A transmitter for transmitting an encoded codeword over a communication channel includes a source to accept source data, an irregular polar encoder operated by a processor to encode the source data with at least one polar code to produce the encoded codeword, a modulator to modulate the encoded codeword, and a front end to transmit the modulated and encoded codeword over the communication channel. The polar code is specified by a set of regular parameters including one or combination of parameters defining a number of data bits in the codeword, a parameter defining a data index set specifying locations of frozen bits in the encoded codeword, and a parameter defining a number of parity bits in the encoded codeword. The polar code is further specified by a set of irregular parameters including one or combination of parameters defining an irregularity of values of at least one regular parameter of the polar code, a parameter defining an irregularity of permutation of the encoded bits, a parameter defining an irregularity of polarization kernels in the polar code, and a parameter defining an irregularity in selection of de-activated exclusive-or operations on different stages of the polar encoding, and wherein the irregular polar encoder encodes the codeword using the regular and the irregular parameters of the polar code.

Certain aspects of the present disclosure generally relate to methods and apparatus for decoding low density parity check (LDPC) codes, and more particularly to non-linear log-likelihood ratio quantization techniques for low-density parity-check (LDPC) decoder architecture.

Embodiments described herein provide a system for dynamically selecting a pre-processing scheme for an LDPC decoder. The system includes a receiver configured to detect transmission of a first data packet and receive a first set of data bits corresponding to a first portion of the first data packet. The system further includes a histogram generator configured to calculate log-likelihood ratios for each data bit from the first set of data bits, and generate a histogram based on the calculated log-likelihood ratios. The receiver is configured to continue receiving a second set of data bits corresponding to a second portion of the first data packet. The system further includes a selector configured to activate or inactivate a log-likelihood ratio pre-processing scheme on the received second set of data bits based on characteristics of the histogram.

A method for decoding a codeword transmitted over a channel demodulates data received over the channel to produce an initial estimate of belief messages for bits of the codeword and decodes the codeword using a belief propagation (BP) decoding that iteratively passes the belief messages between a set of variable nodes representing the bits of the codeword and a set of check nodes representing parity-check constraints on the bits of the codeword until a termination condition is met. The BP decoding selects a look-up table based on a probability of the belief messages and maps, using the look-up table, values of at least two incoming belief messages to values of at least one outgoing belief message that forms an incoming belief message in a subsequent iteration of the BP decoding.

A method for decoding a codeword transmitted over a channel demodulates data received over the channel to produce an initial estimate of belief messages for bits of the codeword and decodes the codeword using a belief propagation (BP) decoding that iteratively passes the belief messages between a set of variable nodes representing the bits of the codeword and a set of check nodes representing parity-check constraints on the bits of the codeword until a termination condition is met. The BP decoding selects a look-up table based on a probability of the belief messages and maps, using the look-up table, values of at least two incoming belief messages to values of at least one outgoing belief message that forms an incoming belief message in a subsequent iteration of the BP decoding.

A decoding method for an iterative message-passing based decoder, such as a low-density parity-check (LDPC) decoder, includes calculating syndrome information for a received word, and initializing variable nodes based on the received word. Each received bit of the received word may be represented by a Likelihood-Ratio (LR) or Log-Likelihood-Ratio (LLR) at a respective variable node. Further, the method includes iteratively updating check nodes, and updating the LRs of variable nodes using the syndrome information, determining an error vector from the LRs of the variable nodes, and determining a transmitted word, corresponding to the received word, by subtracting the error vector from the received word. The syndrome information is calculated based upon a parity check matrix.