Patent application number | Description | Published |
20080316909 | COHERENT DETECTION FOR DIFFERENTIALLY ENCODED OFDM SYSTEMS - A method and system for coherent detection in which a OFDM symbol is multiplied by the complex conjugate of the previous OFDM symbol, which is obtained by one OFDM symbol delay and a complex conjugation circuit. This soft decision is passed through a QPSK slicer to obtain a hard decision. The soft decision is then divided by the hard decisions. The channel phase change between the two OFDM symbols is then obtained. For the first OFDM symbol, the channel is computed. A channel estimate for each ODFM symbol is computed from corresponding channel estimates and channel phase difference estimates. The channel phase difference between each two OFM symbols is computed. The channel phase difference is passed through an exponent operation and multiplied by the soft decision to obtain a refined soft decision that is then passed through another QPSK slicer to obtain the final hard decision. | 12-25-2008 |
20080317022 | ROBUST TECHNIQUE FOR FRAME SYNCHRONIZATION IN DAB-IP SYSTEMS - FEC frame synchronization in a DAB-IP system comprising FEC frames includes receiving FEC packets each comprising a FEC packet header and a FEC data field comprising padding bytes at an end of a last FEC packet received; comparing a received FEC packet header with a known FEC packet header until a number of bit errors in the received FEC packet header is less than or equal to a predetermined amount; and matching the received FEC packet header and the padding bytes until at least one of the following actions occur thereby resulting in receiver locking: a number of successive FEC packet headers mismatches in the received FEC packet header; a predetermined number of FEC packets end without padding matching; and FEC packet header and padding matching occurs. The received FEC packets are tracked after receiver locking has occurred to ensure FEC parity packets are positioned properly in the FEC frames. | 12-25-2008 |
20080317153 | ADAPTIVE TECHNIQUE FOR INTER-CARRIER-INTERFERENCE CANCELING IN OFDM SYSTEMS - ICI canceling in an OFDM system includes taking a FFT of a wireless electrical signal to produce an OFDM signal; estimating a DC component of a frequency-selective channel in the OFDM system; obtaining an initial estimate of data symbols associated with data bits of the OFDM signal; correcting the data bits with a Viterbi decoder; encoding the corrected data bits to acquire corrected data symbols; re-estimating the DC component of the frequency-selective channel using the corrected data symbols; filtering the corrected data symbols and sub-carrier of the frequency-selective channel; calculating a first order differential function of the frequency-selective channel based on successive ones of the corrected data symbols; removing an ICI component from the calculated first order differential function; and re-estimating the data symbols as a function of the removed ICI component. The filtering occurs using a low pass filter comprising a bank of eight filters. | 12-25-2008 |
20090041135 | NULL DETECTION IN DAB, T-DMB, AND DAB-IP SYSTEMS - Detecting Null symbols in a video data frame comprises sending OFDM symbols through a sliding windowed correlation process having a correlation window length proportional to a cyclic prefix length and a delay equal to a FFT size of the symbols, wherein output peaks of the process occur where two similar portions of the symbols coincide; checking peaks in windows sized equal to a duration of a symbol; determining whether the peaks are located in the middle of the windows; determining whether a shift has occurred in the location of the peak of a current window compared to in a second immediately previous window; determining whether the peak in a first immediately previous window is weak compared to that in a second immediately previous window; and declaring that a Null symbol exists in the first previous window when the shift has occurred and the determination of a weak peak exists. | 02-12-2009 |
20090059885 | ADAPTIVE TIME-DOMAIN INTERPOLATION FOR OFDM SCATTERED PILOT SYMBOLS - A receiver for use in a pilot-aided OFDM system and a method of performing channel length estimation of a channel in a wireless communication system includes using transmitted and received wireless signals to estimate a channel carrier function vector at continuous and scattered pilot positions of consecutive OFDM symbols; performing time-domain interpolation by (i) upsampling the estimated the channel carrier function vectors at the scattered pilot positions by inserting zeros in between estimated scattered pilot positions, and (ii) filtering the upsampled vectors using a finite impulse response filter comprising a filter bank comprising a plurality of filters; mapping the channel carrier function vector to only one of the filters in the filter bank located in the finite impulse response filter, wherein the mapping causes noise reduction and enhanced channel estimation thereby increasing a maximum Doppler frequency in the channel. | 03-05-2009 |
