BURST CARRIER FREQUENCY SYNCHRONIZATION AND ITERATIVE FREQUENCY-DOMAIN FRAME SYNCHRONIZATION FOR OFDM

摘要

Transmission of a sequence of data samples includes transmission of a sandwich preamble ("sandamble") that has a first preamble that precedes the sequence of data samples, and a second preamble that follows the sequence of data samples. The sandamble may include several guard regions, including an extended guard region. Various repetitions of data in the sandamble make it useful for aiding time and frequency synchronization of the received signal when it has been subjected to a dispersive channel. In another aspect, a coarse estimate of a frame start position of a received sequence of desired data samples in a received signal sequence may be improved by using the coarse estimate to generate frequency-domain received samples. A frequency-domain correlation is then determined between the frequency-domain received samples and noiseless samples. The improved estimate of the starting position of the sequence of desired samples in the received signal sequence may then be generated based on an argument of the frequency-domain correlation between the frequency-domain received samples and the noiseless samples. The noiseless samples may be generated by demodulating symbols contained in the received signal sequence. In alternative embodiments, the noiseless samples may be generated from pilot symbols that have been multiplexed into the sequence of received samples.