CPLink: Interference-Free Reuse of Cyclic-Prefix Intervals in OFDM-Based Networks

Niranjan M. Gowda, Ashutosh Sabharwal

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


In this paper, we propose a method to reuse the cyclic-prefix (CP) intervals of an ongoing OFDM link, by another link, without degrading the OFDM link performance. We label the link that reuses the CP-intervals as CPLink, as they use only the CP-intervals of the ongoing link labeled, MainLink. We leverage the fact that the most commonly used OFDM receivers discard the samples in CP-intervals to design the CPLink that ensures below-noise-floor interference at every MainLink-receiver. The key contribution in this paper is the design and study of zero-knowledge CPLink, in which the CPLink-transmitter ensures below-noise-floor interference at every MainLink-receiver with no knowledge about the locations or the number of MainLink-receivers. We analytically show that the zero-knowledge CPLink capacity is positive. For LTE frame structure with 20-MHz bandwidth and 2-km cell-radius, we evaluate the CPLink for two kinds of CPLink-receivers: full-duplex base-station and a half-duplex device. Even for the cell-edge CPLink-transmitters, full-duplex zero-knowledge CPLink data rates can be up to 20 Mbps (60 Mbps) when the CP duration is 7% (25%) of the data-symbol duration. The half-duplex CPLink rate is 5-40 Mbps when the CPLink-transmitter is within 250 m of CPLink-receiver. CPLink capacity is found to increase near-linearly with the CP duration, thus mitigating CP overhead.

Original languageEnglish (US)
Article number8566180
Pages (from-to)665-679
Number of pages15
JournalIEEE Transactions on Wireless Communications
Issue number1
StatePublished - Jan 2019


  • 5G
  • cyclic-prefix
  • full-duplex
  • guard-period
  • latency
  • LTE
  • massive MIMO
  • OFDM
  • TDD
  • WiFi

ASJC Scopus subject areas

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


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