Non-line-of-sight node localization based on semi-definite programming in wireless sensor networks

Hongyang Chen, Gang Wang, Zizhuo Wang, H. C. So, H. Vincent Poor

Research output: Contribution to journalArticlepeer-review

153 Scopus citations


An unknown-position sensor can be localized if there are three or more anchors making time-of-arrival (TOA) measurements of a signal from it. However, the location errors can be very large due to the fact that some of the measurements are from non-line-of-sight (NLOS) paths. In this paper, a semi-definite programming (SDP) based node localization algorithm in NLOS environments is proposed for ultra-wideband (UWB) wireless sensor networks. The positions of sensors can be estimated using the distance estimates from location-aware anchors as well as other sensors. However, in the absence of line-of-sight (LOS) paths, e.g., in indoor networks, the NLOS range estimates can be significantly biased. As a result, the NLOS error can remarkably decrease the location accuracy, and it is not easy to accurately distinguish LOS from NLOS measurements. According to the information known about the prior probabilities and distributions of the NLOS errors, three different cases are introduced and the respective localization problems are addressed. Simulation results demonstrate that this algorithm achieves high location accuracy even for the case in which NLOS and LOS measurements are not identifiable.

Original languageEnglish (US)
Article number6087384
Pages (from-to)108-116
Number of pages9
JournalIEEE Transactions on Wireless Communications
Issue number1
StatePublished - Jan 2012

All Science Journal Classification (ASJC) codes

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


  • Wireless sensor networks
  • non-line-of-sight (NLOS)
  • semi-definite programming (SDP)
  • time-of-arrival (TOA)


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