GB2338157A

GB2338157A - Spread spectrum signal generating device utilising a selected one of a plurality of different spreading techniques.

Info

Publication number: GB2338157A
Application number: GB9907745A
Authority: GB
Inventors: Jong-Hyeon Park; Je-Woo Kim
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1998-04-04
Filing date: 1999-04-06
Publication date: 1999-12-08
Anticipated expiration: 2019-04-06
Also published as: JP3150956B2; JPH11331033A; GB9907745D0; CN1233891A; GB2338157B; KR100260445B1; KR19990079400A

Abstract

A device for generating a spread spectrum signal according to various spreading techniques, securing compatibility with an existing spreading technique. The spread spectrum signal generating device first to third spreading parts supporting first to third spreading techniques, respectively. The first spreading part multiplies a coded data signal by an I-arm PN code and a Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal. The second spreading part inverts one of the I-arm PN code and the Q-arm PN code, multiplies the coded data signal by the Q-arm PN code or the inverted Q-arm PN code to generate a second I-arm spread signal and multiplies the code data signal by the I-arm PN code or the inverted I-arm PN code to generate a second Q-arm spread signal. The third spreading part multiplies the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal. A selecting part selects one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a spreading technique determination signal.

Description

2338157 SPREAD SPECTRUM SIGNAL GENERATING DEVICE FOR A SPREAD SPECTRUM

COMMUNICATION SYSTEM The present invention relates to a spread spectrum communication system, and in particular, to a device for generating spread spectrum signals by spreading data signals to be transmitted.

A spread spectrum communication system performs communication using, a signal having a transmission bandwidth wider than a bandwidth of a data signal to be transmitted. Spread spectrum communication systems can be classified as a direct sequence (DS) system, a frequency hopping (FH) system and a time hopping (TH) system. Among these various systems, the direct sequence and the frequency hopping system are more popular than others and can be widely applied to a TRS (Trunked Radio System), a CDMA (Code Division Multiple Access) digital cellular system, a PCS (Personal Communications System) and a satellite communication system.

Figure 1 illustrates a transmitter of a DS/CDMA communication system, which spreads a data signal according to the direct sequence system and transmits the spread signal. Referring to figure 1, data signals di(t) dN(t) to be transmitted are multiplied in multipliers ill 113 by orthogonal codes wl(t)-wN(t) generated from orthogonal code generators 101-103, respectively.

Spreaders (or quadrature spreaders) 141-143 spread the 1 - multiplied signals cl(t)-CN(t) using an I-arm PN (Pseudo Noise) code pI(t) and a Q-arm PN code pQ(t) generated respectively from an I-PN code generator 120 and a Q-PN code generator 130, to generate I-arm spread signals slI(t)sNI(t) and Q-arm spread signals siQ(t)-sNQ(t). A summer 151 sums the I-arm spread signals slI(t)-sNI(t) to generate an I-arm summation signal xI(t), and a summer 152 sums the Q-arm spread signals siQ(t)- sNQ(t) to generate a Q-arm summation signal xQ(t). A mixer 161 mixes the I-arm summation signal xI(t) with an inphase component carrier coswct to output an I-arm modulation signal, and a mixer 162 mixes the Q-arm summation signal xQ(t) with a quadrature-phase component carrier sinwct to output a Qarm modulation signal. An adder 170 adds the I-arm modulation signal to the Q-arm modulation signal to generate a transmission signal s(t). The transmission signal s(t) is radiated into the air through an antenna (not shown) after bandpass filtering and power amplifying.

Conventionally, each of the spreaders 141-143 is composed of multipliers 2 and 4, as illustrated in f igure 2. The multiplier 2 multiplies the orthogonally coded data signal c(t) output from the multipliers 111-113 by the I arm PN code pI(t) generated from the I-PN code generator 120 to generate the I-arm spread signal sI(t). The multiplier 4 multiplies the orthogonally coded data signal c(t) output from the multipliers 111-113 by the Q-arm PN code pQ(t) generated from the Q-PN code generator 130 to generate the Q-arm spread signal sQ(t).

2 - A spread spectrum signal generator for generating spread signals by multiplying an orthogonally coded data signal by an I-arm PN code and a Qarm PN code as shown in figure 2, is disclosed in US Patent No. 5,416,797, entitled "System and Method for Generating Signal Waveforms in a CDMA Cellular Telephone System". However, since this spread spectrum signal generator spreads the data signals using the I-arm PN code and the Q-arm PN code without any modification (i.e. by multiplying the I-arm PN code and the Q-arm PN code by the I-arm orthogonally coded data signal and the Q-arm orthogonally coded data signal, respectively), the I-arm summation signal and the Q-arm summation signal increase in amplitude fluctuation, which may lead to an increase in fluctuation and on/off switching frequency of the transmission signal s (t). This requires a high linearity of a power amplifier in the transmitter, so that a receiver may have a difficulty in restoring clocks and signals.

An improvement proposed disclosed in US Patent No.

Transmitter and Receiver Communication System Using improvement proposed to solve disclosed in Korean Patent entitled lIDS/CDMA Channel".

to solve this problem is 5,712,869, entitled "Data of a Spread Spectrum a Pilot Channel". Another the above stated problem is Application -No42989/1995, Communication System Using Pilot However, since the conventional devices have - 3 inflexible structures, they are unfavorable for a system employing various spreading techniques. For example, in implementing the DS/WMA communication system, the spreadspectrum signal generating technique may be changed according to regions (or countries) where the system is installed. Accordingly, there is a demand for a DS/CDMA communication system capable of supporting various spreading techniques. Furthermore, there is a demand for a system compatible with the existing systems.

Accordingly, a first aspect of the present invention provides a spread spectrum signal generating device for a spread spectrum communication system comprising a spreader for producing an I-arm spread signal and a Q-arm spread signal from a coded data signal and an I-arm PN code and a Qarm PN code according to a selectable one of a plurality of signal spreading techniques selected according to a control signal.

A first aspect of the present invention provides a spread spectrum signal generating device as claimed in claim 1, in which the spreader comprises at least one of: a first spreading part for multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal; a second spreading part for inverting one of the I-arm PN code and the Q-arm PN code, multiplying the coded data signal by the Q-arm PN code or the inverted Q-arm PN code to generate a second I-arm spread signal, and multiplying 4 the code data signal by the I-arm PN code or the inverted I-arm PN code to generate a second Q-arm spread signal; a third spreading part for multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal; and a selecting part for selecting one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a spreading technique determination signal.

Advantageously, embodiments of the present invention to provide a device for generating a spread spectrum signal according to various spreading techniques in a spread spectrum communication system; and/or provide a device for securing compatibility between an existing spreading technique and a new spreading technique in a spread spectrum communication system.

An embodiment provides a transmitter for generating a spread spectrum signal according to various spreading techniques and converting the spread spectrum signal to a transmission signal in a spread spectrum communication system provides a spread spectrum signal generating device for a spread spectrum communication system, comprising an I-arm PN code generator for generating an I-arm PN code; a Q-arm PN code generator for generating a Q-arm PN code; a first spreading part for multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal; a second spreading part for inverting one of the I-arm PN code and the Q- arm PN code, multiplying the coded data signal by the Q-arm PN code or the inverted Q-arm PN code to generate a second I-arm spread signal, and multiplying the code data signal by the I-arm PN code or the inverted I- arm PN code to generate a second Q-arm spread signal; a third spreading part for multiplying the coded data signal by the I-arm PN code and the Q- arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal; and a selecting part for selecting one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a spreading technique determination signal.

