METHODS AND APPARATUS TO ALLOCATE REFERENCE SIGNALS IN WIRELESS COMMUNICATION SYSTEMS

• US 20070253465A1
• Filed: 04/27/2007
• Published: 11/01/2007
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Shen, Zukang, Muharemovic, Tarik
• Granted Patent: US 9,444,650 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: H04J 13/0062 Zadoff-Chu
• CPC Class Codes: H04J 13/14 Generation of codes with a zero correlation zone
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 52/223 predicting future states of the transmission

Abstract

Methods and apparatus to allocate reference signals in wireless communication systems are disclosed. A disclosed example method comprises applying a first cyclic shift to a first reference sequence during a first time interval, and applying a second cyclic shift to a second reference sequence during a second time interval, wherein the first and second cyclic shifts are members of a set of cyclic shifts assigned to devices of a wireless region.

Claims

1. A method comprising:

applying a first cyclic shift to a first reference sequence during a first time interval; and

applying a second cyclic shift to a second reference sequence during a second time interval, wherein the first and second cyclic shifts are members of a set of cyclic shifts assigned to devices of a wireless region.

2. A method as defined in claim 1, wherein the set of cyclic shifts defines an order in which devices of the wireless region are to apply cyclic shifts.

3. A method as defined in claim 1, wherein the second reference sequence is the first reference sequence.

4. A method as defined in claim 1, wherein the first reference sequence is randomly selected.

5. A method as defined in claim 1, further comprising selecting the first and second reference sequence from a set of reference sequence assigned to devices of the wireless region.

6. A method as defined in claim 5, wherein the set of reference sequence defines an order in which devices of the wireless region are to select reference sequence.

7. A method as defined in claim 1, wherein the wireless region is at least one of a wireless communication cell or a wireless communication cell sector.

8. A method as defined in claim 1, wherein the first reference sequence is selected from a set of reference sequences that substantially satisfy a constant amplitude zero autocorrelation property.

9. (canceled)

10. An apparatus comprising:

a reference signal generator to generate a reference sequence based on a parameter assigned to a wireless region, wherein the parameter specifies a first reference sequence to be transmitted by a first device of the wireless region during a first time interval, the first reference sequence being different from a second reference sequence assigned to a second device of a second wireless region adjacent to the first wireless region, the reference sequence generator comprising;

a cyclic shift selector to select a cyclic shift for the first time interval based on the parameter; and

a cyclic shifter to cyclically shift the first reference signal based on the selected cyclic shift; and

a transmit adapter to transmit the cyclically shifted first reference sequence.

11. An apparatus as defined in claim 10, wherein the cyclic shift selector is to select a second cyclic shift for a second time interval based on the parameter;

and wherein the cyclic shifter is to cyclically shift the reference sequence based on the second selected cyclic shift during the second time interval.

12. An apparatus as defined in claim 10, wherein the parameter comprises at least one of a frame number, a sub-frame offset, a slot offset, a transmitted symbol offset, a wireless region identifier, a NodeB identifier, a user endpoint identifier or a group identifier.

14. An apparatus as defined in claim 10, wherein the reference signal generator is to generate a random reference sequence.

15. An apparatus as defined in claim 10, the reference signal generator further comprises a sequence selector to select the reference sequence from a set of reference sequences assigned to the first wireless region based on the parameter.

17. An apparatus as defined in claim 10, further comprising a modulator to modulate the selected reference sequence, the modulator comprising:

a Fourier transform module to perform a Fourier transform of the generated reference sequence;

an inverse Fourier transform module to perform an Inverse Fourier transform; and

an interface to map outputs of the Fourier transform to selected inputs of the Inverse Fourier transform.

13. (canceled)

16. (canceled)

18. An article of manufacture storing machine accessible instructions which, when executed, cause a machine to:

apply a first cyclic shift to a first reference sequence during a first time interval; and

apply a second cyclic shift to a second reference sequence during a second time interval, wherein the first and second cyclic shifts are members of a set of cyclic shifts assigned to devices of a wireless region.

19. An article of manufacture as defined in claim 18, wherein the set of cyclic shifts defines an order in which devices of the wireless region are to apply cyclic shifts.

20. An article of manufacture as defined in claim 18, wherein the second reference sequence is the first reference sequence.

22. An article of manufacture as defined in claim 18, wherein the machine accessible instructions, when executed, cause the machine to select the first and second reference sequences from a set of reference sequences assigned to devices of the wireless region.

23. An article of manufacture as defined in claim 22, wherein the set of reference sequences defines an order in which devices of the wireless region are to select reference sequences.

26. An article of manufacture as defined in claim 18, wherein the machine accessible instructions, when executed, cause the machine to select the first reference sequence from a set of sequences that substantially satisfy a constant amplitude zero autocorrelation property.

21. (canceled)

24. (canceled)

25. (canceled)

27-57. -57. (canceled)