Introduction

In LoRaWAN protocol, the gateway output power refer to the downstream packets sent by Gateway. This output power is controlled by LoRaWAN server.

Gateway maintain a power index in the file: /etc/lora/global_conf.json for example:

"tx_lut_3": {
    "desc": "TX gain table, index 3",        // Index 3 refer to rf_power: 15dB. device will set the pa_gain,mix_gain,dig_gain  
    "pa_gain": 2,                            // to the value mentioned here so to generate 15dB output power. 
    "mix_gain": 10,
    "rf_power": 15,
    "dig_gain": 1
},
"tx_lut_4": {
    "desc": "TX gain table, index 4",
    "pa_gain": 2,
    "mix_gain": 10,
    "rf_power": 16,
    "dig_gain": 0

When LoRaWAN server sends a downlink stream, server will also ask the gateway to use which rf_power as output. So user don't need to consider to control in the gateway side.

If user want to always use a higher power or a lower power. User can modify the pa_gain,mix_gain,dig_gain for specify rf_power to achieve this purpose. This is not recommend, because this might break the regulator for specify country.