Crowd size estimation based on wireless signal absorption

{
  "publication_number": "US10374646B1",
  "country": "US",
  "kind": "B1",
  "title": "Crowd size estimation based on wireless signal absorption",
  "abstract": "Methods and devices for detecting wireless signal absorption using power sensing circuitry. One method includes receiving, by a receiving device having power sensing circuitry, a plurality of wireless signals from a plurality of transmitting devices. The power sensing circuitry may include a local oscillator, a mixer, and a band-pass filter. The method may also include detecting, by the power sensing circuitry, a plurality of power levels for the plurality of wireless signals, where each power level of the plurality of power levels corresponds one of the plurality of wireless signals. The method may further include analyzing, by one or more processors, the plurality of power levels to determine three characteristic power levels of the plurality of power levels. The method may further include calculating, by the one or more processors, an absorption amount based on the three characteristic power levels.",
  "claims": [
    "1. A method of estimating crowd size based on detected wireless signal absorption, the method comprising: receiving, by a receiving device, a plurality of wireless signals from a plurality of transmitting devices; detecting a plurality of power levels for the plurality of wireless signals, wherein each power level of the plurality of power levels corresponds to one of the plurality of wireless signals; analyzing, by one or more processors, the plurality of power levels to determine three characteristic power levels of the plurality of power levels; calculating, by the one or more processors, an absorption amount based on the three characteristic power levels; and estimating, by the one or more processors, a number of people based at least in part on the absorption amount.",
    "2. The method of claim 1, wherein a first characteristic power level of the three characteristic power levels is a maximum power level of the plurality of power levels.",
    "3. The method of claim 2, wherein: a second characteristic power level of the three characteristic power levels is a ⅔ percentile power level of the plurality of power levels; and a third characteristic power level of the three characteristic power levels is a ⅓ percentile power level of the plurality of power levels.",
    "4. The method of claim 3, wherein calculating the absorption amount based on the three characteristic power levels includes: calculating a first difference between the first characteristic power level and the third characteristic power level; calculating a second difference between the first characteristic power level and the second characteristic power level; and calculating a ratio between the first difference and the second difference, wherein the absorption amount is calculated based on the ratio.",
    "5. The method of claim 1, wherein the one or more processors are located within the receiving device.",
    "6. The method of claim 1, wherein the one or more processors are located remote to the receiving device.",
    "7. A receiving device for estimating crowd size based on detected wireless signal absorption, the receiving device comprising: an antenna for receiving a plurality of wireless signals from a plurality of transmitting devices; power sensing circuitry for detecting a plurality of power levels for the plurality of wireless signals, wherein each power level of the plurality of power levels corresponds to one of the plurality of wireless signals; and one or more processors configured to perform operations including: analyzing the plurality of power levels to determine three characteristic power levels of the plurality of power levels; calculating an absorption amount based on the three characteristic power levels; and estimating a number of people based at least in part on the absorption amount.",
    "8. The receiving device of claim 7, wherein a first characteristic power level of the three characteristic power levels is a maximum power level of the plurality of power levels.",
    "9. The receiving device of claim 8, wherein: a second characteristic power level of the three characteristic power levels is a ⅔ percentile power level of the plurality of power levels; and a third characteristic power level of the three characteristic power levels is a ⅓ percentile power level of the plurality of power levels.",
    "10. The receiving device of claim 9, wherein calculating the absorption amount based on the three characteristic power levels includes: calculating a first difference between the first characteristic power level and the third characteristic power level; calculating a second difference between the first characteristic power level and the second characteristic power level; and calculating a ratio between the first difference and the second difference, wherein the absorption amount is calculated based on the ratio.",
    "11. The receiving device of claim 7, wherein the plurality of power levels are received from the power sensing circuitry via a wireless connection.",
    "12. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform operations including: receiving a plurality of wireless signals from a plurality of transmitting devices; detecting a plurality of power levels for the plurality of wireless signals, wherein each power level of the plurality of power levels corresponds to one of the plurality of wireless signals; analyzing the plurality of power levels to determine three characteristic power levels of the plurality of power levels; calculating an absorption amount based on the three characteristic power levels; and estimating a number of people based at least in part on the absorption amount.",
    "13. The non-transitory computer-readable medium of claim 12, wherein a first characteristic power level of the three characteristic power levels is a maximum power level of the plurality of power levels.",
    "14. The non-transitory computer-readable medium of claim 13, wherein: a second characteristic power level of the three characteristic power levels is a ⅔ percentile power level of the plurality of power levels; and a third characteristic power level of the three characteristic power levels is a ⅓ percentile power level of the plurality of power levels.",
    "15. The non-transitory computer-readable medium of claim 14, wherein calculating the absorption amount based on the three characteristic power levels includes: calculating a first difference between the first characteristic power level and the third characteristic power level; calculating a second difference between the first characteristic power level and the second characteristic power level; and calculating a ratio between the first difference and the second difference, wherein the absorption amount is calculated based on the ratio.",
    "16. The non-transitory computer-readable medium of claim 12, wherein the one or more processors are located within a receiving device.",
    "17. The non-transitory computer-readable medium of claim 12, wherein the one or more processors are located remote to a receiving device."
  ],
  "description_excerpt": "A propagating wireless signal can be affected by different materials in different ways prior to arriving at a destination such as a receiving device. For example, different materials may cause the wireless signal to be reflected, scattered, diffracted, and/or absorbed, among other possibilities. Wireless signal absorption is generally characterized by a reduction in the signal power as a portion thereof is converted into heat within the material causing the absorption. The detection of such wireless signal absorption is useful in several applications. In some instances, a material may be characterized based on its frequency-dependent absorption properties. For example, a transmitter positioned near the material may vary the frequency of a transmitted signal over a range of interrogation frequencies, and a receiver positioned on the other side of the material may detect the frequency response.\n\nUsing wireless signal absorption to estimate the number of people surrounding or near a receiving device is problematic for a number of reasons. First, methods may generally require knowledge of the transmitting signal power and/or the position of the transmitter, thereby requiring a system-controlled transmitter at a fixed position. Second, counting a number of people based on a number of wireless signals can be highly inaccurate, where the proportion of the crowd with devices that emit signals can vary drastically, depending on the demographics of the crowd.",
  "cpc": [
    "H04B 1/1018",
    "H04B 1/1027",
    "H04B 1/16",
    "H04B 17/20",
    "H04W 52/367"
  ],
  "ipc": [
    "H04B 1/10",
    "H04B 1/16",
    "H04B 17/20"
  ],
  "assignees": [
    "Cubic Corp"
  ],
  "inventors": [
    "Graham Fletcher"
  ],
  "filing_date": "2018-12-19",
  "publication_date": "2019-08-06",
  "grant_date": "2019-08-06",
  "priority_date": "2018-02-07",
  "application_number": "US-201816225239-A",
  "family_id": "67477046",
  "cited_by_count": 12,
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}