Client signal mapping circuit and mapping method

A mapping method for accommodating a client in a transmission frame, comprising:

• a buffer used amount monitoring step in which a buffer used amount monitoring unit reports a used amount of a buffer configured to temporarily store the client signal;
• a stuff processing determination step in which a stuff processing determination unit determines necessity of insertion of a stuff byte into a transmission frame and a stuff processing amount based on the used amount of the buffer;
• an overhead insertion step in which an overhead insertion unit adds an overhead to the client signal read from the buffer to form a transmission frame;
• and
• a reading control step in which a reading control unit performs control for reading the client signal from the buffer based on determination by the stuff processing determination step,
• the stuff processing determination step comprising:
• comparing the buffer used amount reported from the buffer used amount monitoring unit with a predetermined reference value, and
• adding a pseudo random sequence signal and the comparison result.

A client signal mapping circuit for accommodating a client signal in a transmission frame signal, comprising:

• an asynchronous buffer unit configured to temporarily store the client signal;
• a frequency information generation unit configured to generate frequency information from a clock of the client signal and a clock of a transmission frame signal;
• a random signal superimposing unit configured to superimpose a random signal sequence on the frequency information generated by the frequency information generation unit;
• a reading control unit configured to control reading of the client signal from the asynchronous buffer unit based on the clock of the client signal and the frequency information;
• and
• an overhead insertion unit configured to insert an overhead of a transmission frame signal into a data sequence read from the asynchronous buffer unit.

A client signal demapping circuit for restoring a client signal from a transmission frame signal, comprising:

• an overhead extraction unit configured to extract frequency information from the transmission frame signal;
• a writing control unit configured to perform writing control for the transmission frame based on the extracted frequency information and the clock of the transmission frame;
• a random signal superimposing unit configured to superimpose a random signal sequence on the extracted frequency information;
• a clock recovery unit configured to recover a clock of the client signal based on frequency information on which the random signal sequence is superimposed;
• and
• an asynchronous buffer unit configured to temporarily store the transmission frame based on a control signal from the writing control unit, and read data based on the clock recovered by the clock recovery unit.

A client signal mapping method for accommodating a client signal in a transmission frame signal, comprising:

• a frequency information generation step in which a frequency information generation unit generates frequency information from a clock of the client signal obtained from an asynchronous buffer unit configured to temporarily store the client signal, and a clock of the transmission frame signal;
• a random signal superimposing step in which a random signal superimposing unit superimposes a random signal sequence on the frequency information generated in the frequency information generation step;
• a reading control step in which a reading control unit controls reading of the client signal from the asynchronous buffer unit based on the clock of the client signal and the frequency information;
• and
• an overhead insertion step in which an overhead insertion unit inserts an overhead of a transmission frame signal into a data sequence read from the asynchronous buffer unit.

A client signal demapping method for restoring a client signal from a transmission frame signal, comprising:

• an overhead extraction step in which an overhead extraction unit extracts frequency information from the transmission frame signal;
• a writing control step in which a writing control unit performs writing control for the transmission frame based on the extracted frequency information and the clock of the transmission frame;
• a random signal superimposing step in which a random signal superimposing unit superimposes a random signal sequence on the extracted frequency information;
• a clock recovery step in which a clock recovery unit recover a clock of the client signal based on frequency information on which the random signal sequence is superimposed;
• and
• an asynchronous buffering step of temporarily storing the transmission frame based on a control signal in the writing control step, and reading data based on the clock recovered by the clock recovery step.