Qicai Shi

US Patent:

6563857, May 13, 2003

Filed:

Dec 21, 2001

Appl. No.:

10/036554

Inventors:

Qicai Shi - Coral Springs FL
Robert J. ODea - Ft. Lauderdale FL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 1508

US Classification:

375140, 375145, 375147, 375149

Abstract:

A method and apparatus for direct sequence spread spectrum communication having low complexity. In the transmitter, the data bit is spreaded by a code sequence, a reference code is interleaved with the code sequence, and together they are transmitted by the transmitter. The corresponding receiver recovers the data signal from the received signal by transforming the received signal to a complex base band signal and differentially decoding the base band signal at the chip level. The spreaded signal is despreaded by the chip-level differential operation, thus eliminating the decorrelation operation, and so significantly reducing the cost of the overall system. Furthermore, this system is very robust to any carrier frequency drift since the chip-level differential operation is used, thus releasing the reference clock or crystal requirements, and so further reducing the cost of the system.

US Patent:

6584141, Jun 24, 2003

Filed:

Dec 21, 2001

Appl. No.:

10/036557

Inventors:

Qicai Shi - Coral Springs FL
Robert J. ODea - Ft. Lauderdale FL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 1500

US Classification:

375142, 375140, 375150, 375343

Abstract:

A method and apparatus for DS-CDMA communication having improved timing resolution. In the transmitter, a signal spread by a first sequence of pulses is generated with pulse shape given by where t is time and T is the chip period or pulse width. The pulses have an auto-correlation function In receiver, a second sequence of pulses with pulse shape given by is generated. When correlated with the first sequence of pulses the resulting correlation function is proportional to This correlation function narrower peaks than the correlation function thereby allowing higher time resolution to be achieved. The correlation function is achieved by modification of the transmitter or receiver modulation sequences or by modification of the correlator in the receiver.

US Patent:

6597915, Jul 22, 2003

Filed:

Dec 18, 2001

Appl. No.:

10/022944

Inventors:

Qicai Shi - Coral Springs FL
Jian Huang - Coral Springs FL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04Q 720

US Classification:

455456, 455458, 455 671, 455343, 455573, 455574, 34082549

Abstract:

Location related information is collected for a network of communication devices that each is operable in a coordinating mode and in a non-coordinating mode. While in the coordinating mode, each communication device collects and stores location determining information ( ). Using the location determining information collected by one or more of the communication devices over multiple instances of operation in the coordinating mode, location information is calculated or updated for selected devices within the network ( ). In one embodiment, each device operates to mediate communication activities among others devices of the network while in the coordinating mode.

US Patent:

6728306, Apr 27, 2004

Filed:

Nov 20, 2000

Appl. No.:

09/716837

Inventors:

Qicai Shi - Tamarac FL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 169

US Classification:

375149, 375130, 370342

Abstract:

A system for synchronizing a DS-CDMA receiver ( ) to a received signal ( ) using actual data as opposed to a special training sequence is provided. A chip by chip multiplication ( ) is applied to a sequence of received chip complex values in order to eliminate most traces of bit sign information from the received signal ( ). The foregoing allows multiple bit length sequences of chips extracted from actual data to be combined, e. g. , averaged, in order to reduce random noise. A low noise vector which has been derived from actual data can then be used to synchronize ( ) the receiver ( ) to a desired degree of precision.

US Patent:

6745038, Jun 1, 2004

Filed:

Apr 30, 2001

Appl. No.:

09/845467

Inventors:

Matthew R. Perkins - Sunrise FL
Qicai Shi - Tamarac FL
Neal K. Patwari - Plantation FL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04Q 720

US Classification:

4554561, 4554562, 455 412, 455 413, 455226, 370335, 370342

Abstract:

A technique for intra-piconet location determination and tomography is described. This technique uses received signal strength indicator (RSSI) values in conjunction with transmitted power levels to determine the relative location of each device within a small network employing frequency hopped spread spectrum transmission. In addition to the location determination properties of the invention, the geometry of the devices in the network, as well as the path loss information between pairs of devices, may be used to infer the location of absorbers and reflectors within the piconet. This absorption and reflection information may be used in creating the piconet tomography. The approach described in this specification may be applied in conjunction with the Bluetooth wireless Personal Area Network (PAN) specification to determine device locations, mitigate the effects of multi-path, and perform indoor location and security functions, and other application functions requiring cost-effective location determination.

US Patent:

6816493, Nov 9, 2004

Filed:

Mar 9, 2001

Appl. No.:

09/803322

Inventors:

Qicai Shi - Coral Springs FL
Jian Huang - Coral Springs FL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04L 1228

US Classification:

3703954, 370235, 370311, 709202

Abstract:

A low power consumption protocol for low power communication devices attached to an asynchronous network is described. In this protocol, a communication device is used as a high communication duty cycle Mediation Device (MD), thus permitting other communication devices to use a low communication duty cycle framing structure. The MD functions as a storage and retrieval service for messages between two devices when one device is not able to communicate. When the previously unavailable device becomes available, it can check in with the MD to retrieve any missed messages and respond to these messages accordingly. In a communication network, each of the low power communication devices can be configured to behave as MDs for a small amount of time. Sharing this responsibility among all communication devices in the network allows each device to maintain an low average communication duty cycle. This technique is applicable to a low power, low cost, zero-configuring, self-organizing, asynchronous network.

US Patent:

6876692, Apr 5, 2005

Filed:

Mar 9, 2001

Appl. No.:

09/803285

Inventors:

Qicai Shi - Coral Springs FL, US
Robert J. O'Dea - Ft. Lauderdale FL, US

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04L027/30

US Classification:

375141, 375150, 375152, 375343, 375364, 375367, 342342, 342441, 342479

Abstract:

According to the present invention a received Direct Sequence Code Division Multi-Access (DS-CDMA) signal is differentially decoded at the chip level. A number of signaling schemes can be used in the invention including (1) an ON/OFF signaling scheme in which a pseudo noise number (PN) code is sent only in response to one data bit value, and no signal is sent in response to the other bit value; (2) a Two Code signaling scheme in which bit values of 1 triggers a first PN code to transmitted, and a bit value of 0 triggers a second PN code to be transmitted; and (3) an M-ary signaling method in which a plurality of data bit patterns respectively, trigger a plurality of PN codes to be transmitted. After differential decoding the received signal is despread using one or more PN codes, that can be vector sums of two or more PN codes.

US Patent:

6922432, Jul 26, 2005

Filed:

Mar 9, 2001

Appl. No.:

09/803258

Inventors:

Frederick L. Martin - Plantation FL, US
Qicai Shi - Coral Springs FL, US

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B001/69

US Classification:

375141, 375130, 375140, 375150, 370320

Abstract:

A signaling system is provided in which a spread spectrum code is cyclically shifted by a cyclical shift dictated by a bit pattern of one or more bits. The cyclically shifted spread spectrum code is used to modulate a carrier frequency, and transmitted from a transmitter to a receiver. At the receiver the signal including the cyclically shifted spectrum code is demodulated to recover the cyclically shifted code. The cyclical shift is then determined and the bit pattern which is associated with the cyclical shift is output. The method can be used in direct sequence spread spectrum communication.