Communication device and communication method
A communication device includes a zero-forcing equalizer that receives a receipt signal and execute zero-forcing equalization on the receipt signal, a partial response equalizer that receives the receipt signal and execute partial response equalization on the receipt signal, a first weighted value calculator that calculates a first weighted value based on signal quality of the receipt signal output from the zero-forcing equalizer, a second weighted value calculator that calculates a second weighted value based on signal quality of the receipt signal output from the partial response equalizer, and an estimator that estimates a maximum likelihood sequence by supplying the first weighted value to state transition based on output by the zero-forcing equalizer and supplying the second weighted value to state transition based on output by the partial response equalizer.
1. A communication device comprising:
circuitry configured to:
receive a receipt signal and execute zero-forcing equalization on the receipt signal;
receive the receipt signal and execute partial response equalization on the receipt signal;
calculate a first weighted value based on signal quality of the receipt signal on which the zero-forcing equalization has been executed:
calculate a second weighted value based on signal quality of the receipt signal on which the partial response equalization has been executed; and
estimate a maximum likelihood sequence by supplying the first weighted value to state transition based on output from the zero-forcing equalization and supplying the second weighted value to state transition based on output from the partial response equalization.
2. The communication device according to claim 1 , wherein
the zero-forcing equalization includes a procedure to be processed by a zero-forcing equalization slicer,
the partial response equalization includes a procedure to be processed by a partial response equalization slicer, and
the calculating a first weighted value includes calculating the first weighted value based on a signal-to-noise ratio of the zero-forcing equalization slicer, and the calculating a second weighted value includes calculating the second weighted value based on a signal-to-noise ratio of the partial response equalization slicer.
3. The communication device according to claim 2 , wherein
the first weighted value
has a positive correlation with the signal-to-noise ratio of the zero-forcing equalization slicer, and
has a negative correlation with a sum of the signal-to-noise ratio of the zero-forcing equalization slicer and the signal-to-noise ratio of the partial response equalization slicer, and
the second weighted value has a positive correlation with the signal-to-noise ratio of the partial response equalization slicer, and
has a negative correlation with a sum of the signal-to-noise ratio of the zero-forcing equalization slicer and the signal-to-noise ratio of the partial response equalization slicer.
4. The communication device according to claim 1 , wherein
the receipt signal is a signal on which pulse amplitude modulation 4 (PAM-4) mapping has been executed, and the partial response equalization slicer outputs the receipt signal as a symbol having seven levels.
5. The communication device according to claim 1 , wherein
the zero-forcing equalization includes a procedure to be processed by a decision feedback equalizer.
6. The communication device according to claim 1 , wherein
the partial response equalization includes a procedure to be processed by a decision feedback equalizer.
7. A communication method including:
executing zero-forcing equalization on a receipt signal;
executing partial response equalization on the receipt signal;
calculating a first weighted value based on signal quality of the receipt signal on which zero-forcing equalization has been executed;
calculating a second weighted value based on signal quality of the receipt signal on which partial response equalization has been executed; and
estimating a maximum likelihood sequence by supplying the first weighted value to state transition based on output from the zero-forcing equalization and supplying the second weighted value to state transition based on output from the partial response equalization.