Xiangdong D Liu

US Patent:

20010049284, Dec 6, 2001

Filed:

Dec 15, 2000

Appl. No.:

09/737612

Inventors:

Xiangdong Liu - Germantown MD, US
Lenwood Heath - Blacksburg VA, US

International Classification:

H04B007/185

US Classification:

455/427000, 455/430000, 455/447000, 455/012100

Abstract:

A system and method using a simulated annealing algorithm in a cellular satellite communications network to assign frequency slots to cells in the network. The system and method employ a static stage in which certain frequencies in a non-uniform spectrum are assigned to cells depending upon the predicted traffic demand of all cells, and a dynamic stage which re-evaluates the real time traffic demand of the various cells and assigns or de-assigns frequencies on an as needed basis. The system and method thus delivers more frequencies to cells with a higher capacity enabling those cells to take on more traffic.

US Patent:

20120018585, Jan 26, 2012

Filed:

Jul 26, 2010

Appl. No.:

12/843417

Inventors:

Xiangdong LIU - Boyds MD, US
Joshua Schachter - Dallas TX, US

Assignee:

LOCKHEED MARTIN CORPORATION - Bethesda MD

International Classification:

G05D 1/00
B64G 1/10

US Classification:

2441586, 701 13

Abstract:

A method, a member satellite, and a tangible machine-readable medium are disclosed. An inter-satellite link subsystem may maintain a fixed communication link between the member satellite and a partner satellite of the medium earth orbit centric satellite constellation in a regular, wraparound symmetric, spatially dimensional network. A terrestrial linking subsystem may create a terrestrial link to a ground terminal.

US Patent:

20130080895, Mar 28, 2013

Filed:

Sep 23, 2011

Appl. No.:

13/243845

Inventors:

Alain Rossman - Palo Alto CA, US
Adrian Demetrescu - Barcelona, ES
Arie Grapa - Sunnyvale CA, US
Xiangdong (Eric) Liu - Fremont CA, US

Assignee:

KLIP, INC. - Palo Alto CA

International Classification:

G06F 3/01

US Classification:

715720

Abstract:

An internet client-server method to rapidly preview video files. Source video files are compressed into lower resolution preview video files, thumbnail image files, and stored on a preview internet server. Typically only a small fraction of the source video frames, such as 1 frame in 60, is used for the preview. A user using a touch sensitive computerized device such as a smartphone can view the thumbnail video images while the compressed video files load in the background. When the user touches or swipes an image of interest, or shakes the device, device video preview application software detects the action and directs the device to start playing the preview video file(s). The application software detects when the user swipes the preview video, and changes the rate and direction of playback of the preview video file, and trickplay functionality, often according to the speed and/or direction of the swipe.

US Patent:

63075032, Oct 23, 2001

Filed:

Dec 16, 1998

Appl. No.:

9/212528

Inventors:

Xiangdong Liu - Germantown MD

Assignee:

Hughes Electronics Corporation - El Segundo CA

International Classification:

H04B 7185

US Classification:

34235705

Abstract:

A system (20) and method (40) for determining a user terminal (23) location on the surface of the earth relies on the signal propagation delay and Doppler shift of radio frequency (RF) transmissions between the user terminal (UT) (23) and a satellite (22). An iterative procedure is employed to improve the accuracy of the location determination. Within the procedure, the position of the UT is estimated based on the propagation delay, Doppler shift, and a spherical approximation of the earth's shape. The radius of the earth at the estimated UT position is adjusted using a predetermined model of the earth's shape, such as an ellipsoid approximation. The adjusted radius value is then used to re-estimate the UT location using the spherical approximation. The iterative procedure continues until the estimated UT location converges to a predetermined accuracy. The position of the user terminal location can be determined based on a earth-central angle. alpha.

US Patent:

63170779, Nov 13, 2001

Filed:

Feb 22, 2000

Appl. No.:

9/510921

Inventors:

Mohammad Soleimani - Rockville MD
Xiangdong Liu - Germantown MD

Assignee:

Hughes Electronics Corporation - El Segundo CA

International Classification:

H04B 7185
G01S 502

US Classification:

34235705

Abstract:

In a satellite communication system (20), a method (50) and system of locating terrestrial-based user terminals (UTs). A UT (23) is located by a two-tier estimation procedure. Under this procedure, an initial estimate of the UT location is performed based on absolute signal propagation delay and Doppler shift measured from a communication link between a satellite and the UT. A second, refined estimate of the UT location is then performed based on the results of the initial estimate. The second estimate can be a function of the absolute propagation delay and absolute Doppler, as well as differential delay and differential Doppler measured from transmissions from two or more satellites (21-22) to the UT (23).

US Patent:

20220272757, Aug 25, 2022

Filed:

Feb 25, 2021

Appl. No.:

17/185781

Inventors:

- Bethesda MD, US
Xiangdong LIU - Boyds MD, US

International Classification:

H04W 74/08
H04W 74/00
G01S 19/27
H04L 27/26
H04B 7/185
H04B 7/195

Abstract:

Systems and methods for communication in 4G and 5G broadband satellite networks are provided. The disclosed methods include Global Navigation Satellite System (GNSS)-independent methods, and GNSS assisted methods that do not require transmission of satellite ephemeris information from a base station to user equipment.

US Patent:

20220264502, Aug 18, 2022

Filed:

Feb 16, 2021

Appl. No.:

17/176611

Inventors:

- Bethesda MD, US
Xiangdong Liu - Boyds MD, US

Assignee:

Lockheed Martin Corporation - Bethesda MD

International Classification:

H04W 56/00
H04W 24/08
H04W 74/08
H04W 16/26

Abstract:

Provided herein are various improvements to communication systems and satellite-carried communications. In one example, a method provides communication coverage for at least an endpoint device within a cell. The method includes detecting access preamble communications transferred by the endpoint device during a random access slot of a base station by at least applying a selected quantity of successive sets of processing windows in accordance with a round-trip minimum communication delay expected between the base station and the cell, with each of the successive sets shifted in time by a selected duration. The method also includes determining a round-trip differential communication delay for the endpoint device based on which of the successive sets corresponds to detection of symbol groups of the access preamble communications, and handling return communications transferred by the endpoint device based at least on a combination of the round-trip minimum communication delay and the round-trip differential communication delay.

US Patent:

20140289629, Sep 25, 2014

Filed:

May 18, 2014

Appl. No.:

14/280628

Inventors:

- Palo Alto CA, US
Xiangdong (Eric) Liu - Palo Alto CA, US
Arie Grapa - Palo Alto CA, US

Assignee:

Klip, Inc. - Palo Alto CA

International Classification:

G06F 3/0484
H04L 12/24
G06F 3/0488

US Classification:

715722

Abstract:

An internet client-server method to rapidly preview video files. Source video files are compressed into lower resolution preview video files, thumbnail image files, and stored on a preview internet server. Typically only a small fraction of the source video frames, such as 1 frame in 60, is used for the preview. A user using a touch sensitive computerized device such as a smartphone can view the thumbnail video images while the compressed video files load in the background. When the user touches or swipes an image of interest, or shakes the device, device video preview application software detects the action and directs the device to start playing the preview video file(s). The application software detects when the user swipes the preview video, and changes the rate and direction of playback of the preview video file, and trickplay functionality, often according to the speed and/or direction of the swipe.