Struct LinkSettings 

pub struct LinkSettings { /* private fields */ }

The radio settings of a LoRa link, enough to compute its time-on-air.

A LoRa transmission’s duration is fixed by the spreading factor, the bandwidth, the coding rate, and the frame options, not by the data itself beyond its length. This struct gathers those settings and computes the two numbers a long-range deployment lives by: the airtime of a payload, and the off time a duty-cycle limit then forces before the next transmission.

A higher spreading factor reaches much further but spends far longer on air, so the same payload that takes tens of milliseconds at SF7 can take most of a second at SF12, with a correspondingly longer mandatory silence. The arithmetic is exact and integer-only, so it runs on the smallest node.

Examples

use pamoja_lora::LinkSettings;

// The default European long-range setup: SF12, 125 kHz, coding rate 4/5.
let link = LinkSettings::new(12, 125_000);

// A 10-byte payload takes just under a second on air at SF12.
assert_eq!(link.airtime_us(10), 991_232);

Implementations

impl LinkSettings

pub fn new(spreading_factor: u8, bandwidth_hz: u32) -> Self

Creates link settings from a spreading factor and bandwidth, with LoRa defaults.

The defaults are coding rate 4/5, an 8-symbol preamble, an explicit header, and CRC on, matching a typical uplink.

Arguments

• spreading_factor - the spreading factor; clamped to the LoRa range 5 to 12. SF5 and SF6 carry the data rates RP002-1.0.5 added to several regions.
• bandwidth_hz - the channel bandwidth in hertz, such as 125_000.

Returns

The link settings.

pub fn with_coding_rate(self, denominator: u8) -> Self

Sets the coding rate by its denominator, from 4/5 to 4/8.

Arguments

• denominator - the coding-rate denominator, clamped to 5 to 8 for 4/5 to 4/8.

Returns

The updated settings, for chaining.

pub fn with_preamble(self, symbols: u16) -> Self

Sets the number of preamble symbols.

Arguments

• symbols - the preamble length in symbols; the LoRa default is 8.

Returns

The updated settings, for chaining.

pub fn implicit_header(self) -> Self

Uses an implicit header, which omits the header symbols from each frame.

Returns

The updated settings, for chaining.

pub fn without_crc(self) -> Self

Turns the frame CRC off.

Returns

The updated settings, for chaining.

pub fn spreading_factor(&self) -> u8

Returns the spreading factor.

Returns

The spreading factor, from 5 to 12.

pub fn bandwidth_hz(&self) -> u32

Returns the channel bandwidth in hertz.

Returns

The bandwidth in hertz.

pub fn symbol_time_us(&self) -> u64

Returns the duration of one symbol in microseconds.

Returns

The symbol time, 2^spreading_factor / bandwidth, in microseconds.

pub fn airtime_us(&self, payload_len: usize) -> u64

Returns the time on air of a payload in microseconds.

This is the channel occupancy the transmission costs: how long the radio holds the air, which sets both the duty-cycle budget and a large part of the energy the transmission spends.

Arguments

• payload_len - the payload length in bytes.

Returns

The time on air in microseconds.

pub fn min_off_time_us( &self, payload_len: usize, duty_cycle_permille: u32, ) -> u64

Returns the minimum silence after a transmission to honor a duty-cycle limit.

A duty-cycle limit caps the fraction of time a node may transmit, so after a transmission of a given airtime the node must stay quiet for long enough that the airtime is no more than that fraction of the whole cycle.

Arguments

• payload_len - the payload length in bytes.
• duty_cycle_permille - the duty-cycle limit in parts per thousand, so 10 is 1%.

Returns

The required off time in microseconds, or u64::MAX if the limit is zero.

Trait Implementations

impl Clone for LinkSettings

fn clone(&self) -> LinkSettings

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for LinkSettings

impl Debug for LinkSettings

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for LinkSettings

impl PartialEq for LinkSettings

fn eq(&self, other: &LinkSettings) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for LinkSettings