study spatial degree-of-freedom (DOF) for two mutually interfering broadcast channels (IBC). As the demand for space-division multiple access (SDMA) increases, the IBC where each link has a single transmit node and multiple receive nodes becomes important. This paper presents the results of the lower and upper bounds on the DOF of the IBC. From the derived results, it is shown that for most cases, zero-forcing (ZF) beamforming can achieve the optimal DOF of the IBC except for some special cases. Also, we identify a condition that disabling receive cooperation in the multiple-input multiple-output interference channels causes no DOF loss. It is confirmed that we cannot expect a DOF improvement by enabling in-cell receive cooperation if in at least one of two BSs, the number of antennas is greater than or equal to that of users per cell. Furthermore, we observe a positive result that as the number of users goes to infinity, the total DOF of the IBC converges to the interference-free DOF, which is the maximum achievable DOF in the absence of the inter-cell interference.

Original languageEnglish
Article number6121993
Pages (from-to)393-402
Number of pages10
JournalIEEE Transactions on Information Theory
Volume58
Issue number1
DOIs
Publication statusPublished - 2012 Jan

Keywords

  • Beamforming
  • degrees of freedom
  • inter-cell interference
  • multi-user downlink
  • zero-forcing

ASJC Scopus subject areas

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

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