JPH10126378A - Cdma communication system, mobile station and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mis-identification of a long code and to attain high speed identification of the long code, with respect to the code division multiple access(CDMA) communication system, the mobile station and the communication control method. SOLUTION: A base station 2 conducts spread modulation by using a long code and a short code, and a transmission section 13 transmits spread data that is subject to spread modulation by only a short code at each prescribed position of long codes. A mobile station 1 uses a reception section 4 to receive the data, a short code identification section 7 of a control processing section 6 applies identification processing of the short code to the data, a long code identification section 8 applies identification processing of the long code to the data, based on the identification timing of the short code, a reception level (correlation value) in a same timing group of the long code is stored in a reception level table 10 and a long code corresponding to the maximum reception level is adopted and reception inverse spread demodulation is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA communication system, a mobile station, and a communication control method for operating distributed base stations in an asynchronous manner between base stations. CDMA (Code Division Multiple Access) as one of mobile communication systems including a plurality of base stations and a plurality of mobile stations.
Communication systems include a synchronous system in which the distributed base stations are synchronized with each other and an asynchronous system in which the base stations are not synchronized. The former synchronization method uses GPS (global pos).
Synchronization is performed in accordance with high-precision time information, such as by the sched- ing system.
And so on, so that the cost can be reduced. There is a demand for facilitating identification of the despreading code on the receiving side with respect to the spreading code on the transmitting side in this asynchronous system.

[0002]

2. Description of the Related Art A mobile communication system is an FDMA system,
Various systems such as a DMA system and a CDMA system are known, and as the CDMA system, a system to which the above-described synchronization system is applied has been put to practical use. In this case, a spreading long code having a long cycle is used as the spreading code, and each base station sets the timing of the head position of the same spreading long code so as to have a predetermined time difference based on accurate time information by GPS or the like. You have set. That is, the base station can be identified by the timing of the spreading long code.

At the time of handover, the base station notifies the serving mobile station of timing information of the head position of the spread long code in the adjacent base station, so that the mobile station can spread the new base station. It is easy to determine whether the timing of the head position of the long code is ahead or behind the timing of the head position of the current base station spreading long code, so that synchronization can be easily established with a new base station. And communication can be continued.

However, a CDMA communication system to which the synchronization system is applied requires that all base stations have a high-precision clock function using a GPS device or the like. You need a clock function to adjust with. In addition, each base station needs a configuration for controlling the timing of the head position of the spread long code with this high-precision clock function with high precision. Further, since it is necessary that the installation location of the base station can receive GPS, a problem occurs, for example, in a basement or the like. Therefore, there is a problem that the cost of the whole CDMA communication system increases.

[0005] In contrast to the synchronous system, the asynchronous system does not require a GPS device or the like in each base station, and can reduce the cost of the CDMA communication system. But,
In the asynchronous system, it is necessary to pull in the synchronization of the spread long code every time the communication between the mobile station and the base station starts, and if only the spread long code is used, the time required for identification (search + synchronization) is required. Becomes longer.

Therefore, there is known a means for reducing the time required for identification by using a diffusion short code. For example,
Number of chips of the diffusion short code (2 ^m -1), (2 ^n-
1),... (2 ^r −1) (where m ≠ n ·· ≠ r) and the like are known, and in this case, a correlation value with each of the above-mentioned spread short codes is known. By applying the method of repeating the calculation of, it is possible to reduce the time required for identification as compared with the processing of obtaining the correlation value over the entire length of the spread long code. But,
This method has a problem that the length of the diffusion short code is different.

In addition, double spreading modulation is performed by a spreading long code having 2 ¹² chips and a spreading short code having 2 ⁶ chips, and spreading is performed only by the spreading short code at each predetermined position in the cycle of the spreading long code. The modulated spread data (the spread long code is masked) is transmitted, and the spread data that has been spread-modulated only by the spread short code is subjected to the spread short code identification processing. A two-stage search method for performing long code identification processing is known.

FIG. 12 is an explanatory diagram of cells and sectors.
Base stations BS1, BS2, in a CDMA communication system
Divide the cell by BS3 into 6 sectors each,
Different spreading long codes SC11 to SC for each sector
16, SC21 to SC26 and SC31 to SC36 are assigned, and the mobile station MS at the illustrated position receives spread data from the base station and despreads by the process of identifying the spread long code SC11 of the serving sector. It will be demodulated.

In that case, the base stations BS1, BS2, BS
3 performs, for example, double spreading modulation using a spreading long code and a spreading short code as described above, and masks the spreading long code at each predetermined timing of the spreading long code, so that only the spreading short code is used. , For example, as shown in S in BS1, BS2, and BS3 of FIG. 13, at a predetermined position in the long code cycle, for example, the head position of the long code cycle. CDMA that performs spread modulation only with a spread short code and transmits spread data spread and modulated with a spread long code L1, L2, L3 corresponding to a base station and a spread short code during other periods.
Communication systems are known.

[0010] As a spreading code identification means in a CDMA communication system, for example, means using a matched filter and means using a sliding correlator are known. The former matched filter is capable of high-speed identification, but the circuit scale increases in accordance with the period of the spreading code, and the latter has a relatively small circuit scale, but high-speed identification is difficult. It is.

