def undo(data: bits, coding_rate='1/2') -> bits:
# un-puncturing process i.e. add 'X' bits, which are basically just ignored by the conv decoder
if coding_rate == '3/4':
data = [d[:3] + '??' + d[3] for d in bitstr.split(data, 4)]
elif coding_rate == '2/3':
data = [d + '?' for d in bitstr.split(data, 3)]
return bitstr.merge(data)
def do(data: bits, data_rate: int):
data_len_bytes = len(bitstr.split(data, 8))
conf = Config.from_data_rate(data_rate)
""" Bit-domain """
data, n_pad = padder.do(data, conf.data_bits_per_ofdm_symbol)
data = scrambler.do(data)
data = data[:-n_pad -
6] + '000000' + data[-n_pad:] # Refer to 17.3.5.3 for details.
data = convolutional_coder.do(data)
data = puncturer.do(data, conf.coding_rate)
data = interleaver.do(data, conf.coded_bits_per_ofdm_symbol,
conf.coded_bits_per_carrier_symbol)
symbols = header.do(data_rate, data_len_bytes) + modulator.do(
data, conf.coded_bits_per_carrier_symbol)
""" Frequency-domain """
carriers = subcarrier_mapping.do(symbols)
carriers = pilots.do(carriers)
frames = to_time_domain.do(carriers)
""" Time-domain """
frames = guard_interval.do(frames)
result = merger.do(preambler.short_training_sequence(),
preambler.long_training_sequence(), frames)
logger.info(
f'{data_len_bytes}B @ {data_rate}MB/s ({conf.modulation}, {conf.coding_rate})'
)
return result
def undo(data: bits, coded_bits_ofdm_symbol: int,
coded_bits_subcarrier: int) -> bits:
result = [
undo_one(group, coded_bits_ofdm_symbol, coded_bits_subcarrier)
for group in bitstr.split(data, coded_bits_ofdm_symbol)
]
return bitstr.merge(result)
def do(data: bits, coded_bits_ofdm_symbol: int,
coded_bits_subcarrier: int) -> bits:
result = [
do_one(interleaving_group, coded_bits_ofdm_symbol,
coded_bits_subcarrier)
for interleaving_group in bitstr.split(data, coded_bits_ofdm_symbol)
]
return bitstr.merge(result)
def undo(data: bits) -> bits:
LUT = {
'00': 0,
'01': 1,
'10': 2,
'11': 3,
'0?': 4,
'1?': 5,
'?0': 6,
'?1': 7
}
data = [
LUT[state_transition] for state_transition in bitstr.split(data, 2)
]
out, error_score = trellis_kernel(data)
# logger.debug(f'{len(out)//8}B, error_score={int(error_score)}')
return bitstr.from_list(out)
def do(data: bits, bits_per_symbol: int) -> List[Symbol]:
indexes = [bitstr.to_int(group) for group in bitstr.split(data, bits_per_symbol)]
symbols = [LUT[bits_per_symbol][index] for index in indexes]
return symbols