Traveling pilots within single user, multiple user, multiple access, and/or MIMO wireless communications
View Patent ↗Pilot tones are included within symbols (e.g., orthogonal frequency division multiplexing (OFDM) symbols) transmitted between wireless communication devices. The pilot tones occupy fewer than all tone locations in any given symbol, and the pilot tones occupy different respective locations within different symbols. Generally, these traveling pilots are assigned to different respective tone locations in different symbols. In total, the pilot tones did not cover every single tone location within the symbols used to convey information between devices. Considering for example, when pilots occupy fewer than all tone locations, even among multiple symbols, a device may perform interpolation to generate a pilot tone estimate corresponding to a tone location not occupied by pilot tone within any symbol. Also, power or magnitude of the pilot tones themselves may be boosted or amplified relative to power magnitude of other tones within such symbols.
1. A wireless communication device comprising:
a communication interface; and
processing circuitry that is coupled to the communication interface, wherein at least one of the communication interface or the processing circuitry is configured to:
select a fast Fourier transform (FFT) structure from a plurality of FFT structures;
generate a plurality of OFDM symbols that includes data and pilots modulated on an occupied subset of a plurality of sub-carriers associated with the FFT structure; and
transmit the plurality of OFDM symbols to another wireless communication device to be used by the another wireless communication device to perform channel estimation of a wireless communication channel between the wireless communication device and the another wireless communication device, wherein:
a first FFT structure of the plurality of FFT structures specifies a first number of sub-carriers, a first occupied subset of sub-carriers within the first number of sub-carriers for the first FFT structure, and a first pilot periodicity of a first number of symbols associated with a first pilot pattern of the first FFT structure;
a second FFT structure of the plurality of FFT structures specifies a second number of sub-carriers that is different than the first number of sub-carriers, a second occupied subset of sub-carriers within the second number of sub-carriers for the second FFT structure, and a second pilot periodicity of a second number of symbols associated with a second pilot pattern for the respective FFT;
the plurality of FFT structures includes the first FFT structure, the second FFT structure, and a third FFT structure;
the second FFT structure is double size of the first FFT structure;
the third FFT structure is double size of the second FFT structure;
the first FFT structure has the first pilot periodicity of the first number of symbols; and
the second FFT structure and the third FFT structure both have the second pilot periodicity of the second number of symbols that is different than the first pilot periodicity of the first number of symbols.
2. The wireless communication device of claim 1 , wherein:
the first FFT structure is a 128 FFT structure;
the second FFT structure is a 256 FFT structure; and
the third FFT structure is a 512 FFT structure.
3. The wireless communication device of claim 1 , wherein:
the plurality of FFT structures includes the first FFT structure, the second FFT structure, the third FFT structure, a fourth FFT structure, and a fifth FFT structure;
the fifth FFT structure is half size of the first FFT structure;
the fourth FFT structure is half size of the fifth FFT structure;
the first FFT structure includes the first pilot periodicity having 19 symbols associated with the first pilot pattern;
the fourth FFT structure includes a fourth pilot periodicity having 13 symbols associated with the second pilot pattern; and
the fifth FFT structure includes a fifth pilot periodicity having 14 symbols associated with a third pilot pattern.
4. The wireless communication device of claim 1 , wherein:
the plurality of FFT structures includes the first FFT structure, the second FFT structure, the third FFT structure, a fourth FFT structure, and a fifth FFT structure;
the fifth FFT structure is half size of the first FFT structure;
the fourth FFT structure is half size of the fifth FFT structure;
the first FFT structure includes 2 pilots per OFDM symbols associated with the first pilot pattern; and
the second FFT structure includes 4 pilots per OFDM symbols associated with the second pilot pattern.
5. The wireless communication device of claim 1 , the at least one of the communication interface or the processing circuitry is further configured to:
select the FFT structure from the plurality of FFT structures during a first time period;
generate the plurality of OFDM symbols that includes the data and the pilots modulated on the occupied subset of the plurality of sub-carriers associated with the FFT structure during the first time period;
transmit the plurality of OFDM symbols to the another wireless communication device to be used by the another wireless communication device to perform channel estimation of the wireless communication channel between the wireless communication device and the another wireless communication device during the first time period;
select another FFT structure from the plurality of FFT structures during a second time period;
generate another plurality of OFDM symbols that includes other data and other pilots modulated on another occupied subset of another plurality of sub-carriers associated with the another FFT structure during the second time period; and
transmit the another plurality of OFDM symbols to at least one other wireless communication device to be used by the at least one other wireless communication device to perform channel estimation of at least one wireless communication channel between the wireless communication device and the at least one other wireless communication device during the second time period.
6. The wireless communication device of claim 1 , the at least one of the communication interface or the processing circuitry is further configured to:
generate the plurality of OFDM symbols based on space time block coding (STBC).
7. The wireless communication device of claim 1 further comprising:
a wireless station (STA), wherein the another wireless communication device includes an access point (AP).
8. The wireless communication device of claim 1 further comprising:
an access point (AP), wherein the another wireless communication device includes a wireless station (STA).
