Sensing Wall

This project aims to develop a testbed for testing large-scale wireless sensing application relying on processing of Channel State Information (CSI).

It utilizes the ESP32 platform for the generation of CSI data and contains a framework for the centralized collection and storage of said data from a number of nodes.

Architecture

There are three main components:

• one ESP32 node acting as an WiFi Acess Point (see left node in picture)
• 1-N ESP32 nodes arranged in a 2D grid operating in station mode (see right nodes in picture)
• one powerful server (e.g., laptop) used to store the CSI data in a time-series database (InfluxDB) with tools for visualization (Grafana) and processing (Python)

The following sequence diagram demonstrates the interaction between those three components:

Installation

The installation process contains the following steps:

• building and flashing the ESP32 nodes (AP and N stations) - see Makefile in esp directory.

make ap_flash PORT=/dev/ttyACM0
make sta_flash PORT=/dev/ttyACM2

• start docker (InfluxDB, Grafana, Prometheus) on the server node in server directory:

docker compose run

• installation of server components (InfluxDB, Grafana, Prometheus) - see server/docker-compose.yaml

• connect server node via WiFi to AP node. Therefore, prepare WPA-Supplicant

Setup wpa_supplicant config /etc/wpa_supplicant/wpa_supplicant.conf

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=DE

network={
	ssid="sensing-wall"
	key_mgmt=NONE
}

Setup interface /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)

auto wlp101s0
iface wlp101s0 inet static
    address 192.168.4.11
    netmask 255.255.255.0
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

• offload InfluxDB database to tmpfs to improve performance

Create tmpfs

mount -t tmpfs none /mnt

Create tmpfs on startup /etc/fstab

tmpfs    /mnt    tmpfs    defaults,size=40%      0       0

Link tmpfs

ln -s /mnt/server_influxDb/ influxDb

Init tmpfs via systemd. Create the service file /etc/systemd/system/init-fsram-influxdb.service

[Unit]
Description=Script to init ramfs in /mnt after fstab
After=local-fs.target

[Service]
Type=simple        
ExecStart=/bin/bash -c "cp -rp /home/csibox/sensing_wall/server/influxdb_data_hdd /mnt/server_influxDb"


[Install]
WantedBy=multi-user.target

Test the job

sudo service init-fsram-influxdb start

Enable job on startup

sudo systemctl enable init-fsram-influxdb.service

• start collector

cd server
python3 server_ng_parallel.py

make collector restarting on reboot. Make therefore sure that all required packets are installed for user root. You can check it via using

su
python3 server_ng_parallel.py

Now, create the service file /etc/systemd/system/sensingwallserver.service

[Unit]
Description=Sensingwall Server
After=network.target

[Service]
#StartLimitIntervalSec=0[Service]
Type=simple
Restart=always
RestartSec=1
ExecStart=/usr/bin/python3 /home/csibox/sensing_wall/server/server_ng_parallel.py

[Install]
WantedBy=multi-user.target

Test the job

sudo service sensingwallserver start

Enable job on startup

sudo systemctl enable sensingwallserver.service

• add hosts

127.0.0.1	influxdb
127.0.0.1	prometheus

Print your mounting

We provide a blender file in the mounting directory. You can put the required parts to your 3D-printer and print your onw sensing wall. The model is modular so you can descide on the size of your sensingwall by yourself.

Examples

Grafana

We provide an example Grafana dashboard. You can see the uplink and downlink CSI values there as well as the CSI values for each subcarrier. Please change the MAC filters in the queries according to your setup.

Python

We also provide example queries and their visualisazion in python scripts in the folder examples.

Acknowledgement

This project uses parts of esp32-csi-server and ESP32-CSI-Tool in addition to the example on the official ESP-IDF repo.