Adaptive Two-Dimensional Channel Interpolation

1. A method of inserting pilot symbols into OFDM sub-frames for transmission by a plurality of transmitting antenna, the OFDM sub-frames having a time domain and a frequency domain, each OFDM sub-frame comprising a plurality of OFDM symbols, the method comprising: for each sub-frame, defining a set of at least two OFDM symbols that are to contain pilot symbols for the sub-frame, wherein none of the OFDM symbols of the set are consecutive in time; and at each antenna of said plurality of transmitting antennas, inserting pilot symbols in each OFDM symbol of the set in a scattered pattern that does not interfere with the scattered pattern inserted at any other antenna of said plurality of transmitting antennas; wherein the scattered patterns of the respective antennas are identical but staggered in the frequency domain; wherein the scattered pattern for each antenna is not frequency-adjacent to the scattered pattern for any other antenna.

2. The method of claim 1 , wherein the scattered patterns are regular diamond lattices.

3. The method of claim 1 , wherein the scattered patterns are irregular diamond lattices.

4. The method of claim 1 , wherein the scattered patterns are kite shaped.

5. The method of claim 1 , wherein the number of OFDM symbols per OFDM sub-frame is 7.

6. The method of claim 1 , wherein each OFDM sub-frame comprises 8 sub-carriers.

7. The method of claim 1 , wherein each OFDM sub-frame comprises 10 sub-carriers.

8. The method of claim 1 , wherein each OFDM sub-frame comprises 12 sub-carriers.

9. The method of claim 1 , wherein the pilot symbols are inserted in each of the set of at least two OFDM symbols.

10. The method of claim 1 , wherein the scattered patterns are cyclically offset, both in a time direction and in a frequency direction.

11. The method of claim 1 , wherein the scattered patterns are cyclically offset, both in a time direction and in a frequency direction.

12. The method of claim 1 , wherein each sub-frame comprises first, second, third, fourth, fifth, sixth and seventh OFDM symbols in sequence, and wherein said set of at least two OFDM symbols comprises the first and fourth OFDM symbols.

13. An OFDM transmitter, comprising: one or more transmit antennas; the OFDM transmitter being adapted to insert pilot symbols into OFDM sub-frames for transmission by the plurality of transmit antennas, the OFDM sub-frames having a time domain and a frequency domain, each OFDM sub-frame comprising a plurality of OFDM symbols, wherein the OFDM transmitter is further configured to: for each sub-frame, define a set of at least two OFDM symbols that are to contain pilot symbols for the sub-frame, wherein none of the OFDM symbols of the set are consecutive in time; and at each antenna of said plurality of transmit antennas, insert pilot symbols in each OFDM symbol of the set in a scattered pattern that does not interfere with the scattered pattern inserted at any other antenna of said plurality of transmit antennas; wherein the scattered patterns of the respective antennas are identical but staggered in the frequency domain; wherein the scattered pattern for each antenna is not frequency-adjacent to the scattered pattern for any other antenna.

14. A non-transitory memory medium for inserting pilot symbols into OFDM sub-frames for transmission by a plurality of transmitting antenna, the OFDM sub-frames having a time domain and a frequency domain, each OFDM sub-frame comprising a plurality of OFDM symbols, wherein the memory medium stores program instructions, wherein the program instructions are executable by one or more processors to implement: for each sub-frame, defining a set of at least two OFDM that are to contain pilot symbols for the sub-frame, wherein none of the OFDM symbols of the set are consecutive in time; and at each antenna of said plurality of transmitting antennas, inserting pilot symbols in each OFDM symbol of the set in a scattered pattern that does not interfere with the scattered pattern inserted at any other antenna of said plurality of transmitting antennas; wherein the scattered patterns of the respective antennas are identical but staggered in the frequency domain; wherein the scattered pattern for each antenna is not frequency-adjacent to the scattered pattern for any other antenna.