simulations/models/basic.py

import defs
import numpy as np
import math
import misc
from scipy.spatial import cKDTree
from os import path
import tensorflow as tf

ALPHABET_DIR = path.join(path.dirname(__file__), "../alphabets")


def load_alphabet(name, polar=True):
    apath = path.join(ALPHABET_DIR, name + '.a')
    if not path.exists(apath):
        raise ValueError(f"Alphabet '{name}' was not found in {path.abspath(apath)}")
    data = []
    indexes = []
    with open(apath, 'r') as f:
        header = f.readline().lower()
        if 'd' not in header and 'r' not in header:
            raise ValueError(f"Alphabet {name} header does not specify valid format")
        for i, row in enumerate(f.readlines()):
            row = row.strip()
            if len(row) == 0:
                continue
            cols = row.split(',')
            try:
                if len(cols) == 3:
                    base = 2
                    if 'i' in header:
                        base = 10
                    indexes.append(int(cols[0], base))
                    x = float(cols[1])
                    y = float(cols[2])
                elif len(cols) == 2:
                    indexes.append(i)
                    x = float(cols[0])
                    y = float(cols[1])
                else:
                    raise ValueError()
                if 'd' in header:
                    p = y * math.pi / 180
                    y = math.sin(p) * x
                    x = math.cos(p) * x
                data.append((x, y))
            except ValueError:
                raise ValueError(f"Alphabet {name} line {i + 1}: '{row}' has invalid values")

    data2 = [None] * len(data)
    for i, d in enumerate(data):
        data2[indexes[i]] = d
    arr = np.array(data2, dtype=float)
    if polar:
        arr = misc.rect2polar(arr)
    return arr


class RFSignal(defs.Signal):
    def __init__(self, array: np.ndarray):
        self.amplitude = array[:, 0]
        self.phase = array[:, 1]
        self.frequency = array[:, 2]
        self.symbols = array.shape[0]

    @property
    def rect(self) -> np.ndarray:
        return misc.polar2rect(np.c_[self.amplitude, self.phase])

    def set_rect_xy(self, x_mat: np.ndarray, y_mat: np.ndarray):
        self.set_rect(np.c_[x_mat, y_mat])

    def set_rect(self, mat: np.ndarray):
        polar = misc.rect2polar(mat)
        self.amplitude = polar[:, 0]
        self.phase = polar[:, 1]

    @property
    def apf(self):
        return np.c_[self.amplitude, self.phase, self.frequency]


class BypassChannel(defs.Channel):
    def forward(self, values):
        return values


class AWGNChannel(defs.Channel):
    def __init__(self, noise_level, **kwargs):
        """
        :param noise_level: in dB
        """
        super().__init__(**kwargs)
        self.noise = 10 ** (noise_level / 10)

    def forward(self, values: RFSignal) -> RFSignal:
        values.set_rect_xy(
            values.rect_x + np.random.normal(0, 1, values.symbols) * self.noise,
            values.rect_y + np.random.normal(0, 1, values.symbols) * self.noise,
        )
        return values

    def forward_tensor(self, tensor: tf.Tensor) -> tf.Tensor:
        noise = tf.random.normal([2], mean=0.0, stddev=1.0, dtype=tf.dtypes.float32, seed=None, name=None)
        tensor += noise * self.noise
        return tensor


class BPSKMod(defs.Modulator):

    def __init__(self, carrier_f, **kwargs):
        super().__init__(2, **kwargs)
        self.f = carrier_f

    def forward(self, binary):
        a = np.ones(binary.shape[0])
        p = np.zeros(binary.shape[0])
        p[binary == True] = np.pi
        f = np.zeros(binary.shape[0]) + self.f
        return RFSignal(np.c_[a, p, f])


class BPSKDemod(defs.Demodulator):

    def __init__(self, carrier_f, bandwidth, **kwargs):
        """
        :param carrier_f: Carrier frequency
        :param bandwidth: demodulator bandwidth
        """
        super().__init__(2, **kwargs)
        self.upper_f = carrier_f + bandwidth / 2
        self.lower_f = carrier_f - bandwidth / 2

    def forward(self, values):
        # TODO: Channel noise simulator for frequency component?
        # for now we only care about amplitude and phase
        # ap = np.delete(values, 2, 1)
        # ap = misc.polar2rect(ap)

        result = np.ones(values.symbols, dtype=bool)
        result[values.rect_x[:, 0] > 0] = False
        return result


class AlphabetMod(defs.Modulator):

    def __init__(self, modulation, carrier_f):
        # if N < 2:
        #     raise ValueError("M-ary modulator N value has to be larger than 1")
        self.alphabet = load_alphabet(modulation)
        super().__init__(self.alphabet.shape[0])
        self.f = carrier_f
        self.mult_mat = np.array([2 ** i for i in range(self.N)])

    def forward(self, binary):
        if binary.shape[0] % self.N > 0:
            to_add = self.N - binary.shape[0] % self.N
            binary = np.concatenate((binary, np.zeros(to_add, bool)))
        reshaped = binary.reshape((binary.shape[0] // self.N, self.N))
        indices = np.matmul(reshaped, self.mult_mat)
        values = self.alphabet[indices, :]

        a = values[:, 0]
        p = values[:, 1]
        f = np.zeros(reshaped.shape[0]) + self.f
        return RFSignal(np.c_[a, p, f])  # , indices


class AlphabetDemod(defs.Demodulator):

    def __init__(self, modulation, carrier_f):
        # if N < 2:
        #     raise ValueError("M-ary modulator N value has to be larger than 1")
        self.alphabet = load_alphabet(modulation, polar=False)
        super().__init__(self.alphabet.shape[0])
        self.f = carrier_f
        # self.alphabet = _gen_mary_alphabet(self.alphabet_size, gray=gray, polar=False)
        self.ktree = cKDTree(self.alphabet)

    def forward(self, binary):
        # binary = binary[:, :2]  # ignore frequency
        # rbin = misc.polar2rect(binary)
        indices = self.ktree.query(binary.rect)[1]

        # Converting indices to bite array
        # FIXME: unpackbits requires 8bit inputs, thus largest demodulation is 256-QAM
        values = np.unpackbits(np.array([indices], dtype=np.uint8).T, bitorder='little', axis=1)
        return values[:, :self.N].reshape((-1,)).astype(bool)  # , indices