Therefore, the spreading short code is CDMA
All patterns are the same in the communication system.
^{Since 6} = 64 bits, even if a matched filter is applied, the circuit scale does not increase and high-speed identification becomes possible. A spreading correlator is applied to a spreading long code having a 2 ¹² or ²⁴² bit configuration, and the timing of the spreading long code can be detected by a spreading short code. The identification process can be performed at an extremely high speed.

[0012]

In the above-described process of identifying a spread short code, for example, as shown in CR1 (the output of the correlator corresponding to the base station BS1) in FIG.
When the correlation value exceeds the threshold value TH, it can be identified that the spread short code of the base station BS1 has been identified, and the spread long code is identified based on this timing.

However, the mobile station MS is not located only in the vicinity of the base station BS1.
Radio waves from S2 and BS3 can also be received. For example, as shown by CR2 in FIG. 13, the correlation value of the spread short code S of the base station BS1 exceeds the threshold value TH, and the spread short code S of the base station BS3. May exceed the threshold TH.

In this case, even if the mobile station MS is located in the cell of the base station BS1, the correlation value of the spread short code S of the base station BS3 first exceeds the threshold value TH. The identification process is started for the spread long code of. That is, there is a problem that an incorrect identification process is started.

In FIG. 12, for example, base station BS1
The mobile station MS is located in the sector No. 1, and is identified as a spreading short code, and spreading long codes SC11, SC12,.
If the identification process is performed in the order of
Since the correlation value by 11 exceeds the threshold value, it can be identified as the spread long code SC11. However, when the identification process is performed in the order from the spread long code SC12, the identification process by the spread long code SC11 is the last. In this case, if the correlation value of the spread long code SC12 exceeds the threshold value, the spread long code SC
There is a problem that it is determined that the identification has been made to C12, and an erroneous identification state occurs. It is an object of the present invention to prevent erroneous identification of a spread long code and to enable high-speed identification.

[0016]

The CDMA communication system according to the present invention will be described with reference to FIG. 1. (1) Asynchronous CDMA system including a plurality of base stations 2 and a plurality of mobile stations 1.
In the communication system, the base station 2 performs spread modulation using a spread long code and a spread short code,
The mobile station 1 has a configuration for transmitting spread data that has been subjected to spread modulation using only a spread short code to a predetermined position within the cycle of the spread long code. A long code identification process is performed, and by identifying the spread long code, an identification process using another type of spread long code is performed for a group at the same timing of the spread long code to form a reception level table 10. Table 10
Has a configuration that employs a spreading long code corresponding to the maximum reception level. Therefore, for example, spreading long codes for different sectors in the same cell form the same group because they have the same timing, and the sector having the highest reception level (correlation value) in this group is assigned to the mobile station 1. It is determined that the sector is a service sector, and despread demodulation is performed using a spreading long code corresponding to the sector.

(2) The base station 2 performs spread modulation using a spread long code and a spread short code, and transmits spread data obtained by performing spread modulation using only the spread short code to a predetermined position of the spread long code. The mobile station 1 divides the group with the same timing of the spread long code into a plurality of groups based on the timing based on the identification of the spread short code, and performs identification processing for one divided group to perform other identification. Of the divided group, and a reception level table 10 for the same group is formed by identifying the spread long code, and a spread long code corresponding to the maximum reception level in the reception level table 10 is adopted. Things. In this case, for example, every other odd-numbered sector in the same cell can be set as one divided group, and the even-numbered sector can be set as another divided group. That is, identification processing is performed sequentially for every other or every two.

Further, the mobile station in the CDMA communication system of the present invention performs (3) spread modulation using a spread long code and a spread short code, and performs the spread short code at a predetermined position within the cycle of the spread long code. A short code identification unit 7 that receives spread data that has been subjected to spread modulation by only the short code and performs a process of identifying a spread short code; and a process of identifying a spread long code based on the timing of the short code by the short code identification unit 7. And a reception level table 10 for storing the reception level in the long code identification processing by the long code identification unit 8. The reception level table 10 has a diffusion length corresponding to the maximum reception level. It has a configuration to set the code as a long spreading code in the serving area in the long code generator. It is.

(4) The long code identification unit 8 in the mobile station has a setting control unit, a long code generation unit, and a long code table. Is read out and set in the long code generator, and when the correlation value between the spread long code from the long code generator and the received wave exceeds the threshold value, the long codes are sequentially read for different spread long codes at the same timing. Control to generate from the generation unit, and the reception level corresponding to the spread long code,
It has a configuration in which it is stored in the reception level table 10 and a spread long code corresponding to the maximum reception level of the reception level table 10 is adopted and set in the long code generation unit.

(5) The setting control section in the mobile station divides each group of different spread long codes at the same timing into a plurality of groups, and generates long code initial values of different spread long codes in the divided groups sequentially. When the correlation value from the long code generator from the long code generator exceeds the threshold value, the reception level corresponding to the long code in the group is stored in the reception level table 10. It has a configuration in which a spread long code corresponding to the maximum reception level is adopted and set in the long code generation section.

