Methods and systems for orthogonal frequency division multiplexing (OFDM) multiple zone partitioning
Aspects of the invention include methods and devices for inserting data and pilot symbols into Orthogonal Frequency Division Multiplexing (OFDM) frames having a time domain and a frequency domain. A method involves inserting in at least one zone of a first type a two dimensional array of data and pilot symbols in time and frequency and inserting in at least one zone of a second type a two dimensional array of data and pilot symbols in time and frequency. In some implementations the zone of the first type comprises common pilot symbols that can be detected by all receivers receiving the OFDM frame. In some implementations the zone of the second type comprises dedicated pilot symbols that are only detectable by a receiver that is aware of pre-processing used to encode the dedicated pilot symbols.
1. A method for inserting data and pilot symbols into Orthogonal Frequency Division Multiplexing (OFDM) symbols for transmission on at least one transmitting antenna, each OFDM symbol comprising a plurality of sub-carriers, a number of successive OFDM symbols being grouped into each of a plurality of transmission time intervals, the method comprising:
grouping the transmission time intervals into successive blocks, each block comprising an even number of transmission time intervals; and
inserting data and pilot symbols in a pre-defined time-frequency pattern in each block.
2. The method of claim 1 , wherein the pilot symbols are inserted in a plurality of regularly spaced OFDM symbols in each block.
3. The method of claim 1 , wherein the pilot symbols are inserted in a plurality of regularly spaced subcarriers in each block.
4. The method of claim 1 , wherein the pilot symbols are inserted in a regular diagonal lattice in each block.
5. The method of claim 1 , wherein the pilot symbols are inserted in a diamond shaped lattice in each block.
6. The method of claim 1 , wherein the pilot symbols comprise common pilot symbols for use by a plurality of receivers and dedicated pilot symbols, each dedicated pilot symbol being dedicated to a respective receiver.
7. The method of claim 1 , wherein at least one block uses a first multiple input multiple output (MIMO) format and at least one other block uses at least one other MIMO format.
8. The method of claim 1 , comprising:
inserting the data and pilot symbols in a first pre-defined time-frequency pattern in each block for transmission by a first antenna; and
inserting the data and pilot symbols in a second pre-defined time-frequency pattern in each block for transmission by a second antenna;
the first time-frequency pattern having nulls corresponding to locations of pilot symbols in the second time-frequency pattern; and
the second time-frequency pattern having nulls corresponding to locations of pilot symbols in the first time-frequency pattern.
9. The method of claim 1 , wherein each block consists of 12 sub-carriers over an even number of transmission time intervals.
10. The method of claim 1 , wherein each transmission time interval consists of an odd number of successive OFDM symbols.
11. The method of claim 6 , wherein:
the common pilot symbols are inserted in a first regular diagonal lattice in each block; and
the dedicated pilot symbols are inserted in a second regular diagonal lattice in each block, the second regular diagonal lattice being offset from the first regular diagonal lattice.
12. The method of claim 7 , wherein the MIMO formats are selected from a group consisting of open loop OFDM MIMO, OFDM beam forming, Bell Laboratories Layered Space-Time (BLAST), spatial multiplexing, and space-time transmit diversity.
13. An Orthogonal Frequency Division Multiplexing (OFDM) transmitter, comprising:
coding logic operable to insert data and pilot symbols into OFDM symbols, each OFDM symbol comprising a plurality of sub-carriers, a number of successive OFDM symbols being grouped into each of a plurality of transmission time intervals, the transmission time intervals being grouped into successive blocks, each block comprising an even number of transmission time intervals, and data and pilot symbols being inserted in a pre-defined time-frequency pattern in each block; and
at least one antenna for transmission of the OFDM symbols.
14. The OFDM transmitter of claim 13 , wherein the pilot symbols are inserted in a plurality of regularly spaced OFDM symbols in each block.
15. The OFDM transmitter of claim 13 , wherein the pilot symbols are inserted in a plurality of regularly spaced subcarriers in each block.
16. The OFDM transmitter of claim 13 , wherein the pilot symbols are inserted in a regular diagonal lattice in each block.
17. The OFDM transmitter of claim 13 , wherein the pilot symbols are inserted in a diamond shaped lattice in each block.
18. The OFDM transmitter of claim 13 , wherein the pilot symbols comprise common pilot symbols for use by a plurality of receivers and dedicated pilot symbols, each dedicated pilot symbol being dedicated to a respective receiver.
19. The OFDM transmitter of claim 13 , wherein at least one block uses a first multiple input multiple output (MIMO) format and at least one other block uses at least one other MIMO format.
20. The OFDM transmitter of claim 13 , wherein:
the at least one antenna comprises at least first and second antennas; and
the coding logic is operable to:
insert the data and pilot symbols in a first pre-defined time-frequency pattern in each block for transmission by the first antenna; and
insert the data and pilot symbols in a second pre-defined time-frequency pattern in each block for transmission by the second antenna;
the first time-frequency pattern having nulls corresponding to locations of pilot symbols in the second time-frequency pattern; and
the second time-frequency pattern having nulls corresponding to locations of pilot symbols in the first time-frequency pattern.
21. The OFDM transmitter of claim 13 , wherein each block consists of 12 sub-carriers over an even number of transmission time intervals.
22. The OFDM transmitter of claim 13 , wherein each transmission time interval consists of an odd number of successive OFDM symbols.
23. The OFDM transmitter of claim 18 , wherein:
the common pilot symbols are inserted in a first regular diagonal lattice in each block; and
the dedicated pilot symbols are inserted in a second regular diagonal lattice in each block, the second regular diagonal lattice being offset from the first regular diagonal lattice.
24. The OFDM transmitter of claim 19 , wherein the MIMO formats are selected from a group consisting of open loop OFDM MIMO, OFDM beam forming, Bell Laboratories Layered Space-Time (BLAST), spatial multiplexing, and space-time transmit diversity.