PSEUDORANDOM SEQUENCE GENERATION FOR OFDM CELLULAR SYSTEMS

• US 20090257523A1
• Filed: 12/02/2008
• Published: 10/15/2009
• Est. Priority Date: 04/15/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: DABAK, ANAND G., ONGGOSANUSI, EKO N., VARADARAJAN, BADRI, PANDE, TARKESH
• Granted Patent: US 8,755,453 B2
• Time in Patent Office: Days
• US Class Current: 375/295
• CPC Class Codes: H04B 1/04 Circuits
• CPC Class Codes: H04L 23/02 adapted for orthogonal signalling
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

In one embodiment, a transmitter includes a binary sequence generator unit configured to provide a sequence of reference signal bits, wherein the sequence is an inseparable function of a cell identification parameter, a cyclic prefix mode corresponding to the transmitter and one or more time indices of the sequence. The transmitter also include a mapping unit that transforms the sequence of reference signal bits into a complex reference signal, and a transmit unit configured to transmit the complex reference signal. In another embodiment, a receiver includes a receive unit configured to receive a complex reference signal and a reference signal decoder unit configured to detect a sequence of reference signal bits from the complex reference signal, wherein the sequence is an inseparable function of a cell identification parameter, a cyclic prefix mode corresponding to a transmitter and one or more time indices of the sequence.

Claims

1. A transmitter, comprising:

a binary sequence generator unit configured to provide a sequence of reference signal bits, wherein the sequence is an inseparable function of a cell identification parameter, a cyclic prefix mode corresponding to the transmitter and one or more time indices of the sequence;

a mapping unit that transforms the sequence of reference signal bits into a complex reference signal; and

a transmit unit configured to transmit the complex reference signal.

2. The transmitter as recited in claim 1 wherein the sequence of reference signal bits is generated by a linear feedback shift register capable of employing an initial seed, an update equation and a fast forward parameter.

3. The transmitter as recited in claim 2 wherein the fast forward parameter of the linear feedback shift register is a function of the cell identification parameter and one or more of the time indices.

4. The transmitter as recited in claim 2 wherein the initial seed of the linear feedback shift register is a nonlinear function of the cell identification parameter, the cyclic prefix mode and the time indices.

5. The transmitter as recited in claim 2 wherein the initial seed of the linear feedback shift register is a sum of terms and each term is proportional to a product of integer powers of the cell identification parameter, the cyclic prefix mode, the symbol index and the subframe index.

6. The transmitter as recited in claim 5 wherein for at least one term, the integer powers corresponding to the cell identification parameter, the symbol index, and the subframe index are all greater than zero.

7. The transmitter as recited in claim 5 wherein the initial seed of the linear feedback shift register is given by c_init=2¹⁰·

(7·

(n_s+1)+l+1)·

(2·

N_ID^cell+1)+2·

N_ID^cell+N_CP, where N_ID^cell denotes the cell identification parameter, N_CP denotes the cyclic prefix mode and time indices are a subframe index n_S and a symbol index l.

8. The transmitter as recited in claim 2 wherein the initial seed of the linear feedback shift register is a product of terms and each term is a scaled sum of the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.

9. The transmitter as recited in claim 8 wherein at least one term has a non-zero scaling corresponding to the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.

10. A method of operating a transmitter, comprising:

providing a sequence of reference signal bits, wherein the sequence is an inseparable function of a cell identification parameter, a cyclic prefix mode corresponding to the transmitter and one or more time indices of the sequence;

transforming the sequence of reference signal bits into a complex reference signal; and

transmitting the complex reference signal.

11. The method as recited in claim 10 wherein the sequence of reference signal bits is generated by a linear feedback shift register capable of employing an initial seed, an update equation and a fast forward parameter.

12. The method as recited in claim 11 wherein the fast forward parameter of the linear feedback shift register is a function of the cell identification parameter and one or more of the time indices.

13. The method as recited in claim 11 wherein the initial seed of the linear feedback shift register is a nonlinear function of the cell identification parameter, the cyclic prefix mode and the time indices.

14. The method as recited in claim 11 wherein the initial seed of the linear feedback shift register is a sum of terms and each term is proportional to a product of integer powers of the cell identification parameter, the cyclic prefix mode, the symbol index and the subframe index.

