WO2004086644A1

WO2004086644A1 - Spread code generation method, spread code generation device, and communication method

Info

Publication number: WO2004086644A1
Application number: PCT/JP2004/003924
Authority: WO
Inventors: Hiroyasu Sano
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2003-03-27
Filing date: 2004-03-23
Publication date: 2004-10-07
Also published as: JP2004297593A

Abstract

A spread code generation method generates a spread code unique to a user and used in a radio communication system employing the CDMA (code division multiple access). A sequence phase shift section (2) cyclically shifts, by control of a shift control section (4), a predetermined basic sequence having an excellent self-correlation characteristic over a single or plural bits. Furthermore, a partial sequence addition section (3) adds, by control of an addition control section (5), a copy of the last one bit or a plurality of bits from the end of the sequence after the shifting to the head of the sequence after the shifting. After this, the sequence after the shifting is used as a basic sequence and processing of the sequence phase shift section (2) and the partial sequence addition section (3) is repeatedly executed by a predetermined number of times, thereby generating a spread code unique to the user.

Description

Description Spreading code generation method, spreading code generation device, and communication method

The present invention relates to a spreading code generation method for generating a user-specific spreading code used in a wireless communication system employing Code Division Multiple Access (CDMA), and particularly to a spreading method capable of reducing inter-code interference. The present invention relates to a spread code generation method for generating a code. Background art.

The following describes a conventional wireless communication system that employs CDMA as the communication method. The transmitting-side communication device spreads the transmission data sequence into a wideband signal using a spreading code assigned to the user and transmits the signal. Then, the communication device on the receiving side reproduces the transmission data sequence by performing correlation detection using the same spreading code as the code used for spreading on the transmitting side. In this case, since the received signals of other users have different spreading codes, the signal power is reduced on average. In this way, in the case of the CDMA, all users share the same frequency band and time. Communication is performed, and each user is identified by a uniquely assigned spreading code. '

The condition of the spreading code is that the autocorrelation peak at the synchronization timing is sharp, the autocorrelation has a small absolute value at other time shifts, and the crosscorrelation between different codes has a small absolute correlation at all timings. It is required to be a value. As such a spreading code, a spreading code having excellent correlation, such as an M sequence, which is one of the PN sequences, is used (see Non-Patent Document 1).

Non-patent document 1.

Science and Technology Publisher Mitsuo Yokoyama "Spread Spectrum Communication System" (6.3) However, in the above-mentioned conventional wireless communication system, all users share the same frequency band and time, and perform communication, so that a signal spread with another spreading code causes intersymbol interference. Then, there is a problem that it is difficult to prevent the spreading codes assigned to the user from correlating with each other, that is, it is difficult to completely orthogonalize. In addition, the inter-symbol interference has a problem that the quality of the received signal is degraded because it affects the signal similarly to the noise. In particular, in the case of satellite communication, since the transmission power is limited, an increase in the interference power between codes tends to lead to a deterioration in transmission quality.

The present invention has been made in view of the above, and provides a spread code generation method for generating a spread code capable of suppressing intersymbol interference, and a communication method using the spread code. It is aimed at. Disclosure of the invention

-The spread code generation method according to the present invention includes a spread code generation method for generating a user-specific spread code used in a wireless communication system employing a code division multiple access system, comprising: A fixed basic sequence with excellent characteristics is cyclically shifted over a single or multiple bits, and a copy of the last bit or multiple bits from the last in the shifted sequence is converted to the sequence of the shifted sequence. A code generation step to be added to the beginning, wherein the shifted sequence is used as a next basic sequence, and the code generation step is repeatedly executed a predetermined number of times to generate a user-specific spreading code. And