20090110082 | ROBUST PID FILTERING FOR DVB-H - One embodiment provides a method of performing packet identifier (PID) filtering of a digital video broadcasting-handheld (DVB-H) transport stream and includes processing a PID and a continuity counter (CC) sequence of the DVB-H transport stream, computing a number of mismatched bits between the PID and a desired PID, proceeding to a start of a reset state on a first-in-first-out (FIFO) queue of the DVB-H transport stream when a FIFO buffer becomes full, determining if a number of mismatched bits of a first packet in the FIFO buffer is less than a first threshold value, and proceeding to a start of a run algorithm state only if the number of mismatched bits of the first packet in the FIFO buffer is less than the first threshold value and if there is a valid CC sequence that includes the first packet. | 04-30-2009 |
20090110118 | ADAPTIVE DEINTERLEAVER MEMORY ALLOCATION - A receiver for use in a wireless network comprising a communications channel and a method of allocating deinterleaver memory usage in the receiver, wherein the receiver comprises a processor adapted to organize subchannels of the communications channel and set a number (N) of data bits per soft decision, wherein the soft decision is represented by N data bits; an address decoder adapted to decode the subchannels; a demapper adapted to receive QAM symbols and demap the QAM symbols to soft decisions; a deinterleaver adapted to perform deinterleaving on the soft decisions, wherein the deinterleaver comprises a memory component having a storage size that is a function of the number (N) of bits per soft decision; and a Viterbi decoder adapted to decode the deinterleaved soft decisions. | 04-30-2009 |
20090129344 | ENHANCED STREAM LAYER TRANSMISSION FOR MEDIAFLO MOBILE MULTIMEDIA MULTICAST SYSTEM - Enhancing stream layer transmission for a MediaFLO mobile multimedia multicast system comprising a transmitter and a receiver includes sending a plurality of multicast logical channels (MLC) forming a data frame from the transmitter, wherein each MLC comprises multimedia data streams comprising a stream | 05-21-2009 |
20090154547 | SCATTERED PILOT CORRELATION IN DVB-H SYSTEMS - A method for correlating scattered pilot locations in a sequence of OFDM symbols in a multi-carrier transmission system, and includes mapping pilot locations comprising pilot symbols having predetermined known values, wherein the pilot symbols are positioned among data subcarriers in time and frequency dimensions consisting of received pilot symbols and having a predetermined position pattern in the time and frequency dimensions, wherein the predetermined position pattern comprises a finite number of sub-position patterns each corresponding to positions of the pilot symbols; estimating a Doppler spread in a frequency spectrum between the transmitter and the receiver in the multi-carrier transmission system; estimating a channel length of a set of channel paths received at the receiver; and the receiver automatically selecting one of a plurality of predetermined methods of correlating the scattered pilot locations in the sequence of OFDM symbols based only on the estimating processes. | 06-18-2009 |
20090187946 | FAST CHANNEL SWITCHING FOR ENCRYPTED MEDIAFLO MOBILE MULTIMEDIA MULTICAST SYSTEM - 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. | 07-23-2009 |
20090207311 | TECHNIQUE FOR TUNER AUTOMATIC GAIN CONTROL CIRCUIT FOR MOBILE TELEVISION APPLICATIONS - 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. | 08-20-2009 |
20090213831 | FAST AUDIO/VISUAL RECEPTION IN DVB-H SYSTEMS - An apparatus and method of reducing a channel switching delay in TDM mobile television systems, and comprises receiving a data burst associated with channels for reception on a RF channel bandwidth received on a mobile television receiver, wherein the data burst comprises a plurality of RTP packets and a RTCP packet; buffering the data burst upon reception of a first RTP packet; synchronizing the buffered data burst to allow for reception of playable A/V data; and adjusting the synchronized buffered data burst upon reception of the RTCP packet. The method may further comprise performing the synchronizing upon reception of the RTCP packet. The method may further comprise inserting a null packet in the data burst prior to performing the buffering. The first RTP packet is preferably received prior to reception of the RTCP packet. | 08-27-2009 |
20090220015 | COARSE CARRIER FREQUENCY OFFSET ESTIMATION FOR CMMB MOBILE TV RECEIVER - A method of estimating coarse frequency offset of received symbols based on a received frequency domain sample at a k | 09-03-2009 |
