CDMA communication method and group spreading modulator

Claim 2

The CDMA communication method as claimed in claim 1, wherein said step of selecting characterized by comprising the sub-steps of: dividing peaks of transmission rates of the transmitted data into a plurality of ranks; choosing, when transmitting data at a lowest peak rate, one of row vectors in a maximum dimensional 2 N ×2 N matrix, where N is an integer greater than one, said row vectors having a period of 2 N chip interval; and selecting, when transmitting data at a peak rate of 2 Q times the lowest peak rate, one of row vectors in an 2 N-Q ×2 N-Q matrix, where Q is an integer equal to or less than N, said row vectors having a period of 2 N-Q chip interval.

Claim 3

The CDMA communication method as claimed in claim 2, characterized in that the sub-step of selecting carries out selecting, when selecting a row vector in a 2 k ×2 k matrix as the spreading sequence, where k is an integer smaller than N, such that a row vector is not selected if the row vector or its inverted vector is included as a sub-vector in any one of row vectors in a 2 j ×2 j matrix, where j is an integer greater than k, and if said 2 j ×2 j matrix includes at least one row vector which has already been assigned as the spreading sequence.

Claim 4

The CDMA communication method as claimed in claim 1, characterized in that said step of selecting selects, when the peak data transmission rate is 2 Q times the lowest peak rate, one of 2 Q row vectors in a maximum dimensional 2 N ×2 N matrix as the spreading sequence, said 2 Q row vectors being generated from one of row vectors in the 2 N-Q ×2 N-Q matrix.

Claim 5

The CDMA communication method as claimed in claim 2 or 4, further characterized by comprising the step of generating vacancies in a transmission time in accordance with the transmission rate if the data transmission rate falls below 2 Q times the lowest peak rate during communications.

Claim 6

The CDMA communication method as claimed in claim 2 or 4, further characterized by comprising the step of reassigning the newly selected spreading sequence if the data transmission rate falls in a range from 2 P-1 to 2 P times the lowest peak rate during communications, where P is an integer equal to or less than Q.

Claim 7

The CDMA communication method as claimed in claim 2 or 4, further characterized by comprising the step of generating vacancies in a transmission time in accordance with the transmission rate if the data transmission rate is in a range from 2 P-1 to 2 P times the lowest peak rate, where P is an integer equal to or less than Q.

Claim 8

A CDMA communication method which obtains narrowband modulated signals by modulating transmitted data, performs spreading modulation of the narrowband modulated signals into a wideband signal using spreading sequences, and transmits the wideband signal, said CDMA communication method characterized by comprising the steps of: successively generating increasing dimensional 2 N-R ×2 N-R matrices, where N and R are an integer greater than zero, from a smaller dimensional matrix under a predetermined rule, each of said matrices including row vectors orthogonal to each other; selecting one of said row vectors of one of said matrices as a common first spreading sequence, or selecting as the common first spreading sequence one of a set of orthogonal sequences generated using another generating method; successively generating increasing dimensional 2 R ×2 R matrices from a smaller dimensional matrix under a predetermined rule, each of said matrices including row vectors orthogonal to each other; selecting each row vector in one of said 2 R ×2 R matrices as a second spreading sequence whose rate is 1/2 N-R of that of said common first spreading sequence; and carrying out spreading modulation by multiplying narrowband modulated signals by said common first spreading sequence and each said second spreading sequence.

Claim 9

The CDMA communication method as claimed in claim 8, wherein said step of selecting said second spreading sequence characterized by comprising the sub-steps of: dividing peaks of transmission rates of the transmitted data into a plurality of ranks; choosing, when transmitting data at a lowest peak rate, one of row vectors in a maximum dimensional 2 R ×2 R matrix, where R is an integer greater than one, said row vectors; and selecting, when transmitting data at a peak rate of 2 Q times the lowest peak rate, one of row vectors in an 2 R-Q ×2 R-Q matrix as the second spreading sequence, where Q is an integer equal to or less than R.

