###### tags: `rpi`
# Tutorial about P2P connection using Lora Module and ad-hoc Wifi on Raspberry Pi 3

## 1. TestBed
Laptop
Rasperry Pi 3 (B, B+) x2 (Ubuntu 22.04)
Lora module (lora-sx1276) x2

### SSH (optional)
#### Connect a PC and two Raspberry PIs with Ethernet, and connect the PC to a router. So you can use SSH to control both Raspberry PIs on the computer.
<!--
IP:
Computer: 10.0.1.10
PiB: 10.0.0.1
PiB+: 10.0.1.1
<!-->
## 2. Lora
### Connect LoRa modules to PIs
<!--->
<!-->
:::success
Pin connection on the Raspberry Pi and the mini LoRa chip.
:::
### Enable SPI interface
sudo raspi-config

#Select 3 Interface Options

#Select I4 SPI

#Enter

### Download the sample code from Github to both Raspberry PIs
https://github.com/piepie-tw/lora-sx1276

### Test if the pin connection work
cd /lora-sx1276
sudo python3 test_lora.py

### Display the parameters
##### Frequency, Bandwidth, and Spreading Factor must be the same on 2 Raspberry Pis for P2P to work.
sudo python3 lora_util.py
### P2P connection

#### For receiver
cd 02-p2p/
sudo python3 p2p_recv.py

#### For sender
cd 02-p2p/
sudo pytonh3 p2p_sender.py

### Change LoRaWAN settting
SX127x /
| --- Lora.py # Change setting manually

### Change Tx power
set_pa_config(pa_select = 1)
set_pa_dac(True)
set_pa_config(max_power=0x0f, output_power=0x0f) # Max power
set_pa_config(max_power=0x00, output_power=0x00) # Min power

#### Test Tx power

Compare the difference between max power and min power, and change the setting in p2p_recv.py and p2p_send.py

Max power: 15dBm RSSI: -101
Min power: -4.2dBm RSSI: -30

### Test Throughput, Latency, Packet loss rate, RSSI and SNR

Run lora_test_ssh.py to remotely connect to rpis. Test and copy the log files

Avg Throughput: 3.6769099248991153 kbps
Avg Latency: 217.57399999999998 ms
Packet Loss Rate: 0.0 %
Avg RSSI: -123.0
Avg SNR: 58.0

## 3. WiFi

### Change wifi into ad-hoc mode
essid need to be the same on Pi B and Pi B+
:::info
Attached to external Wi-Fi dongle is required
:::
sudo ifconfig wlan1 down
sudo iwconfig wlan1 mode ad-hoc
sudo iwconfig wlan1 essid Pi_adhoc
sudo iwconfig wlan1 channel 1

### Set IP on Pi B
sudo ifconfig wlan1 up
sudo ifconfig wlan1 192.168.1.5

### Set IP on Pi B+
sudo ifconfig wlan1 up
sudo ifconfig wlan1 192.168.1.6

### Use ping and traceroute to check whether they are connected
ping 192.168.1.6
traceroute 192.168.1.6

### Test throughout: iperf
sudo apt install iperf

Server (192.168.1.6)

iperf -s

Client (192.168.1.5)

iperf -c 192.168.1.6 -t 10 -i 1

Result: 21Mb/s

[ 1] local 192.168.0.108 port 5001 connected with 192.168.0.80 port 55132
[ ID] Interval Transfer Bandwidth
[ 1] 0.0000-10.5462 sec 26.4 MBytes 21.0 Mbits/sec

### Test latency and packet loss rate: mtr
sudo apt install mtr

Client (192.168.0.80)

mtr --no-dns --report --report-cycle 10 192.168.0.108

Result: 14.5 ms

HOST: Pi3B Loss% Snt Last Avg Best Wrst StDev
1.|-- 192.168.0.108 0.0% 10 7.8 14.5 6.9 42.4 10.7

## Flow to get Figs

Run wifi_setting_1.sh on client (192.168.1.5)
Run wifi_setting_2.sh on server (192.168.1.6)

Run T3_wifi_test_server.py on server to activate iperf.
Run T3_wifi_test_client.py on client.

Retrive the log file.

cd wifi_log

Use scp command to copy the log file to the local host.

scp rpi@192.168.0.108:/home/rpi/smartagr/wifi_log/T3_wifi_send_0.log ~/Desktop/

Run `T3_parser_new.py` to get figs.
:::info
Modify to multiple distances is required (todo)
:::

## Experiment result

Test with differnet distance between two nodes: 10cm, 20cm, 40cm, 80cm, 160cm

### Wifi
Throughput

RSSI

### LoRa
Throughput

RSSI

SNR