Interleaving
The term interleaving describes the channel process of exchanging the bit positions during coding. This is usually being done in order to distribute the bit errors resulting from a wrong symbol decision during waveform demodulation over the communication data frame. Therefore, most interleaving coding operations do not introduce redundancy to the interleaved blocks, i.e. the code rate is \(R = 1\).
- class BlockInterleaver(block_size, interleave_blocks)
Bases:
Encoder
,Serializable
An encoding operation interleaving bits in a block-wise fashion.
During encoding, the block interleaver divides a block of \(K_n\)
bit_block_size()
bits into \(\tilde{M}\)interleave_blocks()
of length \(\tilde{K}\). Let\[\mathbf{x} = \left[ x_1, x_2, \dots, x_{K_n} \right]^\intercal \in \left\lbrace 0, 1 \right\rbrace^{K_n}\]be the vector of input bits and
\[\mathbf{y} = \left[ y_1, y_2, \dots, y_{K_n} \right]^\intercal \in \left\lbrace 0, 1 \right\rbrace^{K_n}\]be the vector of interleaved output bits, then
\[y_k = x_{(k \cdot \tilde{M}) \mod{K_n}}\]describes the block interleaving scheme.
- Parameters
block_size (int) – The input / output number of bits the interleaver requires / generates.
interleave_blocks (int) – The number of sections being interleaved.
- Raises
ValueError – If block_size is not dividable into interleave_blocks.
- yaml_tag: Optional[str] = 'BlockInterleaver'
YAML serialization tag.
- encode(bits)
Encodes a single block of bits.
Bit encoding routine during data transmission, encoding a block of \(K_n\) input bits into a block of \(L_n\) code bits.
- Parameters
bits (np.ndarray) – A numpy vector of \(K_n\) bits, representing a single bit block to be encoded.
- Returns
A numpy vector of \(L_n\) bits, representing a single code block.
- Return type
np.ndarray
- Raises
ValueError – If the length of
bits
does not equalbit_block_size()
.
- decode(encoded_bits)
Decodes a single block of bits.
Bit decoding routine during data reception, decoding a block of \(L_n\) code bits into a block of \(K_n\) data bits.
- Parameters
encoded_bits (np.ndarray) – A numpy vector of \(L_n\) code bits, representing a single code block to be decoded.
- Returns
A numpy vector of \(K_n\) bits, representing a single data block.
- Return type
np.ndarray
- Raises
ValueError – If the length of
encoded_bits
does not equalcode_block_size()
.
- property bit_block_size: int
Data bit block size of a single coding operation.
In other words, the number of input bits within a single code block during transmit encoding, or the number of output bits during receive decoding. Referred to as \(K_n\) within the respective equations.
- Returns
Number of bits \(K_n\).
- Return type
int
- property code_block_size: int
Code bit block size of a single coding operation.
In other words, the number of input bits within a single code block during receive decoding, or the number of output bits during transmit encoding. Referred to as \(L_n\) within the respective equations.
- Returns
Number of bits \(L_n\).
- Return type
int
- property block_size: int
The configured block size.
- Returns
The number of bits per block.
- Return type
int
- property interleave_blocks: int
The number of sub-blocks in which which the input block is divided.
- Returns
The number of interleaved sections \(\tilde{M}\).
- Return type
int
- Raises
ValueError – If the number of interleaved sections is less than one.
- property rate: float
Code rate achieved by this coding step.
Defined as the relation
\[R_n = \frac{K_n}{L_n}\]between the
bit_block_size()
\(K_n\) andcode_block_size()
\(L_n\).- Returns
The code rate \(R_n\)
- Return type
float