System and method for mapping symbols for MIMO transmission
Methods and devices are provided for MIMO OFDM transmitter and receivers having odd and/even numbers of transmit antennas. Various methods for pre-coding information bits before space time coding (STC) are described for enabling transmission of information bits over all antennas. Methods of decoding received signals that have been pre-coded and STC coded are also provided by embodiments of the invention. Pilot patterns for downlink and uplink transmission between a base station and one or more wireless terminals for three transmit antenna transmitters are also provided. Variable rate codes are provided that combine various fixed rate codes in a manner that results in codes whose rates are dependent on all the various fixed rate codes that are combined.
1. A method for transmitting on four antennas comprising:
pre-coding information bits to generate four transmit symbols, wherein the pre-coding comprises a pre-coding matrix multiplication and generating the four transmit symbols by mapping M information bits as two sets of M/2 bits, wherein a first transmit symbol and a third transmit symbol are generated based on mapping a first set of the two sets of M/2 bits and wherein a second transmit symbol and a fourth transmit symbol are generated based on mapping a second set of the two sets of M/2 bits;
encoding a first pair of transmit symbols including two of the first transmit symbol, the second transmit symbol, the third transmit symbol and the fourth transmit symbol into a first Alamouti matrix and a second pair of transmit symbols including a different two of the first transmit symbol, the second transmit symbol, the third transmit symbol and the fourth transmit symbol into a second Alamouti matrix;
transmitting the first Alamouti matrix on a first pair of antennas during a first time interval and a second time interval or at a first frequency and a second frequency; and
transmitting the second Alamouti matrix on a second pair of antennas during a third time interval and a fourth time interval or at a third frequency and a fourth frequency, wherein the pre-coding and the encoding are such that all of the information bits are represented in what is transmitted from each of the four antennas.
2. The method of claim 1 , wherein the precoding comprises:
mapping four pairs of the information bits to 4 phase shift keying (“PSK”) symbols by mapping each pair of the four pairs of information bits on a respective one of four rotated 4 PSK mapping constellations; and
generating the four transmit symbols by forming combinations of real and imaginary components of the 4 PSK symbols.
3. The method of claim 2 , wherein the forming combinations of the real and the imaginary components of the 4 PSK symbols comprises:
generating transmit symbols:
s 1 =Re{C 1 }+jRe{C 2 };
s 2 =Re{C 3 }+jRe{C 4 };
s 3 =Im{C 1 }+jIm{C 2 }; and
s 4 =Im{C 3 }+jIm{C 4 };
wherein:
C 1 is a first of the four rotated 4PSK mapping constellations;
C 2 is a second of the four rotated 4PSK mapping constellations;
C 3 is a third of the four rotated 4PSK mapping constellations; and
C 4 is a fourth of the four rotated 4PSK mapping constellations.
4. The method of claim 3 , wherein the 4 PSK symbols are further rotated by an angle.
5. The method of claim 1 , wherein the information bits are precoded using one of a M-ary QAM constellation, a 16 QAM constellation or a 64 QAM constellation.
6. The method of claim 5 , wherein when the information bits are precoded using the M-ary QAM constellation, half of the constellation symbols have even parity and half of the constellation symbols have odd parity.
7. The method of claim 5 , wherein when the information bits are precoded using the 64 QAM constellation, the pre-coding comprises adding a parity bit to 17 bits of data.
8. A processor configured to:
pre-code information bits to generate four transmit symbols, wherein the pre-coding comprises a pre-coding matrix multiplication and generating the four transmit symbols by mapping M information bits as two sets of M/2 bits, wherein a first transmit symbol and a third transmit symbol are generated based on mapping a first set of the two sets of M/2 bits and wherein a second transmit symbol and a fourth transmit symbol are generated based on mapping a second set of the two sets of M/2 bits;
encode a first pair of transmit symbols including two of the first transmit symbol, the second transmit symbol, the third transmit symbol and the fourth transmit symbol into a first Alamouti matrix and a second pair of transmit symbols including a different two of the first transmit symbol, the second transmit symbol, the third transmit symbol and the fourth transmit symbol into a second Alamouti matrix;
generate for transmission on a first pair of antennas the first Alamouti matrix during a first time interval and a second time interval or at a first frequency and a second frequency; and
generate for transmission on a second pair of antennas the second Alamouti matrix during a third time interval and a fourth time interval or at a third frequency and a fourth frequency, wherein the pre-coding and the encoding are such that all of the information bits are represented in what is generated for transmission on the first pair of antennas and the second pair of antennas.
