Patents by Inventor Samir N. Hulyalkar
Samir N. Hulyalkar has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6668014Abstract: A digital communication receiver includes a blind equalizer using the Constant Modulus Algorithm (CMA) to compensate for channel transmission distortion in digital communication systems. Improved CMA performance is obtained by using a partial trellis decoder to predict 1 bit or 2 bits of the corresponding 3-bit transmitted symbol. The predicted bits from the partial trellis decoder are used to reduce the effective number of symbols in the source alphabet, which reduces steady state jitter of the CMA algorithm. Specifically, the received input signal to the CMA error calculation is shifted up or down by a computed delta (&Dgr;), in accordance with the predicted bit(s). In addition, a different constant gamma (&ggr;), for the CMA error calculation is selected in accordance with the predicted bit(s).Type: GrantFiled: December 9, 1999Date of Patent: December 23, 2003Assignee: ATI Technologies Inc.Inventors: Thomas J Endres, Samir N Hulyalkar, Christopher H Strolle, Troy A Schaffer, Raul A Casas, Stephen L Biracree, Anand M Shah
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Publication number: 20030194031Abstract: A diversity receiver is coupled to a composite antenna having first and second antennas physically configured to provide one or more forms of diversity reception. The multiple channel diversity receiver includes first and second RF channels with joint signal processing. First and second RF signals are processed jointly in the multiple channel diversity receiver with respect to tuning, automatic gain control (AGC), baud clock recovery, RF carrier recovery and forward equalization. The multiple channels of the diversity receiver are linked or cross coupled to each other through respective joint processing circuitry. In particular, first and second RF tuners share a common local oscillator and a common AGC feedback loop. First and second front ends share a common baud timing loop and a common pilot carrier recovery loop. Finally, first and second diversity receiver channels share a common sparse equalization filter.Type: ApplicationFiled: April 9, 2003Publication date: October 16, 2003Inventors: Christopher H. Strolle, Anand M. Shah, Thomas J. Endres, Samir N. Hulyalkar, Troy A. Schaffer
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Publication number: 20030152173Abstract: A diversity receiver is coupled to a composite antenna having first and second antennas physically configured to provide one or more forms of diversity reception. The multiple channel diversity receiver includes first and second RF channels with joint signal processing. First and second RF signals are processed jointly in the multiple channel diversity receiver with respect to tuning, automatic gain control (AGC), baud clock recovery, RF carrier recovery and forward equalization. The multiple channels of the diversity receiver are linked or cross coupled to each other through respective joint processing circuitry. In particular, first and second RF tuners share a common local oscillator and a common AGC feedback loop. First and second front ends share a common baud timing loop and a common pilot carrier recovery loop. Finally, first and second diversity receiver channels share a common sparse equalization filter.Type: ApplicationFiled: March 7, 2003Publication date: August 14, 2003Inventors: Christopher H. Strolle, Anand M. Shah, Thomas J. Endres, Samir N. Hulyalkar, Troy A. Schaffer
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Patent number: 6560299Abstract: A diversity receiver is coupled to a composite antenna having first and second antennas physically configured to provide one or more forms of diversity reception. The multiple channel diversity receiver includes first and second RF channels with joint signal processing. First and second RF signals are processed jointly in the multiple channel diversity receiver with respect to tuning, automatic gain control (AGC), baud clock recovery, RF carrier recovery and forward equalization. The multiple channels of the diversity receiver are linked or cross coupled to each other through respective joint processing circuitry. In particular, first and second RF tuners share a common local oscillator and a common AGC feedback loop. First and second front ends share a common baud timing loop and a common pilot carrier recovery loop. Finally, first and second diversity receiver channels share a common sparse equalization filter.Type: GrantFiled: July 30, 1999Date of Patent: May 6, 2003Inventors: Christopher H Strolle, Anand M Shah, Thomas J Endres, Samir N Hulyalkar, Troy A Schaffer
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Patent number: 6426972Abstract: A transmission channel equalizer system may be used to process either signals that have been modulated according to quadrature amplitude modulation (QAM) or vestigial sideband modulation (VSB) to convey digital symbols. The equalizer system includes a sparse digital filter having coefficients which are adaptively updated. The filter system includes a finite impulse response (FIR) filter which processes modulated pass-band RF signals and an infinite impulse response (IIR) filter which processes demodulated base-band signals. At least one of the FIR and IIR filters is implemented as a sparse filter. The filter system is responsive to a control signal to switch between processing QAM and VSB signals. The update algorithm for the equalizer employs a constant modulus algorithm (CMA) to acquire the digital signal and a decision directed (DD) algorithm to track the digital signal. The CMA algorithm used when VSB signals are processed is a single axis CMA (SACMA) algorithm.Type: GrantFiled: June 19, 1998Date of Patent: July 30, 2002Assignee: NxtWave CommunicationsInventors: Thomas J. Endres, Samir N. Hulyalkar, Troy A. Schaffer, Christopher H. Strolle
