Patent ID: 8660433

Claim:
An optical transmitter, comprising: a digital signal processor configured to convert a first data stream into a first sequence of constellation symbols and to generate a data frame that comprises: a first plurality of pilot-symbol blocks, wherein each pilot-symbol block comprises a respective plurality of pilot symbols and a respective guard interval; and a first set of one or more payload-symbol blocks, wherein each payload-symbol block comprises a respective plurality of constellation symbols from the first sequence; and an optical modulator configured to modulate an optical carrier to generate a modulated optical signal for transmission of the data frame over an optical communication link, wherein: at least one payload-symbol block and another block are concatenated without a guard interval between them; the other block is either a pilot-symbol block or a payload-symbol block; and the first plurality of pilot-symbol blocks comprises: a first channel-estimation block having a first polyphase sequence of symbols; and a second channel-estimation block having a second polyphase sequence of symbols different from the first polyphase sequence of symbols.