Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Channel measurements and PHY development for wearable devices] Date Submitted: [Jan. 15, 2007 ] Source: [Dries Neirynck] Company: [University of Bristol – Mobile VCE] Address: [Merchant Venturers Building, Woodland Rd, Bristol, BS8 1UB, UK] Voice:[+31 6 48 06 1793], E-Mail:[d.neirynck@tue.nl, m.a.beach@bristol.ac.uk, walter.tuttlebee@mobilevce.com] Re: [ IEEE 802.15 BAN SG ] Abstract: [Channel measurements, evaluation of current standards and use of MIMO in BAN] Purpose: [To encourage discussion.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. Dries Neirynck - University of Bristol - MVCE

2. Aim Contribute to the drafts of the PAR and 5C by presenting the results of • channel measurement campaigns into personal and body area propagation and of • 802.15.1 and 15.3 PHY simulations using the recorded channel data Performed at the University of Bristol as part of the Mobile VCE Core 3 Programme • Fully detailed technical reports on this research are available to Industrial Members of Mobile VCE. Dries Neirynck - University of Bristol - MVCE

3. Fully detailed technical reports on this research are available to Industrial Members of Mobile VCE: In cooperation with the UK’s leading comms research Universities Dries Neirynck - University of Bristol - MVCE

4. BAN versus PAN In the context of this research defined as: BAN: two (or more) communicating devices are located on the user’s body PAN: only one of the communicating devices is carried by the user Dries Neirynck - University of Bristol - MVCE

5. Overview • Does the user have a significant influence on BAN channel characteristics? • How do existing 802.15 standards perform in the measured channels? • What’s the benefit of using multiple antennas in BAN? Dries Neirynck - University of Bristol - MVCE

6. Does the user have a significant influence on BAN channel characteristics? No indication that user effects were taken into account during design of existing 802.15 standards: Bluetooth (IEEE 802.15.1): • Channel assumptions based on WLAN • Attenuation and fading simply based on distance TX-RX IEEE 802.15.3 • Channel model adapted from 802.11 • Exponentially decaying, Rayleigh fading tapped delay line Dries Neirynck - University of Bristol - MVCE

7. 2 BAN channel measurement campaigns have been carried out Dries Neirynck - University of Bristol - MVCE

8. Dries Neirynck - University of Bristol - MVCE

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12. User has significant influence on channel characteristics • Body shadowing leads to severe signal attenuation • During periods of NLOS, link becomes dependent on multipath propagation in the environment • User motion leads to huge variation in the channel • During periods of motion, coherence time is reduced to tens of milliseconds Dries Neirynck - University of Bristol - MVCE

13. Measured channel characteristics differ from assumptions during development 802.15.1/3 Bluetooth (IEEE 802.15.1) • Channel assumptions based on WLAN measurements • attenuation and fading statistics are simply related to distance between transmitter and receiver • link budget: 62 dB attenuation at 10 metres(observed at much shorter distance in measurements) IEEE 802.15.3 • Exponentially decaying, Rayleigh fading model from 802.11 • RMS delay spread of 25 ns should be tolerated • 99.9% reliability at 10 metres • No indication that body shadowing is taken into account Dries Neirynck - University of Bristol - MVCE

14. How do existing 802.15 standards perform in the measured channels? Dries Neirynck - University of Bristol - MVCE

15. Bluetooth/IEEE 802.15.1 simulation Parameters: • Baseband only, other layers ideal • GFSK modulator (h = 0.28), FEC implemented • Demodulation with phase differentiator • Packet header info known to receiver • Throughput approximated by Throughput = (1-PER) x max. rate • 100 bytes packet length • TX power 0 dBm • Thermal noise + 20 dB RX noise figure • Recorded narrowband channel attenuation 2.4 GHz band Dries Neirynck - University of Bristol - MVCE

16. Bluetooth / IEEE 802.15.3 performs poorly Dries Neirynck - University of Bristol - MVCE

17. IEEE 802.15.3 simulation Parameters: • Baseband only, other layers assumed ideal • Modulation and FEC implemented • Receiver: • noise-whitening matched filter + DFE(4,3), • Viterbi decoder for TC-QAM, • Perfect knowledge of channel and packet header info • Throughput approximated as before • 100 bytes packet length • TX power 10 dBm • Thermal noise + 12 dB RX noise figure • Recorded narrowband channel attenuation 2.4 GHz band Dries Neirynck - University of Bristol - MVCE

18. IEEE 802.15.3 model can perform well Dries Neirynck - University of Bristol - MVCE

19. What’s the benefit of using multiple antennas in BAN? Dries Neirynck - University of Bristol - MVCE

20. The measurement data from the MIMO channel sounder is used MIMO channel sounder (Medav Rusk BRI) • Dual Polar Patch antennas • 2 antennas per ‘terminal’ • 120 MHz @ 5.2 GHz • Office and anechoic chamber • 30 second routine consisting of sitting, standing, turning body and touching toes Dries Neirynck - University of Bristol - MVCE

21. Both the use of spatial and polarisation diversity result in considerable capacity increases Dries Neirynck - University of Bristol - MVCE

22. 2-by-2 Space-time coding is evaluated based on a scheme proposed by Lindskog • 2-by-2 MIMO extension of 802.15.3 based on Lindskog’s adaptation of Alamouti’s scheme for wideband channels • Parameters identical to 802.15.3 simulation • Total TX power kept constant • Except for measured MIMO channels (5.2 GHz!) Dries Neirynck - University of Bristol - MVCE

23. Space-time coding can be used to increase reliability and/or lower TX power Dries Neirynck - University of Bristol - MVCE

24. A 2-by-2 spatial multiplexing extension to 802.15.3 has been investigated • Parameters identical to 802.15.3 simulation • Total TX power kept constant (10 dBm) • Except for measured MIMO channels (5.2 GHz) Dries Neirynck - University of Bristol - MVCE

25. Performance in BAN channels Dries Neirynck - University of Bristol - MVCE

26. How can the PHY exploit the presence of multiple antennas in PAN or BAN? Increase reliability of link with space-time coding • 2-by-2 extension based on Lindskog’s scheme evaluated • 4-5 dB SNR reduction for similar throughput in BAN channels • can be used to extend range or lower TX power Increase throughput of link with spatial multiplexing • 2-by-2 extension achieves predicted doubling of the throughput Dries Neirynck - University of Bristol - MVCE

27. Final Overview • Body shadowing severely attenuates the signal • User motion leads to a very variable channel • This affects the performance of current PAN standards • particularly in the case of Bluetooth/802.15.1 • Use of multiple antennas should be considered Dries Neirynck - University of Bristol - MVCE

28. Thank you!What question do you have?d.neirynck@tue.nlm.a.beach@bristol.ac.ukwalter.tuttlebee@mobilevce.com Dries Neirynck - University of Bristol - MVCE