| 摘要 |
A receiver for detecting and recovering payload data from a received signal comprises a radio frequency demodulation circuit configured to detect the received signal. The received signal has been formed and transmitted by a transmitter to carry the payload data as Orthogonal Frequency Division Multiplexed (OFDM) symbols in one or more of a plurality of time divided frames, each frame including a preamble including a plurality of bootstrap OFDM symbols. One or more of the bootstrap OFDM symbols of the preamble carrying signalling data represented as a relative cyclic shift of a signature sequence which has been combined with the one or more of the bootstrap OFDM symbols. A bootstrap processor is configured to detect the signalling data from the bootstrap OFDM symbols using an estimate of the channel transfer function determined from one or more of the bootstrap OFDM symbols, and a demodulator circuit is configured to recover the payload data from the payload OFDM symbols using the signalling data. The bootstrap processor comprises a channel shaper, which is configured to convolve a time domain copy of the signature sequence with the estimate of the channel impulse response to generate a channel shaped signature sequence, a cross-correlator and a cyclic shift detector. A cross-correlator is configured to cross-correlate the useful part of each of the one or more bootstrap OFDM symbols with the channel shaped copy of the signature sequence, and the cyclic shift detector is configured to estimate the signalling data conveyed by each of the one or more bootstrap OFDM symbols by detecting a cyclic shift of the signature sequence present in each of the one or more bootstrap OFDM symbols from a peak of the samples representing a result of the cross-correlation. Accordingly the signalling data can be detected by identifying the cyclic shift of the signature sequence by cross-correlating the signature sequence with the bootstrap OFDM symbols carrying the signature sequence in the time domain, which can provide a more efficient implementation. |
