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 of receiving signals transmitted by three antennas comprising:
receiving, from each of the three antennas, a respective sequence of orthogonal frequency-division multiplexing (“OFDM”) symbols, wherein the respective sequence of OFDM symbols comprises,
a plurality of the OFDM symbols having a plurality of OFDM sub-carriers carrying data,
at least one pilot of a first antenna of the three antennas that is adjacent in one of time or frequency to a pilot of a second antenna of the three antennas, and
the at least one pilot of the first antenna of the three antennas is adjacent in the other of the time or frequency to a pilot of a third antenna of the three antennas, and
grouping pilots for the three antennas collectively in groups of pilots, each of the groups of pilots containing the pilot associated with the first antenna, the pilot of the second antenna, and the pilot of the third antenna, the groups of pilots being scattered in time and frequency; and
decoding the respective sequence of OFDM symbols to generate received signals.
2. The method of claim 1 , wherein each group of pilots comprises a first and a second pilot on a first OFDM sub-carrier, the first and second pilot are over two time intervals and a third pilot on an adjacent OFDM sub-carrier located in the same time intervals as the first and second pilot on the first OFDM sub-carrier.
3. The method of claim 1 , wherein the respective sequence of OFDM symbols are received on two receive antennas.
4. The method of claim 1 , wherein said receiving and decoding are performed by a mobile station.
5. The method of claim 1 , wherein said receiving and decoding are performed by a base station.
6. The method of claim 1 , further comprising:
determining channel information derived from the pilot symbols.
7. The method of claim 1 , further comprising:
generating channel estimates based on the respective sequence of OFDM symbols.
8. A receiver, comprising:
a plurality of receive antennas; and
processing hardware coupled to the plurality of receive antennas, wherein the processing hardware is configured to:
receive, from each of three transmit antennas, a respective sequence of orthogonal frequency-division multiplexing (“OFDM”) symbols, wherein the respective sequence of OFDM symbols comprises,
a plurality of the OFDM symbols having a plurality of OFDM sub-carriers carrying data,
at least one pilot of a first transmit antenna of the three transmit antennas that is adjacent in one of time or frequency to a pilot of a second transmit antenna of the three transmit antennas, and
the at least one pilot of the first transmit antenna of the three transmit antennas is adjacent in the other of the time or frequency to a pilot of a third transmit antenna of the three transmit antennas, and
group pilots for the three antennas collectively in groups of pilots, each of the groups of pilots containing the pilot associated with the first antenna, the pilot of the second antenna, and the pilot of the third antenna, the groups of pilots being scattered in time and frequency; and
decode the respective sequence of OFDM symbols to generate received signals.
9. The receiver of claim 8 , wherein the plurality of receive antennas comprises one of two, three or four receive antennas.
10. The receiver of claim 8 , wherein the processing hardware comprises one of an application specific integrated circuit, a digital signal processing chip, or a field programmable gate array.
11. The receiver of claim 8 , wherein each group of pilots comprises a first and a second pilot on a first OFDM sub-carrier, the first and second pilot are over two time intervals and a third pilot on an adjacent OFDM sub-carrier located in the same time intervals as the first and second pilot on the first OFDM sub-carrier.
12. The receiver of claim 8 , wherein the processing hardware is further configured to:
a determine channel information derived from pilot symbols.
13. The receiver of claim 8 , wherein the processing hardware is further configured to:
generate channel estimates based on the respective sequence of OFDM symbols.
14. A processor configured to perform operations, comprising:
receiving, from each of three transmit antennas, a respective sequence of orthogonal frequency-division multiplexing (“OFDM”) symbols, wherein the respective sequence of OFDM symbols comprises,
a plurality of the OFDM symbols having a plurality of OFDM sub-carriers carrying data,
at least one pilot of a first transmit antenna of the three transmit antennas that is adjacent in one of time or frequency to a pilot of a second transmit antenna of the three transmit antennas, and
the at least one pilot of the first transmit antenna of the three transmit antennas is adjacent in the other of the time or frequency to a pilot of a third transmit antenna of the three transmit antennas, and
grouping pilots for the three antennas collectively in groups of pilots, each of the groups of pilots containing the pilot associated with the first antenna, the pilot of the second antenna, and the pilot of the third antenna, the groups of pilots being scattered in time and frequency; and
decoding the respective sequence of OFDM symbols to generate received signals.
15. The processor of claim 14 , wherein the processor is communicatively coupled to the three transmit antennas and a plurality of receive antennas.
16. The processor of claim 15 , wherein the plurality of receive antennas comprises one of two, three or four receive antennas.
17. The processor of claim 14 , wherein the processor is one of an application specific integrated circuit, a digital signal processing chip, or a field programmable gate array.
18. The processor of claim 14 , wherein each group of pilots comprises a first and a second pilot on a first OFDM sub-carrier, the first and second pilot are over two time intervals and a third pilot on an adjacent OFDM sub-carrier located in the same time intervals as the first and second pilot on the first OFDM sub-carrier.
19. The processor of claim 14 , wherein the operations further comprise:
determining channel information derived from pilot symbols.
20. The processor of claim 14 , wherein the operations further comprise:
generating channel estimates based on the respective sequence of OFDM symbols.