According to the present invention, in the process of generating a spreading code, a copy of the last (single or multiple) bits of each sequence is added to the beginning of the basic sequence and the sequence after the cyclic shift, thereby providing a delayed wave (multipath). Good correlation characteristics are obtained even when is present. Also, by generating a spread code by cyclically shifting the basic sequence, deterioration due to intersymbol interference is suppressed. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a configuration of a spreading code generation device used in a wireless communication system according to the present invention, FIG. 2 is a diagram showing an example of a configuration of a basic sequence generation unit, and FIG. FIG. 4 is a diagram illustrating a spreading code generation method according to Embodiment 1, and FIG. 4 is a diagram illustrating a correlation characteristic when a base station transmits data to a user to which a first spreading code is assigned. FIG. 5 is a diagram showing correlation characteristics when the base station transmits data to three users to which the first to third spreading codes are individually assigned, and FIG. 6 shows a delay wave FIG. 7 is a diagram illustrating a case where (multipath) exists, FIG. 7 is a diagram illustrating a spread code generation method according to the second embodiment, and FIG. 8 is a diagram illustrating a spread code generation method according to the third embodiment. FIG. 9 shows the configuration of a wireless communication system according to a fourth embodiment of the present invention. FIG. 10 is a diagram showing a slot format according to the fourth embodiment, and FIG. 11 is a diagram showing a correlation sequence obtained by the mobile station of Ch # l after despreading. FIG. 12 is a diagram illustrating a configuration of a wireless communication system according to a fifth embodiment of the present invention. FIG. 13 is a diagram illustrating a slot format of the fifth embodiment. FIG. 14 is a diagram showing a state of power versus time when a received signal is spread with a first spreading code. FIG. 15 is a diagram showing a configuration of a sixth embodiment of the wireless communication system according to the present invention. FIG. 16 is a diagram showing a plurality of carriers for transmitting signals. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a spread code generation method, a spread code generation device, and a communication method using a spread code generated by the spread code generation method (or device) according to the present invention will be described with reference to the drawings. This will be described in detail. The present invention is not limited by the embodiment.

Embodiment 1

FIG. 1 is a diagram showing a configuration of a spread code generation device used in a wireless communication system (CDMA) according to the present invention. Basic sequence generator that generates the basic M sequence 1, a sequence phase shift unit 2 that shifts the M sequence phase by a predetermined bit, a partial sequence addition unit 3 that adds a predetermined partial sequence to the beginning or end of the cyclically shifted sequence, and controls the bit shift amount. It comprises a shift control section 4 and an additional control section 5 for determining the size of the above-mentioned subsequence. As before, the condition of the spreading code used in the CDMA is that the autocorrelation peak at the synchronization timing is sharp, the autocorrelation has a small absolute value at other time shifts, and the cross-correlation between different codes is the same as before. It is required that the absolute value be small at the timing of.

FIG. 2 is a diagram showing an example of the configuration of the basic sequence generation unit 1. In the present embodiment, an M sequence having excellent autocorrelation characteristics is adopted as a basic sequence of a spreading code. The spreading code is not limited to this, and for example, an orthogonal Go 1d code based on a Go 1d sequence may be used.

In the present embodiment, for example, assuming that a base station, which is a communication device on the data transmitting side, transmits data to three users (terminals), the spreading code generator 1 Will be described. FIG. 3 is a diagram showing a spread code generating method according to the first embodiment. Note that the M sequence generated by the basic sequence generation unit 1 in FIG. 2 is “00001 0 0 1 1 0 1 0 1 1 1 1”. Further, for convenience of explanation, the shift amount control by the shift control unit 4 will be described in units of 1 bit, and the size of the additional part determined by the addition control unit 5 will be described as 1 bit.

First, in the spreading code generator, the subsequence adding section 3 copies the last one bit of the basic sequence under the control of the addition control section 5 using the M sequence shown in FIG. The first spreading code (16 bits) is generated by adding it to the beginning of the sequence (see Fig. 3). Here, under the control of the shift control unit 4, the shift process by the sequence phase shift unit 2 is not performed.

