P. Vanveerdeghem, B. Jooris, P. Becue, P. Van Torre, H. Rogier, I. Moerman, J. Knockaert

Reducing Power Consumption in Body-centric Zigbee Communication Links by means of Wearable Textile AntennasP. Vanveerdeghem, B. Jooris, P. Becue, P. Van Torre, H. Rogier, I. Moerman, J. Knockaert

Dept. of Information Technology

Ghent University

2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools

Outline

Introduction Measurement setup

Textile patch antenna w-iLab.t testbed Experiment description

Measurement results General conclusions

2


Introduction

Wireless body-centric sensor networks Smart fabric-integrated textile (SFIT) systems

FP6 Proetex Integrated Project Professional applications vs. consumer applications

Patient health monitoring Rescue worker monitoring People localisation Sports, gaming, etc. Personal communication

3


Introduction

Reducing power consumption Why?

Reducing costs Smaller Light-weight (smaller batteries)

How? Large area fire fighter garment

to deply more efficient antennas– High gain– Large radiation efficiency– Textile patch antenna

» Flexible, low weight, cheap, invisble and unobtrusive integration, etc

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Introduction

Aim Current literature about physical layer

Uncoded data transmission– Basic modulation schemes– Signal-to-noise ratio (SNR)– Bit error rate (BER)

Large complicated testbed / measurement devices Novelty:

Combined characterization:physical layer + network layer

– IEEE 8002.15.4– Low-cost transceiver

» RM090

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Outline




6


Measurement setup

Textile patch antenna Circularly polarized textile patch antenna

Single port Aramid substrate E-textiles

– Antenna patch– Ground plane

FP6 Proetex integrated project– Integration into firefighter suit

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Antenna dimensions [mm]

L 43 l 8 xfeed 7 Substrate Height h 1.73

W 47 w 7 yfeed 6


Measurement setup

Textile patch antenna Dual polarized textile patch antenna

Two ports Two orthogonal polarizations Flexible protective foam E-textiles

– Conducting textilesas antenna patch and ground plane

– Fire-retardant protectivefoam as antenna substrate

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Port 1 Port 2


Measurement setup

Textile patch antenna Dual polarized textile patch antenna

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Antenna specifications (see figure)

Antenna dimensions [mm]

L 45.32W 44.46Ls 14.88Ws 1Fx 5.7Fy 11.4

Substrate Height h 3.94

Substrate parameters Permittivity εr 1.53

tan δ 0.0012


Measurement setup

W-iLab.t testbed setup Integration into firefighter suit

PCB antenna vs. textile antenna RM090

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Measurement setup

W-iLab.t testbed setup indoor office environment (18x90m) 200 nodes / 3 floors Fire fighter

Normal walking speed – fixed path 2 mobile nodes

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Measurement setup

Experiment description Antenna

PCB antenna– Integrated on mobile node

Textile antenna– Connected via cable to mobile node– Dual polarized antenna– Circularly polarized antenna

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Measurement setup

Experiment description Firefighter walking along green path Time slot 1: TX broadcast (200ms)

All fixed nodes Mobile nodes

Time slot 2-3: mobile node 1-2 RSSI and node ID Broadcast to all fixed nodes

RSSI values are recorded Fixed and mobile nodes

Equal transmit power mobile nodes

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Outline




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Measurement results

Measurement 1 Circularly polarized patch antenna Packet loss Patch vs PCB antenna (33/18)

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Node: 1 4 5 6 7 8 9 10 11 12 13 14

Patch 20.27% 20.27% 16.28% 29.24% 16.94% 17.28% 23.92% 26.58% 18.60% 17.61% 23.59% 17.94%

PCB 25.91% 24.92% 24.92% 34.88% 21.59% 25.25% 29.90% 36.54% 23.26% 24.58% 29.24% 21.59%

TX 0.66% 20.60% 0.33% 13.95% 1.33% 1.33% 15.95% 3.65% 1.99% 0.33% 0.33%

15 16 17 19 20 21 22 23 25 26 27 28 29

17.94% 17.61% 17.28% 21.93% 15.61% 15.61% 18.60% 15.28% 19.27% 20.60% 16.61% 21.93% 22.59%

21.59% 26.58% 22.59% 28.24% 21.93% 21.26% 19.60% 20.60% 21.26% 20.60% 22.26% 22.92% 24.92%

0.33% 0.33% 1.33% 0.33% 0.33% 10.30% 0.66% 1.33% 1.66% 12.29% 0.33% 2.66% 9.97%

30 31 33 34 35 36 37 39 40 41 43 44 45

25.58% 23.26% 58.47% 40.86% 49.17% 51.50% 35.22% 58.14% 45.18% 37.87% 57.81% 50.17% 35.22%

24.92% 24.58% 48.17% 38.87% 40.20% 42.19% 31.56% 46.51% 39.53% 37.87% 45.85% 42.52% 34.55%

13.29% 10.63% 98.67% 25.25% 54.15% 99.67% 22.59% 28.24% 54.82% 46.84% 87.04% 95.68% 57.48%

