Short Message Service (SMS)
This feature allows the tracker to send short messages over LoRaWAN. The message can be sent over CLI with the tracker connected to computer using USB port or via bluetooth communication interface using smart phone.
The main application of this feature is to be able to send short messages over LoRaWAN when traditional cellular network is not available.
A position acquisition is performed each time a SMS is sent by the tracker. Position message is sent depending on the configuration of geoloc_method parameter. The position message is characterized as an on demand position message in the common message header.
LoRaWAN duty cycle is disabled when sending/receiving SMS.
CLI commands
The CLI commands required for the lora SMS feature are the following:
lora sms normal <Destination_ID> <message>
lora sms urgent <destination ID> <message>
lora sms receive
Destination identifier
The destination ID is the identifier of the SMS recipient. It can be entered as a decimal or hexadecimal number. Hexadecimal number are prefixed by 0x. The identifier ranges in [0 - 16777215] or in hexadecimal [0 - 0xFFFFFF]
Message
The message is coded in ASCII (usual coding for string) and can have maximum length of 192 characters. In the case where the message is not restricted to a single word, it should be enclosed by double quotes.
Normal vs urgent: The two message types differ in the network processing:
-
normal: means that a non network acknowledged message will be sent. The network will not acknowledge the message reception. In the case where the message is lost by the server, it is not retransmitted by the device.
-
urgent: means that a network acknowledged message will be sent. The network will acknowledge the message reception. In the case where the message is not received by the server, the acknowledge will not be sent. The device will repeat the message up to 4 times (see here).
Examples
-
lora sms normal 123 hello
Send the non acknowledge message (single word) hello to the recipient matching the identifier 123. -
lora sms normal 0x1C "Hello world"
Send the non acknowledge message (multiple words) "hello word" to the recipient matching the identifier 0x1c (28). Note that in this case the double quotes are required. -
lora sms urgent 456 "War is bad"
Send the acknowledge message (multiple words) "war is bad" to the recipient matching the identifier 456. Note that in this case the double quotes are required. -
lora sms receive
Check whether a message is destined for the tracker. If a message for us is pending, it will be sent to us.
Configuration and usage
In order to simplify the readability of the CLI, log messages should be suppressed by entering the command system log off. The tracker should be let in standby mode to minimize the power consumption. The configuration parameter transmit_strat and transmit_strat_custom should be correctly tuned regarding the LoRaWAN region. Please refer to AN-002_LoRa_Transmission_strategy on how to configure LoRaWAN transmit strategy.
Please note that the maximum message size strongly depends on the LoRa DataRate it is sent.
Data rates for Europe LoRaWAN region (EU868)
| Data Rate | Max SMS size |
|---|---|
| DR0 | 46 |
| DR1 | 46 |
| DR2 | 46 |
| DR3 | 110 |
| DR4 | 192 |
| DR5 | 192 |
Data rates for US LoRaWAN region (US915)
| Data rate | Max SMS size |
|---|---|
| DR0 | 6 (should be avoided) |
| DR1 | 48 |
| DR2 | 120 |
| DR3 | 192 |
| DR4 | 192 |
LoRaWAN uplink payload
The LoRaWAN uplink payload format is explained here.
LoRaWAN downlink payload
The LoRaWAN downlink payload format is explained here.