Next, in the spreading code generation apparatus, the sequence phase shift unit 2 performs a cyclic shift of .1 bits on the basic sequence under the control of the shift control unit 4. Then, under the control of the addition control unit 5, the subsequence sequence addition unit 3 copies the last one bit of the sequence after the cyclic shift, adds it to the beginning of this sequence, and adds it to the second spreading code ( 16 bits) (See Fig. 3).

Finally, in the spreading code generation device, sequence phase shift section 2 performs a one-bit cyclic shift on the basic sequence under the control of shift control section 4 in the same procedure as described above. Then, under the control of the subsequence addition section 31 addition control section 5, the last one bit of the cyclically shifted sequence is copied, and it is added to the beginning of this sequence, and the third spreading code (16 bits) is added. Generate (see Fig. 3).

FIG. 4 is a diagram illustrating correlation characteristics when, for example, a base station transmits data to a user to which a first spreading code is assigned. FIG. 5 is a diagram showing a correlation characteristic when data is transmitted to three users to which base stations ヽ first to third spreading codes are individually assigned. ) transmission data S ₁ to each _user; represents a correlation characteristic when the _{_{S 2, 3 3 "0"}} "0""0", (b) the transmission data S ₁ to each _user; S _2, 3 ₃ represents the correlation characteristic when "0""1""0".

As described above, in the present embodiment, the Hirokag code generation apparatus adds a copy of the end (plural) bits of each sequence to the beginning of the basic sequence and the sequence after cyclic shift in the spread code generation process. I decided that. As a result, good correlation characteristics can be obtained even when a delayed wave (multipath) exists (see FIG. 6). Also, a spreading code is generated by cyclically shifting the basic sequence. As a result, deterioration due to intersymbol interference can be suppressed.

In the present embodiment, for convenience of explanation, the shift amount is controlled by the shift control unit 4 in units of 1 bit, but the present invention is not limited to this, and the shift amount may be shifted in units of 2 bits or more. In addition, the size of the additional portion determined by the additional control unit 5 is 1 bit, but is not limited thereto, and may be 2 bits or more as long as it is shorter than the sequence length of the basic sequence and the sequence after cyclic shift.

Embodiment 2

Next, a spread code generating method according to the second embodiment will be described. Note that the configuration of the spread code generation device is the same as that of the first embodiment described above, and thus the same reference numerals are given and the description thereof will be omitted. Also, for the basic sequence generator 1, As in the first embodiment, the M-sequence generation circuit in FIG. 2 is used. In the present embodiment, only operations different from those of the first embodiment described above will be described.

According to the present embodiment, assuming that a base station, which is a communication device on the data transmission side, transmits data to three users (terminals), A case where a spread code is generated will be described. FIG. 7 is a diagram illustrating a spread code generation method according to the second embodiment.

First, the spreading code generation apparatus copies the first bit of the basic sequence under the control of the subsequence addition unit 3 and the addition control unit 5 using the M sequence shown in FIG. The first spreading code (16 bits) is added to the tail (see Fig. 7). Here, under the control of the shift control unit 4, the shift process by the sequence phase shift unit 2 is not performed.

Next, in the spreading code generation apparatus, the sequence phase shift unit 2 performs a one-bit cyclic shift on the basic sequence under the control of the shift control unit 4. Then, under the control of the subsequence sequence addition unit 3 and the control unit 5, the first bit of the sequence after the cyclic shift is copied and added to the end of this sequence, and the second spreading code (16 Bit) (see Figure 7). Finally, in the spreading code generation apparatus, sequence phase shift section 2 performs a one-bit cyclic shift on the basic sequence under the control of shift control section 4 in the same procedure as described above. Then, under the control of the addition control unit 5, the subsequence addition unit 3 copies the first bit of the sequence after the cyclic shift, attaches it to the end of this sequence, and adds a third spreading code (16 bits) (see Fig. 7).

As described above, in the present embodiment, the spreading code generation apparatus adds a copy of the head (multiple) bits of each sequence to the end of the basic sequence and the sequence after the cyclic shift in the spreading code generation process. I decided. As a result, good correlation characteristics can be obtained even when a delayed wave (multipath) is present. In addition, a spreading code is generated by cyclically shifting the basic sequence. Thus, deterioration due to intersymbol interference can be suppressed. Embodiment 3.