46 47 48 49 50 51 52 53 54 55 56 199 200

28.57% 62.13% 35.55% 34.22% 47.84% 27.91% 32.89% 26.25% 23.26% 59.14% 59.47% 32.89% 46.84%

27.24% 46.84% 36.88% 37.21% 36.88% 30.56% 35.22% 27.24% 37.87% 46.84% 46.18% 30.90% 37.21%

23.92% 100.0% 63.12% 51.50% 25.58% 7.97% 19.27% 30.56% 29.24% 55.48% 100.0% 17.28% 62.79%


Measurement results

Measurement 1 RSSI on fixed nodes

Patch higher received power Patch less packet loss

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Measurement results

Measurement 1 Circularly polarized patch antenna

TX node mobile nodes RSSI on mobile nodes Patch antenna

Received power ↑↑ Received packets ↑↑

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Measurement results

Measurement 1 2 Simular results circularly and dual polarized textile

antenna Indication potential benefits of textile antennas

Unfair comparison between both types of antennas (PCB and patch)

RF losses due to RF interconnect and cables New separate PCB antenna

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Measurement results

Measurement 2 Circularly polarized patch antenna Packet loss Patch vs PCB antenna (45/6)

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Node: 1 4 5 6 7 8 9 10 11 12 13 14

Patch 40.20% 17.94% 28.57% 23.92% 32.56% 13.29% 19.27% 37.87% 60.47% 12.62% 53.49% 17.94%

PCB 47.51% 47.84% 43.19% 48.84% 47.84% 48.84% 44.85% 56.15% 45.18% 43.85% 46.18% 44.85%

TX 19.60% 0.33% 0.33% 0.66% 0.33% 3.99% 0.66% 2.33% 0.33% 12.62% 3.65%

15 16 17 19 20 21 22 23 25 26 27 28 29

28.90% 14.29% 13.95% 24.25% 14.29% 53.82% 49.83% 13.62% 15.95% 19.27% 13.95% 17.94% 16.94%

44.52% 44.52% 44.85% 51.16% 42.86% 42.86% 47.18% 42.19% 43.19% 47.18% 42.52% 44.52% 44.19%

1.00% 0.66% 1.33% 29.90% 0.33% 0.33% 3.32% 6.98% 0.33% 11.96% 2.99% 12.29% 1.00%

30 31 33 34 35 36 37 39 40 41 43 44 45

25.58% 22.26% 56.15% 23.92% 43.52% 57.14% 23.26% 58.47% 47.51% 37.21% 46.51% 44.19% 32.89%

48.17% 45.51% 78.07% 47.51% 58.14% 71.76% 48.50% 52.49% 71.76% 57.14% 56.81% 62.46% 58.14%

11.96% 11.30% 80.07% 13.62% 41.53% 46.18% 9.97% 46.51% 63.12% 49.50% 26.25% 46.51% 70.76%

46 47 48 49 50 51 52 53 54 55 56 199 200

19.27% 57.48% 27.24% 27.24% 61.46% 16.94% 21.59% 21.26% 18.27% 57.48% 59.80% 30.56% 40.53%

45.51% 60.47% 51.50% 54.15% 57.14% 45.85% 56.15% 48.84% 46.51% 75.75% 69.10% 54.49% 58.47%

1.66% 95.68% 64.45% 14.62% 11.63% 2.33% 22.92% 16.61% 7.31% 100% 88,04% 12.96% 16.94%


Measurement results

Measurement 2 RSSI on fixed nodes

Patch larger received power Patch less packet loss

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Measurement results

Measurement 2 Circularly polarized patch antenna

TX node mobile nodes RSSI on mobile nodes Patch antenna

Received power ↑↑ Received packets ↑↑

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Measurement results

Measurement results - overview

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Circ. Pol. Patch antenna Dual Pol. Patch antenna

Avg. loss Patch Avg. loss PCB Avg. loss Patch Avg. loss PCB

Meas. 130.8% 31.2% 27.4% 31.4%

26.2% 28.4% 27.2% 31.4%

Meas. 231.0% 52.0% 24.5% 31.8%

29.1% 33.6% 34.9% 51.0%

# nodes with less packet loss than PCB antenna

Circ. Pol. Patch antenna Dual Pol. Patch antenna

Meas. 131 (60%) 27 (53%)

36 (71%) 40 (78%)

Meas. 245 (88%) 48 (94%)

41 (80%) 44 (86%)


Outline




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Conclusion

Using flexible textile patch antennas Comfortable to the wearer Wireless link quality

Improvement both in transmit and receive mode Reducing transmit power

Guaranteeing same amount of packet loss Reducing power consumption Reducing costs (less battery, etc)

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Conclusion

Future research Avoiding RF losses

Integration transceiver on patch antenna Combining sereveral patch antennas

Power combiner Front and back antenna

Polarization One or more dual polarized antennas Transmitting on both orthogonal polarizations

Questions?

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P. Vanveerdeghem, B. Jooris, P. Becue, P. Van Torre, H. Rogier, I. Moerman, J. Knockaert

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