Jun Tan

US Patent:

7477699, Jan 13, 2009

Filed:

Dec 20, 2006

Appl. No.:

11/613349

Inventors:

Fan Wang - Chicago IL, US
Lawrence A. Downing - Hoffman Estates IL, US
Amitava Ghosh - Buffalo Grove IL, US
Chandrasekar Sankaran - Arlington Heights IL, US
Jun Tan - Lake Zurich IL, US

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 7/02
H04L 1/02

US Classification:

375267, 375260, 375299, 375347, 455101, 455103, 455 69, 455104

Abstract:

A radio communications device () that has multiple receive antennas processes received data communications signals to select between space time coding and spatial multiplexing as a selected transmission technique from a base device () that has multiple transmit antennas. A channel throughput (--) for each transmission technique is estimated based on signal to interference and noise ratios (--) of signals being transmitted through a MIMO channel () as measured by a receiver (). The transmission technique with the higher estimated throughput is determined. If spatial multiplexing is determined to have the higher estimated throughput and the throughput of each layer of the spatially multiplexed signal is greater than a threshold, spatial multiplexing is selected. Otherwise, space time coding is selected.

US Patent:

7489755, Feb 10, 2009

Filed:

Feb 9, 2005

Appl. No.:

11/054290

Inventors:

Fan Wang - Vernon Hills IL, US
Amitava Ghosh - Buffalo Grove IL, US
Chandrasekar Sankaran - Arlington Heights IL, US
Jun Tan - Dearborn Heights MI, US

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04L 7/00

US Classification:

375363, 375134, 375135, 375136, 375137, 375145, 375146, 375147, 375246, 375253, 375342, 375365, 375366, 375367, 375370, 375265

Abstract:

Various embodiments are described to provide for the transmission and reception of data in an improved manner. Data transmission is improved by including in a transmitter a null generator () to generate an output data symbol sequence that exhibits nulls in the frequency domain at particular frequencies that an input data symbol sequence does not. A pilot inserter () then adds a pilot symbol sequence to this output data symbol sequence to create a combined symbol sequence. Since the pilot symbol sequence exhibits pilot signals corresponding to the nulls of the output data symbol sequence in the frequency domain, the combined symbol sequence exhibits pilots that are orthogonal to the data in the frequency domain.

US Patent:

7747225, Jun 29, 2010

Filed:

Oct 3, 2006

Appl. No.:

11/538432

Inventors:

Fan Wang - Chicago IL, US
Stanley J. Benes - Round Lake Beach IL, US
Amitava Ghosh - Buffalo Grove IL, US
Jun Tan - Lake Zurich IL, US

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04B 17/00
H04B 1/00
H04B 7/00
H04B 7/185
H04M 1/00
H04W 4/00

US Classification:

455 69, 4555621, 455 6711, 370334, 370318

Abstract:

A subscriber unit () with multiple receive antennas () and a single transmit antenna () derives beamforming weights to be used at a base station () with multiple transmitting antennas (, and ). The downlink beamforming weights are derived at the subscriber unit () from a prior downlink transmission from the base station () to the subscriber device () and an uplink sounding signal is used to carry derived downlink beam forming weights to the base station (). Downlink antenna specific pilots (without weight) are used at the subscriber device () to determine the beamforming weights. Decimated sounding signals, where the number of sounding subcarriers is at least the same as the number of antennas at the base station (), allow multiple users to sound at the same time.

US Patent:

8000305, Aug 16, 2011

Filed:

Jan 10, 2007

Appl. No.:

11/621587

Inventors:

Jun Tan - Lake Zurich IL, US
Amitava Ghosh - Buffalo Grove IL, US
Rapeepat Ratasuk - Hoffman Estates IL, US
Fan Wang - Chicago IL, US
Weimin Xiao - Barrington IL, US

Assignee:

Motorola Mobility, Inc. - Libertyville IL

International Classification:

H04B 7/216

US Classification:

370335, 455434

Abstract:

A system and method for initializing a system communication without previous reservations for random access channel (RACH) access includes a first step of defining at least one spread sequence derived from at least one constant amplitude zero autocorrelation sequence. A next step includes combining the spread sequence with a Walsh code to form an extended spread sequence. A next step includes using the extended spread sequence in a preamble for a RACH. A next step includes sending the preamble to a BTS for acquisition. A next step includes monitoring for a positive acquisition indicator from the BTS. A next step includes scheduling the sending of a RACH message. A next step includes sending the RACH message.

