Manish N Bhardwaj, 48524 Parker St, Newton, MA 02459

7079828, Jul 18, 2006

Feb 27, 2003

10/375306

Jian Cui - Acton MA, US
Manish Bhardwaj - Acton MA, US

Edgewater Computer Systems, Inc. - Ottawa

H04B 1/06

4552781, 455296, 455 631, 375324, 375346

In a multi-user radio receiver, a method and apparatus for reducing the effects of non-linear distortion due to adjacent channel interference (ACI) includes receiving and processing a multi-user information signal to provide a plurality of multi-user information values and then detecting, from the plurality of multi-user information values, at least a first information value having a signal strength which is relatively high compared with the signal strengths of the other plurality of multi-user information values. The apparatus then utilizes the plurality of multi-user information values, the first information value and a spectral representation of the first information value to generate a plurality of second information values having significantly reduced adjacent channel interference with respect to the first information value. The method and apparatus can thus increase the system capacity by increasing the frequency reuse factor in the a receiver system (e. g. a wideband receiver system) for wireless LAN applications.

7415059, Aug 19, 2008

Nov 13, 2003

10/712800

Kanu Chadha - Acton MA, US
Maneesh Soni - Richardson TX, US
Manish Bhardwaj - Acton MA, US

Edgewater Computer Systems, Inc. - Ottawa, Ontario

H03D 1/00
H04L 27/06

375 43, 375354, 375355, 375365, 375368

Using a combination of auto-correlation and cross-correlation techniques provides a symbol timing recovery in a Wireless Local Area Network (WLAN) environment that is extremely robust to wireless channel impairments such as noise, multi-path and carrier frequency offset. An auto-correlator provides an estimate for a symbol boundary, and a cross-correlator is subsequently used to more precisely identify the symbol boundary. Peak processing of the cross-correlation results provides further refinement in symbol boundary detection. In receiving a packet conforming to the IEEE 802. 11a standard, the method requires a minimum of only three short symbols of the 802. 11a short preamble to determine timing, and guarantees timing lock within the duration of the 802. 11a short preamble. This method and system can be easily applied to any other preamble based system such as 802.

7453792, Nov 18, 2008

Nov 14, 2003

10/713562

Kanu Chadha - Stafford TX, US
Manish Bhardwaj - Cambridge MA, US

Edgewater Computer Systems, Inc. - Ottawa, Ontario

H04J 11/00

370203

The invention relates to a novel methodology and apparatus for clock-offset compensation and common-phase offset correction in Frequency Division Multiplexing based wireless local area network (WLAN) environment, such as an Orthogonal Frequency Division Multiplexing (OFDM) environment. A curve fit, such as a threshold-based, least mean squares (LMS) fit of phase of the pilot sub-carriers in each OFDM symbol is used to estimate and counteract the rotation of the data sub-carriers due to residual frequency offset, low frequency phase noise, and clock offset. The invention is particularly well suited to wireless channels with multipath where pilots typically undergo frequency-selective fading. The thresholding LMS is implemented in a hardware-efficient manner, offering cost advantages over a weighted-LMS alternative. Additionally, the invention uses a unique phase-feedback architecture to eliminate the effects of phase wrapping, and avoid the need to refine channel estimates during packet reception.

7733764, Jun 8, 2010

Dec 9, 2003

10/731730

Maneesh Soni - Richardson TX, US
Kanu Chadha - Acton MA, US
Manish Bhardwaj - Cambridge MA, US

Edgewater Computer Systems, Inc. - Ottawa, Ontario

H04J 11/00

370206, 375354, 375362, 370338, 327149, 327158, 365194, 365239

Upon a triggering event, a delay chain shifts data out at a higher rate than incoming packets and a processor controls bypassing circuitry to reduce the latency of hardware implementations of, for example, 802. 11a OFDM receivers, with long delay chains. The signal processing algorithms used to recover symbol timing need a large number of samples stored in a delay chain, often consisting of pipelined registers. Such a delay chain introduces a large lag between the time samples have been acquired by the data converters and the time they are processed. This delay makes it difficult for higher level network layer implementations to meet the deadlines of 802. 11a WLAN protocol. The proposed scheme implements dynamic reduction in the depth of the delay chain once timing recovery has been performed. A multi-step scheme achieves exponential reduction in the number of elements in the delay chain in every step.

7835701, Nov 16, 2010

Mar 29, 2005

11/093031

Manish Bhardwaj - Cambridge MA, US
Garret Shih - Brookline MA, US

Edgewater Computer Systems, Inc. - Ottawa, Ontario

H04B 17/00

455 6711, 455 631, 455 6713, 455 62, 4555521, 455501, 4554261, 455448, 455 71

The present invention allows multi-channel communications equipment to detect and eliminate a false interpretation of interference as a valid signal. The solution is based on the observation that the simultaneous arrival of energy on two independent channels is an impossible event. So, when such an event happens, it is a reliable signature of confusing out-of-band energy for a valid signal.

7894325, Feb 22, 2011

Nov 14, 2008

12/291905

Kanu Chadha - Stafford TX, US
Manish Bhardwaj - Cambridge MA, US

Edgewater Computer Systems, Inc. - Ottawa, Ontario

H04J 11/00

370203

The invention relates to a novel methodology and apparatus for clock-offset compensation and common-phase offset correction in Frequency Division Multiplexing based wireless local area network (WLAN) environment, such as an Orthogonal Frequency Division Multiplexing (OFDM) environment. A curve fit, such as a threshold-based, least mean squares (LMS) fit of phase of the pilot sub-carriers in each OFDM symbol is used to estimate and counteract the rotation of the data sub-carriers due to residual frequency offset, low frequency phase noise, and clock offset. The invention is particularly well suited to wireless channels with multipath where pilots typically undergo frequency-selective fading. The thresholding LMS is implemented in a hardware-efficient manner, offering cost advantages over a weighted-LMS alternative. Additionally, the invention uses a unique phase-feedback architecture to eliminate the effects of phase wrapping, and avoid the need to refine channel estimates during packet reception.

2004015, Aug 5, 2004

Nov 6, 2003

10/703192

Amit Sinha - Marlborough MA, US
Manish Bhardwaj - Cambridge MA, US
Kanu Chadha - Stafford TX, US

Engim, Inc. - Acton MA

H04B001/02

455/042000, 455/102000

A unified digital front end filtering circuit is described for IEEE 802.11g protocol compliant systems. The front end uses polyphase rate conversion filters cascaded with channel extraction and pulse shaping filters to accommodate the different sampling rate requirements for orthogonal frequency division multiplexing (OFDM) and direct sequence spread spectrum (DSSS) modulation, which have to be supported simultaneously, without using separate analog front ends.

2007005, Mar 8, 2007

Jul 27, 2006

11/494282

Manish Bhardwaj - Cambridge MA, US
Jian Cui - Acton MA, US

H04K 1/10

375260000

In estimating and compensating impairments of Orthogonal Frequency Division Multiplexing (OFDM) symbols, a first estimation is obtained by evaluating and comparing received training symbols with transmitted training symbols. A second estimation is obtained by evaluating and comparing a first portion of received payload symbols with estimated payload symbols. A final estimation is obtained by combining the first and second estimations. Compensation of a second portion of the payload symbols is obtained by using the final estimation, while compensation of the first portion of the payload symbols is obtained by using the first estimation. The current method and apparatus, ideal for low rate systems, disclosed herein allows for required signal-to-noise ratio (SNR) performance less then 0.2 dB away from the best achievable performance without the introduction of complex or expensive hardware.