20090222585 | EFFICIENT DECODING OF MEDIAFLO SYSTEM NON REAL-TIME SERVICE FILES - 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. | 09-03-2009 |
20090252026 | TIMING AND FREQUENCY ACQUISITION FOR MEDIAFLO SYSTEMS - An apparatus, logic, and method of performing timing and frequency estimation in a MediaFLO™ mobile multimedia multicast system comprising a receiver and a transmitter, wherein the method comprises receiving a wireless data stream comprising a MediaFLO™ mobile multimedia multicast system superframe comprising Orthogonal Frequency Division Multiplexing (OFDM) symbols; estimating a Fast Fourier Transform (FFT) trigger point for each of the received OFDM symbols; estimating a fine carrier frequency offset of each OFDM symbol; determining the start of the MediaFLO™ mobile multimedia multicast system superframe by locating a Time Division Multiplexed (TDM) pilot symbol in the superframe; estimating a coarse carrier frequency offset of each of the received OFDM symbols; and synchronizing the receiver to the start of the MediaFLO™ mobile multimedia multicast system superframe and the transmitted OFDM symbols based on the fine carrier frequency offset, the TDM pilot symbol, and the coarse carrier frequency offset. | 10-08-2009 |
20090252027 | WIC AND LIC ESTIMATION IN MEDIAFLO SYSTEMS - An apparatus and method for WIC/LIC estimation without channel mode construction in a MediaFLO™ system comprising a receiver, a transmitter and transmission channel, wherein the method comprises receiving a signal comprising a MediaFLO™ mobile multimedia multicast system superframe comprising WIC/LIC symbols; setting a first sparseness index value of the digital signal to zero; setting a local copy WIC/LIC number of the digital signal to one; generating a local copy of all possible values of the WIC/LIC symbols corresponding to a WID/LID value from zero to fifteen; dividing the received WIC/LIC symbol values by a local copy WIC/LIC value corresponding to WIC/LIC number one; performing an IFFT of all the possible values of the WIC and LIC symbols; calculating a second sparseness index value of the IFFT of sixteen possible values of the WIC/LIC symbols; and extracting a WIC/LIC symbol from the digital signal corresponding to the second sparseness index. | 10-08-2009 |
20090252237 | DOUBLE LAYER MAXIMUM RATIO COMBINING FOR OFDM RECEIVER DESIGN WITH INTER-CARRIER-INTERFERENCE CANCELLING - An apparatus, method, and system for reducing a C/N in an OFDM receiver using diversity combining techniques in the presence of ICI, wherein the apparatus comprises an encoded data estimator adapted to estimate data received in the OFDM receiver; a pair of ICI estimators operatively connected to the encoded data estimator and adapted to calculate an inter-carrier-interference term of the data; and a pair of diversity combining equalizers adapted to compensate multi-path interference of the data, wherein a first one of the diversity combining equalizers is operatively connected to the encoded data estimator, and a second one of the diversity combining equalizers is operatively connected to the pair of ICI estimators. The diversity combining equalizer may comprise a MRC diversity combining equalizer. Preferably, the encoded data estimator, the pair of ICI estimators, and the pair of diversity combining equalizers are implemented on a DVB-T/H diversity SoC. | 10-08-2009 |
20090252238 | RE-ACQUISITION OF SYMBOL INDEX IN THE PRESENCE OF SLEEP TIMER ERRORS FOR MEDIAFLO SYSTEMS - A technique for re-acquiring a symbol index in the presence of sleep timer errors in a MediaFLO™ (Forward Link Only) mobile multimedia multicast system comprising a receiver and a transmitter, wherein the method comprises receiving a digital signal comprising a superframe comprising one or more Orthogonal Frequency Division Multiplexing (OFDM) symbols in the receiver comprising a timer; waking up the receiver from a sleep mode of operation by an amount of time equal to a maximum error introduced by the timer plus a time to reacquire a beginning of each OFDM symbol plus a time to reacquire a symbol index; and reacquiring the symbol index. | 10-08-2009 |
20090252239 | ROBUST FINE FREQUENCY AND TIME ESTIMATION IN MEDIALFLO SYSTEM RECEIVERS - A technique for estimating a carrier frequency offset and a timing offset in a MediaFLO™ (Forward Link Only) system, wherein the method comprises 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. | 10-08-2009 |
