Abstract:
A system for periodic noise avoidance including a timing discriminator receiving an input signal from a communications channel. The input signal includes data packets and empty slots with periodic noise. The timing discriminator outputs a first error measurement of periodic noise width and a second error measurement of periodic noise position. A first loop filter inputs the first error measurement and outputs a width of the empty slots. A second loop filter inputs the second error measurement and outputs a frequency of the periodic noise. An oscillator inputs the width of the empty slots and the frequency, and outputs an empty slot waveform to the timing discriminator.
Abstract:
Directly computing Feed Forward Equalizer (FFE) coefficients and Feed Back Equalizer (FBE) coefficients of a Decision Feedback Equalizer (DFE) from a channel estimate. The FBE coefficients have an energy constraint. A recursive least squares problem is formulated based upon the DFE configuration, the channel estimate, and the FBE energy constraint. The recursive least squares problem is solved to yield the FFE coefficients. The FFE coefficients are convolved with a convolution matrix that is based upon the channel estimate to yield the FBE coefficients. A solution to the recursive least squares problem is interpreted as a Kalman gain vector. A Kalman gain vector solution to the recursive least squares problem may be determined using a Fast Transversal Filter (FTF) algorithm.
Abstract:
Cancellation of interference in a communication system with application to S-CDMA. A relatively straight-forward implemented, and computationally efficient approach of selecting a predetermined number of unused codes is used to perform weighted linear combination selectively with each of the input spread signals in a multiple access communication system. If desired, the predetermined number of unused codes is always the same in each implementation. Alternatively, the predetermined number of unused codes are selected from within a reordered code matrix using knowledge that is shared between the two ends of a communication system, such as between the CMs and a CMTS. While the context of an S-CDMA communication system having CMs and a CMTS is used, the solution is generally applicable to any communication system that seeks to cancel narrowband interference. Several embodiments are also described that show the generic applicability of the solution across a wide variety of systems.
Abstract:
Computing optimal Linear Equalizer (LE) coefficients gopt from a channel estimate h. A channel impulse response h is first estimated based upon either a known training sequence or an unknown sequence. The channel estimate is formulated as a convolution matrix H. The convolution matrix H is then related to the LE coefficients in a matrix format equation, the matrix format equation based upon the structure of the LE, the convolution matrix, and an expected output of the LE. A Fast Transversal Filter (FTF) algorithm is then used to formulate a recursive least squares solution to the matrix format equation. Computing the recursive least squares solution yields the LE coefficients using structured equations.
Abstract:
A method for determining a fading correction factor to be used for correcting a sample of a power delay profile of a received signal in a communication system, the fading correction factor associated with a fading channel characteristic through which the received signal propagates, includes estimating a number (N) of complex samples, obtaining fading channel autocorrelation sequence (R(n)) of the fading channel for a plurality (n) of complex samples, the number of the plurality (n) of complex samples corresponding to the number (N) of complex samples, and computing the fading correction factor based on the number (N) of complex samples, autocorrelation sequence (R(n)), and the number of the plurality (n) of complex samples.
Abstract:
A technique for estimating a carrier frequency offset and a timing offset in a MediaFLO™ (Forward Link Only) communication system, wherein the method comprises includes receiving Orthogonal Frequency Division Multiplexing (OFDM) symbols; interpolating pilots on odd or even symbols of the received OFDM symbols; determining a phase difference between two successive symbols using the interpolated pilots; obtaining an estimate of the carrier frequency offset and the timing offset from the determined phase difference between two successive symbols; and correcting a sampling frequency in accordance with the estimated carrier frequency offset and timing offset.
Abstract:
Enhancing a stream layer transmission for a MediaFLO™ mobile multimedia multicast system comprising a transmitter and a receiver. Code word (CW) computations are performed on a current channel being accessed by the receiver. A favorite channel that a user is statistically mostly likely to switch to on the receiver at any particular time is anticipated. The Overhead Information Symbols (OIS) for each favorite channel is periodically monitored. The receiver remains in a sleep mode while data bursts are received from non-favorite channels, and then wakes up during data bursts of the favorite channel. The same CW computations are performed on the favorite channel as were being performed on the current channel. A cyclic redundancy check (CRC) is performed once the CW computations are performed upon selecting the favorite channel.
Abstract:
A technique for providing stable tracking performance to an AGC loop circuit comprises amplifying a wideband radio frequency signal; detecting signals and blockers adjacent to the radio frequency signal; lowering a gain of the radio frequency signal; mixing a local oscillator signal with the radio frequency signal; shifting a frequency of the radio frequency signal from a radio frequency to an intermediate frequency; continuously varying a gain of the intermediate frequency signal; converting the intermediate frequency signal into a digital output signal; comparing the digital output signal with predefined thresholds comprising an upper threshold and a lower threshold; switching a post mixer amplifier (PMA) to a high gain state when an input of a variable gain amplifier (VGA) is greater than the upper threshold, and switching the PMA to a low gain state when an input of the VGA is lower than the lower threshold.
Abstract:
Transmitting data in a digital video broadcasting for handheld (DVB-H) receiver comprises a transport stream (TS) demultiplexer adapted to extract internet protocol (IP) datagrams from TS data packets; a packet identifier (PID) filter adapted to extract the TS data packets based on the PIDs of the TS data packets; a Multi Protocol Encapsulation-Forward Error Correction (MPE-FEC) random access memory (RAM) unit operatively connected to the TS demultiplexer; a Reed-Solomon decoder operatively connected to the MPE-FEC RAM unit; an IP to TS encapsulator operatively connected to the MPE-FEC RAM unit; a TS multiplexer operatively connected to each of the PID filter and the IP to TS encapsulator, wherein the TS multiplexer is adapted to combine both DVB-Terrestrial (DVB-T) and DVB-H TS data packets into a single combined TS data packet; and a host interface operatively connected to the TS multiplexer.
Abstract:
A technique for decoding code packets of file delivery protocol (FDP) and file delivery control protocol (FDCP) messages, the FDP messages comprising fields having values used to generate an indices of a data packets, the FDCP messages comprising a value of a minimum number of code packets required, the code packets formed from a linear combination of the data packets of a file fragment, the method includes constructing data structures adapted to decode the code packets of the file fragment, the data structures comprising at least one of code nodes, a code graph, an inverse code graph, a data packet decode array, and a data packet decode order list, processing the FDP messages until a parameters required for decoding are extracted, and populating the inverse code graph with a reference to the code node.