How to avoid channel jamming in Lora basic sender

ksckung · July 13, 2021, 8:26am

Hardware: HTCC-AB01
The program is base on

LoRaSender_ReadBattery.ino
hdc1080demo.ino

If I have many nodes, how to aovid channel jamming? i.e: list the channel before sending?

Code:

kscccc/CubeCell-Lora-sensor-network/blob/main/LoRaSender_ReadBattery_HDC1080_sleep_V003.ino

//Power on Vbat
//60s,Vbatt+HDC,20dBm,Vext 20ms delay, Green LED,Average 113uA (sleep 10.8uA,1PLC peak 141.57mA,CRO peak 1060mA)
//Use GPIO0 to power the HDC1080
//LED on GPIO5, blink after LoraTX

/* Heltec Automation Ping Pong communication test example
 *
 * Function:
 * 1. CubeCell read battery voltage and transmit via LoRa.
 * 
 * Description:
 * 1. Only hardware layer communicate, no LoRaWAN protocol support;
 * 2. This examplese can communicate with other ESP32 LoRa device,
 *    WiFi LoRa 32, Wireless Stick, Wireless Stick Lite, etc. 
 * 3. This example is for CubeCell hardware basic test.
 *
 * HelTec AutoMation, Chengdu, China
 * 成都惠利特自动化科技有限公司
 * https://heltec.org
 *

This file has been truncated. show original

Xiao-H · July 15, 2021, 1:41am

Method 1: host polling mode

The host polling mode is the way that the host calls one by one. The principle is very simple, and the response is realized by roll call. If the master sends the message to slave 1, only slave 1 can respond to the master because the slave has different address settings. After receiving the command from the host, slave 1 uploads the data to the host. The host then poll other slave data in the same polling mode

Method 2: from the machine timing upload mode

The principle of timing upload mode is that the host broadcasts and sends information to the slave. After receiving the host information, the slave synchronizes the time, and then uploads the information according to the time we set. For example, after the host sends the information, the upload time of slave 1 is 1 second, and that of slave 2 is 2 seconds… And so on

Method 3: active upload from slave

Slave active upload, Lora module has its own RSSI function networking mode is relatively reliable active upload mode. This transmission method is to detect the RSSI signal strength in the environment when the slave needs to upload data. If the RSSI strength in the current environment is larger, wait for the RSSI value to become smaller before uploading. If the upload is successful, the host will give feedback to the slave and decide whether to upload again. However, this method is not suitable for Lora module without RSSI function, because the more frequently the slave uploads, the higher the probability of communication failure, which is what we call co frequency interference.

Summarizing the above three methods, they all adopt the principle of staggering the upload time of the slave module, so as to solve the problem of co-frequency interference.

ksckung · July 19, 2021, 4:47am

As I know LoraWan has similar features.
Is it possible to make a Lora receiver compatible with LoraWan node?
Any example?