Struct Backoff

Source

pub struct Backoff { /* private fields */ }

Expand description

A device’s count of how long the network has been silent.

§Examples

A 1.0.4 device that stops hearing its network, starting two rates above its default:

use pamoja_lorawan::adr::{Backoff, Standing};
use pamoja_lorawan::Version;

let mut backoff = Backoff::recommended(Version::V1_0_4);
let mut data_rate = 2;
let mut sent = 0;
let mut steps = Vec::new();

while sent < 200 {
    let step = backoff.uplink(Standing { default_data_rate: data_rate == 0 });
    sent += 1;
    if step.restore_power {
        steps.push((sent, "power"));
    }
    if step.lower_data_rate {
        data_rate -= 1;
        steps.push((sent, "rate"));
    }
    if step.restore_channels {
        steps.push((sent, "channels"));
    }
}

// Power a delay after the limit, then a rate every delay, then the channels.
assert_eq!(steps, [(96, "power"), (128, "rate"), (160, "rate"), (192, "channels")]);
assert!(!backoff.uplink(Standing { default_data_rate: true }).request_ack);

Implementations§

Source §

impl Backoff

Source

pub const fn recommended(version: Version) -> Backoff

A count from zero, with the limit and delay RP002-1.0.5 section 3.3 recommends for every region.

§Arguments

version - the revision whose steps to follow.

§Returns

The count, asking after ADR_ACK_LIMIT unanswered uplinks and stepping every ADR_ACK_DELAY after that.

§Examples

use pamoja_lorawan::adr::Backoff;
use pamoja_lorawan::Version;

assert_eq!(Backoff::recommended(Version::V1_0_4), Backoff::new(Version::V1_0_4, 64, 32));

Source

pub const fn new(version: Version, limit: u32, delay: u32) -> Backoff

A count from zero, with a limit and delay a device was commissioned with.

§Arguments

version - the revision whose steps to follow.
limit - how many unanswered uplinks before it starts asking.
delay - how many more before its first step, and between each step after that. Treated as one if given as zero, since a step every zero uplinks is not a thing a device can do.

§Returns

The count.

Source

pub fn uplink(&mut self, standing: Standing) -> Step

Counts one new uplink, and says what to do before sending it.

Call this once per uplink the frame counter moves for. A repeated transmission of the same uplink is not a new one and does not count, which is the same rule the frame counter itself follows.

§Arguments

standing - where the device stands against its defaults right now.

§Returns

Whether to ask the network for an answer, and which step, if any, this uplink takes.

§Examples

use pamoja_lorawan::adr::{Backoff, Standing};
use pamoja_lorawan::Version;

let mut backoff = Backoff::recommended(Version::V1_0_3);
let above = Standing { default_data_rate: false };
for _ in 0..63 {
    assert!(!backoff.uplink(above).request_ack);
}

// The sixty-fourth unanswered uplink is the one that starts asking.
assert!(backoff.uplink(above).request_ack);