The third spreading part includes a f irst spreading element having a structure that is the same as the f irst spreading part for spreading the coded data signal to generate the first I-arm spread signal and the first Q-arm spread signal; a second spreading element having a structure that is the same as the second spreading part for spreading the coded data signal to generate the second I-arm spread signal and the second Q-arm spread signal; a first adder for adding the first I-arm spread signal generated from the f irst spreading element to the second I-arm spread signal generated from the second spreading element to generate the third I-arm spread signal; and a second adder for adding the first Q-arm spread signal generated from the first spreading element to the second Q-arm spread signal generated from the second spreading - 6 element to generate the third Q-arm spread signal.

F, is A second aspect of the present invention provides A' spread spectrum signal generating method for a spread spectrum communication system, the method comprising the step of producing an I-arm spread signal and a Qarm spread signal from a coded data signal and an I-arm PN code and a,Qarm PN code according to a selectable one of a plurality of signal spreading techniques selected 10 according to a control signal.

An embodiment provides a spread spectrum signal generating method, in which the step of spreading comprises at least one of the steps of: multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal, inverting one of the I-arm PN code and the Q-arm PN code, multiplying the coded data signal by the Q-arm PN code or the inverted Q- arm PN code to generate a second I-arm 20 spread signal, and multiplying the code data signal by the I-arm PN code or the inverted I-arm PN code to generate a second Q-arm spread signal, multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I- arm spread signal and a third Q-arm spread signal; and selecting one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a spreading technique determination signal.

7 - A third aspect of the present invention a spread spectrum signal generating device for a spread spectrum communication system comprising a spreader for producing an I-arm spread signal and a Q-arm spread signal from a coded data signal and an I-arm PN code and a Q-arm PN code comprising a second spreading part for inverting one of the I-arm PN code and the Q- arm PN code, multiplying the coded data signal by the Q-arm PN code or the inverted Qarm PN code to generate a second I-arm spread signal, and multiplying the code data signal by the I-arm PN code or the inverted Iarm PN code to generate a second Q-arm spread signal.

An embodiment provides a spread spectrum signal generating device as claimed in claim 22, in which the spreader further comprises at least one of either a first spreading part for multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal, and/or a third spreading part for multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal; and a selecting part for selecting one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a spreading technique determination signal.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a diagram illustrating a transmitter of a common DS/CDMA communication system; Figure 2 is a diagram illustrating a spreader of FIG. 1 according to the prior art;

Figure 3 is a diagram illustrating a transmitter of a DS/CDMA communication system according to an embodiment of the present invention; Figure 4 is a detailed diagram illustrating a crossing control spreader of figure 3; Figure 5 is a detailed diagram illustrating a first spreading part (210) of figure 4; Figures 6A and 6B are detailed diagrams illustrating is a second spreading part (220) of figure 4; Figure 7 is a diagram illustrating a modification of the second spreading part (220) of figures 6A and 6B; Figure 8 is a detailed diagram illustrating a third spreading part (230) of figure 4; Figure 9 is a diagram illustrating that the crossing control spreaders select spreading techniques according to spreading technique determination signal; Figure 10 is a diagram illustrating a spreading scheme according to a first embodiment of the present 25 invention; Figure 11 is a diagram illustrating a spreading scheme according to a second embodiment of the present invention; Figure 12 is a diagram illustrating a spreading 9 - scheme according to a third embodiment of the present invention; and Figure 13 is a diagram illustrating a spreading scheme according to a fourth embodiment of the present invention.

Figure 3 illustrates a transmitter of a DS/CDMA communication system according to an embodiment of the present invention. The novel transmitter includes crossing control spreaders (or crossing control quadrature spreaders) 201-203 which are controlled by control signals CCQS1-CCQSN, in place of the conventional spreaders 141143 shown in figure 1. The control signals CCQS1-CCQSN are used to determine the spreading technique effected by the spreaders 201-203. When the crossing control spreaders 201-203 spread the orthogonally coded data signals using the I-arm PN code and the Q-arm PN code according to a first spreading technique shown in figure 5 to generate the I-arm spread signals and the Q-arm spread signals, the I-arm spread signals are generated using the the I-arm PN code and the Qarm spread signals are generated using the Q-arm PN code.

Further, when the crossing control spreaders 201-203 spread the orthogonally coded data signals using the I-arm PN code and the Q-arm PN code according to a second spreading technique shown in figures 6A and 6B to generate the I-arm spread signals and the Q-arm spread signals, the Iarm PN code and the Q-arm PN code are crossly supplied.

- That is, the crossing control spreaders 201-203 use the Qarm PN code in generating the I-arm spread signals and use the I-arm PN code in generating the Q-arm spread signals.

Preferably, one of the I-arm PN code and the Q-arm PN code is inverted.

is In addition, the crossing control spreaders 201-203 can generate the Iarm spread signals and the Q-arm spread signals according to a third spreading technique shown in figure 8. The third spreading technique, being a combination of the first and second spreading techniques, adds the I-arm spread signals sxI(t) and syI(t) generated respectively according to the first and second spreading techniques to generate an I-arm spread signal scI(t) and adds the Q-arm spread signals sxQ(t) and syQ(t) generated respectively according to the first and second spreading technique to generate a Q-arm spread signal scQ(t).

As stated above, the crossing control spreaders 201- 203 are so constructed as to support the first to third spreading techniques. The crossing control spreaders 201203 employing the first spreading technique is compatible with the existing spreader shown in figure 1. Further, the crossing control spreaders 201-203 employing the second spreading technique together with the first spreading technique can reduce the fluctuation and the on/off switching frequency of the transmission signal. The third spreading technique accommodating the first and second spreading techniques in the same channel can also reduce the fluctuation and the on/off frequency of the transmission signal.

Referring to figure 3, a first data signal di(t) to be transmitted is multiplied in a multiplier 111 by a first orthogonal code wl(t) generated from a first orthogonal code generator 101, to generate a first orthogonally coded data signal cl(t). The first crossing control spreader 201 spreads the first orthogonally coded data signal cl(t) using an I-arm PN code pI(t) generated from an I-PN code generator 120 and a Q-arm PN code pQ(t) generated from a Q-PN code generator 130, to generate a first 1-arm spread signal slI(t) and a first Q-arm spread signal slQ(t). A second data signal d2(t) to be transmitted is multiplied in a multiplier 112 by a second orthogonal code w2(t) generated from a second orthogonal code generator 102, to generate a second orthogonally coded data signal c2(t). The second crossing control spreader 202 spreads the second orthogonally coded data signal c2(t) using the I-arm PN code pI(t) generated from the I-PN code generator 120 and the Q-arm PN code pQ(t) generated from the Q-PN code generator 130, to generate a second I-arm spread signal s21(t) and a second Q-arm spread signal s2Q(t). In the same manner, signal dN(t) is multiplied in a multiplier 1 an N-th data 13 by an N-th orthogonal code wN(t) generated from an N-th orthogonal code generator 103, to generate an N-th orthogonally coded data signal cN(t). The N-th crossing control spreader 203 spreads the N- th orthogonally coded data signal cN(t) 12 using the I-arm PN code pI(t) generated from the I-PN code generator 120 and the.Q-arm PN code pQ(t) generated from the Q-PN code generator 130, to generate an N-th I-arrd spread signal sNI(t) and an N-th Q-arm spread signal sNQ (t).

