Clarence A Roberts

US Patent:

6363105, Mar 26, 2002

Filed:

Feb 17, 1998

Appl. No.:

09/024120

Inventors:

Essam Sourour - Raleigh NC
Greg Bottomley - Cary NC
David Barrow - Durham NC
Rajaram Ramesh - Cary NC
Clarence V. Roberts - Raleigh NC

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

H04L 2730

US Classification:

375150, 375343, 329358

Abstract:

A flexible sliding correlator for use in a spread spectrum receiver divides baseband signal samples into different groups, associates each group with a different section of a spreading code, and combines ones of the signal samples with corresponding values in the spreading code section. The groupings and spreading code sections can be changed during operation of the receiver to maximize performance of the receiver under different or changing conditions. In addition, the sample and spreading code value combinations can be further combined in different ways, and the further combinations can be changed during operation of the receiver. According to another aspect of the invention, the baseband signal can be sampled either uniformly or non-uniformly. The phase and frequency of the baseband sampling can be adjusted during operation of the receiver so that samples are taken very close to the optimum sampling position, at the peak of a chip waveform in the baseband signal.

US Patent:

6377615, Apr 23, 2002

Filed:

Sep 30, 1999

Appl. No.:

09/408624

Inventors:

Essam A. Sourour - Cary NC
Clarence V. Roberts - Raleigh NC

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

A61F 206

US Classification:

375150, 375142

Abstract:

Delays in a spread spectrum signal transmitted in a communications medium according to a spreading sequence may be determined by receiving a composite signal including the spread spectrum signal from the communications medium. The composite signal is correlated with the spreading sequence according to a first correlation length, to produce first time-offset correlations of the composite signal with the spreading sequence. Selected ones of the first time-offset correlations of the composite signal then are further correlated with the spreading sequence according to a second correlation length that is longer than the first correlation length, to produce second time-offset correlations of the composite signal with the spreading sequence. At least one of the second time-offset correlations may be selected. By providing variable length accumulation searchers, power and/or processing time can be saved by performing limited correlations for those delays that do not appear to be qualified candidates to be ultimately selected.

US Patent:

6567483, May 20, 2003

Filed:

Jul 1, 1999

Appl. No.:

09/345409

Inventors:

Paul W. Dent - Pittsboro NC
Clarence V. Roberts - Raleigh NC

Assignee:

Ericsson, Inc. - Research Triangle Park NC

International Classification:

H03D 100

US Classification:

375343, 375150, 708422

Abstract:

A technique for correlating a stream of signal sample values with a predetermined binary code having a plurality of binary code bits is disclosed. The technique is realized by forming precombinations of groups of the signal sample values in the stream, and then temporally ordering the precombinations. Particular ones of the temporally ordered precombinations are selected based upon particular combinations of the plurality of binary code bits. The particular selected ones of the temporally ordered precombinations are then combined to form a correlation.

US Patent:

6621858, Sep 16, 2003

Filed:

Dec 4, 2000

Appl. No.:

09/729524

Inventors:

Essam Sourour - Raleigh NC
Greg Bottomley - Cary NC
David Barrow - Durham NC
Rajaram Ramesh - Cary NC
Clarence V. Roberts - Raleigh NC

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

H04B 169

US Classification:

375150

Abstract:

A flexible sliding correlator for use in a spread spectrum receiver divides baseband signal samples into different groups, associates each group with a different section of a spreading code, and combines ones of the signal samples with corresponding values in the spreading code section. The groupings and spreading code sections can be changed during operation of the receiver to maximize performance of the receiver under different or changing conditions. In addition, the sample and spreading code value combinations can be further combined in different ways, and the further combinations can be changed during operation of the receiver. According to another aspect of the invention, the baseband signal can be sampled either uniformly or non-uniformly. The phase and frequency of the baseband sampling can be adjusted during operation of the receiver so that samples are taken very close to the optimum sampling position, at the peak of a chip waveform in the baseband signal.

US Patent:

7433977, Oct 7, 2008

Filed:

Nov 28, 2006

Appl. No.:

11/563732

Inventors:

David E. Barrow - Durham NC, US
Clarence V. Roberts - Raleigh NC, US

Assignee:

Telefonaktiebolaget LM Ericsson (publ)

International Classification:

G06F 13/28
G06F 13/00

US Classification:

710 22, 710 34, 710308

Abstract:

A DMA controller maintains a count of data transferred in each DMA operation, and saves the transferred data count at the end of the DMA operation. The DMA controller may then begin a subsequent DMA transfer operation, without waiting for a processor to read the transferred data count. The transferred data count may be written to memory at an address specified in a transferred data count save address register; may be saved to a transferred data count register dedicated to the DMA channel; or may be saved to a transferred data count register shared between two or more DMA channels. The processor may read the transferred data count and, if applicable, clear the relevant transfer data count register, subsequent to the DMA controller beginning another DMA operation on that DMA channel.

US Patent:

6212398, Apr 3, 2001

Filed:

Dec 3, 1998

Appl. No.:

9/205535

Inventors:

Clarence V. Roberts - Raleigh NC
Raymond C. Henry - Wake Forest NC

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

H04Q 732

US Classification:

455502

Abstract:

A method for rapidly reacquiring a timing reference after a sleep period in a wireless telephone receiving pilot signals from one or more base stations in a wireless network, wherein the wireless telephone has a master timer (local time reference), a fast, accurate clock source, a slow, less accurate but power efficient clock source and a memory. The method includes the steps of entering the sleep period by storing one or more parameters related to the pilot signals and how the pilot signals are changing over time, calculating a prediction of the parameters of the pilot signals after a sleep period based on the stored parameters, storing the prediction, starting the slow clock, and stopping the master timer (local time reference) and fast clock source. The method further includes the steps of ending the sleep period by generating a wake-up interrupt by the slow clock after the sleep period, restarting the master timer and fast clock source responsive to the wake-up interrupt, and reacquiring pilot signals using the predictions stored previously. A time correction factor can then be computed that closely aligns the received pilot signals on the prediction which is then weighted and the master timer is adjusted by the weighted time correction.