Bit log likelihood ratio evaluation
First Claim
1. In a wireless communications user terminal (UT), a method for generating bit log likelihood ratio (LLR) values for two-layered quadrature phase-shift keying (QPSK) turbo decoding, the method comprising:
- receiving a two-layered QPSK signal with in phase (I) and quadrature (Q) components per symbol and with an energy ratio selected from a group comprising k12 and k22;
selecting a mismatched energy ratio (k2) between k12 and k22; and
generating said bit LLR values for the two-layered QPSK turbo decoding, using the mismatched k2 energy ratio and including determining said LLR values for four bits (b3, b2, b1, and b0), wherein determining the bit LLR values includes determining the bit LLR values for each b0 and b2 bit as follows;
1 Assignment
0 Petitions
Accused Products
Abstract
A system and method are provided for generating bit log likelihood ratio (LLR) values for two-layered Quadrature Phase-Shift Keying (QPSK) turbo decoding in a wireless communications user terminal (UT). The method includes receiving a two-layered QPSK signal with an energy ratio that is unknown, but typically defined as either k12 or k22. The method selects a mismatched energy ratio (k2) between k12 and k22, and generating bit LLR values for two-layered QPSK turbo decoding, using the mismatched k2 energy ratio. For example, if the received two-layered QPSK signal is known to have an energy ratio of about 4 or about 6.25. Then, k2 is selected to be about 5.0625. Alternately stated, the mismatched k2 energy ratio in selected by determining the approximate midpoint between k12 and k22.
-
Citations
4 Claims
-
1. In a wireless communications user terminal (UT), a method for generating bit log likelihood ratio (LLR) values for two-layered quadrature phase-shift keying (QPSK) turbo decoding, the method comprising:
-
receiving a two-layered QPSK signal with in phase (I) and quadrature (Q) components per symbol and with an energy ratio selected from a group comprising k12 and k22; selecting a mismatched energy ratio (k2) between k12 and k22; and generating said bit LLR values for the two-layered QPSK turbo decoding, using the mismatched k2 energy ratio and including determining said LLR values for four bits (b3, b2, b1, and b0), wherein determining the bit LLR values includes determining the bit LLR values for each b0 and b2 bit as follows; - View Dependent Claims (2)
-
-
3. A wireless communications user terminal (UT) for generating bit log likelihood ratio (LLR) values for two-layered quadrature phase-shift keying (QPSK) turbo decoding, the UT comprising:
-
a receiver having an air interface input to accept a two-layered QPSK signal with in phase (I) and quadrature (Q) components and with an energy ratio selected from a group comprising k12 and k22, and having outputs to supply a complex received signal components and complex channel estimates; and a LLR module having inputs to receive the complex received signal components and complex channel estimates, the LLR module determining four bit LLR values (b3, b2, b1, and b0), and the LLR module selecting a mismatched energy ratio (k2) between k12 and k22, and supplying said bit LLR values for two-layered QPSK turbo decoding at an output, using the mismatched energy ratio (k2), wherein the LLR module determines the LLR values for each b0 and b2 bit as follows; - View Dependent Claims (4)
-
Specification