US Patent:

20070071125, Mar 29, 2007

Filed:

Sep 18, 2006

Appl. No.:

11/532545

Inventors:

Jun Tan - Dearborn Heights MI, US
Amitava Ghosh - Buffalo Grove IL, US
Fan Wang - Vernon Hills IL, US

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H04K 1/10

US Classification:

375260000

Abstract:

Various embodiments are described to provide for the transmission of data in an improved manner. Data transmission is improved by including in a transmitter a null generator to embed frequency domain nulls into a data symbol sequence to produce a null-embedded data symbol sequence. A symbol inserter inserts a control symbol sequence into the frequency domain nulls of the null-embedded data symbol sequence to produce a combined symbol sequence. A modulator then encodes the combined symbol sequence using IFDMA/DFT-S-OFDM. This approach allows the assignment of a single IFDMA/DFT-S-OFDM code to each user for data and control (pilot, e.g.) signaling, simplifying code management. Frequency hopping techniques may also be employed to lower the pilot overhead.

US Patent:

20070165730, Jul 19, 2007

Filed:

Oct 6, 2006

Appl. No.:

11/539220

Inventors:

Nick W. Whinnett - Marlborough, GB
Amitava Ghosh - Buffalo Grove IL, US
Jun Tan - Lake Zurich IL, US

Assignee:

MOTOROLA, INC. - Schaumburg IL

International Classification:

H04K 1/10

US Classification:

375260

Abstract:

A transmitter comprises functionality () for generating a block of input modulation symbols for example from received data bits. An M-point discrete Fourier transform () is applied to the block of input modulation symbols resulting in a frequency domain symbol block. This block is fed to an N-point inverse discrete Fourier transform () (N>M) thereby generating a time domain transmit signal. In addition, the transmitter () comprises an inter-symbol processor () which determines inter-symbol values corresponding to inter-symbol times of the time domain transmit signal and an attenuation processor () which attenuates at least one of the input modulation symbols in response to the inter-symbol values. By attenuating selected input modulation symbol(s) a significantly reduced amplitude variation and specifically peak-to-average amplitude variation can be achieved.

US Patent:

20070291635, Dec 20, 2007

Filed:

May 22, 2007

Appl. No.:

11/751658

Inventors:

Weidong Yang - Schaumburg IL, US
Jun Tan - Lake Zurich IL, US
Brian K. Classon - Palatine IL, US
Kevin L. Baum - Rolling Meadows IL, US
Vijay Nangia - Algonquin IL, US

Assignee:

MOTOROLA, INC. - Schaumburg IL

International Classification:

H04J 11/00

US Classification:

370208

Abstract:

An apparatus and method for switching between a first and a second Orthogonal Frequency Division Multiplexing (OFDM) communication mode includes a first step of determining an operational modulation scheme. A next step includes estimating a first performance factor for the modulation scheme in the first communication mode and a second performance factor for the modulation scheme in the second communication mode. A next step includes comparing the first and second performance factors against at least one selection criterion. A next step includes selecting the communication mode in response to the selection criterion and the modulation scheme. A next step includes transmitting on the selected communication mode using the modulation scheme.

US Patent:

20090154605, Jun 18, 2009

Filed:

Dec 12, 2007

Appl. No.:

11/954998

Inventors:

Jun Tan - Lake Zurich IL, US
Amitava Ghosh - Buffalo Grove IL, US
Fan Wang - Chicago IL, US

Assignee:

MOTOROLA, INC. - Schaumburg IL

International Classification:

H03D 1/00
H04L 27/06

US Classification:

375341

Abstract:

A method, wireless device, and wireless communication system perform Maximum Likelihood Detection. At least one data signal is accepting on at least one communication channel (). The data signal is modulated with a plurality of transmitted bit values. The at least one data signal is sampled in a characteristic function domain of the data signal to produce characteristic function samples (). A probability density function associated with the at least one data signal is determined, based upon the characteristic function samples (). Soft decision values are determined, based upon the probability density function, for each transmitted bit value for each dimension of the at least one data signal ().