Systems and methods for approximating log likelihood ratios in a communication system

摘要

Systems and methods for computing log likelihood ratios in a communication system are described. A demodulated symbol may be received. A set of scalars may be determined based on a modulation order, a signal-to-noise ratio for the symbol, and a bit of the symbol. At least one log likelihood ratio for the bit may be approximated using a piecewise linear process based on the scalars and the symbol.

主权项

1. A method for computing log likelihood ratios in a communication system, comprising:
receiving a demodulated symbol corresponding to a modulated symbol; determining, from a primary scalar table, a first set of scalars based on a modulation order of the modulated symbol, the first set of scalars including a demodulation scalar and a signal-to-noise ratio (SNR) scalar; determining intermediate values based on the demodulated symbol, an SNR of the demodulated symbol, and the first set of scalars, the intermediate values including a first intermediate value that is a product between the demodulating scalar and an in-phase component of the demodulated symbol, a second intermediate value that is a product of the demodulating scalar and a quadrature component of the demodulated symbol, and a third intermediate value that is a product of the SNR scalar and the SNR; selecting a secondary scalar table from among a plurality of secondary scalar tables based on the modulation order; determining, from the selected secondary scalar table, a second set of scalars based on the SNR of the demodulated symbol and a bit of the demodulated symbol; and approximating, based at least on the first intermediate value, the second intermediate value, the third intermediate value, and the second set of scalars, at least one log likelihood ratio for the bit of the demodulated symbol using a piecewise linear process.