Tao Chen

US Patent:

6356601, Mar 12, 2002

Filed:

Nov 29, 2000

Appl. No.:

09/725351

Inventors:

Tao Chen - San Diego CA
Shimman Patel - San Diego CA

Assignee:

Qualcomm Incorporated - San Diego CA

International Classification:

H04L 2706

US Classification:

375340, 375225, 375343, 714796

Abstract:

Techniques for detecting zero rate frames in a received data transmission. A modulated signal is received and demodulated in accordance with a particular demodulation format to generate demodulated symbols. The demodulated symbols are partitioned into a number of received frames. For each received frame, a quality metric is computed and compared against a threshold value. The threshold value is selected based, in part, on the quality metrics of received frames. Based on the comparison result, the received frame is indicated as being either transmitted and received in error (i. e. , erased or bad) or not transmitted at all (i. e. , zero rate or empty). The quality metric can relate to an energy of a received frame, a distance between a received frame and a codeword corresponding to the received frame, or other metrics. The threshold value can be selected based on the quality metrics computed for decoded frames or received frames identified as good, and can be dynamically adjusted based on current information available at the receiver. The method is advantageously used in a CDMA communications system.

US Patent:

6359868, Mar 19, 2002

Filed:

Oct 10, 2000

Appl. No.:

09/686350

Inventors:

Tao Chen - San Diego CA

Assignee:

Qualcomm Incorporated - San Diego CA

International Classification:

H04J 1300

US Classification:

370335, 370342, 370482

Abstract:

In the present invention, high speed data is provided by transmitting data on multiple carrier frequencies, multiple code channels and/or from multiple base stations. In a first embodiment of the present invention, multiplexed code symbols are transmitted on a plurality of carrier frequencies from the same base station. In second embodiment, code symbols are transmitted on multiple carrier frequencies with at least one corner frequency providing the code symbols is a multiple code channels. In a third embodiment, a subset of the multiplexed code symbols are redundantly provided on a different carrier from at least one additional base station. In a fourth embodiment, multiplexed symbols as transmitted on different carriers from the same base station and are redundantly transmitted on another set of carriers from a different base station. In a fifth embodiment, code symbols are multiplexed onto carriers from a plurality of base stations for increased throughput. In a sixth embodiment, code symbols are transmitted on carriers from a first base station and redundantly provided on at least one additional base station on the same carriers as used by the first base station.

US Patent:

6373823, Apr 16, 2002

Filed:

Jan 28, 1999

Appl. No.:

09/239454

Inventors:

Tao Chen - San Diego CA
Jack M. Holtzman - San Diego CA
Keith Saints - San Diego CA
Fuyun Ling - San Diego CA

Assignee:

Qualcomm Incorporated - San Diego CA

International Classification:

H04J 314

US Classification:

370252, 455 69, 455522

Abstract:

A power control system for controlling the transmission power in a system wherein the transmission power may be gated or capped. The receiver employs a combination of closed loop and outer loop power control. The outer loop is frozen upon detection by the receiver that the signal has been capped or gated.

US Patent:

6374085, Apr 16, 2002

Filed:

May 8, 2000

Appl. No.:

09/566535

Inventors:

Keith W. Saints - San Diego CA
Tao Chen - San Diego CA

Assignee:

Qualcomm Incorporated - San Diego CA

International Classification:

H04B 100

US Classification:

455 69, 455522

Abstract:

The present invention provides a method and apparatus for providing improved quality or power control by recognizing the delays inherent in a closed-loop communication system. The mobile station or receiver properly adjusts its forward link quality or power level thresholds or measurements with which it compares incoming frames or portions thereof to reflect the level it anticipates receiving (after the delay). For example, the mobile station can recognize that at a given measurement time, two outstanding messages have not been executed by the transmitter (where each message indicates a corresponding increase of 1 dB). As a result, the mobile station can adjust its measurement threshold down by 2 dB to more closely correspond to future power adjustments. If the currently received frame or portion thereof is still below the readjusted threshold, then the mobile station sends out a new message to request a further increase in the forward link channel.