Next, a spreading code generation method according to the third embodiment will be described. Note that the configuration of the spread code generation device is the same as that of the first embodiment described above, and thus the same reference numerals are given and the description thereof will be omitted. Also, basic sequence generation section 1 uses the M-sequence generation circuit of FIG. In the present embodiment, only operations different from those of the above-described first or second embodiment will be described.

Also in the present embodiment, on the assumption that a base station, which is a communication device on the data transmitting side, transmits data to three users (terminals), the spreading code generation device generates three spreading codes. The case will be described. FIG. 8 is a diagram illustrating a spread code generation method according to the third embodiment.

First, in the spreading code generator, the subsequence sequence adding section 3 copies the first bit of the basic sequence under the control of the addition control section 5 using the M sequence shown in FIG. Add to the end. Furthermore, the last one bit of the basic sequence is copied and added to the beginning of the basic sequence to generate the first spreading code (17 bits) '(see Fig. 8). Here, under the control of the shift control section 4 ', the shift processing by the sequence phase shift section 2 is not performed.

Next, in the spreading code generation device, the sequence phase shift unit 2 performs a one-bit cyclic shift on the basic sequence under the control of the shift control unit 4. Then, under the control of the partial sequence addition section 31 ′ addition control section 5, the first bit of the sequence after the cyclic shift is copied, and it is added to the end of this sequence. Furthermore, the last one bit of the sequence after the cyclic shift is copied and added to the beginning of this sequence to generate a second spreading code (17 bits) (see Fig. 8).

Finally, in the spreading code generation device, sequence phase shift section 2 performs a one-bit cyclic shift on the basic sequence under the control of shift control section 4 in the same procedure as described above. Then, under the control of the addition control unit 5, the subsequence addition unit 3 copies the first bit of the sequence after the cyclic shift and adds it to the end of this sequence. Furthermore, copy the last 1 bit of the sequence after cyclic shift and add it to the beginning of this sequence. Then, a third spreading code (17 bits) is generated (see FIG. 8).

As described above, in the present embodiment, in the spreading code generation process, the spreading code generation apparatus sets the start and end of the base sequence and the sequence after the cyclic shift to copy and start the last bit of each sequence, respectively. We decided to add a copy of the bit. As a result, good correlation characteristics can be obtained even when a delayed wave (multipath) exists. In addition, spreading codes are generated by cyclically shifting the basic sequence. As a result, deterioration due to intersymbol interference can be suppressed.

In this embodiment, for convenience of explanation, the size of the additional portion determined by the additional control unit 5 is made equal (.1 bit) before and after, but is not limited to this, and may be larger than the sequence length of each sequence. If it is short, it can be 2 bits or more. :

Embodiment 4.

FIG. 9 is a diagram showing the configuration of a wireless communication system according to a fourth embodiment of the present invention. Specifically, (a) shows the configuration of a communication device (base station) on the transmission side, and (b) Represents the configuration of the communication device (mobile station) on the receiving side. The base station according to the present embodiment uses the first to N-th spreading codes generated by the methods of Embodiments 1 to 3 to transmit data S _x (t), S ₂ (t),. .., 11 1-N, and a multiplexing unit 12 for multiplexing the spread signals. Note that the spread code generation apparatuses according to Embodiments 1 to 3 described above may be located inside the base station or outside the base station. Also, the mobile station of the present embodiment includes a despreading unit 21 for despreading with the user-specific spreading code, a correlation sequence calculating unit 22 for correlating with a given reference signal, and a known sequence. An in-phase addition unit 23 for in-phase addition, a square value calculation unit 24 for calculating a power value from the in-phase addition result, and a channel estimation unit 25 for calculating a channel estimation value using the in-phase addition result. A delay unit 26 for adding a predetermined delay to the spread signal, a sampling unit 27 for sampling the despread signal after the delay, and a phase compensation unit 2 for compensating the phase of the sampling signal based on the channel estimation value 8 and a data determination unit 29 for determining a signal after phase compensation.

