Kannan Malini Ramchandran

US Patent:

6400773, Jun 4, 2002

Filed:

Jun 4, 1999

Appl. No.:

09/326246

Inventors:

Brian Scott Krongold - Champaign IL
Kannan Ramchandran - Champaign IL
Douglas L. Jones - Champaign IL

Assignee:

The Board of Trustees of the University of Illinois - Urbana IL

International Classification:

H04L 2728

US Classification:

375260, 375295, 370484

Abstract:

Optimum bit rates and power levels are determined for subchannels in multicarrier communication systems. A tangent of the rate-power curve has a slope. The slope is defined by the quotient difference between high/low power and high/low rate. A particular is evaluated to find its corresponding total power followed by an update of , in the form of an increase or decrease, to get closer to the optimal solution. Each is evaluated to find the optimal operating point for each subchannel on the rate-power curve by summing the power allocated to the subchannels, and comparing the result to the power budget. Look-up tables are stored for individual channels, but similarity between channels permits joint use of look-up tables by multiple channels. The tables are used to determine the rate-power characteristics at each iteration. An optimal solution is found when either a newly chosen power allocation meets the power budget exactly or a newly chosen power budget equals the high or low power of a previous iteration.

US Patent:

6418549, Jul 9, 2002

Filed:

Jul 12, 1999

Appl. No.:

09/351631

Inventors:

Kannan Ramchandran - Champaign IL
Jim Chou - Redondo Beach CA
Igor Kozintsev - Savoy IL

Assignee:

Merunetworks, Inc. - Santa Clara CA

International Classification:

G06F 1100

US Classification:

714811, 714748

Abstract:

Method and apparatus for image transmission using arithmetic coding, based on continuous error detection uses a controlled amount of added redundancy. A continuous error detection scheme is provided, wherein there is a trade-off between the amount of added redundancy and the time needed to detect an error once it occurs. Herein, there is no need for the cyclic redundancy check (CRC) to wait until an entire block of data has been received and processed before an error can be detected. The invention can be used to great advantage both in the automatic repeat request (ARQ) and other concatenated coding schemes. Errors in the received bit stream are detected by introducing added redundancy, e. g. , a forbidden symbol, in the arithmetic coding operation. The forbidden symbol is never intended to be encoded.

US Patent:

7099273, Aug 29, 2006

Filed:

Jan 29, 2002

Appl. No.:

10/061574

Inventors:

Sungwon Ha - San Jose CA, US
Sung-wook Han - San Jose CA, US
Tae-eun Kim - Sunnyvale CA, US
Vaduvur Bharghavan - San Jose CA, US
Upamanyu Madhow - Santa Barbara CA, US
Kannan Ramchandran - Berkeley CA, US

Assignee:

Bytemobile, Inc. - Mountain View CA

International Classification:

H04J 1/16
H04J 3/14

US Classification:

370229, 370235, 370236

Abstract:

Improved data transport and management within a network communication system may be achieved by utilizing a transmit timer incorporated within the sender device and exploiting host-level statistics for a plurality of connections between a sender and receiver. The period of the transmit timer may be periodically adjusted based on a ratio of the smoothed round-trip time and the smoothed congestion window, thereby reducing or eliminating bursty data transmission commonly associated with conventional TCP architectures. For applications having a plurality of connections between a sender and a receiver that share a common channel, such as web applications, the congestion window and smoothed round trip time estimates for all active connections may be used to initialize new connections and allocate bandwidth among existing connections. This aspect of the present invention may reduce the destructive interference that may occur as different connections compete with one another to maximize the bandwidth of each connection without regard to other connections serving the same application. Error recovery may also be improved by incorporating a short timer and a long timer that are configured to reduce the size of the congestion window and the corresponding transmission rate in response to a second packet loss with a predefined time period in order to increase resilience to random packet loss.