US Patent:

6512925, Jan 28, 2003

Filed:

Dec 3, 1998

Appl. No.:

09/204803

Inventors:

Tao Chen - San Diego CA
Jack M. Holtzman - San Diego CA
Leonid Razoumov - San Diego CA
Shim Patel - San Diego CA
Keith Saints - San Diego CA

Assignee:

Qualcomm, Incorporated - San Diego CA

International Classification:

H04Q 722

US Classification:

455442, 455522

Abstract:

Method and apparatus for adjusting the transmission power of base stations in simultaneous communication with a mobile station. The methods described provide for the transmission power of the base stations to be aligned. In the first exemplary embodiment, the transmitters are attached to a separate control unit through communication links. The control unit then derives the most likely command stream and send that to the base stations. In the second exemplary embodiment, the control unit periodically receives the final or average transmit level in a period and an aggregate quality measure for the feedback during a period from each of the transmitters. The control unit determines the aligned power level and transmits a message indicative of the aligned power level to the transmitters. In the third exemplary embodiment, the transmitters send the control unit a message indicative of the transmit power of transmissions to the receiver. The control unit determines the aligned transmit power based on the current transmit power.

US Patent:

6529527, Mar 4, 2003

Filed:

Jul 7, 2000

Appl. No.:

09/612075

Inventors:

Tao Chen - San Diego CA
Raymond Tah-Sheng Hsu - San Diego CA

Assignee:

Qualcomm, Inc. - San Diego CA

International Classification:

H04J 306

US Classification:

370503, 370510

Abstract:

A method and apparatus for reducing transmission delay in a wireless communication system that carries packetized voice and data information. Interruptions in the traffic channels cause loss of synchronization between a header compressor and a header decompressor. Rather than transmitting resynchronization information on the traffic channel, the information dropped by an interruption is re-transmitted on a non-traffic channel in parallel with the traffic channel. At the remote station, information from the traffic channel and the non-traffic channel is reassembled before input into the decompressor. Alternatively, the non-traffic channel can be used to carry overflow information so that a higher average data rate can be achieved than the average data rate of the traffic channel alone.

US Patent:

6535478, Mar 18, 2003

Filed:

Jul 17, 2001

Appl. No.:

09/908665

Inventors:

Ramin Rezaiifar - San Diego CA
Olivier Glauser - San Diego CA
Tao Chen - San Diego CA

Assignee:

Qualcomm Incorporated - San Diego CA

International Classification:

H04J 1302

US Classification:

370206, 370342, 370532, 370537, 375146

Abstract:

A novel and improved method and apparatus for generating a reduced peak amplitude high data rate channel comprised of a set of lower rate channels is described. The set of lower rate channels are phase rotated before being summed and transmitted. The amount of phase rotation is dependent on the number of channels used to form the higher rate channel. In an embodiment where two lower rate channels are used, the in-phase and quadrature-phase components of the two channels are complex multiplied before upconversion with an in-phase and quadrature-phase sinusoids. For a high rate channel comprised of more than two lower rate channels, the in-phase and quadrature-phase component of each channel is upconverted with a set of sinusoids that are phase offset from one another.

US Patent:

6535739, Mar 18, 2003

Filed:

Apr 7, 2000

Appl. No.:

09/546219

Inventors:

Tao Chen - San Diego CA

Assignee:

Qualcomm Incorporated - San Diego CA

International Classification:

H04Q 720

US Classification:

455437, 455552, 455561, 370331, 370332, 370335

Abstract:

The present invention is directed to a digital wireless telecommunications system that includes a plurality of base station of differing spectral capabilities, and a plurality of remote stations capable of transmitting data to and receiving transmissions from the plurality of base stations. The invention herein provides a method for remote station hand-off between base stations of a narrower spectral capacity and base stations of a wider spectral capacity. A method is provided for a wireless telecommunications infrastructure to facilitate a remote station hand-off from a set of narrowband compliant base stations to at least one wideband compliant base station while a remote station is in the coverage area of both types of base stations. Additionally, the invention herein provides remote station apparatus, base station apparatus, and base station controller apparatus for performing the handoff methodology of the present invention.