Claims
- 1. A method comprising:
receiving input data representative of a communication signal in a first order; applying a fast Fourier transform (FFT) operation to the input data to produce intermediate data; storing the intermediate data in a second order in a random access memory (RAM); selectively addressing the RAM to retrieve the intermediate data in a third order.
- 2. The method of claim 1, further comprising storing at least a portion of the input data in the RAM in the first order.
- 3. The method of claim 1, further comprising outputting a portion of the intermediate data produced by the FFT operation.
- 4. The method of claim 1, wherein the third order and the first order have the same order.
- 5. The method of claim 1, wherein the RAM comprises a single RAM memory bank.
- 6. The method of claim 5, wherein the single RAM memory bank includes:
multiple read ports for reading data from the RAM; and multiple write ports for writing data to the RAM.
- 7. The method of claim 1, wherein the RAM comprises multiple RAM memory banks.
- 8. The method of claim 7, wherein each of the RAM memory banks includes:
a read port for reading data from the RAM; and a write port for writing data into the RAM.
- 9. The method of claim 7, further comprising addressing the RAM memory banks such that entries from the RAM memory banks are read concurrently.
- 10. The method of claim 7, further comprising addressing the RAM memory banks such that entries are written to the RAM memory banks concurrently.
- 11. The method of claim 1, wherein applying an FFT operation includes applying an FFT butterfly operation.
- 12. The method of claim 11, wherein applying an FFT butterfly operation include applying multiple FFT butterfly operations.
- 13. The method of claim 12, wherein applying multiple FFT butterfly operations includes performing stages of FFT butterfly operations.
- 14. The method of claim 13, further comprising:
performing a first stage of butterfly operations to obtain a first set of intermediate data; storing the first set of intermediate data in the RAM; performing a second stage of butterfly operations using the intermediate data from the first stage of butterfly operations as input for the second stage of butterfly operations to obtain a second set of intermediate results; and replacing the first set of intermediate results in the RAM with the second set of intermediate results.
- 15. The method of claim 1, wherein applying an FFT operation includes:
reading input data from the RAM; performing arithmetic operations on the input data; and writing intermediate data output by the arithmetic operations to the RAM.
- 16. The method of claim 15, further comprising replacing the input data read from the RAM with the intermediate data output by the FFT operation.
- 17. The method of claim 1, wherein applying an FFT operation includes:
applying an FFT butterfly operation; and multiplying at least a portion of the data output by the FFT butterfly operation by a twiddle factor.
- 18. The method of claim 1, further comprising discarding a guard interval of the communication signal.
- 19. The method of claim 1, further comprising applying one or more stages of FFT operations to perform FFT processing.
- 20. The method of claim 1, further comprising applying one or more stages of FFT operations to perform IFFT processing.
- 21. The method of claim 20, further comprising appending a guard interval to the intermediate data.
- 22. The method of claim 1, further comprising selectively retrieving input data for the FFT operation.
- 23. The method of claim 1, wherein selectively addressing the RAM to output the intermediate data in a third order includes reading a first portion of the intermediate data first and reading a second portion of the intermediate data second.
- 24. The method of claim 23, wherein the first portion of the intermediate data is the last half of the stored intermediate data, and the second portion of the intermediate data is the first half of the stored intermediate data.
- 25. The method of claim 1, wherein the input data representative of the communication symbol is 64 data sample points, and further comprising applying three stages of FFT operations.
- 26. The method of claim 1, wherein receiving input data representative of a communication signal includes receiving input data representative of an orthogonal frequency division multiplexing (OFDM) signal.
- 27. A device comprising:
a fast Fourier transform (FFT) unit that applies an FFT operation to input data to produce intermediate data, wherein the input data is received in a first order; a random access memory (RAM) that stores the intermediate data in a second order; and a controller that selectively addresses the RAM to retrieve the intermediate data in a third order.
- 28. The device of claim 27, wherein the RAM stores at least a portion of the input data in the first order.
- 29. The device of claim 27, wherein the RAM includes multiple RAM memory banks.
- 30. The device of claim 29, wherein each of the RAM memory banks includes:
a read port; and a write port.
- 31. The device of claim 27, wherein the RAM includes:
multiple read ports; and multiple write ports.
- 32. The device of claim 27, further comprising a second random access memory (RAM) that stores data for a guard interval.
- 33. The device of claim 27, wherein the FFT operation applies an FFT butterfly operation to the input data.
- 34. The device of claim 27, further comprising a twiddle factor table that stores twiddle factors.
- 35. The device of claim 34, wherein the FFT operation applies an FFT butterfly operation, and multiplies a portion of the results of the FFT butterfly operation by twiddle factors from the twiddle factor table.
- 36. The device of claim 27, wherein the FFT operation includes an IFFT operation.
- 37. The device of claim 27, wherein the first order and the third order have the same order.
- 38. The device of claim 27, wherein the input data includes 64 sample data points representative of the signal.
- 39. The device of claim 27, wherein the communication signal is an orthogonal frequency division multiplexing (OFDM) signal.
- 40. The device of claim 27, wherein the device is a wireless communication device.
- 41. The device of claim 27, wherein the communication signals are wireless communication signals.
- 42. The device of claim 41, wherein the wireless communication signals are transmitted according to the IEEE 802.11a standard.
Parent Case Info
[0001] This application claims priority from U.S. Provisional Application Serial No. 60/316,472, filed Sep. 1, 2001, the entire content of which is incorporated herein by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60316472 |
Sep 2001 |
US |