OFDM/DMT/ digital communications system including partial sequence symbol processing

• US 8,547,823 B2
• Filed: 07/02/2004
• Issued: 10/01/2013
• Est. Priority Date: 08/22/1996
• Status: Expired due to Fees

• Current Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Original Assignee: Tellabs Operations Incorporated (Infinera Corp.)
• Inventors: Marchok, Daniel J., Younce, Richard C., Melsa, Peter J. W.
• Primary Examiner(s): Ngo, Ricky
• Assistant Examiner(s): NGUYEN, PHUONGCHAU BA
• Application Number:
  US10/883,916
• Publication Number:
  US 20040246890A1
• Time in Patent Office: 3,378 Days
• Field of Search: 370/204, 370/290, 370/321, 370/322, 370/326, 370/329, 370/330, 370/337, 370/345, 370/347, 370/442, 370/443, 370/458, 370/459, 370/498, 370/508
• US Class Current: 370/210
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2628 Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators H04L27/2634 takes precedence
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2657 Carrier synchronisation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/1453 of modulation type

Abstract

A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

Claims

1. A method of managing a symbol, represented by a plurality of samples over a symbol time period, in a digital communications system, the method comprising:

causing, in a processing unit, a first subset of the plurality of samples corresponding to beginning and end portions of the symbol to be supplied to a filter engine; and

causing, in the processing unit, a second subset of the plurality of samples of the symbol corresponding to a middle portion of the symbol to be bypassed around the filter engine.

2. The method of claim 1, further comprising temporarily storing the first and the second subsets of the plurality of samples.

3. The method of claim 1, further comprising filtering the first subset of the plurality of samples by the filter engine.

4. The method of claim 3, wherein filtering further includes filtering the beginning and the end portions of the symbol symmetrically.

5. The method of claim 4, wherein filtering symmetrically includes adding a sample at the beginning portion of the symbol to a corresponding symmetric sample at the end portion of the symbol.

6. The method of claim 4, wherein filtering symmetrically includes:

multiplying a coefficient to a sample at the beginning portion of the symbol; and

multiplying the coefficient to a corresponding symmetric sample at the end portion of the symbol.

7. An apparatus for managing a symbol represented by a plurality of samples over a symbol time period, the apparatus comprising:

a symbol buffer configured to temporarily store the plurality of samples of the symbol; and

a bypass controller, connected to the symbol buffer, that causes a first subset of the plurality of samples corresponding to beginning and end portions of the symbol to be supplied to a filter engine and causes a second subset of the plurality of samples corresponding to a middle portion of the symbol to be bypassed around the filter engine.

8. The apparatus of claim 7, further comprising another symbol buffer connected to the bypass controller that temporarily stores the plurality of samples of another symbol.

9. The apparatus of claim 7, the filter engine is connected to the bypass controller.

10. The apparatus of claim 9, wherein the filter engine implements a FIR filter.

11. The apparatus of claim 9, wherein the filter engine implements a symmetric filter.

12. The apparatus of claim 9, wherein the filter engine includes symmetric taps.

13. The apparatus of claim 9, wherein the filter engine includes an adder that adds a sample at the beginning portion of the symbol to a corresponding symmetric sample at the end portion of the symbol.

14. The apparatus of claim 9, wherein the filter engine includes a multiplier that multiplies a coefficient to a sample at the beginning portion of the symbol and multiplies the coefficient to a corresponding symmetric sample at the end portion of the symbol.

15. An article of manufacture, comprising a non-transitory computer-readable medium having stored thereon computer-readable code with executable instructions to manage a symbol over a symbol time period, the computer-readable code, when executed by a processor, causes an apparatus to:

cause a first subset of the plurality of samples corresponding to beginning and end portions of the symbol to be supplied to a filter engine; and

cause a second subset of the plurality of samples corresponding to a middle portion of the symbol to be bypassed around the filter engine.

16. The article of manufacture of claim 15, wherein the computer-readable code, when executed by the processor, further causes the apparatus to temporarily store the first and the second subsets of the plurality of samples.

17. The article of manufacture of claim 15, wherein the computer-readable code, when executed by the processor, further causes the apparatus to filter the first subset of the plurality of samples.

18. The article of manufacture of claim 17, wherein the computer-readable code, when executed by the processor, further causes the apparatus to filter the beginning and the end portions symmetrically.

19. The article of manufacture of claim 18, wherein the computer-readable code, when executed by the processor, further causes the apparatus to, in filtering symmetrically, add a sample at the beginning portion of the symbol to a corresponding symmetric sample at the end portion of the symbol.

20. The article of manufacture of claim 18, wherein the computer-readable code, when executed by the processor, further causes the apparatus to, in filtering symmetrically:

multiply a coefficient to a sample at the beginning portion of the symbol; and

multiply the coefficient to a corresponding symmetric sample at the end portion of the symbol.