SoftNull: Many-Antenna Full-Duplex Wireless via Digital Beamforming

Evan Everett, Clayton Shepard, Lin Zhong, Ashutosh Sabharwal

Research output: Contribution to journalArticlepeer-review

113 Scopus citations


In this paper, we present and study a digital-controlled method, called SoftNull, to enable full-duplex in many-antenna systems. Unlike most designs that rely on analog cancelers to suppress self-interference, SoftNull relies on digital transmit beamforming to reduce self-interference. SoftNull does not attempt to perfectly null self-interference, but instead seeks to reduce self-interference sufficiently to prevent swamping the receiver's dynamic range. Residual self-interference is then cancelled digitally by the receiver. We evaluate the performance of SoftNull using measurements from a 72-element antenna array in both indoor and outdoor environments. We find that SoftNull can significantly outperform half-duplex for small cells operating in the many-antenna regime, where the number of antennas is many more than the number of users served simultaneously.

Original languageEnglish (US)
Article number7575689
Pages (from-to)8077-8092
Number of pages16
JournalIEEE Transactions on Wireless Communications
Issue number12
StatePublished - Dec 2016


  • Full-duplex
  • interference
  • massive MIMO
  • MIMO
  • precoders

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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