SAMPLING CLOCK ALIGNMENT AND TIME OFFSET SIGNALING FOR SYMBOL-ALIGNED FRAMES

摘要

Systems and methods for sampling clock alignment and time offset signaling are disclosed herein. A transmitter broadcasting symbol-aligned frames at multiple baseband sampling rates can benefit from generating the frames to have durations that can be represented by an integer number of samples at two or more of the baseband sampling rates. In some embodiments, a transmitter adds samples to a frame to ensure that its duration meets such a criteria. Furthermore, the problem of signaling network time in symbol-aligned frames is simplified by sampling clock alignment. Approaches for signaling time offset of a transmission to the nearest millisecond boundary are also presented.

主权项

1. A method, comprising:
generating a first data frame with a first baseband sampling rate; generating a second data frame with a second baseband sampling rate; and wirelessly broadcasting the first data frame and the second data frame, wherein generating the first data frame comprises generating a set of orthogonal frequency division multiplexing (OFDM) symbols, the set of OFDM symbols comprising at least a first OFDM symbol and a last OFDM symbol,
wherein each OFDM symbol of the set of OFDM symbols comprises a useful portion and a cyclic prefix,wherein generating said each OFDM symbol comprises:
converting a block of frequency-domain data to time-domain samples using an inverse fast Fourier transform having a transform size to form the useful portion; andforming the cyclic prefix by prepending to said each OFDM symbol a copy of a plurality of time-domain samples from the end of the useful portion of the OFDM symbol,wherein the last OFDM symbol of the set of OFDM symbols comprises a cyclic postfix,wherein generating the last OFDM symbol further comprises forming the cyclic postfix by appending to the last OFDM symbol a copy of at least one time-domain sample from the beginning of the useful portion of the OFDM symbol, andwherein the size of the cyclic postfix is chosen based at least in part upon the first baseband sampling rate and the second baseband sampling rate.