20090252256 | FAST ACQUISITION IN MEDIAFLO SYSTEMS - A technique of acquisition in a MediaFLO™ (Forward Link Only) mobile multimedia multicast system, wherein the method comprises receiving a superframe comprising a first digital symbol in a receiver operating in a first state of operation; assuming the first received digital symbol to be a Time Division Multiplexed (TDM) pilot symbol; calculating a first sparseness index of the first symbol; storing the first sparseness index; operating the receiver in a second state of operation; receiving a second digital symbol; calculating a second sparseness index for the second digital symbol; the receiver remaining in the second state of operation when the second sparseness index is greater than the first sparseness index, wherein the second digital symbol is assumed to be the TDM pilot symbol; and verifying that the last assumed TDM pilot symbol is the correct TDM pilot of the superframe. | 10-08-2009 |
20090268656 | Fast Common Overhead Services Acquisition for MediaFlo - A technique for fast common overhead services acquisition for MediaFLO™ mobile multimedia multicast system, wherein encoding overhead information symbol (OIS) information in a first burst of MLC of each superframe, OIS comprises control channel (CC) information and reserved flow data comprising primary flow data, service information data, notification flow data, configuration flow data, and presentation metadata; encoding padding in second MLC burst; encoding parity bytes in third and fourth MLC bursts; encoding primary flow data in final MLC burst per superframe; encoding the remaining reserved flow data at the end of superframe; transmitting wireless data stream comprising first MLC at ½ forward error correction (FEC) rate and receiving it in receiver; determining a correctness of CC information by checking cyclic redundancy check (CRC) bits at the end of each received data packet; and transmitter sending size wise remainder of reserved flows at the end of superframe. | 10-29-2009 |
20090268665 | Method and Apparatus for Locating MediaFLO Capable Wireless Devices - Estimating a current location of a receiver in a MediaFLO™ (Forward Link Only) mobile multimedia multicast system comprises receiving digital signals comprising a MediaFLO™ superframe comprising orthogonal frequency division multiplexing (OFDM) symbols; performing slot | 10-29-2009 |
20090268803 | Channel Estimation for High Doppler Mobile Environments - An apparatus and method of applying a fast algorithm to a pilot-based channel estimation process includes receiving, in a receiver, a signal comprising information bits transmitted in a wireless channel, executing a pilot-based channel estimation process running on a decision-directed turbo estimation procedure having a p structure for a vector of pilots and an upper bound N for a channel spread based on a feedback of detected information bits via OFDM, encoding the detected information bits, re-encoding the detected information bits at a decoder output, re-constructing and subtracting an ICI term from the received signal, modulating the detected information bits, estimating channel symbols in a per-carrier basis based on a diagonal matrix of a full matrix involved in the pilot-based channel estimation, and performing training of the wireless channel based on an entire vector of the channel symbols. | 10-29-2009 |
20090271684 | Iterative decoding between turbo and RS decoders for improving bit error rate and packet error rate - A technique for iterative decoding between turbo and Reed Solomon (RS) decoders for improving bit error rate (BER) and packet error rate (PER) in a receiver in a wireless communication system comprises receiving data samples comprising turbo encoded packets and RS code words at the receiver; decoding turbo encoded packets of the received data samples using a turbo decoder; decoding RS code words of the received data samples using a RS decoder; feeding the RS decoded data to turbo decoder to perform a plurality of iterations; and correcting data errors present in the received data samples. | 10-29-2009 |
20090285096 | HARDWARE ACCELERATED PROTOCOL STACK FOR MEDIAFLO - Protocol stack layer processing for a MediaFLO™ mobile multimedia multicast system comprising a transmitter comprising a host processor and a host memory component. The processing includes a receiver that receives a wireless data stream comprising a MediaFLO™ mobile multimedia multicast system superframe comprising any of audio, video, and text media frames arranged in multiplexed Multicast Logical Channels (MLCs) and received from the transmitter, wherein each MLC is divided into 16 byte data packets, and wherein each MLC carries up to three logical sub-channels comprising stream | 11-19-2009 |
20090285314 | ADAPTIVE FREQUENCY DOMAIN EQUALIZATION IN OFDM BASED COMMUNICATION SYSTEM - An apparatus, system, and method of performing adaptive frequency domain equalization in an Orthogonal Frequency Domain Multiplexing (OFDM) based communication system transmitting data information, wherein the method comprises receiving OFDM symbols comprising scattered pilots; obtaining channel estimates on every third bin of the scattered pilots in a frequency domain, wherein the channel estimates are obtained by performing an interpolation in a time domain across the received OFDM symbols; estimating an original channel based on the channel estimates, wherein the original channel in the time domain is estimated by applying a finite impulse response (FIR) low-pass filter in a frequency domain, wherein the FIR low-pass filter is adaptive according to a delay span of an original channel impulse response and is sufficiently wide to cover the delay span of the original channel impulse response; and dividing the received OFDM symbols by the channel estimate to obtain transmitted data information. | 11-19-2009 |
