Robert D Macleod, 5752 Houston Ave, Milton, MA 02186

6831574, Dec 14, 2004

Oct 3, 2003

10/678203

Diane G. Mills - Wilmington MA
Robert B. MacLeod - Nashua NH
Thomas P. McElwain - Merrimack NH
Dianne E. Egnor - Nashua NH

BAE Systems Information and Electronic Systems Integration INC - Nashua NH

H03M 700

341 50, 714786, 714752

A Turbo multi-user detector (MUD) processing system in multiple access communications channels that decreases the likelihood of improper decoding of the final values of interest, thereby allowing for a reduction in the number of iterations performed and lowers complexity without negatively impacting performance. The present invention comprises a multi-user detector serially concatenated to two decoder sections in such a manner that data flows iteratively from the MUD and to each detector stage and back to the MUD to correct for errors.

7110439, Sep 19, 2006

Mar 25, 2002

10/105918

Robert B. MacLeod - Nashua NH, US

BAE Systems Information and Electronic Systems Integration Inc. - Nashua NH

H04B 1/707

375147

A system is provided for use with a multi-user detector MUD, which dramatically decreases the processing time for separating out interfering transmissions from a number of users by eliminating from each processing iteration consideration of those bit estimates for which the probability or estimate of their value exceeds a predetermined threshold and can therefore be declared “certain”. In a Turbo MUD environment in which the output of the MUD is coupled back to the MUD through an error correction system, the output of the error correction is thresholded such that those bit estimates having probabilities or estimates greater than a predetermined threshold are assigned a quantized value and are eliminated from further processing by the MUD. For certain low-complexity processing Turbo MUDs there can be as much of a reduction as one-third in processing time, whereas for full MUD processing, the reduction in processing time can be as much as 1/30th.

7126890, Oct 24, 2006

Sep 19, 2003

10/497557

Rachel E. Learned - Waltham MA, US
Robert B. MacLeod - Nashua NH, US

Bae Systems Information and Electronic Systems Integration INC - Nashua NH

G11B 7/00

369 4432, 369 4428, 369 5333

Techniques for reading data from a storage medium () having a high track density prone to adjacent track interference are disclosed. One or more sensing elements () are used to extract data stored on adjacent tracks. Multiuser detection () is then used to detect/decode a single track that is closely spaced to its neighboring tracks, resolve interference from adjacent tracks, or to simultaneously detect/decode multiple adjacent closely packed tracks.

7190747, Mar 13, 2007

Apr 25, 2003

10/423695

Robert B MacLeod - Nashua NH, US
Joshua D Niedzwiecki - Manchester NH, US
Kari M Karwedsky - Merrimack NH, US

BAE Systems Information and Electronic Systems Integration Inc. - Nashua NH

H04L 27/06

375344

Techniques for compensating for frequency mismatch between transmitters and receivers of a multiuser communication system having a plurality of users are disclosed. In particular, the mismatch of carrier frequency estimates are estimated and compensated for each user of the system. This is accomplished without increasing the training overhead of the system. Symbol phase drift and offset is computed by estimating phase error profile parameters (e. g. , slope and offset). The disclosed techniques may be used to correct for symbol rotation in any one decision region, or in neighboring decision regions.

7236546, Jun 26, 2007

Sep 10, 2003

10/659567

Dianne E Egnor - Somerville MA, US
Robert B MacLeod - Nashua NH, US

Bae Systems Information and Electronic Systems Integration Inc. - Nashua NH

H03D 1/00
H04L 27/06

375341, 375262, 375340, 714786, 714794, 714795

A multiple access processing system for a plurality of users employing a multiuser detector processing partial blocks of data within a window. The multiuser detector processes the data for all users within a processing window and is interrupted at successive frame boundaries. Once an entire block is processed by the MUD, the blocks for that user are decoded and the processing continues.

7245673, Jul 17, 2007

Jun 25, 2003

10/486871

Robert B. MacLeod - Nashua NH, US

Bae Systems Information and Electronic Systems Integration Inc. - Nashua NH

H03D 1/00

375340, 706236, 329341

Windowed multiuser detection techniques are disclosed. A window of data is established, and certain central bits within the window are selected as reliable, while other side bits are ignored. The selected bits are demodulated. The windowed multiuser detector moves along to the next window in such a manner that the next group of central bit decisions lay contiguous with the previous set, and eventually every bit to be demodulated has at some point been a central bit decision. Most any type of MUD algorithm (e. g. , MMSE algorithm MUD or M-algorithm MUD) can be used to compute estimates in the windowed data. Unreliable windowed data are distinguished from reliable data (e. g. , weighting or other de-emphasis scheme).

7783110, Aug 24, 2010

Apr 10, 2006

11/400922

Robert B MacLeod - Nashua NH, US

BAE Systems Information and Electronic Systems Integration Inc. - Nashua NH

G06K 9/46

382190, 375341, 342195, 342204

One embodiment is a system for processing a complex ambiguity function (CAF) comprising creating a CAF surface from incoming data and a model vector, wherein the CAF surface has at least one feature, processing for a peak value, establishing a sub-window about the peak, wherein the peak is within the sub-window, and flattening the peak.

7817754, Oct 19, 2010

Dec 1, 2005

11/292233

Robert B. MacLeod - Nashua NH, US

BAE Systems Information and Electronic Systems Integration Inc. - Nashua NH

H03D 1/00
H03K 9/00
H04L 27/00

375343, 375316, 375340, 370320, 370335, 370342, 370441, 370479, 370515, 708300, 708314, 708422, 708426

Performing approximate diagonalization of a correlation metric by user permutation to improve Multiuser Detector (MUD) processing. The system reorders the entries in the S-Matrix in order to move the bit decisions closer together in the decision tree. In one embodiment the reordering is a sequential pairwise correlation.