US Patent:

7400774, Jul 15, 2008

Filed:

Aug 29, 2003

Appl. No.:

10/651854

Inventors:

Rohit Puri - San Jose CA, US
Kannan Ramchandran - El Cerrito CA, US

Assignee:

The Regents of the University of California - Oakland CA

International Classification:

G06K 9/36
G06K 9/46

US Classification:

382238, 382240

Abstract:

Encoding digital data by using cues at a decoder. An encoder selects an index to indicate a target codeword from the complete space of all codewords to a decoder. The index identifies a group or a set of codewords that contain the target codeword. The sets are represented by a bit-length that is smaller than the code word bit-length thus achieving compression. Two or more codewords in such a set are separated by a predetermined distance and all such sets of codewords considered together form the complete space of all codewords. The encoder sends syntax information, including the index, to specify the decoding. The decoder then uses a set of candidate cues in a comparison operation to determine the target codeword from the indexed set. Processing complexity can be allocated among the encoder, decoder and other possible devices as, for example, in a digital network.

US Patent:

7444418, Oct 28, 2008

Filed:

May 9, 2002

Appl. No.:

10/143441

Inventors:

Jim Chou - Berkeley CA, US
Kannan Ramchandran - Berkeley CA, US

Assignee:

Bytemobile, Inc. - Mountain View CA

International Classification:

G06F 15/16

US Classification:

709231, 709203, 709230, 725111, 725117

Abstract:

Multimedia information communicated between a transmitter and a receiver may be transcoded by intercepting the multimedia information within a network communication system. The available transmission rate of the downlink channel may be estimated by, for example, calculating a ratio of the smoothed round trip time of packets communicated to the receiver and a smoothed congestion window associated with the downlink channel. If the transmission rate at which the multimedia information is encoded is greater than the available transmission rate, the multimedia information may be transcoded to conform the multimedia information to the available transmission rate. The transcoded multimedia information may then be transmitted to the receiver over the downlink channel using a transmission timer.

US Patent:

7643558, Jan 5, 2010

Filed:

Mar 24, 2003

Appl. No.:

10/396982

Inventors:

Harinath Garudadri - San Diego CA, US
Kannan Ramchandran - El Cerrito CA, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H04N 7/18

US Classification:

37524023, 37524025, 37524026

Abstract:

According to one aspect of the present invention, a method and apparatus is provided in which input data (e. g. , input video data) is encoded in accordance with a first coding standard (e. g. , MPEG-4) to generate encoded data. The input data is also encoded based on a reconstruction of the input data to generate encoded side information associated with the input data. The encoded data are transmitted to a destination (e. g. , a decoding subsystem) over a first channel and the encoded side information are transmitted to the destination over a second channel. The encoded data and the encoded side information are decoded and combined at the destination to generate output data.

US Patent:

7652577, Jan 26, 2010

Filed:

Feb 5, 2007

Appl. No.:

11/702980

Inventors:

Upamanyu Madhow - Santa Barbara CA, US
Ben J. Wild - Oakland CA, US
Kannan Ramchandran - El Cerrito CA, US

Assignee:

Checkpoint Systems, Inc. - Thorofare NJ

International Classification:

G08B 13/14

US Classification:

3405721, 3405722

Abstract:

Systems and methods for beamforming in radio frequency identification (RFID) applications are disclosed. A beamforming system uses a distributed architecture and techniques for antenna beamforming using a feedback control loop to direct radio frequency (RF) energy onto a specific region, referred to as an interrogation zone, which includes a calibration node where one or more RFID tags may be located. The distributed architecture of the beamforming system is resistant to fading and shadowing effects, providing accurate RFID reader operation even in environments with multi-path reflections or environmental changes, such as people moving around or changes in the location of equipment.

US Patent:

7881258, Feb 1, 2011

Filed:

Mar 21, 2007

Appl. No.:

11/689386

Inventors:

Jeffrey M. Gilbert - Palo Alto CA, US
Kannan Ramchandran - El Cerrito CA, US
Guocong Song - San Jose CA, US

Assignee:

Sibeam, Inc. - Sunnyvale CA

International Classification:

H04W 4/00
H04W 72/00
G06F 15/16

US Classification:

370329, 370465, 455450, 709231

Abstract:

A system is disclosed having a transmitter to wirelessly transmit multi-media data. The transmitter includes a module to packetize phase units of a multimedia frame that is to be transmitted. The system also includes a receiver to receive the multimedia frame received from the transmitter. The receiver includes a post processing module to perform error concealment on the phase units.