Credit score: CC0 Public Area

Researchers in UC Santa Barbara professor Yasamin Mostofi’s lab have enabled, for the primary time, counting a stationary seated crowd utilizing WiFi indicators, and with out counting on individuals to hold a tool. The approach, which additionally counts via partitions, wants solely a wi-fi transmitter and receiver outdoors the world of curiosity the place the gang is seated. It has quite a lot of functions, together with sensible vitality administration, controlling the gang dimension throughout a pandemic, enterprise planning and safety.

“Our proposed strategy makes it potential to estimate the variety of seated individuals in an space from outdoors,” mentioned Mostofi, a professor {of electrical} and laptop engineering at UCSB. “This strategy makes use of solely the obtained energy measurements of 1 WiFi hyperlink, doesn’t depend on individuals to hold a tool and works via partitions.”

The proposed methodology and experimental outcomes appeared within the current nineteenth ACM Worldwide Convention on Cell Techniques, Functions, and Companies (MobiSys).

Within the crew’s experiments, one WiFi transmitter and one WiFi receiver (each off-the-shelf) are in an space the place plenty of persons are seated. The transmitter sends a wi-fi sign whose obtained energy is measured by the receiver. By utilizing solely such obtained sign energy measurements, the receiver estimates how many individuals are current—an estimate that carefully matches the precise quantity.

Credit score: College of California – Santa Barbara

This innovation builds on earlier work within the Mostofi Lab, which has pioneered sensing with on a regular basis radio frequency indicators reminiscent of WiFi since 2009. As an example, their 2018 paper confirmed how WiFi can rely a crowd of cell individuals. Nonetheless, individuals needed to transfer round to be counted.

“Counting a stationary seated crowd is a significantly difficult downside as a result of lack of main physique movement,” mentioned Mostofi. Her lab’s success on this endeavor is as a result of new proposed methodology they developed.

“Whereas the individuals within the crowd are stationary, i.e., with no main physique movement besides respiration, they don’t keep nonetheless for an extended time period and often interact in small in-place pure physique motions referred to as fidgets,” Mostofi defined. “As an example, they might modify their seating place, cross their legs, test their telephones, stretch, or cough, amongst others.”

The researchers have proposed that the combination collective pure fidgeting and in-place motions of a seated crowd carry essential data on the gang rely, and have proven, for the primary time, the way to extract the combination fidgets and rely the full variety of individuals based mostly on them.

“Take into account the Crowd Fidgeting Durations (CFPs), which we outline because the time durations through which no less than one particular person within the WiFi space is fidgeting, in addition to the Crowd Silent Durations (CSPs), which we outline because the time durations through which not one of the persons are fidgeting. These durations are simply extractable from the obtained WiFi indicators,”mentioned Belal Korany, the principle Ph.D. scholar on the venture. “Intuitively talking, the larger the variety of individuals, the upper the possibility that CFPs are longer and the CSPs are shorter. Thus, these durations implicitly carry data on the full variety of individuals.”

The researchers then developed a brand new mathematical mannequin that statistically describes the collective fidgeting habits of a stationary crowd, i.e., the CFPs and CSPs, and explicitly relates them to the full variety of seated individuals.

In creating their mathematical formulation, they first reveal how this downside resembles a a number of decades-old queuing idea downside, a seemingly unrelated downside from a totally totally different subject. “Queuing idea is a department of arithmetic that research ready traces in methods that contain the arrival of consumers, who require a service from an entity that features plenty of servers,” mentioned Mostofi. They then present how the CSPs are much like the instances when no buyer is at a queue that has infinite servers, whereas the CFPs resemble the instances when no less than one buyer is being served at such a queue. This then permits them to borrow mathematical instruments from queuing idea to develop a totally new approach for counting the full variety of stationary individuals.

“We have now examined this know-how extensively in several places, and with totally different numbers of individuals in a number of totally different seating configurations,” mentioned Korany. The lab has examined their new know-how with 47 experiments in 4 totally different environments (together with through-wall settings), through which as much as and together with 10 persons are seated and behaving usually, whereas a pair of WiFi transceivers make WiFi measurements. Their experiments embody numerous events, reminiscent of attending a lecture/presentation, watching a film or studying in a library.

Their analysis outcomes present a really excessive counting accuracy, with the estimated variety of individuals being zero or one particular person off from the true variety of individuals 96.3% of the time in non-through-wall settings, and 90% of the time in through-wall settings. Total, their outcomes present the potential of this new know-how for crowd-counting in real-world situations, reminiscent of for limiting the full variety of individuals in a crowd throughout a pandemic.

Crowd counting via partitions, with WiFi

Extra data:
Outcomes: net.ece.ucsb.edu/~ymostofi/CountingStationaryCrowd

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College of California – Santa Barbara

Do not fidget! WiFi will rely you (2021, September 13)
retrieved 13 September 2021
from https://techxplore.com/information/2021-09-dont-fidget-wifi.html

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