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Patent number: 6418164Abstract: An adaptive equalizer for use in blind equalization systems to compensate for transmission channel distortion and noise in a digital communication system uses multiple quantization levels for implementation of the Constant Modulus Algorithm (CMA). Different quantization levels are used in different regions of the CMA error function for both passband and baseband equalizers. In one embodiment, a quantizer with a step rise having logarithmic scale is used to digitize the CMA error function. In particular, a quantizer with a step rise in which each level of the quantizer step rise is a power of 2 is used to digitize the CMA error function. In another embodiment, a quantizer with a step rise in which each level of the quantizer step rise is the sum of two or more logarithmic scales is used to digitize the CMA error function.Type: GrantFiled: January 14, 1999Date of Patent: July 9, 2002Assignee: Nxtwave Communications, Inc.Inventors: Thomas J Endres, Samir N Hulyalkar, Christopher H Strolle, Troy A Schaffer
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Apparatus and method for peer-to-peer link monitoring of a wireless network with centralized control
Publication number: 20020085503Abstract: Centrally controlled wireless networks require reliable communications between the central controller and each of the stations within the wireless networks. The structure of a wireless network is often dynamic, or ad-hoc, as stations enter and exit the network, or are physically relocated. The selection of the central controller for the network may also be dynamic, either because the current central controller desires to exit the network, or because the communication between the current central controller and one or more of the stations is poor. This invention discloses a method and apparatus for assessing the quality of the communication paths among all stations in the network. This assessment is useful as a continual monitor of the quality of the network, and can be utilized to select an alternative central control station based upon the quality of communication paths to and from this station. Additionally, the quality assessment can be utilized to establish relay communication paths, as required.Type: ApplicationFiled: February 20, 2002Publication date: July 4, 2002Applicant: Philips Electronics North America CorporationInventors: Samir N. Hulyalkar, Yonggang Du, Christoph Herrmann, Chiu Ngo, Peter Klaus May -
Patent number: 6347084Abstract: A method for synchronizing timestamps in a network (e.g., a wireless ATM network) that includes a control node and a plurality of other nodes that communicate with one another over a common channel mediated by a medium-access control subsystem (e.g., one that uses a reservation-based TDMA protocol). The method includes the steps of sending a first command from the control node, at a first time, then storing a starting timestamp value in a register within the control node and each of the other nodes, in response to the first command, and then sending a second command from the control node, at a second time later than the first time. Each of the other nodes computes the difference between the starting timestamp value and a current timestamp value, and then adds the computed difference to the current timestamp value.Type: GrantFiled: May 28, 1998Date of Patent: February 12, 2002Assignee: U.S. Philips CorporationInventors: Samir N. Hulyalkar, Elik Shekhter, Leon Steiner
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Patent number: 6339585Abstract: A method of transmitting information in a communications system. The method preferably includes the steps of establishing a communications link between a base station and a temporary node, attempting to maintain a second communication link between the base station and a wireless terminal and upon a determination that the second link cannot be established or satisfactorily maintained, transmitting information from the first base station to the temporary node so that the temporary node can retransmit the information to the wireless terminal, attempting to reestablish the second link and upon such establishment, discontinuing the transmission of subsequent information from the base station to the temporary node and directly transmitting the subsequent information to the wireless terminal from the base station. A system to carry out the foregoing steps is also provided.Type: GrantFiled: May 5, 1998Date of Patent: January 15, 2002Assignee: Philips Electronics North America Corp.Inventors: Samir N. Hulyalkar, Chiu Y. Ngo, Dinesh C. Verma
