| 摘要 |
A transmitter for transmitting payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols, the transmitter comprising a frame builder configured to receive the payload data to be transmitted and to receive signalling data for use in detecting and recovering the payload data at a receiver, and to form the payload data with the signalling data into frames for transmission. The transmitter also comprising a modulator configured to modulate a first OFDM symbol with the signalling data and to modulate one or more second OFDM symbols with the payload data, a signature sequence processor circuit for providing a signature sequence, a combiner circuit for superimposing the signature sequence over the first OFDM symbol, a prefixing circuit for prefixing a guard interval to the first OFDM symbol to form a preamble, and a transmission circuit for transmitting the preamble and the one or more second OFDM symbols. The combiner is configured to combine the signature sequence with the first OFDM symbol, and the guard interval is formed from time domain samples of a part of the signature sequence. By arranging for the guard interval of the OFDM symbol carrying the signalling data to include samples formed only from the part of the signature sequence, there is any increased likelihood of a receiver detecting the signature sequence. To increase robustness against multipath, a postfix might be added on top of the prefix proposed. |
