Investigation into off-body links for wrist mounted antennas in bluetooth systems

Mohammad W. Abdullah, Xenofon Fafoutis, Evangelos Mellios, Maciej Klemm, Geoffrey Hilton

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

11 Citations (Scopus)
392 Downloads (Pure)


This paper presents a detailed investigation into off-body links for wrist mounted Bluetooth Low Energy (BLE) devices for an indoor environment and revolves around three low profile antennas (microstrip patch, printed monopole and external monopole). It studies the received signal strength across different usage scenarios and obstructions such as body shadow, wall and ceiling through measurement campaigns carried out in a 2-storey house. It is observed that RSSIs show little variation from the mean value at any position in a given room of the house. In the living room, the average RSSI for patch, printed and external monopole is close to -61,-73 and -61 dBm respectively. The study describes the effect of usual obstructions such as wall and ceiling to off-body links and shows that the range of RSSI for any antenna (30 dBm at P=0.5 for Patch Antenna) is bounded at one end by the CDF of wall plus body shadow and at the other end by CDF of Line of Sight (LOS). The effect of body shadowing is studied in greater detail. It is observed that the microstrip patch antenna in LOS, under a ceiling and behind a wall, drops by approximately 15dB, 5dB and 10dB at P=0.4 when it goes into body shadow. The study also suggests that the Access Point (AP) on the ceiling provides better off-body links as compared to it in the adjacent room. The study compares the overall performance of the three antennas across all possible usage scenarios, obstructions & polarizations and concludes that the external monopole and patch antenna performs better than printed monopole by approximately 10-13 dBm. Finally, the study shows the variation of Packet Error Rate (PER) with RSSI and determines threshold values of RSSI for acceptable PERs, for reliable and robust applications.
Original languageEnglish
Title of host publication2015 Loughborough Antennas & Propagation Conference (LAPC 2015)
Subtitle of host publication Proceedings of a meeting held 2-3 November 2015, Loughborough, Leicestershire, United Kingdom
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages5
ISBN (Electronic)9781479989430
ISBN (Print)9781479989423
Publication statusPublished - Mar 2016
EventAntennas & Propagation Conference (LAPC), 2015 - UK, Loughborough, United Kingdom
Duration: 2 Nov 20153 Nov 2015


ConferenceAntennas & Propagation Conference (LAPC), 2015
Country/TerritoryUnited Kingdom

Structured keywords

  • Digital Health


  • Indoor Propagation
  • Off-Body Link
  • Microstrip Patch
  • Monopole
  • Received Signal Strength Indicator (RSSI)
  • Bluetooth
  • Body-Shadow
  • Packet Error Rates
  • Microstrip antennas
  • Antenna measurements
  • Wrist
  • Microstrip
  • Patch antennas
  • Shadow mapping


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