15. The method as recited in claim 14 wherein for at least one term, the integer powers corresponding to the cell identification parameter, the symbol index, and the subframe index are all greater than zero.

16. The method as recited in claim 14 wherein the initial seed of the linear feedback shift register is given by c_init=2¹⁰·

(7·

(n_s+1)+l+1)·

(2·

N_ID^cell+1)+2·

N_ID^cell+N_CP, where N_ID^cell denotes the cell identification parameter, N_CP denotes the cyclic prefix mode and time indices are a subframe index n_S and a symbol index l.

17. The method as recited in claim 11 wherein the initial seed of the linear feedback shift register is a product of terms and each term is a scaled sum of the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.

18. The method as recited in claim 17 wherein at least one term has a non-zero scaling corresponding to the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.

19. A receiver, comprising:

a receive unit configured to receive a complex reference signal; and

a reference signal decoder unit configured to detect a sequence of reference signal bits from the complex reference signal, wherein the sequence is an inseparable function of a cell identification parameter, a cyclic prefix mode corresponding to a transmitter and one or more time indices of the sequence.

20. The receiver as recited in claim 19 wherein the sequence of reference signal bits is generated by a linear feedback shift register capable of employing an initial seed, an update equation and a fast forward parameter.

21. The receiver as recited in claim 20 wherein the fast forward parameter of the linear feedback shift register is a function of the cell identification parameter and one or more of the time indices.

22. The receiver as recited in claim 20 wherein the initial seed of the linear feedback shift register is a nonlinear function of the cell identification parameter, the cyclic prefix mode and the time indices.

23. The receiver as recited in claim 20 wherein the initial seed of the linear feedback shift register is a sum of terms and each term is proportional to a product of integer powers of the cell identification parameter, the cyclic prefix mode, the symbol index and the subframe index.

24. The receiver as recited in claim 23 wherein for at least one term, the integer powers corresponding to the cell identification parameter, the symbol index, and the subframe index are all greater than zero.

25. The receiver as recited in claim 23 wherein the initial seed of the linear feedback shift register is given by c_init=2¹⁰·

(7·

(n_s+1)+l+1)·

(2·

N_ID^cell+1)+2·

N_ID^cell+N_CP, where N_ID^cell denotes the cell identification parameter, N_CP denotes the cyclic prefix mode and time indices are a subframe index n_S and a symbol index l.

26. The receiver as recited in claim 20 wherein the initial seed of the linear feedback shift register is a product of terms and each term is a scaled sum of the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.

27. The receiver as recited in claim 26 wherein at least one term has a non-zero scaling corresponding to the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.

28. A method of operating a receiver, comprising:

receiving a complex reference signal; and

detecting a sequence of reference signal bits from the complex reference signal, wherein the sequence is an inseparable function of a cell identification parameter, a cyclic prefix mode corresponding to a transmitter and one or more time indices of the sequence.

29. The method as recited in claim 28 wherein the sequence of reference signal bits is generated by a linear feedback shift register capable of employing an initial seed, an update equation and a fast forward parameter.

30. The method as recited in claim 29 wherein the fast forward parameter of the linear feedback shift register is a function of the cell identification parameter and one or more of the time indices.

31. The method as recited in claim 29 wherein the initial seed of the linear feedback shift register is a nonlinear function of the cell identification parameter, the cyclic prefix mode and the time indices.

32. The method as recited in claim 29 wherein the initial seed of the linear feedback shift register is a sum of terms and each term is proportional to a product of integer powers of the cell identification parameter, the cyclic prefix mode, the symbol index and the subframe index.

33. The method as recited in claim 32 wherein for at least one term, the integer powers corresponding to the cell identification parameter, the symbol index, and the subframe index are all greater than zero.

34. The method as recited in claim 32 wherein the initial seed of the linear feedback shift register is given by c_init=2¹⁰·

(7·

(n_s+1)+l+1)·

(2·

N_ID^cell+1)+2·

N_ID^cell+N_CP, where N_ID^cell denotes the cell identification parameter, N_CP denotes the cyclic prefix mode and time indices are a subframe index n_S and a symbol index l.

35. The method as recited in claim 29 wherein the initial seed of the linear feedback shift register is a product of terms and each term is a scaled sum of the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.

36. The method as recited in claim 35 wherein at least one term has a non-zero scaling corresponding to the cell identification parameter, the cyclic prefix mode, the subframe index and the symbol index.