Abstract: In comb-form spectrum communication systems using repeated complementary sequence modulation, a transmitting signal is constituted by assigning one set of N auto-complementary sequences to each user, where N is an integer equal to or higher than 2, and by transforming the N sequences to N repeated signals which have comb-form spectra without overlapping in frequency with one another with a method of repeating each sequence of the set of auto-complementary sequences a plurality of times, and by assigning the N complementary sequences with auto-complementary sequence characteristics to the N comb-form spectra. Thus, the near-far problem is solved by making the cross-correlation between a signal input to a user's station but addressed to another station and the user's reference code sequence, zero.

Abstract: A CDMA communications system using multiple spreading sequences is characterized in that, by providing means of that a sequence-set consisting of M kinds of basic spreading sequences, each sequence having code length L, is prepared, an information-set consisting of &ggr; components, not including the value 0 is made of a modulated sequence-set which are made by multiplying the said respective basic spreading sequences by an original information-set consisting of M components including (M−&ggr;) pieces of the value 0, resulting in production of a selected sequence-set consisting of &ggr; selected spreading sequences, means of that a modulated synthesized sequence sD is produced by adding up all of the said selected spreading sequences, that a repeated core spreading sequence group sDN is produced of the said respective selected sequences, that an enveloped sequence eD is produced as an baseband transmit-data-frame by arranging the rear and the front parts of the said repeated core spreading sequence as t

Abstract: A system using a transmitter which comprises means of generating 4 extended sequences EA0, EA1, EB0 and EB1 using a set (A0,A1) of auto-complementary sequences with length L chips consisting of complete complementary sequences and another similar set (B0,B1), and means of generating a transmitting frame sP obtained by multiplying a cascaded sequence ÊA made of extended sequences EA0 and EA1 by a pilot information {circumflex over (p)}, generating a transmitting frame sD obtained by multiplying a cascaded sequence ÊB made of extended sequences EB0 and EB1 by data b, synchronously adding both the transmitting frames to produce a symbol frame, and transmitting a carrier wave modulated thereby, and a receiver which comprises means of applying a front portion r0 of the synchronously received baseband frame demodulated by above described carrier wave to matched filters M(A0) and M(B0), and applying a rear portion r1 of the synchronously received frame to matched filters M(A1) and M(B1), and means of gen

Abstract: When communications are performed between a transmitter 2 and a receiver 3 via a transmission path 4, the transmitter prepares a basic sequence consisting of two-phase or four-phase tips, and transmits an expanded transmission frame which is constructed by repeatedly arranging one or a plurality of the basic sequence so as to obtain a finite length periodic sequence with a comb-form spectrum and by adding the replica of one or a plurality of tips of a back portion and front portion of the finite length periodic sequence to the outside of the front portion and the outside of the back portion of the finite length periodic sequence; and the receiver demodulates the expanded transmission frame using a matched filter which is matched with the finite length periodic sequence which is the central part of the expanded transmission frame, that is not including the added tips. In other words, the present invention can simplify the construction of communication equipment by using two-phase signals or four-phase signals.

Abstract: A signal receiving system for spread spectrum communication including receiving a signal produced by multiplying a data to be transmitted by a predetermined spread code sequence through spread spectrum modulation and performing spread spectrum demodulation by multiplying the received signal by an attenuation spread code sequence prepared by predetermined attenuation or amplification to each chip of the spread code sequence used on that modulation.