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Patent number: 6337878Abstract: An adaptive equalizer for use in blind equalization systems to compensate for transmission channel distortion and noise in a digital communication system quantizes the input signal samples to generate a quantized implementation of the Constant Modulus Algorithm (CMA). To quantize the input signal samples, a nearest-element decision device (a slicer), that is typically present in a digital receiver, is used to pre-compute the quantized CMA error function. The number of unique values for the CMA error term is thereby reduced, and the reduced number of CMA error term values are stored in a lookup table. By greatly reducing the number of received signal values used in the CMA error calculation a relatively small lookup table can be used to compute the CMA error function. Passband implementation is accommodated by incorporating the signal de-rotation factor into the lookup table entries. In one embodiment the CMA multiply operation is replaced with shifts and adders.Type: GrantFiled: March 3, 1999Date of Patent: January 8, 2002Assignee: Nxt Wave CommunicationsInventors: Thomas J Endres, Samir N Hulyalkar, Christopher H Strolle, Troy A Schaffer
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Publication number: 20010029197Abstract: The system transmits data between terminals of a wireless network. In the system, a base station/central controller (“BS/CC”) controls transmission of data from a transmitting terminal to plural receiving terminals, where the data is ordered in slots of a control data frame (“CDF”), and where each slot is reserved for a data transmission between the transmitting terminal and a specific receiving terminal. Specifically, the BS/CC divides the plural receiving terminals into a set of power-saving terminals and a set of non-power-saving terminals, and then reserves a set of slots in the CDF for data transmission between the transmitting terminal and the power-saving terminals, and another set of slots in the CDF for data transmission between the transmitting terminal and the non-power-saving terminals.Type: ApplicationFiled: May 24, 2001Publication date: October 11, 2001Applicant: Philips Electronics North America CorporationInventor: Samir N. Hulyalkar
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Patent number: 6285892Abstract: The system transmits data between terminals of a wireless network. In the system, a base station/central controller (“BS/CC”) controls transmission of data from a transmitting terminal to plural receiving terminals, where the data is ordered in slots of a control data frame (“CDF”), and where each slot is reserved for a data transmission between the transmitting terminal and a specific receiving terminal. Specifically, the BS/CC divides the plural receiving terminals into a set of power-saving terminals and a set of non-power-saving terminals, and then reserves a set of slots in the CDF for data transmission between the transmitting terminal and the power-saving terminals, and another set of slots in the CDF for data transmission between the transmitting terminal and the non-power-saving terminals.Type: GrantFiled: November 24, 1998Date of Patent: September 4, 2001Assignee: Philips Electronics North America Corp.Inventor: Samir N. Hulyalkar
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Patent number: 6198728Abstract: A protocol, method, and apparatus for managing network communications which are particularly well suited for ATM communications across a wireless medium. Contiguous time slots within a frame are allocated to each node having traffic to send. Each node is assured a nominal bandwidth, and excess bandwidth is distributed by demand. The allocation of excess bandwidth can be dependent upon the size of the buffer at each node, as well as the time-criticality of each message. Nodes communicate their requests for allocation by appending such control information to the first of their transmitted packets. The allocation, of each node's transmit and receive time slots, is transmitted to all the nodes at the beginning of each frame. Thereafter, each node need not participate on the network until their allocated time periods, thereby allowing portable devices to enter inactive states to conserve power.Type: GrantFiled: December 19, 1996Date of Patent: March 6, 2001Assignee: Phillips Electronics North America Corp.Inventors: Samir N. Hulyalkar, Chiu Ngo, Yonggang Du
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Patent number: 6178209Abstract: A slicer for a decision feedback error equalizer system which processes trellis encoded data using the ATSC trellis code is implemented in two parts. A first part includes a single-stage trellis decoder which estimates the value of a single bit of the symbol. The second part includes two trellis decoders each of which estimates the values of respective subsets of the symbols in the alphabet given that the single bit is zero or one. A multiplexer is responsive to the single stage trellis decoder to direct the received digital samples to one of the two trellis decoders in the second part of the slicer. An alternative slicer includes a first part which estimates two bits of the output symbols and selects from among four decoders in the second part in order to fully decode the symbols. The smart slicer can be generalized for any set-partitioned code with or without a feedback convolutional code.Type: GrantFiled: June 19, 1998Date of Patent: January 23, 2001Assignee: Sarnoff Digital CommunicationsInventors: Samir N. Hulyalkar, Thomas J. Endres, Troy A. Schaffer, Christopher H. Strolle
