Communication device, communication method, computer program and adaptive equalizer

A communication method for receiving a packet including a preamble part having a continuous waveform, a sync part having a specific pattern and a data part, which have been modulated by changing electrical load, the method comprising:

• detecting the preamble part from a received signal and extracting sampling timing based on the continuous waveform;
• detecting the sync part from the received signal based on the sampling timing and outputting a timing signal indicating a start position of the sync part;
• giving and holding a delay with respect to the received signal so that the head of the sync part is not outputted until the detection of the sync part is determined in the step of detecting the sync;
• performing adaptive equalization using the sync part based on the timing signal by inputting the received signal delayed by the delay holding step;
• and
• performing decoding processing of an equalized output signal obtained by the adaptive equalization step.

A computer program product stored on a computer-readable medium that when executed by a processor performs steps for receiving a packet including a preamble part having a continuous waveform, a sync part having a specific pattern and a data part, which have been modulated by changing electrical load, allowing the computer to function as

• a preamble detection unit configured to detect the preamble part from a received signal to extract sampling timing based on the continuous waveform;
• a sync detection unit configured to detect the sync part from the received signal based on the sampling timing to output a timing signal indicating a start position of the sync part;
• a delay buffer configured to give delay to the received signal so that the head of the sync part is not outputted until the sync detection unit determines the detection of the sync part;
• an adaptive equalization unit configured to perform adaptive equalization using the sync part based on the timing signal by inputting the received signal delayed by the delay buffer;
• and
• a decoding unit configured to perform decoding processing of an equalized output signal from the adaptive equalization unit.

An adaptive equalizer for performing equalization processing of a transmission signal modulated by changing electrical load, comprising:

• a delay line in which plural delay elements having delay time corresponding to a sampling period respectively are connected in series;
• first multipliers for performing multiplication of first type of tap coefficients corresponding to a first change direction of electrical load and second multipliers for performing multiplication of second type of tap coefficients corresponding to a second change direction of electrical load respectively with respect to the transmission signal inputted to the delay line as well as time-series input data including output signals from respective delay elements of the delay line;
• selectors for selecting any one of outputs from the first multipliers and the second multipliers by each input data according to the change direction (namely, positive/negative sign of input data) of electrical load,
• an accumulator for adding and averaging weighted time-series input data selected by the selectors to output an equalized signal;
• and
• the learning circuit adjusting tap coefficients selected by the selectors so that the difference between the received signal and the reference signal is reduced.

An adaptive equalizer for performing equalization processing of a transmission signal modulated by changing an electrical load, the adaptive equalizer comprising:

• a feedforward delay line in which plural delay elements having a delay time corresponding to a sampling period respectively to which the transmission signal is inputted are connected in series;
• a feedback delay line in which plural delay elements having a delay time corresponding to a sampling period respectively to which a reference signal for learning is inputted;
• first multipliers for performing multiplication of first type of tap coefficients corresponding to a first change direction of electrical load and second multipliers for performing multiplication of second type of tap coefficients corresponding to a second change direction of electrical load respectively with respect to time-series input data including the transmission signal and output signals of respective delay elements in the feedforward delay line as well as time-series feedback data having output signals of respective delay elements in the feedback delay line;
• selectors for selecting any one of outputs from the first multipliers and the second multipliers by each input data and feedback data according to the change direction, namely, positive/negative sign of input data or feedback data, of an electrical load;
• and
• the learning circuit adjusting tap coefficients selected by the selectors so that the difference between the received signal and the reference signal is reduced.