Device-Free Wi-Fi Sensing (DFWS) has garnered significant attention in research circles,
thanks to the widespread availability of Wi-Fi signals and its capability to provide relatively
precise sensing with minimal infrastructure requirements.
One of the primary advantages of DFWS lies in its ability to
harness the omnipresent Wi-Fi signals for passive detection of various human activities such as movement,
falls, gestures, and location tracking, among others. Unlike traditional sensing methods that rely on dedicated devices
like sensors or cameras, DFWS utilizes the inherent patterns within Wi-Fi signals to discern human presence and behavior.
This technology holds promise across diverse domains such as the Internet of Things (IoT), Human Activity Recognition (HAR),
and elderly care, owing to its unobtrusive nature and ability to facilitate pervasive sensing.
The inception of 'Sensorless Sensing' can be traced back to early efforts in human detection utilizing
Wireless Sensor Networks (WSN) and the Received Signal Strength Indicator (RSSI).
These pioneering endeavors laid the groundwork for subsequent advancements in localization and tracking,
paving the way for the widespread adoption of DFWS-based applications.
A notable evolution in DFWS came with the utilization of Channel State Information (CSI) in the 802.11n standard,
offering a finer-grained insight into the Physical (PHY) layer. This enhancement enabled the extraction of valuable
information at the frame level, augmenting the capabilities of DFWS beyond what was achievable with RSSI-based methods."
ESP32 is a low cost IoT device can also be used to acquire CSI.
This provides low cost deployment of the solution to the problem.
Provide Amplitude and Phase information of the CSI.
Not limited to LLTF but also HT-LLTF and other parameters.
Can be used an edge device for computation.
Can be used for application development.
Reconfigurable according to application.
Steps to acquire CSI by ESP32
This toolkit is used with WROOM 32 and ESP32 WROVER
Steps to acquire CSI are as follows:
Step-1: Setup the wireless network to acquire CSI.
Step-2: Make Client/Server architecture to generate traffic.
Step-3: Acquire CSI to configure ESP32 on the same channle on which Wireless Network is established.
Earlier Version of Espressif
ESP32 console based Configuration Settings
There are few configurations which are very necessary to acquire CSI.
We have included all these settings in the manuscript and discuused very much in detail.
These setting includes CPU clock setting, we need to set at maximum so that we can acquire CSI at maximum rate.
UART baud rate is very necessary to acquire CSI from ESP32 board.
This settings depends on the board type of ESP32 we are using to acquire CSI.
Third settings is the SSID information, which need to set before acquring the CSI.
The last but the most important setting is the Enabling to get CSI.
All these settings can be performed thorigh source code but the more easy way is by using console.
There are different options are available to set the clock frequency of the processor.
The best is to select maximum which is 240MHz.
In some cases this is observed that low clock rate can also work but this is better to select the clock rate maximum.
The baud rate settings is necessary in case you are using UART port to commuincate to the ESP32.
The Baud rate depends upon the board type you are using to acquire CSI.
There are many kinds of board are available in the market. Select that board which provides you maximum baud rate which is 2M.
The CSI gathering can be performed without using this. But still we have done this to avoid any confusion.
The important thing to acquire CSI is the channel number which are you uisng for transmission
This is better to filter the channel number and MAC address to minimze the traffic otherwise the traffic need to be filter at later stage.
The most important setting of the ESP32 is the enabling the CSI by using the console.
This must be enable before configuring ESP32.