The generated I-arm spread signals slI(t)-sNI(t) are summed by a summer 151 to generate an Iarm summation signal xI(t). The Q-arm spread signals s1Q(t)-sNQ(t) are summed by a summer 152 to generate a Q-arm summation signal xQ(t). The I- arm summation signal xI(t) is mixed with an in-phase component carrier coswct by a mixer 161, to generate an I-arm modulation signal. The Q-arm summation signal xQ(t) is mixed with a quadrature phase is component carrier sinwct by a mixer 162, to generate a Qarm modulation signal. The I-arm modulation signal and the Q-arm modulation signal output from the mixers 161 and 162 are added to each other by an adder 170, to generate a transmission signal s (t). The transmission signal s (t) is radiated into the air through an antenna (not shown) after bandpass filtering and power amplifying.

The orthogonal code generators 101-103 may be realised by Walsh code generators. The crossing control spreaders 201-203 generate the spread signals according to spreading technique determination signals WQS1-CCQSN, as shown in figure 4.

Referring to figure 4, each of the crossing control 13 - spreaders 201-203 is composed of a first spreading part 210 supporting the first spreading technique, a second spreading part 220 supporting the second spreading technique, a third spreading part 230 supporting the third spreading technique which is a combination of the first and second spreading techniques, a first selector 240 and a second selector 250. The first selector 240 selects one of the I-arm spread signals generated from the first to third spreading parts 210-230 according to the control signal WQS. The second selector 250 selects one of the Qarm spread signals generated from the first to third spreading parts 210-230 according to the control signal WQS.

is The first spreading part 210 spreads the orthogonally coded data signal c(t) using the I-arm PN code pI(t) and the Q-arm PN code pQ(t) to generate an I-arm spread signal saI(t) and a Q-arm spread signal saQ(t). The second spreading part 220 spreads the orthogonally coded data signal c(t) using the I-arm PN code pI(t) and the Q-arm PN code pQ(t) to generate an I-arm spread signal sbI(t) and a Q-arm spread signal sbQ(t). The third spreading part 230 spreads the orthogonally coded data signal c(t) using the I-arm PN code pI(t) and the Q-arm PN code pQ(t) to generate an I-arm spread signal scI(t) and a Q-arm spread signal scQ(t). The generated I-arm spread signals saI(t), sbI (t) and scI (t) are applied to signal inputs A, B and C of the f irst selector 240, respectively. The generated Qarm spread signals saQ (t), sbQ (t) and scQ (t) are applied 14 to signal input ends A, B and C of the second selector 250, respectively. The first selector 240 selects one of the I-arm spread signals saI (t), sbI (t) and scI (t) in response to the control signal WQS received at a selection signal input end SEL and outputs the selected spread signal as the I-arm spread signal sI (t) through an output end OUT. The second selector 250 selects one of the Q-arm spread signals saQ(t), sbQ(t) and scQ(t) in response to the control signal WQS received at a selection signal input end SEL and outputs the selected spread signal as the Q-arm spread signal sI(t) through an output end OUT.

The first to third spreading parts 210-230 can be constructed as shown in figures 5, 6A (or 6B) and 8, respectively.

Referring to figure 5, the first spreading part 210 includes multipliers 211 and 212. The multiplier 211 multiplies the orthogonally coded data signal c(t) by the I-arm PN code pI(t) to generate the I-arm spread signal saI(t). The multiplier 212 multiplies the orthogonally coded data signal c (t) by the Q-arm PN code pQ (t) to generate the Q-arm spread signal saQ(t). Here, it is noted that the first spreading part 210 generates the I-arm spread signal saI(t) using the I-arm PN code pI(t) and generates the Q- arm spread signal saQ(t) using the Q-arm PN code pQ(t). That is, in the first spreading part 210, the I-arm PN code pI(t) is applied to the I-arm and the Qarm PN code pQ(t) is applied to the Q-arm. The I-arm is - spread signal saI (t) and the Q-arm spread signal saQ (t) output from the first spreading part 210 are given by saI (t) = c (t) - pI (t) saQ(t) = c(t).pQ(t).... (1) Referring to figure 6A, the second spreading part 220 includes multipliers 211, 212 and 213. The multiplier 211 multiplies the orthogonally coded data signal c(t) by the inverted Q-arm PN code to generate the I-arm spread signal sbI (t) The multiplier 212 multiplies the orthogonally coded data signal c(t) by the I-arm PN code pI(t) to generate the Q-arm spread signal sbQ(t). The multiplier 213 multiplies the Q-arm PN code pQ(t) by a value 11-111 to generate the inverted Q-arm PN code. It is noted that the second spreading part 220 generates the I-arm spread signal sbI(t) using the inverted Q-arm PN code and generates the Q-arm spread signal sbQ(t) using the I-arm PN code pI (t). That is, in the second spreading part 220 of figure 6A, the inverted Q-arm PN code is crossly applied to the I-arm and the I-arm PN code pI (t) is crossly applied to the Q-arm. The I-arm spread signal sbl(t) and the Q-arm spread signal sbQ(t) output from the second spreading part 220 of figure 6A are given by sbI(t) = -c(t).pQ(t) sbQ(t) = c(t)-pI(t).... (2) The second spreading part 220 can also be constructed 16 - as shown in figure GB.

Referring to figure GB, the second spreading part 220 includes multipliers 211, 212 and 214. The multiplier 211 multiplies the orthogonally coded data signal c(t) by the Q-arm PN code pQ(t) to generate the I-arm spread signal sbI (t). The multiplier 212 multiplies the orthogonally coded data signal c(t) by the inverted I-arm PN code to generate the Q-arm spread signal sbQ(t). The multiplier 214 multiplies the I-arm PN code pI(t) by a value 11-111 to generate the inverted I-arm PN code. It is noted that the second spreading part 220 generates the I-arm spread signal sbI(t) using the Q- arm PN code pQ(t) and generates the Q-arm spread signal sbQ(t) using the inverted I-arm PN code. That is, in the second spreading part 220 of figure GB, the Q-arm PN code pQ(t) is crossly applied to the Iarm and the inverted I-arm PN code is crossly applied to the Q-arm. The I-arm spread signal sbI(t) and the Q-arm spread signal sbQ(t) output from the second spreadin g part 220 of figure 6B are given by sbI(t) = c(t)-pQ(t) sbQ(t) = -c(t)-pI(t) ... (3) The second spreading part 220 may be constructed as shown in figure 6A to generate the spread signals of equation (2) or may be constructed as shown in figure GB to generate the spread signals of equation (3). Although the spread signals of equations (2) and (3) are different from each other, they have the same effect. Here, as to the effect of the second spreading part 220, it is possible to reduce the fluctuation and the on/of frequency of the transmission signal by using the first spreading technique for some of N channels and using the second spreading technique for the rest of N channels, as compared with the case where the first spreading technique is used for all of N channels. The fact that the second spreading part 220 has the same effect no matter whether it is constructed as shown in figure 6A or 6B will be apparent from the following description.

Figure 7 illustrates various modifications of the second spreading part 220. For the second spreading part 220 shown in figure 6A, an inverter 221 multiplies the Q- arm PN code pQ(t) by the value 11-111 to invert the Q-arm PN code pQ(t). For the second spreading part 220 shown in figure 6B, an inverter 222 multiplies the I-arm PN code pI(t) by the value 11-111 to invert the I- arm PN code pI(t).

Inversion of the Q-arm PN code pQ(t) may also be implemented by using inverter 223 or 225 instead of the inverter 221, because the resulting spread signal of equation (2) is identical no matter which of the inverters 221P 223 and 225 is used in inverting the I-arm PN code pI(t). Similarly, inversion of the I-arm PN code pI(t) may also be implemented by using inverter 224 or 226 instead of the inverter 222, because the resulting spread signal of equation (3) is identical no matter which of the inverters 222, 224 and 226 is used in inverting the I-arm PN code pI(t).

Referring to figure 8, the third spreading part 230--includes a first spreading element 210 being equivalent 5 to the first spreading part 210, a second spreading part 220 being equivalent to the second spreading part 220, and adders 231 and 232. That is, the third spreading part 230 including the first spreading element 210( and the second spreading element 220, employs the third spreading technique combined with the first and second spreading techniques in order to reduce the fluctuation and the on/off frequency of the transmission signal.

is In figure 8, the received orthogonally coded data signal c (t) is applied in common to an x-arm and a y-arm as an x-arm orthogonally coded data signal cx(t) and a yarm orthogonally coded data signal cy(t), respectively. In the x-arm, the first spreading element 210(. spreads the orthogonally coded data signal cx(t) using the I-arm PN code pI(t) and the Q-arm PN code pQ(t) according to the first spreading technique, and generates an I-arm spread signal sxI(t) and a Q-arm spread signal sxQ(t). In the yarm, the second spreading element 220., spreads the orthogonally coded data signal cy(t) using the I-arm PN code pI(t) and the Q-arm PN code pQ(t) according to the second spreading technique, and generates an I-arm spread signal syI(t) and a Q-arm spread signal syQ(t). The I-arm spread signal sxI(t) in the x-arm is added to the I-arm spread signal syI (t) in the y-arm by the adder 231, to - 19 generate an I-arm spread signal scI(t). The Q-arm spread signal sxQ(t) in the x-arm is added to the Q-arm spread signal syQ(t) in the y-arm by the adder 232, to generate a Q-arm spread signal scQ(t). That is, the adder 231 adds the I-arm spread signals sxi(t) and syI(t) from the first and second spreading elements 21C and 22C to generate the I-arm spread signal scI(t) according to the third spreading technique, and the adder 232 adds the Q-arm spread signals sxQ(t) and syQ(t) from the first and second spreading element 210 and 220 to generate the Q-arm spread signal scQ(t) according to the third spreading technique.

Although the adders 231 and 232 are included in the is third spreading part 230 in this embodiment, they can be externally connected to the third spreading part 230. The first spreading element 210 in the third spreading part 230 has the same structure as the first spreading part 210 shown in figure 5, and the second spreading element 2200 has the same structure as the second spreading part 220 shown in figure 6A or 6B. When the firstspreading element 210( and the second spreading element 220 having the structure shown in figure 6A are used, the I-arm spread signal scI(t) and the Q-arm.spread signal s-cQ(t) of the third spreading part 230 are given by SCI(t) = SXI(t) + SYI(t) = cx(t)-PI(t) - cy(t)-PQ(t) c(t).[PI(t) PQ (t) 1 SCQ(t) = SXQ(t) + SYQ(t) CX(t)-PQ(t) + CY(t).PI(t) C(t).[pi(t) + PQ(t)l.... (4) Further, when the first spreading element 210 and the second spreading element 220 having the structure shown in figure 6B are used, the I-arm spread signal scI (t) and the Q-arm spread signal scQ (t) of the third spreading part 230 are given by is SCI(t) = SXI(t) + SYI(t) cx(t)-PI(t) + cy(t)-PQ(t) C(t)-[pj(t) + PQ (t) 1 SCQ(t) = SXQ(t) + SYQ(t) cx(t)-PQ(t) - cy(t)-PI(t) c(t)-[PQ(t) PI (t) (5) Turning back to figure 3, the crossing control spreaders 201-203 for N channels implemented spreaders as shown in any one of f igures 5, 6A (or 6B) and f igure 8 according to the spreading technique determination signals CCQS1-CCQSN. For example, for WQS1=1(01), the crossing control spreader 201 is constructed to support the first spreading technique shown in figure 5. For WQS1=2(10), the crossing control spreader 201 is constructed to support the second spreading technique shown in figure 6A (or 6B). Further, for WQS1=3(11), the crossing control spreader 201 is constructed to support the third spreading technique shown in figure 8. If the spreading technique determination signals CQS1-CQSN for N channels have the same values, the crossing control spreaders 201-203 will have the same structures. On the contrary, if the respective spreading technique determination signals CCQS1-CCQSN for N channels have the different values, all the crossing control spreaders 201-203 will have the different structures.

If the spreading technique determination signals WQS1-WQSN are all set to 11111, the spreading scheme of figure 3 will be equivalent to the spreading scheme of the DS/WMA communication system shown in figure 1. Since the spreading scheme with this structure has the increased fluctuation and the high on/off frequency of the transmission signal, it is useful when necessary to provide compatibility with the existing system.

Accordingly, in an embodiment, the spreading technique determination signals WQS1-WQSN are properly set to 11111, 11211 and 11311, so as not only to reduce the fluctuation and the on/off frequency of the transmission signal but also to secure the compatibility with the existing system. To this end, the crossing control spreaders receive the spreading technique determination signals CQS1-CQSN as illustrated in figure 9, and perform spreading according to the received spreading technique determination signals CQS1-CQSN.

Figures 10 to 13 illustrate various modifications of the spreading scheme, which can reduce the fluctuation and the on/off frequency of the transmission signal, securing the compatibility with the existing system.

Referring to figure 10, the spreading scheme according to a f irst embodiment of the present invention spreads a first signal using the first spreading technique to generate first spread signals, spreads a second signal using the second spreading technique to generate second spread signals, spreads a third signal using the first spreading technique to generate third spread signals, spreads a fourth signal using the second spreading technique to generate fourth spread signals,..., and spreads an N-th signal using the second spreading is technique to generate N-th spread signals. That is, the spreading scheme according to the first embodiment of the present invention is constructed such that the first and second spreading parts are interlaced with each other by the channel unit.

Referring to figure 11, the spreading scheme according to a second embodiment of the present invention spreads a first signal using the first spreading technique to generate first spread signals, spreads a second signal using the second spreading technique to generate second spread signals, spreads a third signal using the third spreading technique to generate third spread signals, spreads a fourth signal using the first spreading technique to generate fourth spread signals, spreads a 23 fifth signal using the second spreading technique to generate fifth spread signals, spreads a sixth signal using the third spreading technique to generate sixti'^ spread signals,..., and spreads an N-th signal using the 5 third spreading technique to generate N-th spread signals. That is, the spreading scheme according to the second embodiment is constructed such that the first to third spreading parts are disposed by turns by the channel unit.

Referring to figure 12, the spreading scheme according to a third embodiment spreads a first signal using the first spreading technique to generate first spread signals, spreads a second signal using the first spreading technique to generate second spread signals, spreads a third signal using the first spreading technique to generate third spread signals, spreads a fourth signal using the second spreading technique to generate fourth spread signals, spreads a fifth signal using the second spreading technique to generate fifth spread signals, spreads a sixth signal using the second spreading technique to generate sixth spread signals,..

spreads an Nth signal using the second spreading technique to generate Nth spread signals. That is, the spreading scheme according to the third embodiment is constructed such that a group of the spreaders using the first technique is included with a group of the second spreading parts by the channel group unit.

Referring to figure 13, the spreading scheme - 24 according to a fourth embodiment spreads a first signal using the first spreading technique to generate first spread signals, spreads a second signal using the second--spreading technique to generate second spread signals, spreads a third signal using the first spreading technique to generate third spread signals, spreads a fourth signal using the second spreading technique to generate fourth spread signals, spreads a fifth signal using the first spreading technique to generate fifth spread signals, spreads a sixth signal using the second spreading technique to generate sixth spread signals,.... and spreads an N-th signal using the third spreading technique to generate N-th spread signals. That is, the spreader according to the fourth embodiment is constructed such that the first and second spreading techniques are alternately used for N channels and the third spreading technique is used for one of N channels.

The spreading schemes according to the first to third 20 embodiments, shown in figures 10 to 13, have a structure including the first spreading parts supporting the first spreading technique and the second spreading parts supporting the second spreading technique, or another structure including the first spreading parts, the second spreading parts and the third spreading parts supporting the third spreading technique, instead of including the same spreading parts. Here, the first to third spreading parts are disposed by turns by the channel unit or by the channel group unit. This is to reduce the fluctuation and - 25 the on/off frequency of the transmission signal by the connection between the f irst and second spreading parts, securing the compatibility with the existing system by including the first spreading part.

Now, if it is assumed that the spreading scheme according to the present invention is constructed as shown in figure 10, the crossing control spreader 201 supports the first spreading technique and the crossing control spreader 202 supports the second spreading technique. In operation, the crossing control spreader 201 spreads the received orthogonally coded data signal cl(t) for the first channel using the I-arm PN code pI(t) and the Q-arm PN code pQ(t) to generate the I-arm spread signal slI(t) for the first channel and the Q-arm spread signal slQ(t) for the first channel. The crossing control spreader 202 spreads the received orthogonally coded data signal c2(t) for the second channel using the Iarm PN code pI(t) and the Q-arm PN code pQ(t) to generate the I-arm spread signal s21(t) for the second channel and the Q-arm spread signal s2Q(t) for the second channel. The summer 151 sums the I-arm spread signals siI(t) (where i=I-N) for the first to N-th channels to the generate the Iarm summation signal xI(t), and the summer 152 sums the Q-arm spread signals siQ(t) (where i=l-N) for the first to N-th channels to generate the Q-arm summation signal xQ(t). The mixer 161 mixes the I-arm summation signal xI(t) with the in-phase component carrier coswet to output the Iarm modulation signal, the mixer 162 mixes the Q-arm summation 26 signal xQ(t) with the quadrature phase component carrier sinwct to output the Q-arm modulation signal. The I-arm modulation signal and the Q-arm modulation signal output from the mixers 161 and 162 are added by the adder 170 to generate the transmission signal s(t). Here, the reduction in the fluctuation of the transmission signal s(t) means the reduction in the fluctuation of the I-arm summation signal xI(t) and the Q-arm summation signal xQ(t), and the reduction in the on/off frequency of the transmission 10 signal means that the I-arm summation signal xI(t) and the Q-arm summation signal XQ(t) do not become zero simultaneously. This is apparent from the following Table 1.

TABLE 1 cl(t) C2(t) pI(t) pQ(t) xIl(t xQl(t x12(t xQ2(t x13(t xQ3(t 0 0 0 0 2 2 0 2 2 0 0 0 0 1 2 -2 2 0 0 -2 0 0 1 0 -2 2 -2 0 0 2 0 0 1 1 -2 -2 0 -2 -2 0 0 1 0 0 0 0 2 0 0 2 0 1 0 1 0 0 0 -2 2 0 0 1 1 0 0 0 0 2 -2 0 0 1 1 1 0 0 -2 0 0 -2 - 27 1 0 0 0 0 0 -2 0 0 -2 1 0 0 1 0 0 0 2 -2 0 1 0 1 0 0 0 0 -2 2 0 1 0 1 0 0 2 0 0 2 1 0 0 -2 -2 0 -2 -2 0 1 0 1 -2 2 -2 0 0 2 1 0 2 -2 2 0 0 -2 1 1 2 2 0 2 2 0 is In Table 1, cl (t) is the orthogonally coded data signal for the first channel, c2(t) is the orthogonally coded data signal for the second channel, pI(t) is the I5 arm PN code and pQ (t) s the Q-arm PN code. Further, xIl(t) and xQl(t) are the I-arm summation signal and the Q-arm summation signal generated when the crossing control spreaders 201 and 202 are all constructed to employ the first spreading technique. In addition, x12(t), xQ2(t), 10 x13(t) and xQ3(t) are the I-arm summation signals and the Q-arm summation signals generated when the crossing control spreaders 201 and 202 are constructed to employ the first and second spreading techniques, respectively. Among these, x12(t) and xQ2(t) are the I-arm summation signal and the Q-arm summation signal generated when the crossing control spreader 202 is constructed to employ the second spreading technique shown in figure 6A. That is, the crossing control spreader 202 spreads the orthogonally 28 coded data signal using the inverted Q-arm PN code applied to the I-arm and the I-arm PN code applied to the Q-arm to generate the I-arm spread signal and the Q-arm spread signal. Further, x13(t) and xQ3(t) are the summation signals generated when the crossing control spreader 202 is constructed to employ the second spreading technique shown in figure 6B. That is, the crossing control spreader 202 spreads the orthogonally coded data signal using the Q-arm PN code applied to the I-arm and the inverted I-arm PN code applied to the Q-arm to generate the I-arm spread signal and the Q-arm spread signal. The summation signals in Table 1 are obtained by summing the I-arm spread signals and the Q-arm spread signals generated from the crossing control spreader 201 employing the first spreading technique and the crossing control spreader 202 employing the second spreading technique, on the assumption that the number of the channels is 2.

The I-arm summation signal xIl(t) and the Q-arm summation signal xQl(t) generated from the crossing control spreaders 201 and 202 both employing the first spreading technique are given by xIl(t) = slI(t) + s21(t) cl(t)-pI(t) + c2(t)-pI(t) xQl(t) = slQ(t) + s2Q(t) cl(t)-pQ(t) + c2(t).pQ(t) 25.... (6) Here, in calculating the I-arm summation signal and the Q-arm summation signal, the value 11011 denotes 11+111 and the value 1,111 denotes 11-111.

29 - The I-arm summation signal x12(t) and the Q-arm summation signal xQ2(t) generated from the crossing control spreaders 2 0 1. and 202 employing the first spreading technique and the second spreading technique shown in figure 6A, respectively, are given by X12(t) S1I(t) + S21(t) cl(t).pI(t) - C2(t).pQ(t) xQ2 (t) S 1 Q (t) + S 2 Q (t) c 1 (t) - pQ (t) + c2 (t) - p I (t) (7) Here, in calculating the I-arm summation signal and the Q-arm summation signal, the value 1,011 denotes 11+111 and the value 11111 denotes 11-111.

The I-arm summation signal x13(t) and the Q-arm summation signal xQ3(t) generated from the crossing control spreaders 201 and 202 employing the first spreading technique and the second spreading technique shown in figure 6B, respectively, are given by x13(t) S1I(t) + s21(t) cl(t)-pI(t) + c2(t)-pQ(t) xQ3(t) slQ(t) + S2Q(t) cl(t)-pQ(t) - C2(t) -pI(t) ... (8) Here, in calculating the I-arm summation signal and the Q-arm summation signal, the value 11011 denotes 11+111 and the value 11111 denotes 11-111.

- For the I-arm summation signals and the Q-arm summation signals given by equations (6) to (8), the RMS (Root -Mean- Square) values and the power values of the transmission signal s(t) generated from the adder 170 are shown in Table 2.

TABLE 2 xIl(t xQl(t Vrmsl PWR1 x12(t xQ2(t x13(t xQ3(t Vrms2 PWR2 2 2 4-J-2 8 0 2 2 0 2,1-2 2 2 -2 4-,12- 8 2 0 0 -2 2-2 2 -2 2 4-42 8 0 0 2 2,12- 2 0 0 0 0 2 0 0 2 2 r2- 2 0 0 0 0 0 -2 2 0 2,1-2- 2 0 0 0 0 0 2 -2 0 2 r2 2 0 0 0 0 -2 0 0 -2 2 J2- 2 0 0 0 0 -2 0 0 -2 2 f -2- 2 0 0 0 0 0 2 -2 0 2 2 2 0 0 0 0 0 -2 2 0 2,f21 2 0 0 0 0 2 0 0 2 2 J2- 2 2 -2 4,r2_ 8 0 -2 -2 0 2,1-2- 2 -2 2 4-2 8 -2 0 0 2V-2- 2 - 31 2 -2 4.v'2 8 2 0 0 -2 22 2 2 2 4,F2- 8 0 2 2 0 2V-2 2 In Table 2, Vrmsl and PWR1 denote the RMS value and the power value of the transmission signal s(t) generated when the crossing control spreaders 201 and 202 are both constructed to employ the first spreading technique. Further, Vrms2 and PWR2 denote the RMS value and the power value of the transmission signal s(t) generated when the crossing control spreaders 201 and 202 are constructed to employ the first and second spreading techniques, respectively. It can be understood that the Vrmsl and PWR1 have increased fluctuation and the increased on/off frequency of the transmission signal, when the crossing control spreaders 201 and 202 are both constructed to employ the first spreading technique. Here, the power value of the transmission signal switches between 1,811 and,,o,, with the increased fluctuation.

Unlike this, the RMS value Vrms2 and the power value PWR2 of the transmission signal generated when the crossing control spreader 201 employs the first spreading technique and the crossing control spreader 202 employs the second spreading technique shown in figures 6A or 6B, have the constant values 2-J-2- and 2, respectively.

Furthermore, the on/off switching of the transmission signal s(t) does not occur.

32 - Accordingly, when the spreading scheme according to the present invention is constructed as shown in figures 10 to 13, it is possible to prevent the fluctuatioiproblem and the on/off switching problem of transmission signal in the existing spreading scheme shown in f igure 1. That is, as shown in figures. 10 to 13, by composing the spreading scheme alternately using the first and second spreading - techniques for N channels or alternately using the first, second and third spreading techniques for N channels, it is possible to solve the problems caused in the conventional spreader using the single spreading technique.

the As described above, a DS/CDMA communication system according to an embodiment of the present invention spreads the data signals for the respective channels using various spreading techniques such as the f irst spreading technique, the second spreading technique and the third spreading technique, and converts the spread signals to the transmission signal. Since this system supports the second and third spreading techniques as well as the first spreading technique, it can reduce the fluctuation and on/off frequency of the transmission signal, securing the compatibility with the existing system.

While the invention has been shown and described with reference to a certain preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein 33 - without departing from the spirit and scope of the invention as def ined by the appended claims. For example, the embodiment may be applied to other spread spectrum communication system as well as the CDMA communication system. Further, the embodiment can be applied to a device for spreading the differently coded data signals rather than the orthogonally coded data.signals.

- 34

Claims

A spread spectrum signal generating device for a:-. spread spectrum communication system comprising a spreader for producing an I-arm spread signal and a Q-arm spread signal from a coded data signal and an I-arm PN code and a Q-arm PN code according to a selectable one of a plurality of signal spreading techniques selected according to a control signal.

A spread spectrum signal generating device as claimed in claim 1, in which the spreader comprises at least one of: a first spreading part for multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal; a second spreading part for inverting one of the I-arm PN code and the Q-arm PN code, multiplying the coded data signal by the Q-arm PN code or the inverted Q-arm PN code to generate a second I-arm spread signal, and multiplying the code data signal by the I-arm PN code or the inverted I-arm PN code to generate a second Q-arm spread signal; a third spreading part for multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal; and a selecting part for selecting one of the I-arm spread signals and one of the Q-arm spread signals F generated from the first to third spreading parts according to a spreading technique determination signal.

3 - A spread spectrum signal generating device as claimed in claim 2, wherein said selecting part comprises:

a first selector for selecting one of the I-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal; and a second selector for selecting one of the Q-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal.

A spread spectrum signal generating device as claimed in either of claims 2 or 3, wherein said first spreading part comprises:

first multiplier for multiplying the coded data signal by the I-arm PN code to generate the first I-arm spread signal; and second multiplier for multiplying the coded data signal by the Q-arm PN code to generate the first Q-arm spread signal.

A spread spectrum signal generating device as claimed in any preceding claim, wherein said second spreading part comprises:

an inverter foZ inverting the Q-arm PN code; - 36 1 0 a first multiplier for multiplying the coded data signal by the inverted Q-arm PN code to generate the second I-arm spread signal; and a second multiplier for multiplying the coded data signal by the I-arm PN code to generate the second Q-arm spread signal.

A spread spectrum signal generating device as claimed in any of claims 2 to 5, wherein said second spreading part comprises: an inverter for inverting the I-arm PN code; a first multiplier for multiplying the coded data signal by the Q-arm PN code to generate the second I-arm spread signal; and a second multiplier for multiplying the coded data signal by the inverted 1-arm PN code to generate the second Q-arm spread signal.

7. A spread spectrum signal generating device as claimed in either of claims 5 or 6, wherein the inverter multiplies the Q-arm PN code or the Iarm PN code by a value 11-111.

8. A spread spectrum signal generating device as claimed in any of claims 2 to 7, wherein said third spreading part comprises:

a first spreading element having a same structure as the first spreading part, for spreading the coded data signal to generate the first I-arm - 37 is spread signal and the first Q-arm spread signal; a second spreading element having a samE structure as the second spreading part, for spreading the coded data signal to generate the second I-arm spread signal and the second Q-arm spread signal; a first adder for adding the first I-arm spread signal generated from the first spreading element to the second I-arm spread signal generated from the second spreading element to generate the third I-arm spread signal; and a second adder for adding the first Q-arm spread signal generated from the first spreading element to the second Q-arm spread signal generated from the second spreading element to generate the third Q-arm spread signal.

9. A spread spectrum signal generating device substantially as described herein with reference to and/or as illustrated in figures 3 to 13.

A transmitter for a spread spectrum communication system, comprising: a plurality of orthogonal code generators for generating orthogonal codes for respective channels; a plurality of multipliers for multiplying data signals for the respective channels by the orthogonal codes generated from the corresponding orthogonal code generators to generate I-arm coded data signals and Q-arm coded data signals- for the respective - 38 -.

channels; an I-arm PN code generator for generating an Iarm PN code; a Qarm PN code generator for generating a Q-arm PN code; a plurality of crossing control spreaders comprising a spread signal generating devices as claimed in any of claims 1 to 9 each connected to corresponding ones of the plurality of multipliers for multiplying deriving an I-arm spread signal and a Q-arm spread signal from the I-arm coded data signals and the Q-arm coded data signals and the I-arm PN code; and a first summer for summing the I-arm spread signals output from the respective crossing control spreaders to generate an I-arm summation signal; a second summer for summing the Q-arm spread signals output from the respective crossing control spreaders to generate a Q-arm summation signal; a first mixer for mixing the I-arm summation signal with a first carrier signal to generate an Iarm modulation signal; a second mixer for mixing the Q-arm summation signal with a second carrier signal to generate a Qarm modulation signal; and an adder for adding the I-arm modulation signal to the Q-arm modulation signal to -generate a transmission signal.

39 11.

A spread spectrum signal generating method for a spread spectrum communication system, the method comprising the step of producing an Iarm spread signal and a Q-arm spread signal from a coded data signal and an I-arm PN code and a Q-arm PN code according to a selectable one of a plurality of signal spreading techniques selected according to a control signal.

12. A spread spectrum signal generating method as claimed in claim 11, in which the step of spreading comprises at least one of the steps of: multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal, inverting one of the I-arm PN code and the Q-arm PN code, multiplying the coded data signal by the Qarm PN code or the inverted Q- arm PN code to generate a second I-arm spread signal, and multiplying the code data signal by the I-arm PN code or the inverted I-arm PN code to generate a second Q-arm spread signal, multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third iarm spread signal and a third Q-arm spread signal; and selecting one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a - 40 spreading technique determination signal.

13. A spread spectrum signal generating method "as claimed in claim 12, wherein the step of selecting comprises:

selecting one of the I-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal; and selecting one of the Q-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal.

14. A spread spectrum signal generating method as claimed in either of claim 12 to 13 multiplying a coded data signal and the Q-arm code to generate signal and a first Q-arm spread step of:

multiplying the coded data signal by the I-arm PN code to generate the first I-arm spread signal; and multiplying the coded data signal by the Q-arm PN code to generate the first Q-arm spread signal.

wherein step of by the I-arm PN code a first I-arm spread signal comprises the 15. A spread spectrum signal generating method as claimed in any of claims 12 to 14, wherein the step of inverting one of the I-arm PN code and the Q-arm PN code comprises the steps of:

41 - inverting the Qarm PN code; multiplying the coded data inverted Q-arm PN code to generate'. multiplying the coded data signal by the I-arm PN code to generate the second Q-arm spread signal.

signal by the 16. A spread spectrum signal generating method as claimed in any of claims 12 to 15, wherein the steps of inverting one of the I-arm PN code and the Q-arm PN code comprises the steps of:

inverting the I-arm PN code; multiplying the coded data signal by the Q-arm PN code to generate the second I-arm spread signal; and multiplying the coded data signal by the inverted I-arm PN code to generate the second Q-arm spread signal.

A spread spectrum signal generating method as claimed in either of claims 15 or 16, wherein the steps of inverting multiplies the Q-arm PN code or the I-arm PN code by a value 11-111.

18. A spread spectrum signal generating method as claimed in any of claims 12 to 17, wherein the steps of multiplying the coded data signals by the I-arm PN code and the Q-arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal comprises the steps of:

42 is spreading part, for spreading the coded data signal to generate the first I-arm spread signal and the first Q-arm spread signal; spreading the coded data signal to generate the second I-arm spread signal and the second Q-arm spread signal; adding the first I-arm spread signal generated from the first spreading element to the second Iarm spread signal generated from the second spreading element to generate the third I-arm spread signal; and adding the first Q-arm spread signal generated from the first spreading element to the second Q-arm spread signal generated from the second spreading element to generate the third Q-arm spread signal.

19. A spread spectrum signal generating method substantially as described herein with reference to and/or as illustrated in figures 3 to 13.

20. A transmission method for a spread spectrum communication system, the method comprising the steps of: generating orthogonal codes for respective channels; multiplying data signals for the respective channels by the orthogonal codes generated from the corresponding orthogonal code generators to generate I-arm coded data signals and Q-arm coded data signals for the respective channels; is generating an I-arm PN code; generating a Q-arm PN code; generating an I- arm spread signal and a Q-arm spread signal from the I-arm coded data signals and the Q-arm coded data signa ls and the I-arm PN coded data signals using a spread spectrum signal generating method as claimed in any of claims 11 to 19; and summing the I-arm spread signals output from the respective crossing control spreaders to generate an I-arm summation signal; summing the Q-arm spread signals output from the respective crossing control spreaders to generate a Q-arm summation signal; mixing the I-arm summation signal with a first carrier signal to generate an I- arm modulation signal; mixing the Q-arm summation signal with a second carrier signal to generate a Q-arm modulation signal; and adding the I- arm modulation signal to the Q-arm modulation signal to generate a transmission signal.

21. A transmission method for a spread spectrum communication system substantially as described herein with reference to and/or as illustrated in figures 3 to 13.

A spread spectrum signal generating device for a spread spectrum communication system comprising a spreader for producing an I-arm spread signal' and a Q-arm spread signal from a coded data signal and an I-arm PN code and a Q-arm PN code comprising a second spreading part for inverting one of the I-arm PN code and the Q-arm PN code, multiplying the coded data signal by the-Q-arm PN code or the inverted Qarm PN code to generate a second I-arm spread signal, and multiplying the code data signal by the I-arm PN code or the inverted I-arm PN code to generate a second Q-arm spread signal.

23. Aspread spectrum signal generating device as claimed in claim 22, in which the spreader further comprises at least one of either a first spreading part for multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal, and/or a third spreading part for multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal; and a selecting part for selecting one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a spreading technique determination signal.

24. A spread spectrum signal generating device as claimed in claim 23, wherein said selecting part comprises: a first selector for selecting one of the I-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal; and a second selector for selecting one of the Q-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal.

25. A spread spectrum signal generating device as claimed in either of claims 23 or 24, wherein said first spreading part comprises: a first multiplier for multiplying the coded data signal by the I-arm PN code to generate the first I-arm spread signal; and a second multiplier for multiplying the coded data signal by the Q-arm PN code to generate the first Q-arm spread signal.

26. A spread spectrum signal generating device as claimed in any of claims 22 to 25, wherein saidsecond spreading part comprises:

an inverter for inverting the Q-arm PN code; a first multiplier for multiplying the coded data signal by the inverted Q-arm PN code to generate the second I-arm spread signal; and - 46 a second multiplier for multiplying the coded data signal by the I-arm PN code to generate the second Q-arm spread signal.

27. A spread spectrum signal generating device as claimed in any of claims 22 to 26, wherein said second spreading part comprises: an inverter for inverting the I-arm PN code; a first multiplier for multiplying the coded data signal by the Q-arm PN code to generate the second I-arm spread signal; and a second multiplier for multiplying the coded data signal by the inverted I-arm PN code to generate the second Q- arm spread signal.

28. A spread spectrum signal generating device as claimed in either of claims 26 or 27, wherein the inverter multiplies the Q-arm PN code or the I-arm PN code by a value 11-111.

29. A spread spectrum signal generating device as claimed in any of claims 22 to 28, wherein said third spreading part comprises:

a first spreading element having a same structure as the first spreading part, for spreading the coded data signal to generate the first I-arm spread signal and the first Q-arm spread signal; a second spreading element having a same structure as the second spreading part, for spreading the coded data signal to generate the second I-arm spread signal and the second Q-arm spread signal; a first adder for adding the first I-arm spread signal generated from the first spreading element to the second I- arm spread signal generated from the second spreading element to generate the third I-arm spread signal; and a second adder-for adding the first Q- arm spread signal generated from the first spreading element to the second Q-arm spread signal generated from the second spreading element to generate the third Q-arm spread signal.

30. A spread spectrum signal generating device substantially as described herein with reference to and/or as illustrated in figures 3 to 13.

31. A transmitter for a spread spectrum communication system, comprising:

a plurality of orthogonal code generators for generating orthogonal codes for respective channels; a plurality of multipliers for multiplying data signals for the respective channels by the orthogonal codes generated from the corresponding orthogonal code generators to generate I-arm coded data signals and Q-arm coded data signals for the respective channels; an I-arm PN code generator for generating an I arm PN code; - 48 a Q-arm PN code generator for generating a Q-arm PN code; a plurality of crossing control spreaders comprising a spread signal generating devices as claimed in any of claims 22 to 30 each connected to corresponding ones of the plurality of multipliers for multiplying deriving an I-arm spread signal and a Q-arm spread signal from the I-arm coded data signals and the Q-arm coded data signals and the I-arm PN code; and a first summer for summing the I-arm spread signals output from the respective crossing control spreaders to generate an I-arm summation signal; a second summer for summing the Q-arm spread signals output from the respective crossing control spreaders to generate a Q-arm summation signal; a first mixer for mixing the I-arm summation signal with a first carrier signal to generate an Iarm modulation signal; a second mixer for mixing the Q-arm summation signal with a second carrier signal to generate a Qarm modulation signal; and an adder for adding the I-arm modulation signal to the Qarm modulation signal to generate a transmission signal.

32. A spread spectrum signal generating method for a spread spectrum communication system, the method comprising the steps of:

producing an I-arm spread signal and a Q-arm 49 - spread signal from a coded data signal and an I-arm PN code and a Q-arm PN code by inverting one of the I-arm PN code and the Q-arm PN code, multiplying the coded data signal by the Q-arm PN code or the inverted Q-arm PN code to generate a second I-arm spread signal, and multiplying the code data signal by the I-arm PN code or the inverted I-arm PN code to generate a second Q-arm spread signal.

33. A spread spectrum signal generating method as claimed in claim 32, further comprising at least one of the steps of either multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm is spread signal and a first Q-arm spread signal, multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I arm spread signal and a third Q-arm spread signal; and selecting one of the I-arm spread signals and one of the Q-arm spread signals generated from the first to third spreading parts according to a spreading technique determination signal.

34. A spread spectrum signal generating method as claimed in claim 33, wherein the step of selecting comprises the steps of:

selecting one of the I-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal; and selecting one of the Q-arm spread signals generated from the first to third spreading parts according to the spreading technique determination signal.

35. A spread spectrum signal generating method as claimed in either claim 33 or 34, wherein the step of multiplying a coded data signal by the I-arm PN code and the Q-arm PN code to generate a first I-arm spread signal and a first Q-arm spread signal comprises the step of:

multiplying the coded data signal by the I-arm PN code to generate the first I-arm spread signal; and multiplying the coded data signal by the Q-arm PN code to generate the first Q-arm spread signal.

36. A spread spectrum signal generating method as claimed in any of claims 32 to 35, wherein the step of inverting one of the 1-arm PN code and the Q-arm PN code comprises the step of: inverting the Q-arm PN code; multiplying the coded data signal by the inverted Q-arm PN code to generate the second I-arm spread signal; and multiplying the coded data signal by the I-arm PN code to generate the second Q-arm spread signal.

51 - 37. A spread spectrum signal generating method as claimed in any of claims 32 to 36, wherein the step 1 o' inverting one of the I-arm PN code and the Q-arm PN code comprises the steps of:

inverting the I-arm PN code; multiplying the coded data signal by the Q-arm PN code to generate the second I-arm spread signal; and multiplying the coded data signal by the inverted I-arm PN code to generate the second Q-arm spread signal.

38. A spread spectrum signal generating method as claimed in either of claims 36 or 37, wherein the step of inverting multiplies the Q-arm PN code or the I-arm PN code by a value 11- 111.

39. A spread spectrum signal generating method as claimed in any of claims 32 to 38, wherein the step of multiplying the coded data signal by the I-arm PN code and the Q-arm PN code to generate a third I-arm spread signal and a third Q-arm spread signal comprises the steps of:

spreading the coded data signal to generate the first I-arm spread signal and the first Q-arm spread signal; spreading part, for spreading the coded data signal to generate the second I-arm spread signal and - 52 the second Q-arm spread signal; adding the first I-arm spread signal generated from the first spreading element to the second I-arm spread signal generated from the second spreading element to generate the third I-arm spread signal; and adding the first Q-arm spread signal generated from the first spreading element to the second Q-arm spread signal generated from the second spreading element to generate the third Q-arm spread signal.

40. A spread spectrum signal generating. method substantially as described herein with reference to and/or as illustrated in figures 3 to 13.

A transmission method for a spread spectrum communication system, the method comprising the steps of: generating orthogonal codes for respective channels; multiplying data signals for the respective channels by the orthogonal codes generated from the corresponding orthogonal code generators to generate I-arm coded data signals and Q-arm coded data signals for the respective channels; generating an I-arm PN code; generating a Q-arm PN code; producing an I-arm spread signal and a Q-arm spread signal from the I-arm coded data signals and the Q-arm coded data signals and the I-arm PN code 53 - using a spread spectrum signal generating method as claimed in any of claims 32 to 40; and summing the I-arm spread signals output from the respective crossing control spreaders to generate an I-arm summation signal; summing the Q-arm spread signals output from the respective crossing control spreaders to generate a Q-arm summation signal; mixing the I-arm summation signal with a first carrier signal to generate an I- arm modulation signal; mixing the Q-arm summation signal with a second carrier signal to generate a Q-arm modulation signal; and adding the I- arm modulation signal to the Q-arm modulation signal to generate a transmission signal.

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