9. A wireless communication device comprising:
a communication interface; and
processing circuitry that is coupled to the communication interface, wherein at least one of the communication interface or the processing circuitry configured to:
select a fast Fourier transform (FFT) structure from a plurality of FFT structures;
generate a plurality of OFDM symbols that includes data and pilots modulated on an occupied subset of a plurality of sub-carriers associated with the FFT structure; and
transmit the plurality of OFDM symbols to another wireless communication device to be used by the another wireless communication device to perform channel estimation of a wireless communication channel between the wireless communication device and the another wireless communication device, wherein:
a first FFT structure of the plurality of FFT structures specifies a first number of sub-carriers, a first occupied subset of sub-carriers within the first number of sub-carriers for the first FFT structure, and a first pilot periodicity of a first number of symbols associated with a first pilot pattern of the first FFT structure;
a second FFT structure of the plurality of FFT structures specifies a second number of sub-carriers that is different than the first number of sub-carriers, a second occupied subset of sub-carriers within the second number of sub-carriers for the second FFT structure, and a second pilot periodicity of a second number of symbols associated with a second pilot pattern for the respective FFT;
the plurality of FFT structures includes the first FFT structure, the second FFT structure, a third FFT structure, a fourth FFT structure, and a fifth FFT structure;
the first FFT structure is a 32 FFT structure and has the first pilot periodicity of the first number of symbols;
the second FFT structure is a 64 FFT structure and has the second pilot periodicity of the second number of symbols;
the third FFT structure is a 128 FFT structure and has a third pilot periodicity of a third number of symbols;
the fourth FFT structure is a 256 FFT structure and has a fourth pilot periodicity of a fourth number of symbols; and
the fifth FFT structure is a 512 FFT structure and has the fourth pilot periodicity of the fourth number of symbols that is different than at least one of the first pilot periodicity of the first number of symbols, the second pilot periodicity of the second number of symbols, or the third pilot periodicity of the third number of symbols.
10. The wireless communication device of claim 9 , wherein:
the first FFT structure includes the first pilot periodicity having 13 symbols associated with the first pilot pattern;
the second FFT structure includes the second pilot periodicity having 14 symbols associated with the second pilot pattern; and
the third FFT structure includes the third pilot periodicity having 19 symbols associated with a third pilot pattern.
11. The wireless communication device of claim 9 , the at least one of the communication interface or the processing circuitry is further configured to:
generate the plurality of OFDM symbols based on space time block coding (STBC).
12. The wireless communication device of claim 9 further comprising:
a wireless station (STA), wherein the another wireless communication device includes an access point (AP).
13. The wireless communication device of claim 9 further comprising:
an access point (AP), wherein the another wireless communication device includes a wireless station (STA).
14. A method for execution by a wireless communication device, the method comprising:
selecting a fast Fourier transform (FFT) structure from a plurality of FFT structures;
generating a plurality of OFDM symbols that includes data and pilots modulated on an occupied subset of a plurality of sub-carriers associated with the FFT structure; and
transmitting, via a communication interface of the wireless communication device, the plurality of OFDM symbols to another wireless communication device to be used by the another wireless communication device to perform channel estimation of a wireless communication channel between the wireless communication device and the another wireless communication device, wherein:
a first FFT structure of the plurality of FFT structures specifies a first number of sub-carriers, a first occupied subset of sub-carriers within the first number of sub-carriers for the first FFT structure, and a first pilot periodicity of a first number of symbols associated with a first pilot pattern of the first FFT structure;
a second FFT structure of the plurality of FFT structures specifies a second number of sub-carriers that is different than the first number of sub-carriers, a second occupied subset of sub-carriers within the second number of sub-carriers for the second FFT structure, and a second pilot periodicity of a second number of symbols associated with a second pilot pattern for the respective FFT;
the plurality of FFT structures includes the first FFT structure, the second FFT structure, and a third FFT structure;
the second FFT structure is double size of the first FFT structure;
the third FFT structure is double size of the second FFT structure;
the first FFT structure has the first pilot periodicity of the first number of symbols; and
the second FFT structure and the third FFT structure both have the second pilot periodicity of the second number of symbols that is different than the first pilot periodicity of the first number of symbols.
15. The method of claim 14 , wherein:
the first FFT structure is a 128 FFT structure;
the second FFT structure is a 256 FFT structure; and
the third FFT structure is a 512 FFT structure.
16. The method of claim 14 , wherein:
the plurality of FFT structures includes the first FFT structure, the second FFT structure, the third FFT structure, a fourth FFT structure, and a fifth FFT structure;
the fifth FFT structure is half size of the first FFT structure;
the fourth FFT structure is half size of the fifth FFT structure;
the first FFT structure includes the first pilot periodicity having 19 symbols associated with the first pilot pattern;
the fourth FFT structure includes a fourth pilot periodicity having 13 symbols associated with the second pilot pattern; and
the fifth FFT structure includes a fifth pilot periodicity having 14 symbols associated with a third pilot pattern.
17. The method of claim 14 , wherein:
the plurality of FFT structures includes the first FFT structure, the second FFT structure, the third FFT structure, a fourth FFT structure, and a fifth FFT structure;
the fifth FFT structure is half size of the first FFT structure;
the fourth FFT structure is half size of the fifth FFT structure;
the first FFT structure includes 2 pilots per OFDM symbols associated with the first pilot pattern; and
the second FFT structure includes 4 pilots per OFDM symbols associated with the second pilot pattern.
18. The method of claim 14 further comprising:
generating the plurality of OFDM symbols based on space time block coding (STBC).
19. The method of claim 14 , wherein the wireless communication device includes a wireless station (STA), wherein the another wireless communication device includes an access point (AP).
20. The method of claim 14 , wherein the wireless communication device includes an access point (AP), wherein the another wireless communication device includes a wireless station (STA).