The spread spectrum communication system for making communication by spreading an energy of a signal to a band width which is fairly wider than that of information has been known. According to the spread spectrum communication system, a spectrum of the signal is spread by using a spreading code. A pseudo-noise sequence (PN sequence) is used as a spreading code. There is an M sequence (Maximum-length linear shift-register sequence) as an example of the spreading code. A gold code obtained by arithmetically operating outputs of the two M sequences by the exclusive OR is used.
The CDMA system is a multiple accessing system using a function which can identify the user by the spreading code among the spread spectrum communication systems. Although the PN sequence such as an M sequence or the like has ordinarily been used as a spreading code hitherto, the CDMA using chaos spreading codes has been proposed. A technique of digitally forming the chaos spreading code has been disclosed in JP-A-2003-140885.
A point of realizing the communication of the spread spectrum communication system such as a CDMA by using the chaos spreading code has been disclosed in JP-B-3234202.
The chaos CDMA disclosed in the above Patent Document is a system which uses the chaos spreading code in place of the existing PN sequence such as an M sequence or the like and allocates one spreading code to one user. Therefore, it is considered to use orthogonal modulation in order to effectively use a channel. According to the conventional construction, however, there is such a problem that a modulator or a demodulator is necessary for orthogonal modulation and demodulation besides a spreading unit or an inverse spreading unit.
It is, therefore, an object of the invention to provide a communicating apparatus and a communicating method in which an increase in scale of hardware is suppressed and a communication channel can be effectively used.