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Table 2 Expected efficiency of practical WETI operation

From: Smart home gateway system over Bluetooth low energy with wireless energy transfer capability

  Frequency band    
  5725–5875 MHz 2400–2483.5 MHz 869.4–869.65 MHz 433.05–434.79 MHz 138.2–138.45 MHz 40.66–40.79 MHz 26.85–27.255 MHz
Maximum duty cycle, % a,b 100 100 10 100 10 100 100
Maximum power, mW a 25 EIRP 10 EIRP 500 ERP 10 ERP 500 ERP 500 ERP 500 ERP
Antenna length, cm 2.6 6.1 17.2 34.5 108.5 368.6 555.6
Maximum distance between gateway and sensor for WETI, m c 0.8 1.2 31.8 9 200 680 1025
Amount of power transfered into energy and buffered, mW c,d 0 0 0.02 0.0017 0.86 10 22.7
Harvesting time for enabling transmission of one BLE packet, s c,d,e infinity infinity 1.8 22 0.05 0.004 0.002
Portion of energy for powering active BLE transceiver replenished by WETI, % c,d,f 0 0 0.03 0.003 1.4 16.4 37.2
  1. aAccording to [36]
  2. bRelative to 1 hour, see [36]
  3. cAssumed that the transmitter is using the maximum possible transmit power
  4. dDistance between the gateway and the sensor is 5 m
  5. eRefer to Table 4 in [6]; for the TI CC2540 BLE transceiver, the energy required for sending an ADV_NONCONN_IND packet is 39 μJ
  6. fPower consumption for active mode was assumed to equal 61.1 mW; this is the average power consumed by TI CC2540 BLE transceiver while sending maximum-size frames (see Table four in [6]). The consumption for receiving acknowledgments is included