Here, the communication method according to the present embodiment will be described. At the base station, the number of mobile stations Each of the spreading units (111-11-111N) according to the first to Nth spreading codes generated by the method according to the first to third embodiments uses known sequences # 1 to #N, Transmission data S ₁

(t) to S _N (t) are spread for each symbol. Then, the multiplexing unit 12 multiplexes the spread signal and transmits the multiplexed signal over the wireless transmission.

On the other hand, in each mobile station, first, each despreading unit 21 despreads the known sequence portion of the received signal in symbol units using the first to Nth spreading codes unique to the user, and obtains a desired correlation sequence. Is extracted.

FIG. 10 is a diagram showing a slot format according to the fourth embodiment. In the present embodiment, the first to Nth spreading codes are assigned to each user (mobile station) (channels Ch i to N), and known sequences # 1 to #N are assigned to some of the slots. Has been introduced. In this known sequence, bits having an arbitrary code are arranged in the channel direction at the same symbol time. When focusing on the channel direction, the amount of phase shift of the spreading code increases as the channel number (1 to N) increases. For example, when each mobile station performs despreading using the unique spreading code at the same timing, a unique correlation sequence corresponding to the shift amount of the spreading code is obtained. That is, when the code multiplexing number is N, an N-bit correlation sequence is output.

The first 1 figure known sequence (t) ~S ₇ (t) is ".", "1", "0", "0", "0", "1", "1" (N = 7) FIG. 7 is a diagram showing a correlation sequence obtained after despreading by the mobile station of Ch # 1 in the case of. In this way, the mobile station of Ch # 1 obtains a correlation sequence of "010001 1", and although not shown, the mobile station of Ch # 2 obtains a correlation sequence of "10001 10". In addition, other mobile stations can obtain a correlation sequence that is cyclically shifted by 1 bit with the increase in channel number. In the present embodiment, the case where the phase shift amount between adjacent channels is in units of 1 bit is not limited to this, and the shift may be performed in units of 2 bits or more. Also, the shift may be performed at unequal bit intervals.

Next, in each mobile station, the correlation sequence calculation unit 22 calculates a correlation between the despread signal and a predetermined reference signal of the same symbol for each received symbol, and Establish a period. 'Next, the in-phase addition unit 23 increases the correlation power by performing in-phase addition on the correlation sequences output from the correlation sequence calculation unit 22 over the number of symbols. Then, channel estimation section 25 performs channel estimation using the in-phase addition result. Thus, in the present embodiment, while adding power for the number of code multiplexes in one symbol to improve S / N (Signal to Noise ratio), in-phase addition is performed for the number of symbols in the known sequence. By doing so, slot position detection processing and synchronization establishment processing are performed.

Further, the square value calculating section 24 calculates a power value (correlation value) from the in-phase addition result, and outputs the value to the sampling section 27. The delay unit 26 adds a time corresponding to the processing time of the correlation sequence calculation unit 22, the in-phase addition unit 23, and the square value calculation unit 24 to the despread signal of the despreading unit 21, Make adjustments. The sampling section 27 samples the despread signal after the delay adjustment based on the correlation value of the output of the square value calculation section 24. The phase compensator 28 compensates the phase of the sampled despread signal based on the channel estimation value output from the channel estimation unit 25. Then, the data determination section 29 determines the signal after the phase compensation and outputs a data series of “0” or “1”. -.

As described above, in the present embodiment, the mobile station despreads the known sequence portion of the received signal using the user-specific spreading code generated and assigned by the method of Embodiments 1 to 3, The synchronization establishment process and the channel estimation process were performed using the results. Thus, the same effects as in Embodiments 1 to 3 can be obtained, slot positions can be detected with high accuracy, and channel estimation with high accuracy can be realized. "

Although the case has been described with the present embodiment where the phase shift amount of the spreading code increases as the channel number (1 to N) increases, the present invention is not limited to this, and the channel number (1 to N) increases. , The phase shift amount of the spreading code may be reduced.