20090290496 | ROBUST DEFRAMING OF MAC LAYER PACKET FOR MEDIAFLO SYSTEMS - A technique for finding errors in the fragment headers of the fragments of service layer packets without depending on the erasure indicators of Medium Access Channel (MAC) layer packets of a wireless signal in a wireless communication system, wherein method comprises determining if length of the fragment header is between 121 and 127; determining if length of the fragment header is equal to 127, and if the fragment header is not the last fragment header in a service layer packet being formed; determining if summation of length of the fragment header for a value N is greater than 122 subtracted by number of fragments collected from a MAC layer packet including fragment header; and determining if fragment header is not the last fragment header in the service layer packet being formed, and if fragment header length is less than residual number of bytes in the MAC layer packet. | 11-26-2009 |
20090290663 | COARSE FREQUENCY OFFSET ESTIMATION FOR DIGITAL MULTIMEDIA BROADCASTING - A method of estimating a coarse frequency offset of Digital Multimedia Broadcasting (DMB) transmission frames includes receiving the DMB transmission frames including a synchronization channel having a phase reference symbol, circularly shifting the phase reference symbol by applying a circular shift to the phase reference symbol, numerically correlating the circularly shifted phase reference symbol with a known correct phase reference symbol to obtain a highest peak and a side peaks of the numeric correlation, and computing a phase reference symbol angle based on a multiplication of the peak and a carrier spacing of the DMB transmission frames. The peak is determined when the circularly shifted phase reference symbol is equal to the known correct phase reference symbol. The peak and side peaks corresponding to the peak are operated in a range of a maximum value of the circular shift. | 11-26-2009 |
20090323789 | Doppler Frequency Estimation in Wireless Communication Systems - An apparatus and method for estimating Doppler frequency in a wireless communication network, wherein the method comprises determining a first correlation coefficient (c | 12-31-2009 |
20090323790 | Doppler Frequency Estimation and Adaptation for MediaFLO Systems - A technique for Doppler frequency estimation and adaptation in a MediaFLO™ (Forward Link Only) receiver system includes receiving Orthogonal Frequency Division Multiplexing (OFDM) symbols in the receiver, dividing a Doppler frequency range into N ranges corresponding to N interpolation filters; determining a correlation between two OFDM symbols separated by time; estimating a Doppler frequency by the correlation of OFDM symbols; determining a ratio of the correlation of OFDM symbols; comparing the determined ratio of the correlation of OFDM symbols with a look up table of α stored at a receiver to determine a corresponding Doppler frequency; mapping α ranges stored at the look up table to suitable interpolation filters; estimating an interpolation filter from the mapped α ranges mapped against determined α ratio; adapting Time Domain Interpolation (TDI) to the selected interpolation filter; and synchronizing receiver to the TDI filter. | 12-31-2009 |
20090323871 | Application of Superfast Algorithms to a Pilot-Based Channel Estimation Process - An apparatus and method of applying a superfast algorithm to a pilot-based channel estimation process includes receiving a signal comprising information bits transmitted in a wireless channel, executing the pilot-based channel estimation process having p structures for a vector of pilot structures and an upper bound N for a channel spread, determining a result of a matrix inversion of a channel correlation matrix for an error channel estimation offline without performing a matrix inversion, storing pilot information of the received signal for channel recovery in a transform domain, representing the Toeplitz inverse by a FFT representation, detecting and estimating nonzero taps of a channel impulse response of the wireless channel, obtaining a non-structured minimum mean-square-error (MMSE) estimate as a first estimate of locations of the nonzero taps, and replacing the non-structured MMSE estimate by an estimate computed by a tap detection algorithm. | 12-31-2009 |