Decoding method and decoding device for a CDMA transmission system for demodulating a received signal available in serial code concatenation
First Claim
1. A decoding method for demodulating a received signal available in serial code concatenation in a code-division multiple access transmission system, a two-step coding being carried out at the transmitting end of the transmission system, a first step of the two-step coding including a Hadamard orthogonal multi-step inner code, a second step of the two-step coding including an outer error-correcting code of a predefined rate, the method comprising:
- providing a soft-in/soft-out decoder in a receiver of the transmission system, a first decoder step of the soft-in/soft-out decoder including an inner decoder, a second decoder step of the soft-in/soft-out decoder including an outer decoder; and
processing soft values as reliability information at an output and an input of the soft-in/soft-out decoder, a soft output of the inner decoder being a soft input for the outer decoder, a channel reliability information output from a preceding demodulation being an input for the inner decoder, wherein the first decoder step of the soft-in/soft-out decoder and the second decoder step of the soft-in/soft-out decoder are configured to decode the received signal coded in the two-step coding, wherein the receiver includes an incoherent receiver structure including a RAKE receiver, wherein a soft input of the inner decoder includes a-priori information for systematic bits of Walsh functions of the inner code, the inner Hadamard code being decoded by entering an a-priori information vector L(u) into an instruction of the inner decoder, the instruction being such that for each bit decision, in a summing of a numerator and a denominator of a term to be expressed logarithmically of each considered element of a square-law-combining fast Hadamard transform resultant decision vector w, three terms are multiplied, a first term of the three terms being a-priori probabilities P(xj), a second term of the three terms being an exponentiated vector element, a third term of the three terms being a modified Bessel function of the first type of power (L-1) with argument, L being a number of fingers of the RAKE receiver, x being a Walsh function.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and a device for decoding for use in a code-division multiple access (CDMA) transmission system for demodulating a received signal available in serial code concatenation, with a two-step coding being carried out at the transmitting end of the transmission system, including an orthogonal, multi-step inner Hadamard code and an outer, error-correcting code of a predefined rate. In the receiver, a soft-in/soft-out decoder is provided, at whose input and output soft values are processed as reliability information, i.e., L-values. The soft output of the first decoder step, or inner code is the soft input for the decoder step, or outer code, that follows in each case, the first decoder step receiving the output values of the preceding demodulation, which contain the channel'"'"'s reliability information. A soft output is used by the decoder, in particular a MAP decoder, as a-priori information for the systematic bits of the Walsh function of the inner code for decoding of the inner code.
236 Citations
4 Claims
-
1. A decoding method for demodulating a received signal available in serial code concatenation in a code-division multiple access transmission system, a two-step coding being carried out at the transmitting end of the transmission system, a first step of the two-step coding including a Hadamard orthogonal multi-step inner code, a second step of the two-step coding including an outer error-correcting code of a predefined rate, the method comprising:
-
providing a soft-in/soft-out decoder in a receiver of the transmission system, a first decoder step of the soft-in/soft-out decoder including an inner decoder, a second decoder step of the soft-in/soft-out decoder including an outer decoder; and
processing soft values as reliability information at an output and an input of the soft-in/soft-out decoder, a soft output of the inner decoder being a soft input for the outer decoder, a channel reliability information output from a preceding demodulation being an input for the inner decoder, wherein the first decoder step of the soft-in/soft-out decoder and the second decoder step of the soft-in/soft-out decoder are configured to decode the received signal coded in the two-step coding, wherein the receiver includes an incoherent receiver structure including a RAKE receiver, wherein a soft input of the inner decoder includes a-priori information for systematic bits of Walsh functions of the inner code, the inner Hadamard code being decoded by entering an a-priori information vector L(u) into an instruction of the inner decoder, the instruction being such that for each bit decision, in a summing of a numerator and a denominator of a term to be expressed logarithmically of each considered element of a square-law-combining fast Hadamard transform resultant decision vector w, three terms are multiplied, a first term of the three terms being a-priori probabilities P(xj), a second term of the three terms being an exponentiated vector element, a third term of the three terms being a modified Bessel function of the first type of power (L-1) with argument, L being a number of fingers of the RAKE receiver, x being a Walsh function. - View Dependent Claims (2, 3)
û
k being a bit of the soft output of the inner decoder, wj being a respective element of the vector w, IL−
1 being the modified Bessel function of the first type of power L−
1,j being a respective vector element index, N being a size of the code words of the inner code, s being a non-centrality of a distribution of maxima of the vector w over time, σ
2 being a mean noise power.
-
-
4. A decoding method for demodulating a received signal available in serial code concatenation in a code-division multiple access transmission system, a two-step coding being carried out at the transmitting end of the transmission system, a first step of the two-step coding including a Hadamard orthogonal multi-step inner code, a second step of the two-step coding including an outer error-correcting code of a predefined rate, the method comprising:
-
providing a soft-in/soft-out decoder in a receiver of the transmission system, a first decoder step of the soft-in/soft-out decoder including an inner decoder, a second decoder step of the soft-in/soft-out decoder including an outer decoder; and
processing soft values as reliability information at an output and an input of the soft-in/soft-out decoder, a soft output of the inner decoder being a soft input for the outer decoder, a channel reliability information output from a preceding demodulation being an input for the inner decoder, wherein the first decoder step of the soft-in/soft-out decoder and the second decoder step of the soft-in/soft-out decoder are configured to decode the received signal coded in the two-step coding, wherein the receiver includes a coherent receiver structure, wherein a soft input of the inner decoder includes a-priori information for systematic bits of Walsh functions of the inner code, and wherein the inner code includes a Hadamard code, the Hadamard code being decoded by;
adding an a-priori information vector L(u) for systematic bits of a Walsh function of the Hadamard code to an input vector Lc·
y from a channel;
performing a fast Hadamard transformation so as to provide a fast Hadamard transform resultant vector w;
then generating exponential functions with ½
·
wj as an argument, wj being a respective element of the vector w; and
adding, dividing and expressing logarithmically elements of a result vector z for each symbol û
K to be decoded according to the equation;
zj being a respective element of the resultant vector z, j being a respective vector element index, N being a size of the Walsh functions of the inner code;
wherein, with respect to Term 1 and Term 2 of the equation, for each step at least one maximum is used so as to provide a simplified decoder instruction of the equation, the simplified decoder instruction expressed by the relation;
so thatwj being a respective element of the vector w, LI(û
k) being the soft output of the inner decoder, u being a bit, y being a vector.
-
Specification