Struct OESS

pub struct OESS { /* private fields */ }

Encoder / decoder using the OESS algorithm

The implementation follows https://doi.org/10.1109/JLT.2022.3201901. Most of the algorithm is implemented in trellis::Trellis though.

Implementations

impl OESS

pub fn new(e_max: usize, n_max: usize, ask: ASK) -> OESS

Returns a new OESS instance

OESS is sensitive to the maximum energy parameter. If there is a lower maximum energy that would allow the same number of bits in the index, all sequences with energy higher than this lower maximum energy will not be used. Thus the OESS algorithm is only defined for the lowest maximum energy that allows for a certain number of bits in the index. More specifically the following condition must hold:

|S(e_max - 8)| < 2^k ≤ |S(e_max)|

• |S(E)| is the cardinality of the set of all amplitude sequences with energy less than or equal to E
• k is a positive integer (equal to the number of bits in the index)

To find an acceptable e_max argument use OESS::optimal_e_max().

pub fn optimal_e_max(e_max: usize, n_max: usize, ask: &ASK) -> usize

Returns the next lower optimal e_max value

An ESS encoder with the provided arguments can encode a certain number of bits. This function returns the lowest e_max parameter so that an ESS encoder with the new e_max still encodes the same number of bits.

Trait Implementations

impl DistributionMatcher for OESS

fn amplitude_distribution(&self) -> Vec<f32>

Returns the probabilities of the amplitude values

The probabilities are returned as an array with the lowest index corresponding to the lowest amplitude.

Calculation for the partial trellis is based on formula (36) in section IV-D in https://doi.org/10.1109/JLT.2022.3201901.

fn n_max(&self) -> usize

Returns the number of amplitudes in an amplitude sequence

fn e_max(&self) -> usize

Returns the maximum allowed energy for an amplitude sequence

fn ask_num(&self) -> usize

Returns the number of the used ASK, e.g. 8 if 8-ASK is used

fn encode(&self, data: &Integer) -> Result<Vec<usize>, &str>

Returns the amplitude sequence for the given data or an error message if the data is imvalid

fn decode(&self, amplitude_sequence: &[usize]) -> Result<Integer, &str>

Returns the data for the given amplitude sequence or an error message if the data is invalid

fn num_sequences_possible(&self) -> Integer

Returns the maximum number of possible amplitude sequences

fn energy_distribution(&self) -> Vec<f32>

Returns the probabilities of the amplitude sequence energies

fn num_sequences(&self) -> Integer

Returns the number of used amplitude sequences

fn num_data_bits(&self) -> u32

Returns the number of bits encoded per amplitude sequence

fn average_energy(&self) -> f32

Returns the average energy of amplitude sequences