Abstract: A spectrum spread communication method includes a step of generating a data block formed by a plurality of M bits of transmission data in the CDMA communication method, a step of modulating an orthogonal sinusoidal wave by the repeated series of the data block to generate a spread symbol, a step of transmitting the symbol, a step of performing reverse spread of the reception input by using the orthogonal sinusoidal wave, thereby completely isolating the multi-user component including the multi rate.

Abstract: A de-correlating discriminating system of code division multiple access signals including a system structure composed of a plurality of cells, each of the plurality of cells including a base-station and a plurality of user-stations, each of the user-stations including a user-transmitter and a user-receiver, communicating through a multi-access channel with the base station which includes a base-station receiver and a base-station transmitter, and the user-transmitter is capable of transmitting a data symbol to convey a data with a spreading sequence and a pilot symbol that is the spreading sequence to identify a channel from the user transmitter to the base-station receiver and the base-station receiver includes a minimum means square error detector to analyze an input vector that is a received signal containing both multiple users specific data responses.

Abstract: here is provided a new multi-user receiver configuration technique which solves the problems of the user signal separation function of the multi-user receiver such as the interference canceller, decorrelator, and least square error detection. That is, there is provided a code-division multiplex signal decorrelation/identification method for realizing much more excellent performance than the aforementioned methods in the aspect of the power band amplitude product required for one-bit transfer as the evaluation reference of the CDMA method. A function for successively judging the best user is added to the conventional least square error detector MMSE-D shown by a dotted line in the block diagram of the successive detection type least square error detection method (SD-MMSE).

Abstract: This invention provides techniques for a CDMA system having high spectrum efficiency with low transmit power. Each transmitter comprises means of selecting some core-sequences out of multiple sequences to make them convey plural data, means of producing an enveloped selected sequence with such a method as to arrange as guard sequences to a repeated sequence made by repeating each of the selected core-sequences, means of modulating a user specific orthogonal carrier frequency by the enveloped selected sequence to produce a transmit-symbol, and means of transmitting the transmit-symbols. And a receiver comprises means of demodulating a receive-symbol with one of the user specific carrier frequencies to produce a base-band receive-symbol, means of separating respective components corresponding to the sequences selected by the user, by analyzing the base-band receive-symbol with a matrix composed of a channel response vector from the user to the receiver to detect plural data on the components.

Abstract: A direct sequence spread spectrum system consisting of modulator and demodulator wherein the spreading sequence with zero correlation zone properties, and the despreading consists of multiplying the received signal with the same spreading sequence, followed by a low pass filter, decoder and deinterleaver. The bit rate of the spreading sequence for each user is normally much higher than the input encoded data bit rate, and therefore it spreads the system spectrum.

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.