Abstract:
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 3 processing of each medium access control (MAC) time unit of a data channel to identify a transmitter identity (TxID) of each transmitter; identifying corresponding geographical coordinates of each TxID; regenerating the digital signals for each of the transmitters using a local-area differentiator (LID) and a wide-area differentiator (WID) of the transmitters; dividing the digital signals by the corresponding regenerated transmitted signal to obtain channel estimates between the receiver and the corresponding transmitters; detecting a first peak in the channel estimates to determine a distance between the receiver and the corresponding transmitters; calculating a time difference of arrival of the digital signals; and estimating a current location of the receiver.
Abstract:
A method of estimating coarse frequency offset of received symbols based on a received frequency domain sample at a kth sub-carrier of a 53rd Orthogonal Frequency Division Multiplexing (OFDM) data symbol in a jth time slot (TS) of a receiver in a China Multimedia Mobile Broadcasting (CMMB) mobile television network includes dividing a received sample, Ykj, into two sets of noise only tones and data plus noise tones Dkj, obtaining a received sample only if there is a coarse frequency offset mismatch between a transmitter and the receiver, dividing a summation of a power of the data plus noise tones by a summation of a power of the noise only tones to obtain Λkj, and estimating an integer coarse frequency offset estimate, Δ{circumflex over (f)}Ij, of the received symbols when the Λkj is a maximum.
Abstract:
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.
Abstract:
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 0, 1, and 2 data packet, and parity data bits; switching, by the transmitter, an order of the multimedia data streams of the MLC transmitted by the transmitter; sending a signal to the receiver from the transmitter to specify a mode of transmission of the MLC, wherein the mode of transmission comprises an order of transmitting the data packets of the MLC; inserting, by the transmitter, a flag in control information transmitted in the stream 0 data packets; decoding, by the receiver, the flag to determine the mode of transmission; and performing, by the receiver, a CRC of the stream 0 data packet.
Abstract:
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 2, stream 1, and stream 0; and an Application Specific Integrated Circuit (ASIC) memory component operatively connected to the receiver, wherein the ASIC memory component performs processing of the data packets using hardware components comprising, a Medium Access Control (MAC) layer core; a stream layer core; a decryption layer core; a defragmentation layer core; and a sync layer core.
Abstract:
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.
Abstract:
An apparatus and method for estimating Doppler frequency in a wireless communication network, wherein the method comprises determining a first correlation coefficient (c1) between a currently received Orthogonal Frequency Division Multiplexed (OFDM) symbol and an OFDM symbol received previous to the currently received OFDM symbol, and a second correlation coefficient (c2) between the currently received OFDM symbol and an OFDM symbol received immediately previous to the OFDM symbol received previous to the currently received OFDM symbol; performing a leaky integration across OFDM symbols of the resulting first and second correlation coefficients (c1, c2) to obtain an estimate of the first and second correlation coefficients; dividing the second correlation coefficient (c2) by the first correlation coefficient (c1) to obtain a correlation coefficient ratio; and using the correlation coefficient ratio as an estimate of the Doppler frequency in the wireless communication system.
Abstract:
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.
Abstract:
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.
Abstract:
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.