Claim 10

The CDMA communication method as claimed in claim 9, characterized in that the sub-step of selecting the second spreading sequence carries out selecting, when selecting a row vector in a 2 k ×2 k matrix as the spreading sequence, where k is an integer smaller than R, such that a row vector is not selected if the row vector or its inverted vector is included as a sub-vector in any one of row vectors in a 2 j ×2 j matrix, where j is an integer greater than k, and if said 2 j ×2 j matrix includes at least one row vector which has already been assigned as the second spreading sequence.

Claim 11

The CDMA communication method as claimed in claim 8, characterized in that said step of selecting the second spreading sequence selects, when the peak data transmission rate is 2 Q times the lowest peak rate, where Q is an integer equal to or less than R, one of 2 Q row vectors in a maximum dimensional 2 R ×2 R matrix as the spreading sequence, said 2 Q row vectors being generated from one of row vectors in the 2 R-Q ×2 R-Q matrix.

Claim 12

The CDMA communication method as claimed in claim 9 or 11, further characterized by comprising the step of generating vacancies in a transmission time in accordance with the transmission rate if the data transmission rate falls below 2 Q times the lowest peak rate during communications.

Claim 13

The CDMA communication method as claimed in claim 9 or 11, further characterized by comprising the step of reassigning the newly selected second spreading sequence if the data transmission rate falls in a range from 2 P-1 to 2 P times the lowest peak rate during communications, where P is an integer equal to or less than Q.

Claim 14

The CDMA communication method as claimed in claim 9 or 11, further characterized by comprising the step of generating vacancies in a transmission time in accordance with the transmission rate if the data transmission rate is in a range from 2 P-1 to 2 P times the lowest peak rate, where P is an integer equal to or less than Q.

Claim 15

The CDMA communication method as claimed in any one of claims 1-14, characterized in that a spread signal is further multiplied by a spreading sequence with a period longer than that of the spreading sequence used for generating said spread signal.

Claim 16

The CDMA communication method as claimed in claim 4 or 11, further characterized by comprising at a receiving end the steps of: receiving the transmitted signal which has been spread using the selected spreading sequence; despreading the received transmitted signal; and deciding the transmitted data from the despread signal for every 2 N-Q chip interval or 2 R-Q chip interval.

Claim 17

A transmitter characterized by comprising a modulator for generating a spread transmitted signal using the CDMA method as claimed in any one of claims 1-15.

Claim 18

A receiver characterized by comprising a despreader and demodulator for recovering the transmitted data using the CDMA communication method as claimed in claim 16.

Claim 19

A group spreading modulator for spreading a plurality of narrowband signals into a wideband signal, said group spreading modulator characterized by comprising: multiple basic modulator elements arranged in an N-layer hierarchical structure, where N is an integer greater than one, each of said basic modulators having three inputs and a single output, two inputs of the three inputs being supplied with modulation signals, and a remaining input being supplied with a periodic signal for spreading which is multiplied by one of the two modulation signals, wherein a number of said basic modulator elements being halved as the layer rises by one step in the N-layer hierarchical structure such that 2 (N-1) said basic modulator elements are placed at a primary layer, 2 (N-2) said basic modulator elements are placed at a secondary layer, 2 (N-3) said basic modulator elements are places at a third layer, and wherein outputs of the basic modulator elements at a layer are input to the basic modulator elements at an immediately upper layer as the modulation signals, and the periodic signals for spreading are used which halve their periods as the layer rises by one step, so that the topmost basic modulator element outputs a signal that is a sum total of 2 N spread modulation signals.

Claim 20

The group spreading modulator as claimed in claim 19, characterized in that said basic modulator elements at a higher layer include an input terminal for directly accepting the narrowband modulated signals.

Claim 21

The group spreading modulator as claimed in claim 19 or 20, wherein said basic modulator elements are arranged in a plurality of R-layer hierarchical structures instead of the N-layer hierarchical structure, where R is an integer less than N, and wherein said group spreading modulator characterized by comprising: 2 (N-R) group modulator units, each of which includes a multiplier for multiplying an output of a topmost basic modulator element of each of the R-layer hierarchical structures by an orthogonal code sequence with a period of 2 (N-R) chip interval; and an adder for summing up outputs of said 2 (N-R) group modulator units.