Wireless communication device and method
SISO decoding of a reception signal having a scrambled symbol arrangement is realized using a process having reduced complexity. Coordinates are generated for a reference point obtained by scrambling and mapping a symbol number not a symbol reference point position. This reference point simulates transmission-side scrambling and is generated for each symbol number by a first mapping unit. Because the binary expression of a corresponding original signal number is retained, a bit likelihood calculation unit can easily calculate a bit likelihood based on the distance between the reference point and a reception signal. The calculated bit likelihood is then deinterleaved and subjected to SISO error-correcting decoding. The thus obtained bit likelihood is then reinterleaved and used to calculate a symbol probability. Soft symbols are generated through the multiplication of all the calculated symbol probabilities by corresponding reference points output by a second mapping unit similar to the first mapping unit.
1. A wireless communication device comprising:
a transmission side baseband signal processing unit which includes:
a means for converting a modulation bit sequence into a symbol mapping number;
a means for generating a scramble code for the symbol mapping number;
a symbol mapping number converting means for scrambling the symbol mapping number using the scramble code to convert the symbol mapping number into a transmission symbol mapping number;
a means for performing mapping according to the transmission symbol mapping number and a corresponding modulation scheme; and
a modulation transmission means for converting an output of the mapping into a time signal and converting and transmitting the time signal into a transmission frequency, and
a reception side baseband signal processing unit which includes:
a means for receiving and detecting a signal transmitted by the modulation transmission means,
a channel equalization means for performing channel equalization or its equivalent process on the detected signal;
a means for generating a first reference point symbol mapping number for generating a reference point in the modulation scheme;
a means for scrambling the first reference point symbol mapping number using the scramble code to convert the first reference point symbol mapping number into a first reference point transmission symbol mapping number;
a first reference point mapping means for performing mapping according to the first reference point transmission symbol mapping number and the modulation scheme;
a means for calculating a distance between an output of the first reference point mapping means and an output of the channel equalization means; and
a means for calculating a bit likelihood by referring to the first reference point symbol mapping number and the distance.
2. The wireless communication device of claim 1 , wherein the transmission side baseband signal processing unit further includes a means for performing error correction encoding and a first interleaving means for performing interleaving on an error correction encoded signal and outputting an interleaved signal to the symbol mapping number converting means, and the reception side baseband signal processing unit further includes a means for deinterleaving the bit likelihood, a means for performing soft-input soft-output error correction decoding on the deinterleaved signal, a second interleaving means for applying the same interleaving pattern as the first interleaving means to the soft-input soft-output error correction decoded output, a means for converting a bit likelihood output from the second interleaving means into a bit probability, a symbol mapping probability calculating means for calculating a symbol mapping probability from the bit probability based on the modulation scheme, a means for generating a second reference point symbol mapping number for soft symbol calculation, a means for generating a second reference point transmission symbol mapping number using the scramble code for the second reference point symbol mapping number, a second reference point mapping means for performing mapping according to the second reference point transmission symbol mapping number and the modulation scheme, a soft symbol calculating means for calculating a soft symbol from an output of the symbol mapping probability calculating means and an output of the second reference point mapping means, and a turbo equalization means for feeding back an output of the soft symbol calculating means to the channel equalization means.