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

Outline Introduction Measurement setup Textile patch antenna w-iLab.t testbed Experiment description Measurement results General conclusions 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 4

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 –Low-cost transceiver »RM090 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 5

Outline Introduction Measurement setup Textile patch antenna w-iLab.t testbed Experiment description Measurement results General conclusions 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 7 Antenna dimensions [mm] L43l8x feed 7Substrate Height h1.73 W47w7y feed 6

Measurement setup Textile patch antenna Dual polarized textile patch antenna Two ports Two orthogonal polarizations Flexible protective foam E-textiles –Conducting textiles as antenna patch and ground plane –Fire-retardant protective foam as antenna substrate 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 8 Port 1Port 2

Measurement setup Textile patch antenna Dual polarized textile patch antenna 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 9 Antenna specifications (see figure) Antenna dimensions [mm] L45.32 W44.46 Ls14.88 Ws1 Fx5.7 Fy11.4 Substrate Height h3.94 Substrate parameters Permittivity ε r 1.53 tan δ0.0012

Measurement setup W-iLab.t testbed setup Integration into firefighter suit PCB antenna vs. textile antenna RM090 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 10

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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 11

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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 12

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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 13

Outline Introduction Measurement setup Textile patch antenna w-iLab.t testbed Experiment description Measurement results General conclusions 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 14

Measurement results Measurement 1 Circularly polarized patch antenna Packet loss Patch vs PCB antenna (33/18) 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 15 Node: Patch20.27% 16.28%29.24%16.94%17.28%23.92%26.58%18.60%17.61%23.59%17.94% PCB25.91%24.92% 34.88%21.59%25.25%29.90%36.54%23.26%24.58%29.24%21.59% TX0.66%20.60% 0.33%13.95%1.33% 15.95%3.65%1.99%0.33% %17.61%17.28%21.93%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% 1.33%0.33% 10.30%0.66%1.33%1.66%12.29%0.33%2.66%9.97% %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% %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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 16

Measurement results Measurement 1 Circularly polarized patch antenna TX node mobile nodes RSSI on mobile nodes Patch antenna Received power Received packets 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 17

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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 18

Measurement results Measurement 2 Circularly polarized patch antenna Packet loss Patch vs PCB antenna (45/6) 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 19 Node: Patch40.20%17.94%28.57%23.92%32.56%13.29%19.27%37.87%60.47%12.62%53.49%17.94% PCB47.51%47.84%43.19%48.84%47.84%48.84%44.85%56.15%45.18%43.85%46.18%44.85% TX19.60%0.33% 0.66%0.33%3.99%0.66%2.33%0.33%12.62%3.65% %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% 44.85%51.16%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% 3.32%6.98%0.33%11.96%2.99%12.29%1.00% %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% %57.48%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 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 20

Measurement results Measurement 2 Circularly polarized patch antenna TX node mobile nodes RSSI on mobile nodes Patch antenna Received power Received packets 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 21

Measurement results Measurement results - overview 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 22 Circ. Pol. Patch antennaDual Pol. Patch antenna Avg. loss PatchAvg. loss PCBAvg. loss PatchAvg. loss PCB Meas %31.2%27.4%31.4% 26.2%28.4%27.2%31.4% Meas %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 antennaDual Pol. Patch antenna Meas (60%)27 (53%) 36 (71%)40 (78%) Meas (88%)48 (94%) 41 (80%)44 (86%)

Outline Introduction Measurement setup Textile patch antenna w-iLab.t testbed Experiment description Measurement results General conclusions 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 23

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) 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 24

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? 2nd International Workshop on Measurement-based Experimental Research, Methodology and Tools 25