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Patent number: 6032261Abstract: A bus bridge for interconnecting a plurality of buses, which bridge includes a plurality of bridge portals, each portal being coupled to a respective one of the buses, and further includes a plurality of switching subsystems, each of which is coupled to a respective one of the bridge portals. The plurality of switching subsystems collectively constitute a switching system which interconnects the plurality of bridge portals. The bus bridge further includes a plurality of cycle clock subsystems, each of which is operatively associated with a respective bridge portal and the respective switching subsystem coupled thereto. Each cycle clock subsystem includes a cycle clock generator which generates a cycle clock, and a cycle counter which receives the cycle clock at a reset input thereof and produces a cycle count output which constitutes a common timing reference for the respective switching subsystem and the respective bridge portal. The bus bridge is preferably an IEEE 1394 serial bus bridge.Type: GrantFiled: December 30, 1997Date of Patent: February 29, 2000Assignee: Philips Electronics North America Corp.Inventor: Samir N. Hulyalkar
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Patent number: 5881363Abstract: In a CATV return channel between a transmitter and a headend receiver, the transmitter is provided with a precoder having programmable but fixed coefficients. The receiver is provided with an ingress rejection filter (IRF) having programmable but fixed coefficients. A non-precoded training sequence is sent from the transmitter to the receiver during a training interval. A multipath and an ingress in the CATV return channel are estimated at the receiver based upon the training sequence sent by the transmitter and received by the receiver. The precoder coefficients and the IRF coefficients are calculated and the precoder and the ingress rejection filter are programmed with the calculated coefficients, respectively. The precoder and the ingress rejection filter use the respective calculated coefficients during a data transmission interval to simultaneously compensate for undesirable effects of multipath and ingress noise in the CATV return channel during data transmission from the transmitter to the headend.Type: GrantFiled: April 29, 1996Date of Patent: March 9, 1999Assignee: Philips Electronics North AmericaInventors: Monisha Ghosh, Samir N. Hulyalkar
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Patent number: 5878086Abstract: A method and apparatus for improved interference rejection, where the rejection is being accomplished by an IIR filter at the transmitter with complementary characteristics to an FIR filter of the receiver, such as a Tomlinson-Harashima transmit-precoder. The improvement is accomplished by providing the ability to preset the transmit and receive filters to the same state, thereby allowing for subsequent receptions to be deterministic. This method and apparatus is particularly useful for correcting for time-varying interference through the use of repeatable, deterministic, training sequences.Type: GrantFiled: September 19, 1996Date of Patent: March 2, 1999Assignee: Philips Electronics North America CorporationInventor: Samir N. Hulyalkar
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Patent number: 5841484Abstract: A blind-equalization method and apparatus are disclosed for equalization of a channel of an HDTV receiver. The HDTV receiver comprises a rejection filter corresponding to a precoder for which precoding is implemented at a television transmitter for combating co-channel interference, wherein the television transmitter transmits a digital television signal. The HDTV receiver further comprises an equalizer having an input and an output. The equalization method comprises the steps of initiating an equalization with a blind slicing mode. The method further comprises changing the equalization to a training sequence mode upon an occurrence of a no flutter condition. While in the training sequence mode, if a flutter condition occurs, then the equalization is returned to the blind slicing mode. A determination of the occurrence of the flutter condition is based upon an estimate of a negative derivative of the Signal-to-Noise Ratio (SNR) at the output of the equalizer, dS.sub.Type: GrantFiled: July 2, 1997Date of Patent: November 24, 1998Assignee: Philips Electronics North North America CorporationInventors: Samir N. Hulyalkar, Monisha Ghosh
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Patent number: 5832041Abstract: A 64 QAM signal constellation reduces phase noise as compared with a rectangular constellation, but requires a fairly simple decoder. The constellation has decision regions which are approximately rectangular; allows for quadrant decoding; and has constellation points representable by a small number of bits.Type: GrantFiled: October 21, 1994Date of Patent: November 3, 1998Assignee: Philips Electronics North America CorporationInventor: Samir N. Hulyalkar
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Patent number: 5787080Abstract: A reservation-based wireless asynchronous transfer mode (ATM) local area network includes a system architecture of mobile nodes (MNs), each MN for communicating with various ones of the other MNs. A plurality of services is supported wherein each service has respective quality-of-service (QoS) requirements. A medium access control (MAC) layer using a reservation-based communications protocol is provided, wherein the protocol divides all MAC-based communications between a control channel and a data channel, the control channel and the data channel together making up a control-data superframe (CDS). The protocol further utilizes the control channel for allocating a bandwidth of the data channel to each service.Type: GrantFiled: June 3, 1996Date of Patent: July 28, 1998Assignee: Philips Electronics North America CorporationInventors: Samir N. Hulyalkar, Chiu Y. Ngo