Method for transmitting multiple code words in a multiple antenna system
Provided is a method of sending multiple codewords in a wireless communication system using a plurality of transmitting antennas. The method includes the steps of encoding a plurality of parallel information bit streams to generate a plurality of parallel codewords; modulating the plurality of parallel codewords to generate a plurality of parallel modulated symbol streams; performing a DFT (Discrete Fourier Transform) on the modulated symbol streams to generate a plurality of frequency domain symbol streams; performing a pre-coding process on the plurality of frequency domain symbol streams; mapping the plurality of precoded frequency domain symbol streams to resource elements; performing an IFFT (Inverse Fast Fourier Transform) on the plurality of frequency domain symbol streams to generate SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols; performing shifting, at a predetermined time interval, on layers at which the plurality of parallel codewords, the plurality of parallel modulated symbol streams, or the plurality of frequency domain symbol streams; and transmitting the SC-FDMA symbol.
1. A method of transmitting multiple codewords in a wireless communication system using a plurality of transmission antennas, the method comprising:
generating a plurality of parallel codewords by encoding a plurality of parallel information bit streams;
generating a plurality of parallel modulated symbol streams by modulating the plurality of parallel codewords;
generating a plurality of frequency domain symbol streams by performing Discrete Fourier Transform (DFT) on the modulated symbol streams;
precoding the plurality of frequency domain symbol streams;
mapping the precoded frequency domain symbol streams onto resource elements;
generating Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols by performing Inverse Fast Fourier Transform (IFFT) on the plurality of frequency domain symbol streams;
performing shifting that changes layers to which the plurality of parallel codewords, the plurality of parallel modulated symbol streams, or the plurality of frequency domain symbol streams is mapped at a predetermined time interval; and
transmitting the SC-FDMA symbols.
2. The method of claim 1 , wherein:
the shifting is performed after generating the plurality of frequency domain symbol streams by performing the DFT, and
the time interval is a plurality of the SC-FDMA symbols.
3. The method of claim 1 , wherein the time interval is a single SC-FDMA symbol.
4. The method of claim 1 , further comprising mapping the layers to the plurality of transmission antennas.
5. The method of claim 4 , wherein the number of the layers is smaller than or equal to the number of transmission antennas.
6. The method of claim 4 , wherein the layers are mapped onto one or more of the transmission antennas.
7. The method of claim 1 , wherein different Modulation and Coding Schemes (MCSs) are applied to the plurality of parallel codewords and the plurality of parallel modulated symbol streams.
8. The method of claim 1 , wherein:
different coding rates are applied to the plurality of parallel codewords, and
an identical modulation order is applied to the plurality of parallel modulated symbol streams.
9. The method of claim 1 , wherein the shifting is performed only when the SC-FDMA symbols are retransmitted.
10. The method of claim 1 , wherein:
the shifting is performed after generating the SC-FDMA symbols, and
the time interval is a single SC-FDMA symbol.
11. An apparatus for transmitting multiple codewords in a wireless communication system using a plurality of transmission antennas, the apparatus comprising:
encoders for generating a plurality of parallel codewords by encoding a plurality of parallel information bit streams;
mappers for generating a plurality of parallel modulated symbol streams by modulating the plurality of parallel codewords;
DFT units for generating a plurality of frequency domain symbol streams by performing Discrete Fourier Transform (DFT) on the modulated symbol streams;
a precoder for precoding the plurality of frequency domain symbol streams;
resource element mappers for mapping the precoded frequency domain symbol streams onto resource elements;
signal generators for generating Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols by performing Fast Fourier Transform (IFFT) on the plurality of frequency domain symbol streams;
a shifting unit for performing shifting that changes layers to which the plurality of parallel codewords, the plurality of parallel modulated symbol streams, or the plurality of frequency domain symbol streams is mapped at a predetermined time interval; and
the plurality of transmission antennas for sending the SC-FDMA symbols.