Adaptive optical transponder

A method of controlling an Optical domain Adaptive Dispersion Compensation Module (OADCM), the method comprising:

• i) measuring signal distortion of an incoming signal in the electrical domain;
• ii) processing the signal-distortion measurements to produce at least one OADCM control value;
• and
• iii) applying the OADCM control value to the OADCM.

A method of translating channel states into a Channel Value (CV) at a time t and state i assuming that a channel has a memory length L:

• i) estimating tap weight-vectors h1 and h2;
• ii) calculating a CV value according to the equation:
• CV
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• where, ai(k,t)=000 . . . 0 when i=0 at time t;
• ai(k,t)=000 . . . 1 when i=1 at time t;
• ...............................
• ai(k,t)=111 . . . 1 when i=2L−1 at time t;
• iii) determining a mean square error estimate using the CV value;
• and
• iv) determining operation of a controller in the Initialization or Adaptive Control Mode based on the mean square error estimate.

A method of Blind Channel Initialization, the method comprising:

• i) calculating tap-weight vectors h1 and h2, each having respective elements;
• ii) operating an Electrical domain Adaptive Dispersion Compensation Module until it reaches a static status;
• iii) Computing a first mean square error value;
• iv) shifting elements of the tap-weight vector h2 by one element and repeating step iii) to obtain a second mean square error value;
• v) repeating step iv) until a first non-zero element reaches an end of tap-weight vector h2, thus obtaining a first set of mean square error values;
• vi) shifting the elements of the tap-weight vector h1 by one element and repeating steps iii) to v) to obtain a second set of mean square error values;
• vii) halving the original values of the two left-most non-zero elements in both h1 and h2 and repeating steps iii) to vi) to obtain a third set of mean square error values;
• viii) doubling the original values of the two left-most non-zero elements in both h1 and h2 and repeating steps iii) to vi) to obtain a fourth set of means square error values;
• and
• ix) Selecting a smallest mean square error value of the combined first means square error value, second mean square error value, and the first, second, third and fourth sets of mean square errors values corresponding to values that are best initial values of tap-weight vectors h1 and h2.