METHOD AND APPARATUS FOR ORTHOGONAL PILOT TONE MAPPING IN MULTIPLE-IN AND MULTIPLE-OUT (MIMO) AND SPATIAL DIVISION MULTIPLE ACCESS (SDMA) SYSTEMS

• US 20100208834A1
• Filed: 02/13/2009
• Published: 08/19/2010
• Est. Priority Date: 02/13/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: van Nee, Richard, van Zelst, Albert
• Granted Patent: US 8,270,517 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0447 utilizing uniform distribution
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

Methods and apparatus for orthogonal pilot tone mapping in Multiple-In and Multiple-Out (MIMO) and Spatial Division Multiple Access (SDMA) systems are disclosed. An aspect of the method includes identifying a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel; identifying a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over at least one dimension; and transmitting the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods.

Claims

1. A method for wireless communication comprising:

identifying a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel;

identifying a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over one or more dimensions; and

transmitting the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods.

2. The method of claim 1, wherein the one or more dimensions are chosen from a set consisting of a space dimension, a time dimension, and a frequency dimension.

3. The method of claim 1, wherein the orthogonal pilot tone mapping is added to a plurality of OFDM symbols

4. The method of claim 3 wherein the orthogonal pilot tone mapping is added to fixed subcarriers of the plurality of OFDM symbols.

5. The method of claim 1, further comprising overlaying a pilot tone pattern with an orthogonal code to achieve orthogonality in a plurality of dimensions.

6. The method of claim 5 wherein the orthogonal code is obtained by taking one entry from one of a row and a column of a Hadamard matrix.

7. The method of claim 1 wherein the orthogonal pilot tone mapping is repeated every predetermined plurality of symbols in a packet.

8. The method of claim 3, further comprising altering the pilot tone mapping with a sequence longer than the pilot tone mapping to create a pattern of orthogonal pilot tone mapping that has a longer repetition period than the pilot tone mapping.

9. The method of claim 8 wherein the sequence is a pseudo random sequence, such as given in Section 17.3.5.9 of the IEEE 802.11 standard.

10. A communication apparatus comprising.

means for identifying a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel;

means for identifying a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over one or more dimensions; and

means for transmitting the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods.

11. The communication apparatus of claim 10, wherein the one or more dimensions are chosen from a set consisting of a space dimension, a time dimension, and a frequency dimension.

12. The communication apparatus of claim 10, wherein the orthogonal pilot tone mapping is added to a plurality of OFDM symbols.

13. The communication apparatus of claim 12 wherein the orthogonal pilot tone mapping is added to fixed subcarriers of the plurality of OFDM symbols.

14. The communication apparatus of claim 10, further comprising means for overlaying a pilot tone pattern with an orthogonal code to achieve orthogonality in a plurality of dimensions.

15. The communication apparatus of claim 14 wherein the orthogonal code is obtained by taking one entry from one of a row and a column of a Hadamard matrix.

16. The communication apparatus of claim 10 wherein the orthogonal pilot tone mapping is repeated every predetermined plurality of symbols in a packet.

17. The communication apparatus of claim 12, further comprising a means for altering the pilot tone mapping with a sequence longer than the pilot tone mapping to create a pattern of orthogonal pilot tone mapping that has a longer repetition period than the pilot tone mapping.

18. The communication apparatus of claim 17 wherein the sequence is a pseudo random sequence, such as given in Section 17.3.5.9 of the IEEE 802.11 standard.

19. An apparatus for communications comprising:

a processing system configured to;

identify a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel;

identify a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over one or more dimensions; and

transmit the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods.

20. The communication apparatus of claim 19, wherein the one or more dimensions are chosen from a set consisting of a space dimension, a time dimension, and a frequency dimension.

21. The communication apparatus of claim 19, wherein the orthogonal pilot tone mapping is added to a plurality of OFDM symbols.

22. The communication apparatus of claim 21 wherein the orthogonal pilot tone mapping is added to fixed subcarriers of the plurality of OFDM symbols.

23. The communication apparatus of claim 19, wherein the processing system is further configured to overlay a pilot tone pattern with an orthogonal code to achieve orthogonality in a plurality of dimensions.

24. The communication apparatus of claim 23 wherein the orthogonal code is obtained by taking one entry from one of a row and a column of a Hadamard matrix.

25. The communication apparatus of claim 19 wherein the orthogonal pilot tone mapping is repeated every predetermined plurality of symbols in a packet.

26. The communication apparatus of claim 25, wherein the processing system is further configured to alter the pilot tone mapping with a sequence longer than the pilot tone mapping to create a pattern of orthogonal pilot tone mapping that has a longer repetition period than the pilot tone mapping.

27. The communication apparatus of claim 26 wherein the sequence is a pseudo random sequence, such as given in Section 17.3.5.9 of the IEEE 802.11 standard.

28. A computer-program product for wireless communications comprising:

a machine-readable medium encoded with instructions executable to;

identify a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel;

identify a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over one or more dimensions; and

transmit the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods.

29. A wireless communications device comprising:

a symbol identifier configured to identify a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel;

a pilot tone mapper coupled to the symbol identifier to identify a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over one or more dimensions; and

a transmitter coupled to the pilot tone mapper to transmit the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods.