JP3477827B2 - Spreading code generation method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread code generating method and device used in spread spectrum communication, and more particularly, in a receiver used in a so-called CDMA (code division multiple access) type digital cellular mobile terminal. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread code generating method and apparatus for detecting the timing of a direct spread spectrum spread code and despreading a received signal.

[0002]

2. Description of the Related Art In a spread spectrum communication system, a carrier is modulated (spread) by a pseudo noise (PN) code sequence on the side of a transmitting device such as a base station, and is transmitted on the side of a transmitting device on the side of a receiving device such as a mobile terminal. After a correlation (despreading) process using a spreading code generated by a spreading code generator having the same structure, baseband demodulation is performed to obtain data.

In the so-called CDMA system cellular, which is a kind of the spread spectrum communication system, means for utilizing a plurality of good signals from a plurality of the same base stations existing by multipath (called path diversity or RAKE reception). Or a means for simultaneously receiving signals sent from a plurality of base stations (soft handoff).

Particularly during soft handoff, in order to select and receive a base station having a strong signal, the work of frequently switching the base station used for demodulation is performed in the receiver, and the signal of a certain base station currently being received is received. Shortening the time it takes to detect a signal from another base station with a higher signal strength and actually receive a strong signal (switch from one base station signal to another base station signal) It is very important because it can receive strong signals faster and last longer.

[0005]

By the way, in order to synchronize the spreading sequence in the mobile terminal with the sequence of the base station, the spreading sequence generator is operated at a high speed to proceed or at a low speed (or I was using a means of delaying (stopping).

However, this method has a drawback that it takes time to synchronize. In the case of so-called CDMA cellular, the spread code period is about 27 ms and
It takes 3.8ms even if the speed is doubled. To increase the speed 7 times, a clock 8 times the speed of the spread code is required. However, due to the limitation of the operation speed of the device, this speed cannot be increased as much as possible, and it is also considered that the power consumption is increased.

The present invention has been made in view of the above-mentioned circumstances, and spread code generation that makes it possible to reduce the time required to switch a receiver to a signal transmitted by a different base station. The purpose is to provide a method and a device.

[0008]

A spreading code generating method according to the present invention is a spreading code generating method for spread spectrum communication, which is an M sequence which is the basis of a spreading code, and is located at any position of the sequence. The M-series of the M-series is generated by generating the M-series in which the code 0 is inserted and controlling the number of clocks validated by the enable signal in the one-chip period using a clock that is an integer multiple of the chip rate of the generated M-series. M sequence generation step of advancing or delaying generation, vector acquisition step of obtaining delay time of spread code used in spread spectrum communication as shift vector value, and vector having elements of states of respective registers of the M sequence generation step A first M-sequence output step of outputting a first M-sequence shifted in time by multiplying
A second M-sequence further delayed by one spreading rate
Second M-sequence output step of outputting the M-sequence and a selection step of switching the first M-sequence output and the second M-sequence output at an externally set timing to output a spread code. By having it, the above-mentioned subject is solved.

The spread code generator according to the present invention is a spread code generator for spread spectrum communication, which is an M sequence that is the basis of a spread code, and a code 0 is inserted at any position of the sequence. Generated M sequences, and using a clock that is an integral multiple of the chip rate of the generated M sequences to control the number of clocks that are enabled by the enable signal for one chip period, thereby promoting the generation of M sequences. The M-sequence generating means for delaying, the vector obtaining means for obtaining the delay time of the spread code used in spread spectrum communication as a shift vector value, and the vector having the state of each register of the M-sequence generating means as an element. The first M shifted in time by applying
First M sequence output means for outputting a sequence, and the first M sequence
Second M-sequence output means for outputting a second M-sequence obtained by further delaying the sequence by one spreading rate, and switching between the first M-sequence and the second M-sequence at a timing set externally. The above-mentioned problem is solved by having a selecting means for outputting the spread code.

Here, only the vector corresponding to the time difference of each spreading code transmitted by the plurality of transmitters is stored, and the stored vector is read to obtain the vector, and the vector is received from the plurality of transmitters. It is preferable to adjust the amount of fine adjustment due to the propagation delay to the side by advancing or delaying the generation of the M sequence.

This is to shift in time by multiplying a vector whose element is the state of each register of the M-sequence generator used as a spread code in a spread spectrum communication system such as the so-called CDMA cellular system. Is conventionally known, but the so-called CDMA cellular spreading code cannot be applied as it is because 0 is inserted at the end to set the code length to 2 ⁿ . In the present invention, a means for time shifting using vector multiplication even if 0 is inserted, and a time difference correction of a spreading sequence between base stations are performed using this means, and a propagation delay amount from each base station to a mobile station (small It provides a means for realizing adjustment of (adjustment amount) by actually advancing / delaying the M-sequence generator.

[0012]

By spreading the spreading code by switching between the output of the first M-sequence and the output of the second M-sequence, vector multiplication is used in a so-called CDMA cellular spreading code which is an irregular type of the M-sequence. The time adjustment of the spreading code is realized. As a result, it is possible to significantly reduce the time required for adjusting the spreading code time.

When this method is used, time correction can be performed in an extremely short time, but it is necessary to have a considerable number of vector values in order to generate all the timings. Therefore, adjustment using this method is performed by the base station. It is used for adjusting the time difference between the spread codes, and a method for actually advancing / retarding the M sequence generator is used for delay correction based on the propagation time difference from each base station to the mobile terminal. By using the vector multiplication only for the time correction between the base stations having a large amount of time adjustment, it is possible to reduce the time required for the sequence synchronization at the time of switching the base stations while keeping the implementation circuit scale small.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a spread code generator used for spread spectrum communication as one embodiment of the present invention.

In FIG. 1, as the M-sequence generator 11 which is a pseudo-random number generator, one having a structure as shown in FIG. 2 can be used. The circuit of FIG. 2 is a general simple M-sequence generator, and a detailed description will be given later.

In FIG. 1, the data demodulator 20 detects whether the timing at which the data is currently being demodulated is ahead or behind the timing of the received data, and the lead / lag information is used to control the PN generator. It is output to the unit 23. The reason why the data demodulator 20 outputs two output lines is to represent not only the information of the lead or the delay but also the information when the timing is correct.

The tracking control register 21 has a C
A signal indicating whether or not to perform tracking control is input from the PU 19 via the CPU bus. The instruction signal is input to the PN generator control unit 23 as a selection signal.

The slew controller 24 includes a CPU 1
A signal for instructing whether to advance and time the M-sequence generation or to adjust the M-sequence generation is delayed is input from 9 through the CPU bus, and advance / delay information is input to the PN generator control unit 23. .

The slew counter 25 instructs the slew controller 24 on the adjustment time. The PN generator controller 23 selects either the lead / lag information from the data demodulator 20 or the lead / lag information from the slew controller 24 based on the selection signal from the tracking control register 21. It That is, when tracking control is performed, the lead / lag information from the data demodulator 20 is selected, and when tracking control is not performed, lead / lag information from the through control unit 24 is selected. In other words, the information from the data demodulator 20 is selected during the data demodulation, and the information from the through control unit 24 is selected otherwise. Then, the PN generation is controlled by any of the lead / lag information.

The shift vector output unit 10 includes a CPU
Information on which shift vector should be output is input from 19 via the CPU bus, and the vector is output from the shift vector output device 10.

In the present embodiment, the shift vector is stored in the vector output device 10. However, in order to save the memory for the vector output device 10 to store 512 kinds of vectors, the CPU 19 shifts the shift vector. Is C
It may be sent to the vector output device 10 via the PU bus and stored therein.

The switching set value storage unit 17 includes the CPU 1
The Pilot_PN_Offset value corresponding to the shift vector is input from 9 via the CPU bus and stored.

The register 26 includes CPU 19 to CPU
An initialization signal is input via the bus. This initialization signal is input to the register when the power is turned on in order to synchronize the M-sequence generator 11 and the counter 16.

Part of an example (512 ways) of Pilot_PN delay vector (shift vector) is shown in Table 1 below.

[0025]

[Table 1]

The shift vector output circuit 10 in FIG.
Outputs the vector value to be multiplied to perform the time shift. The output of the shift vector output circuit 10 and the output of the M-sequence generator 11 are supplied to the vector multiplier 12 to perform vector multiplication. The output of the vector multiplier 12 is input to the flip-flop 13 at the same time as it is input to the selector 14, and is equivalent to one chip (each spreading code is hereinafter referred to as a chip, and the speed of the spreading code is referred to as a chip rate).
Is delayed. The selector 14 is a circuit that selects the output signal of the vector multiplier and the signal further delayed by one chip.

The timing generator 15 is the M-sequence generator 1.
1 is a circuit that gives timing for operating the counter 16, the flip-flop 13, and the counter 16. The counter 16 counts the timing at which the M-sequence generator is in the spread sequence having a period of 2 ^m , and is counted up for each chip including 0 when it is forcibly inserted. That value is supplied to the comparator 18 and is used to generate a signal for switching the selector 14. The switching set value 17 is set to different values depending on how much the shift is performed, and is used by the comparator 18 to generate a signal for switching the selector 14.

Here, the pseudo noise M series that is the basis for forming the spread signal will be described.

For example, in a so-called CDMA cellular system, spread spectrum communication is used. Generally, in spread spectrum communication, a transmission information signal is multiplied by pseudo noise having a wider band. This pseudo noise is a CD
In the spread spectrum of the direct spread system such as the MA system cellular, it is called a spread code, and the M sequence is often used. An example of this M-sequence generator is shown in FIG. 2, and the circuit shown in FIG. 2 is one used in so-called CDMA system cellular.

The generator polynomial of the M-sequence generator 11 shown in FIG. 2 is expressed as follows. ^{P (x) = x 15 +} x 13 + x 9 + x 8 + x 7 + x 5 +1

When the circuit of FIG. 2 is continuously operated,
The output value (or internal operation state) is as in the normal M series shown in A of FIG. In general, when the order of the M sequence (corresponding to the number of registers RG in the circuit of FIG. 2) is m, its period is 2 ^m −1. In the example of FIG. 2, fifteen registers RG1 to RG15 (and the exclusive OR circuit E
X1 to EX5) are connected in series, the cycle is 2 ¹⁵
It becomes -1.

On the other hand, in the so-called CDMA cellular system, the cycle is 2 ^m (m = 15 in the actual example) for the convenience of the system, and as shown in FIG.
One state has been inserted. That is, so-called CDM
In the A-system cellular, 0 is inserted after 14 consecutive 0's, which becomes the end of the M series (output values M _N-14 to M).
_{Since N} is 0, 0 will end up 15 times in a row). As shown in FIG. 4, this spreading code starts with an initial value (initial state) M ₁ and repeats a sequence in which 0 is inserted at the end. This insertion of 0 can be realized by stopping the generation of the M series for one chip using the enable signal obtained from the timing generator 15.

Next, the time shift of the M sequence using vector multiplication will be described. Multiplying the state vector of the M-sequence generator (the vector having the state of each register RG in FIG. 2 as an element) V _M by another vector (time shift vector) V _S , the time-shifted sequence M ′ (scalar) Is obtained. M ′ = V _S · V _M where V _M is the state vector of the M sequence generator V _{S is the} time shift vector M ′ is the time-shifted M sequence

In the case of the M-sequence generator shown in FIG.
The vector to shift by 4 chips is (1, 0,
1,1,1,1,0,1,0,1,0,0,0,0,
1). In order to realize all the delays of 2 ^m −1 periods by this method, it is necessary to prepare 2 ^m −1 sets of shift vectors. Here, the chip means each spreading code as described above, and the speed of the spreading code is the chip rate. In the shift vector output circuit 10 according to the present invention, the time difference (offset) of the spread code transmitted by each transmission side (base pole), that is, Pilot
Since _PN_Offset is in units of 64 chips, 2 ^m / 64 =
It suffices if 2 ^m-6 different shift vector patterns are stored. For example, when m = 15, there are 512 ways.

It is already known that time-shifting (delaying) can be performed by multiplying the state vector of the M-sequence generator by a certain vector.
In the case of the spreading code used in the DMA system cellular, since 0 is inserted in the M sequence, it cannot be applied as it is.

FIG. 5 shows a so-called CDMA cellular spreading code (A delay-free spreading code) and a 4-chip shifted sequence (B 4-chip delayed spreading code and C vector multiplication result). And are shown. That is, A of FIG. 5 shows an output of a spreading code generator using an M sequence generator, B shows a signal delayed by four chips, and C shows a result of delaying by vector multiplication by a conventional method. .

Shifted by the vector multiplication of C in FIG.
In the case of the original M_iAgainst M_i-4Is true,
I found that it was different from the series I wanted (B in Fig. 5).
It This is a so-called CDMA cellular spreading code.
However, due to the forced insertion of 0 in the M series
Yes, and in the case of this delay over 0, the result of vector multiplication is
It will not fit. For example, M in the sequence of A in FIG.
_FiveWhen M is delayed by 4 chips by vector multiplication, M₁Got
This is the result of the vector multiplication because it does not cross 0
(C) is correct. On the other hand, in the sequence of A in FIG.
M₁4 chips delayed by vector multiplication gives
Since it crosses 0, the vector multiplication result (C) is M _N-3Tona
Therefore, M shown in B of FIG._N-2Not correct, unlike.
In addition, when 0 is inserted in the sequence of A of FIG.
Since it is stopped, the vector multiplication result of C is indicated by the arrow in the figure.
, The same value (previous value M_N-4) Will continue
It

In order to solve such inconvenience, the spread code generating circuit shown in FIG. 1 is proposed. Here, returning to FIG. 1 again, the timing generator 15 will be described.

In order to advance the M-sequence generator, a clock which is an integral multiple of that in normal operation is used to operate at higher speed than usual. This is shown in A to D of FIG. In the example of FIG. 6, eight times as many clocks are used, and in the normal operation, the M-sequence generator is operated once every eight clocks. The registers and flip-flops in the M-sequence generator have been described using the synchronous operation using enable, but the same applies to the asynchronous method in which the number of clocks supplied in one chip period is changed and controlled. When advancing the M-sequence generator, it is possible to operate at high speed by inserting an enable between the enable generated during normal operation (Fig. 6).
In the example, the enable signal is active low).

As shown in the example of FIG. 6C, since enables can be inserted up to 7 times during normal enables, it is possible to advance at speeds up to 7 times, and 27 cycles per cycle.
In the ms series, the maximum is 3.8 ms, and it is possible to move at any timing. In the case of delaying, the M-sequence generator is stopped by not outputting the enable signal generated during normal operation. In this case, it is 1 to remove enable
With only one chip, a 27 ms sequence requires up to 27 ms to move to any timing. The zero insertion is also realized by using this delay method. CDM
The last M _{N of the} M sequence used in the A-system cellular is 0, and 0 is inserted by stopping the normal operation once when this M _N is output. Therefore, based on the value of the counter 16, the timing generation circuit 15 removes the enable once at the end of the sequence or the M sequence generator 11
When 0 is output 14 times in succession, 0 is inserted by removing the enable once.

Next, a method of realizing the time shift of the M sequence by using the vector multiplication will be described. In this example, the case of delaying by 4 chips is used as an example. First, a vector multiplication is used to perform a delay of 3 chips. The reason why the number of chips is not four is because the selector 14 switches between the result of the vector multiplier 12 and the result delayed by one chip by using a flip-flop, which results in a one-chip delay. However, it is because it is considered that a sequence one chip earlier than the desired shift amount is required as a multiplication result. Therefore, the output of the vector multiplier 12 must be advanced by one chip even when no shift is performed. In order to obtain a sequence that is one chip earlier than the desired shift amount as a result of the multiplication, a method of advancing the shift vector value by one chip and a method of advancing the M sequence generator by one chip are considered. , Either may be used, and the former is used in this example.

7A to 7E, A shows the output of the M-sequence generator 11, B shows the output of the vector multiplier 12, C shows the output of the flip-flop 13, and D shows the output of the selector 14, respectively. In E, the output from the comparator 18, which is the switching control signal of the selector 14, is shown.

Since the M-sequence generator 11 is delayed by one chip when 0 is inserted in the M-sequence generator, the output of the vector multiplier 12 maintains the previous value of M _N-3 . That is, at that time, the state M _N-3 is inserted, and then the shift of one chip continues until the initial value (M ₁ ) is output. 4 desired
Comparing with the chip delay sequence (output of the selector of D in FIG. 7), the end of the sequence (M _N ) as a multiplication result from the time of inserting 0
However, before inserting 0 and after the initial value (M ₁ ), 1 chip shift occurs. On the other hand, the output of the flip-flop is M _N-4 at the time of inserting 0, and is shifted by one chip, but when compared with the signal of the desired 4-chip delay, before the insertion of 0 and from the output of the flip-flop, after the last M _{N of} the series. Match, but there is a 1-chip shift from the time of inserting 0 to M _N-1 .

Utilizing this property, a switching signal for the selector 14 is generated as shown in E of FIG. 7, and when this signal is "H" (high level), the output of the vector multiplier 21 (FIG. 7). In the case of "L" (low level), the output of the flip-flop 13 is selected, so that the so-called CDM
It is possible to generate a signal (D in FIG. 7) obtained by delaying the spreading code used in the A-system cellular by 4 chips. This switching signal is obtained by comparing the counter value N _C with the switching set value N _S. When indicating the counter is zero when the M-sequence generator outputs 0 insertion component (the M ₁ 1, the M ₂ 2), the comparator if the following conditions are met outputs "H".

0 ≦ N _C <N _S (N _S is the shift amount, 4 if 4 chip shift)

By using the above circuit, the spreading code used in so-called CDMA cellular can be shifted by using vector multiplication, and a sequence shifted by one chip can be obtained after setting the shift vector. This makes it possible to obtain a shifted sequence in a much shorter time than the method of actually advancing or delaying the M sequence generator.

However, using this means to have a vector with a spreading sequence of one cycle of 2 ^m (2 ^{15 in} so-called CDMA cellular) can significantly increase the circuit scale.
Therefore, there is a vector corresponding to the shift between the base stations (in the so-called CDMA cellular, since the shift amount of the spreading code transmitted by the base station is a unit of 64 chips, 512), the time difference based on the propagation distance difference from each base station is M. By using the method of adjusting the sequence generator by actually advancing or delaying it, the time shift of the spreading sequence can be performed in a short time without making the circuit size too large. Since the propagation time from the base station is about 20 chips at most, it takes time to advance or delay the 20-chip M-sequence generator, but when using the method of advancing or delaying the M-sequence generator without using vector multiplication. Since a maximum of 32,767 (= 2 ^m −1) chip shift is required for the above, the effect is great.

8A to 8C describe the time difference between the spread codes of the base station 1 and the base station 2. Spread codes are transmitted between the base station 1 and the base station 2 with a time difference of 64 chips (the base station 2 is delayed by 64 chips from the base station 1), and the base station 2 is far from the base station 1 as seen from the mobile terminal. This is an example in which a delay of 2 chips occurs and a total delay of 66 chips occurs. There are 512 kinds of timings at which each base station transmits a spread code, with 64 chip intervals for one period 2 ¹⁵ . In this example, when the base station 1 is being received, the spreading code is as shown in FIG.
However, in order to switch this to the base station 2 in FIG. 8B, 64 chips are delayed by a method utilizing vector multiplication, and the remaining 2 chips are delayed by 2 chips in the spreading code generator to adjust the timing. The spreading code delayed by two chips is shown in C of FIG.

Although the embodiments of the present invention have been described above, the following can be summarized. That is, first, the M-sequence delay means using vector multiplication is Pilot_PN_Offset.
It has 512 sets corresponding to. By this, 2 ¹⁵ -1
However, the size of the table for storing the shift vector becomes 1/64.

Secondly, the amount of delay that cannot be produced by vector multiplication is adjusted and realized by a method of speeding up or stopping the operation of the circuit described at the beginning.

This method is actually convenient. That is,
The timing of the Pilot_PN code transmitted by the base station is arranged at intervals of an integral multiple of 64 chips. The difference in the amount of time shift of the Pilot_PN code due to the difference in the base station is dealt with by means of vector multiplication, and the propagation delay from the base station is made by means of advancing or delaying the generator. The change of the delay time by the vector multiplier is almost instantaneous, for example, about 2 μs.
Since the temporal distribution of the Pilot_PN code due to the propagation delay is considered to fall within the range of approximately 20 μs, it is considered that it can be realized in 25 μs at the maximum for timing adjustment and 12.5 μs in average.

[0052]

According to the spread code generating method of the present invention, in the spread code generating method for spread spectrum communication, the M sequence generating step of generating the M sequence which is the basis of the spread code and the spread spectrum communication are performed. A vector acquisition step of converting the delay time of the spreading code used to a vector value,
A first M-sequence output step of outputting a first M-sequence that is temporally shifted by multiplying the vector whose elements are states of the registers in the M-sequence generation step, and the first M-sequence A second M-sequence output step of outputting a second M-sequence delayed by one spread rate, and switching between the first M-sequence output and the second M-sequence output at a timing set externally. And a step of selecting the spread code to be output, the synchronization with the M sequence from the transmitting side can be effectively performed in a short time.

Further, according to the spread code generator of the present invention, in the spread code generator for spread spectrum communication, the M sequence generating means which is the basis of the spread code and the spread code used in the spread spectrum communication are provided. Vector acquisition means for converting the delay time into a vector value, and outputting a first M-sequence shifted in time by multiplying the vector whose element is the state of each register in the M-sequence generation step. M-sequence output means, second M-sequence output means for outputting the second M-sequence obtained by further delaying the first M-sequence by one spread rate, and the first M-sequence at externally set timing. Since it has the selecting means for switching the generating means and the second M-sequence generating means to output the spread code, the synchronization with the M-sequence from the transmitting side can be effectively performed in a short time.

That is, by switching between the first M-sequence output and the second M-sequence output to output the spreading code, vector multiplication is performed in a so-called CDMA cellular spreading code which is an irregular type of the M-sequence. It is used to realize the time adjustment of the spreading code. As a result, it is possible to significantly reduce the time required for adjusting the spreading code time.

Further, only the vector corresponding to the time difference of each spreading code transmitted by a plurality of transmission sides (for example, a plurality of base stations) is stored, and the stored vector is read to obtain the vector, The propagation delay amount from each transmission side to the reception side is adjusted by advancing or delaying the generation of the M sequence to adjust the fine adjustment amount due to the propagation delay amount from the plurality of transmission sides to the reception side (for example, a mobile terminal). Fine adjustment) can be realized by actually advancing / delaying the M-sequence generator.

That is, the means for applying the vector multiplication to the correction of the spread code time difference between a plurality of transmission sides, for example, base stations is used, and the time difference correction due to the difference in the propagation delay time from each base station is the same as the conventional one. By using a means to actually advance or delay the spread code generator, the number of prepared vectors can be reduced, and the time required for time shift of the spread code can be shortened without increasing the circuit scale too much. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 M used in so-called CDMA cellular
It is an example of a sequence generator.

FIG. 3 is a diagram for explaining a difference between an M sequence and a spreading code used in so-called CDMA cellular.

FIG. 4 is a diagram for explaining the periodicity of spreading codes used in CDMA cellular.

FIG. 5 is a diagram for explaining a difference in results when a signal obtained by delaying a CDMA cellular spreading code by 4 chips and simply applying vector multiplication.

FIG. 6 is a diagram for explaining a control method when the M-sequence generator is advanced or delayed.

FIG. 7 is a diagram for explaining the circuit operation in the block diagram of FIG.

FIG. 8 is a diagram for explaining a time difference of spreading codes between base stations.

[Explanation of symbols]

10 Shift vector output circuit 11 M series generator 12 vector multiplier 13 Flip-flops (for 1-chip delay) 14 selector 15 Timing generator 16 counter 17 Switching timing setting circuit 18 Comparator 19 CPU 20 data demodulator 21 Tracking control register 23 PN generator controller 24 Slew control unit 25 slew counter

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04J 13/00-13/06 H04B 1/69-1/713 H03K 3/84

Claims (8)

(57) [Claims] 1. A spread code generating method for spread spectrum communication, which generates and generates an M sequence which is a basis of a spread code, in which a code 0 is inserted at any position of the sequence. An M-sequence generation step of advancing or delaying the generation of the M-sequence by controlling the number of clocks enabled by the enable signal for one chip period using a clock that is an integer multiple of the chip rate of the M-sequence. A vector acquisition step of obtaining a delay time of a spreading code used in spreading communication as a shift vector value; and a vector obtained by multiplying a vector whose elements are states of each register of the M sequence generation step by the shift vector. A first M-sequence output step of outputting one M-sequence, and a second M-sequence output step further delaying the first M-sequence by one spreading rate.
Second M-sequence output step of outputting the M-sequence of, and a selection step of switching the first M-sequence output and the second M-sequence output at a timing set from the outside to output a spread code. A spread code generating method having: 2. The spread code generation method according to claim 1, wherein the shift vector in the vector acquisition step is a vector corresponding to a time difference between spread codes transmitted by a plurality of transmission sides. 3. The spreading code according to claim 2, further comprising an adjusting step of adjusting a propagation delay from the plurality of transmitting sides to a receiving side by advancing or delaying the generation of the M sequence. Method of occurrence. 4. When the clock for generating the M-sequence is n times the chip rate, the M-sequence generating step is performed.
It is in the normal operation and enable the period of one clock per chip period, thereby advancing the generation of the M-sequence by inserting enabled during normal enabled, also the M-sequence by removing the enable in normal operation The spreading code generation method according to claim 1, wherein the generation is delayed. 5. A spread code generator for spread spectrum communication, which generates and generates an M sequence which is the basis of a spread code and in which a code 0 is inserted at any position of the sequence. M-sequence generation means for advancing or delaying the generation of the M-sequence by controlling the number of clocks that are enabled by the enable signal for one chip period using a clock that is an integral multiple of the chip rate of the M-sequence Vector acquisition means for obtaining a delay time of a spreading code used in spreading communication as a shift vector value, and a vector which is temporally shifted by multiplying the vector whose element is the state of each register of the M-sequence generation means . First M-sequence output means for outputting the second M-sequence, and a second M-sequence output means for further delaying the first M-sequence by one spreading rate.
Second M-sequence output means for outputting the second M-sequence, and selecting means for switching the first M-sequence and the second M-sequence at a timing set from the outside to output a spread code. A spreading code generator characterized by. 6. The spread code generator according to claim 5, wherein the vector acquisition means stores only a vector corresponding to a time difference between spread codes transmitted by a plurality of transmitters. 7. The adjusting means for adjusting the propagation delay from the plurality of transmitting sides to the receiving side by advancing or delaying the generation of the M sequence in the M sequence generating means. The spreading code generator described. 8. When the clock for generating the M-sequence is n times the chip rate, the M-sequence generating means
It is in the normal operation and enable the period of one clock per chip period, thereby advancing the generation of the M-sequence by inserting enabled during normal enabled, also the M-sequence by removing the enable in normal operation 6. The spread code generator according to claim 5, wherein generation is delayed.