Abstract: For transmission, a modulation method with a high bit rate is applied to subchannels with good transmission path characteristics, and a modulation method with a low bit rate is applied to subchannels with poor transmission path characteristics. In doing this, transmission path characteristic detection units 19 and 29 detect information on transmission path characteristics from received signals, and maximum bit-rate calculation units 20 and 30 use a minimization algorithm of a matroid convex function in order to determine a combination of values of transmission power for each of the subchannels that results in the maximum bit rate of the entire band. A combination of the determined transmission power and the modulation method (bit rate) is used for transmitting signals.

Abstract: A transmitter which transmits transmission symbols using a multicarrier system is used. The transmitter has a part configured to adjusted a phase rotation amount for each of N data symbols; a part configured to carry out inverse Fourier transform on the data symbols having undergone the phase adjustment and generating the transmission symbols; and a phase calculating part configured to determine the phase rotation amount with the use of a complex neural network. The phase calculating part has N neurons which derive, from N complex input signals to which a temporarily determined phase rotation has been carried out, one complex output signal after inverse Fourier transform, and use the complex output signal as the complex input signal for a next time; and a state updating part configured to update the phase rotation amount according to a value of an objective function calculated from the complex output signal.

Abstract: An electronic switching system having a call-forwarding function for effecting call forwarding between subscribers. Discrimination information is added to call forwarding data for respective subscriber terminals. The discrimination information indicates whether or not each of the subscriber terminals is already registered as an elternative destination from the other subscriber terminals. When a call forward to one of the subscriber terminals is to be registered, the corresponding discrimination information is read. When the read discrimination information indicates that the subscriber terminal is not yet registered as an alternative destination, the subscriber terminal is allowed to be registered as an alternative destination. When the read discrimination information indicates that the subscriber terminal is already registered as an alternative destination, the subscriber terminal is inhibited from being registered as an alternative destination.