Stateless Radio Uplink and Downlink Monitoring

I am working on a radio-controlled drone/robot project. For the radio communication, I am using LoRa in a peer-to-peer configuration, which is a stateless radio communication technology. The downside of stateless radio communication is that its communication is stateless. Ergo, you can't make sure that a transmission has been received. This would be if the drone goes out of range or the radio communication is disrupted otherwise.

To mitigate this problem, I have invented a novel lightweight algorithm heavily inspired by the vector clock alrogithm and heart beat algorithm. It is a stateless fire-and-forget ping pong to exchange incrementing number pair where each node has its number. If both nodes have the numbers sent with the heartbeat matching, the link can be considered stable, if one of the numbers is off, you can derive whether the uplink or downlink is having problems. Thus allowing lightweight monitoring of uplink and downlink radio communication to detect a lost link, without a chatty callback to acknowledge every transmission.

The below sequence diagram shows the algorithm in detail. Once steps 1 - 6 have been executed, the system only needs to loop steps 5 and 6 indefinitely.

sequenceDiagram;
    A->>A: 1.1 generate random value for own vector (VA)
    B->>B: 1.2 generate random value for own vector (VB)
   
    A->>A: 2.1 increment own vector (VA)
    A->>B: 2.2 send own vector (VA)
    B->>B: 2.3 save peer vector (VA)
    
    B->>B: 3.1 increment own vector (VB)
    B->>A: 3.2 send own vector (VB)
    A->>A: 3.3 save peer vector (VB)
    
    A->>A: 4.1 increments own vector (VA)
    A->>B: 4.2 send own vector (VA) and peer vector (VB)
    B->>B: 4.3 save new peer vector (VA)
    
    B->>B: 5.1 increment own vector (VB)
    B->>A: 5.2 send own vector (VB) and peer vector (VA)
    A->>A: 5.3 check if own vector (VA) matches with the value received from the peer to ensure the uplink is stable
    A->>A: 5.4 check if peer vector (VB) has only incremented by 1 to ensure the downlink is stable
    A->>A: 5.5 save new peer vector (VB)
    
    A->>A: 6.1 increments own vector (VA)
    A->>B: 6.2 send own vector (VA) and peer vector (VB)
    B->>B: 6.3 check if own vector (VB) matches with the value received from the peer to ensure the uplink is stable
    B->>B: 6.4 check if peer vector (VA) has only incremented by 1 to ensure the downlink is stable
    B->>B: 6.5 save new peer vector (VA)

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I develop this proof of concept with a pair of two RangePi USB dongles. They are based on Raspberry Pi RP2040 and LoRa Modules. It takes about 15 seconds up to two minutes to complete.

Below you can see the modules working:

Connection not Ensured on First Node

First Exchange of "Vector Clock Values" via heartbeat broadcast on First Node

State of Ensured Connection on First Node

State of Ensured Connection on Second Node