9. The processor of claim 8 , wherein the precoding comprises:
mapping four pairs of the information bits to 4 phase shift keying (“PSK”) symbols by mapping each pair of the four pairs of the information bits on a respective one of four rotated 4 PSK mapping constellations; and
generating the four transmit symbols by forming combinations of real and imaginary components of the 4 PSK symbols.
10. The processor of claim 9 , wherein the forming combinations of the real and the imaginary components of the 4 PSK symbols comprises the processor:
generating transmit symbols:
s 1 =Re{C 1 }+jRe{C 2 };
s 2 =Re{C 3 }+jRe{C 4 };
s 3 =Im{C 1 }+jIm {C 2 }; and
s 4 =Im {C 3 }+jIm {C 4 };
wherein:
C 1 is a first of the four rotated 4PSK mapping constellations;
C 2 is a second of the four rotated 4PSK mapping constellations;
C 3 is a third of the four rotated 4PSK mapping constellations; and
C 4 is a fourth of the four rotated 4PSK mapping constellations.
11. The processor of claim 10 , wherein the 4 PSK symbols are further rotated by an angle.
12. The processor of claim 8 , wherein the information bits are precoded using one of a M-ary QAM constellation, a 16 QAM constellation or a 64 QAM constellation.
13. The processor of claim 12 , wherein when the information bits are precoded using the M-ary QAM constellation, half of the constellation symbols have even parity and half of the constellation symbols have odd parity.
14. The processor of claim 12 , wherein when the information bits are precoded using the 64 QAM constellation, the pre-coding comprises adding a parity bit to 17 bits of data.
15. A device comprising:
four antennas;
communication circuitry; and
processing hardware coupled to the four antennas and the communication circuitry, wherein the processing hardware is configured to operate with the four antennas and the communication circuitry to:
pre-code information bits to generate four transmit symbols, wherein the pre-coding comprises a pre-coding matrix multiplication and generating the four transmit symbols by mapping M information bits as two sets of M/2 bits, wherein a first transmit symbol and a third transmit symbol are generated based on mapping a first set of the two sets of M/2 bits and wherein a second transmit symbol and a fourth transmit symbol are generated based on mapping a second set of the two sets of M/2 bits;
encode a first pair of transmit symbols including two of the first transmit symbol, the second transmit symbol, the third transmit symbol and the fourth transmit symbol into a first Alamouti matrix and a second pair of transmit symbols including a different two of the first transmit symbol, the second transmit symbol, the third transmit symbol and the fourth transmit symbol into a second Alamouti matrix;
transmit the first Alamouti matrix on a first pair of antennas during a first time interval and a second time interval or at a first frequency and a second frequency; and
transmit the second Alamouti matrix on a second pair of antennas during a third time interval and a fourth time interval or at a third frequency and a fourth frequency, wherein the pre-coding and the encoding are such that all of the information bits are represented in what is transmitted from each of the four antennas.
16. The device of claim 15 , wherein the precoding comprises:
mapping four pairs of the information bits to 4 phase shift keying (“PSK”) symbols by mapping each pair of the four pairs of the information bits on a respective one of four rotated 4 PSK mapping constellations; and
generating the four transmit symbols by forming combinations of real and imaginary components of the 4 PSK symbols.
17. The device of claim 16 , wherein the forming combinations of the real and the imaginary components of the 4 PSK symbols comprises:
generating transmit symbols:
s 1 =Re{C 1 }+jRe{C 2 };
s 2 =Re{C 3 }+jRe{C 4 };
s 3 =Im{C 1 }+jIm {C 2 }; and
s 4 =Im {C 3 }+jIm {C 4 };
wherein:
C 1 is a first of the four rotated 4PSK mapping constellations;
C 2 is a second of the four rotated 4PSK mapping constellations;
C 3 is a third of the four rotated 4PSK mapping constellations; and
C 4 is a fourth of the four rotated 4PSK mapping constellations.
18. The device of claim 17 , wherein the 4 PSK symbols are further rotated by an angle.
19. The device of claim 15 , wherein the information bits are precoded using one of a M-ary QAM constellation, a 16 QAM constellation or a 64 QAM constellation.
20. The device of claim 19 , wherein when the information bits are precoded using the M-ary QAM constellation, half of the constellation symbols have even parity and half of the constellation symbols have odd parity.