Embodiment 5- FIG. 12 is a diagram showing a configuration of a wireless communication system according to a fifth embodiment of the present invention. Specifically, (a) shows the configuration of a communication device (base station) on the transmitting side, and (b) Represents the configuration of the communication device (mobile station) on the receiving side. The base station according to the present embodiment includes a multiplier 13 for multiplying the spread signal of Ch # 1 by a predetermined gain (G). It is configured to include a despreading unit 31 that despreads the received signal of Ch # 1 with a common spreading code. Here, Ch # 1 is a dedicated channel of a known sequence, and all users share the first spreading code. In addition. Other configurations of the base station and the mobile station according to the present embodiment are basically the same as those of the fourth embodiment described above, and thus the same reference numerals are given and the description thereof will be omitted. The present embodiment is different from Embodiment 4 described above. Only the operation will be described. Here, a communication method according to the present embodiment will be described. In the base station, spreading section 11... 1 spreads known sequence S ₁ (t) for each symbol using the first spreading code generated by the method according to the first to third embodiments. Then, the multiplier 13 multiplies the spread known sequence by a predetermined amount of gain. Also, each spreading section (1 1-2-11-N) according to the number of mobile stations to be accommodated is transmitted using the second to Nth spreading codes generated by the method of Embodiments 1 to 3. S ₂ (t) to S _N (t) are spread for each symbol. Then, the multiplexing unit 12 multiplexes all the spread signals and transmits the multiplexed signals on the radio transmission path. .

On the other hand, in each mobile station, first, each despreading section 31 despreads the received signal in symbol units using a first spreading code provided to each user, and extracts a desired correlation sequence. . '

FIG. 13 is a diagram showing a slot format according to the fifth embodiment. In the present embodiment, a known sequence (power amplification) spread with a first spreading code is assigned to channel Ch # l, and a second channel for each user (mobile station) is assigned to channel # 2 to #N. Transmission data S ₂ (t) to S _N (t) spread with the Nth spreading code are assigned. FIG. 14 is a diagram showing a state of power versus time when a received signal is spread with a first spreading code. Thus, when the received signal is spread by the first spreading code, The signal after despreading has higher power than the signal of each user. Therefore, the power of the signal after the in-phase addition becomes larger than the signal of each user, and the correlation power value obtained by the square value calculation becomes the largest, so that the slot position detection processing and the synchronization establishment processing are performed with high accuracy. It can be performed.

In addition, the delay unit 26 adds a time corresponding to the processing time of the in-phase adder 23 and the square value calculator 24 to the received signal to adjust the delay. The despreading unit 21 despreads the delay-adjusted received signal using a user-specific spreading code to extract a desired signal. The sampling section 27 samples the despread signal based on the relative value of the output of the square value calculation section 24.

As described above, in the present embodiment, one of the spreading codes generated by the methods of Embodiments 1 to 3 is used as a spreading code common to each user, and the base station uses a spreading code common to each user. The known sequence after spreading the known sequence using a code and amplifying the signal power is multiplexed with the spread signal of each user and transmitted, and the mobile station uses a common spreading code for each user. The received signal is despread, and the synchronization establishment process and channel estimation process are performed using the result. Thereby, the same effect as in Embodiment 13 can be obtained, the slot position can be detected with high accuracy, and highly accurate channel estimation can be realized.

Embodiment 6

FIG. 15 is a diagram showing a configuration of a wireless communication system according to a sixth embodiment of the present invention. FIG. 16 is a diagram showing a plurality of carriers for transmitting signals. In the present embodiment, as the communication device on the transmission side, the configuration of the communication device on the transmission side of Embodiment 4 or 5 (the transmission data S _u (t) to S _1N (t) shown in FIG. A configuration including a spreading unit 11 1 to ^^ that spreads with a spreading code, and a spreading unit 1 L that spreads transmission data S _M1 (1 :) to S _MN (t) with first to N _{M th} spreading codes. 1 configuration with to N _M, comprises a plurality accordance considerable) to carrier number, it converts the frequency of the frequency converter 1 4 one 1 ~M 1 each multiplexer 1 and second output signals, multiplexer 15 multiplexes the frequency-converted signal and outputs the multiplexed signal. In the communication device on the receiving side, the frequency selection unit The signal of the desired carrier selected by 41 is demodulated using the communication device on the receiving side according to the fourth or fifth embodiment.

As described above, in the present embodiment, by using a plurality of carriers, the communication capacity is increased without increasing inter-code interference. In this embodiment, information for selecting a carrier is notified using a specific channel of a specific carrier in order to determine which carrier carries a signal to the own mobile station. Industrial applicability

As described above, the spreading code generation method, the spreading code generation device, and the communication method according to the present invention are useful for a wireless communication system employing CDMA, and are particularly useful for generating a user-specific spreading code. Suitable for technology.

Claims

The scope of the claims

1. In a spreading code generation method for generating a user-specific spreading code used in a wireless communication system employing a code division multiple access method,

A predetermined basic sequence having excellent autocorrelation characteristics is cyclically shifted over one or more bits, and a copy of the last one bit or a plurality of bits from the last in the shifted sequence is copied. A code generation step to add to the beginning of the sequence, '

A spreading code generation method, characterized in that a user-specific spreading code is generated by repeatedly executing the code generation step a predetermined number of times using the shifted sequence as a basic sequence of. .

'2. In a spreading code generation method for generating a user-specific spreading code used in a wireless communication system employing a code division multiple access scheme,

A predetermined basic sequence having excellent auto-correlation characteristics is cyclically shifted over one or more bits, and a copy of one or more bits from the beginning of the shifted sequence is copied to the end of the sequence after the shift. A code generation step to be added to the tail,

A spreading code generation method, characterized in that a user-specific spreading code is generated by repeatedly executing the code generation step a predetermined number of times using the shifted sequence as a next basic sequence.

3. In a spreading code generation method for generating a user-specific spreading code used in a wireless communication system employing a code division multiple access scheme,

A predetermined basic sequence having excellent autocorrelation characteristics is cyclically shifted over one or more bits, and a copy of the last one bit or a plurality of bits from the last in the shifted sequence is copied. At the beginning of the series, A code generation step of adding a first bit or a copy of a plurality of bits from the beginning of the sequence after the shift to the end of the sequence after the shift,

4. In a spread code generation device that generates a user-specific spread code used in a wireless communication system employing a code division multiple access scheme,

Sequence phase shift means for cyclically shifting a predetermined basic sequence having excellent autocorrelation characteristics over single or multiple bits,

Subsequence adding means for adding a part (subsequence) of the shifted sequence to the beginning or end of the shifted sequence;

With

Using the sequence after the shift as a basic sequence, the processing in the sequence phase shift means and the partial sequence addition means is repeatedly executed a predetermined number of times to generate a user-specific spreading code. Spreading code generator.

5. The subsequence adding means adds a last one bit or a copy of a plurality of bits from the last (the subsequence) in the sequence after the silat to the beginning of the sequence after the shift. Spreading code generator according to claim 4

6. The subsequence adding means adds a first bit or a copy of a plurality of bits from the head (the subsequence) in the shifted sequence to the end of the shifted sequence. 5. The spread code generation device according to claim 4, wherein:

7. The subsequence adding means performs the last one bit in the shifted sequence. Alternatively, a copy of a plurality of bits from the end (the subsequence) is added to the beginning of the sequence after the shift, and a copy of the first one bit or a plurality of bits from the start in the sequence after the shift 5. The spread code generation device according to claim 4, wherein (the subsequence) is added to the end of the sequence after the shift.

8. In a communication method between a base station and a mobile station in a wireless communication system employing a code division multiple access method,

A predetermined basic sequence having excellent autocorrelation characteristics is cyclically shifted over one or more bits, and a part (subsequence) of the shifted sequence is added to the beginning or end of the shifted sequence. A code generation process is performed to generate a first spread code. Thereafter, the code generation process is repeated and performed a predetermined number of times using the shifted sequence as a next basic sequence, thereby obtaining a user ( Mobile station) a spreading code generating step for generating unique second to 'N'th (arbitrary integer) spreading codes;

The base station uses the first to N-th spreading codes to spread the first to N-th known sequences and the first to N-th transmission data according to the number of accommodated mobile stations for each symbol, A transmission processing step of multiplexing and transmitting the spread signal,

Each of the mobile stations extracts the desired known sequence by despreading the known sequence portion of the received signal in symbol units using the first to N-th spreading codes assigned to the user. A reception processing step of performing synchronization establishment processing and channel estimation processing using

A communication method comprising:

9. The base station according to claim 8, wherein the transmission processing step is executed by a plurality of carriers, and each of the mobile stations executes the reception processing step after selecting a carrier to be used. Communication method described in.

10. In the spreading code generation step, the last code in the shifted sequence is 9. The communication method according to claim 8, wherein one bit or a copy of a plurality of bits from the end is added to the beginning of the sequence after the shift. 11. The spreading code generation step is characterized in that a copy of the first one bit or a plurality of bits from the top (the subsequence) in the sequence after the shift (the subsequence) is added to the end of the sequence of the shift '. 9. The communication method according to claim 8, wherein:

1 2. In the spreading code generation step, a copy of one bit at the end or a plurality of bits from the end of the sequence after the shift (the subsequence) is added to the beginning of the sequence after the shift. And further adding a first bit or a copy of a plurality of bits from the head (the subsequence) in the sequence after the shift to the end of the sequence after the shift. Communication method according to clause 8. 13 3. In a communication method between a base station and a mobile station in a wireless communication system adopting the code division multiple access method,

A predetermined basic sequence having excellent autocorrelation characteristics is cyclically shifted over one or more bits, and a part (subsequence) of the shifted sequence is added to the beginning or end of the shifted sequence. A code generation process is performed to generate a first spread code, and thereafter, the shifted sequence is used as a next basic sequence, and the code generation process is repeatedly performed a predetermined number of times to execute the code generation process. A second to Nth (arbitrary integer) spreading code generating step,

The base station spreads a known sequence for each symbol using a specific spreading code for a dedicated channel defined in advance, and further uses the remaining spreading codes to generate first to fourth mobile stations corresponding to the number of mobile stations to be accommodated. A transmission processing step of spreading the (N-1) th transmission data for each symbol, multiplexing and transmitting all the spread signals,

Each mobile station uses the specific spreading code for the dedicated channel to receive A reception process step of extracting a desired known sequence by despreading the signal in symbol units and performing synchronization establishment processing and channel estimation processing using the extraction result;

A communication method comprising:

5 14. The base station, wherein the transmission processing step is performed on a plurality of carriers, and each of the mobile stations, after selecting a carrier to be used, executes the reception processing step. 13 Communication method described in 3.

15. In the spreading code generation step, the last 10.1 bits of the sequence after the shift or a copy of a plurality of bits from the last (the partial sequence) is added to the beginning of the sequence after the shift. The communication method according to claim 13, wherein the communication method is performed. '

16. In the spreading code generation step, a copy of the first 115 bits or a plurality of bits from the head (the subsequence) in the shifted sequence is added to the end of the shifted sequence. The communication method according to claim 13, wherein:

17. In the spread code generation step, a copy of the last 201 bits or a plurality of bits from the end (the subsequence) of the sequence after the shift is added to the beginning of the sequence after the shift. And further adding a first bit or a copy of a plurality of bits from the head (the subsequence) in the sequence after the shift to the end of the sequence after the shift. Communication method according to paragraph 13.