(6) The setting control unit in the mobile station stores one or a plurality of spreading long codes identified in the past, and starts identification of the spreading long codes using the spreading long codes as priority codes. It can have a priority code table.

(7) The priority code table of the mobile station is as follows:
A configuration for updating the priority of the stored priority code in accordance with the process of identifying the spread long code can be provided.

(8) Long code determination section 8 of mobile station
Sets the initial values of a plurality of types of spreading long codes at the same time to generate different spreading long codes at the same timing, and spreads the spreading long codes from the plurality of long code generating units. It is possible to have a changeover switch for sequentially switching and outputting within the cycle of the long code, and a correlator for adding the spread long code output through this changeover switch.

(9) Long code determination section 8 of mobile station
Is a code table that stores values at different timings from the beginning timing of a plurality of types of spread long codes, and a long code is generated by switching values of spread long codes at different timings stored in the code table. And a changeover switch to be set in the section.

Further, the communication control method in the CDMA system according to the present invention is characterized in that (10) the base station 2 performs spread modulation with a spread long code and a spread short code, and at a predetermined position within the cycle of the spread long code, The mobile station 1 transmits spread data subjected to spread modulation using only the spread short code, and performs identification processing of the spread long code based on the timing by the identification of the spread short code. Identification processing is performed by using different spread long codes for the same group of spread long codes at the same timing, the reception level is detected, and this reception level is stored in the reception level table 10. Includes the process of despreading demodulation using the corresponding spreading long code

(11) The base station 2 transmits spread data obtained by performing spread modulation using the spread long code and the spread short code, and performing spread modulation using only the spread short code at a predetermined position within the cycle of the spread long code. Then, the mobile station 1 divides the inside of the group of the spread long code at the same timing into a plurality of parts, performs an identification process for each of the divided groups with different spread long codes, and, when identification is impossible, different spread long codes for the other divided groups. , An identification process is performed. When identification is possible, reception levels corresponding to different spread long codes in the group are detected and stored in the reception level table 10, and the reception levels corresponding to the maximum reception levels in the reception level table 10 are corresponded. It includes a process of performing despread demodulation using a spread long code.

(12) In the process of identification using a spread long code in the communication control method, the beginning timings of a plurality of different spread long codes are set to be the same, and different timings within the cycle of the spread long code are used. The method may include initiating identification with different spreading long codes.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the principle of the present invention, which includes a mobile station 1 and a base station 2. The base station 2 is distributed and connected to an upper station 3 such as an exchange. CDMA
1 shows a communication system. The base station 2 includes a receiving unit 12, a transmitting unit 13, and a control unit 14, and the mobile station 1 includes a receiving unit 4
, A transmission unit 5, and a control processing unit 6. The control processing unit 6 includes a short code identification unit 7, a long code identification unit 8, a long code table 9, a reception level table 10, The antenna 11 is included.

Under the control of the control unit 14, the base station 2 sends from the transmission unit 13 the spread short codes of the same pattern and the different patterns assigned to each base station 2 or sector as described above. Double-spread modulation with a spread long code (hereinafter, "spread" is omitted), and mask a long code at a predetermined position such as the start position of the long code cycle (spread modulation with an inverted long code), and short-circuit The data is transmitted as spread data that is spread-modulated only by the code.

The short code identification unit 7 of the mobile station 1
For example, it includes a matched filter, a short code generation unit, and a timing detection unit, and the long code identification unit 8 includes, for example, a long code generation unit, a sliding correlator, and a threshold value determination unit. The spread data from the base station 2 is received by the reception unit 4 via the antenna 11 and the short code identification unit 7 of the control processing unit 6 performs short code identification processing.

After the identification of the short codes, the long code identification section 8 sequentially generates different long codes to perform a long code identification process. In this case, the reception level (correlation value) in the process of identifying a long code is stored in the reception level table 10, and despread demodulation is performed by adopting the long code having the maximum reception level. Thus, a long code for despread demodulation can be generated in synchronization with a correct long code.

As shown in FIG. 12, the cells corresponding to the base station 2 have different long codes in the sectors obtained by dividing the cells of the base stations BS1, BS2, and BS3. It will be in a synchronized state.
In this case, for example, by performing identification processing for odd-numbered sectors, and then performing identification processing for even-numbered sectors, interference in adjacent sectors can be reduced and a correct long code can be quickly drawn. it can.

FIG. 2 is an explanatory view of a main part of a base station according to an embodiment of the present invention, wherein 21 is an antenna, 22 is a transmitting section, and 23 to
25 is a modulator such as a balanced modulator, 26 is a short code generator, 27 is an inverted long code generator, 28 is a long code generator, and 29 is a timing controller. 14 is shown, and the system of the receiving unit 12 is not shown.

For example, the control data of the control channel is spread-modulated by the short code from the short code generator 26 in the modulator 23, and spread by the inverted long code from the inverted long code generator 27 in the modulator 24. The modulation is performed by the modulation unit 25 and the long code generation unit 28
Is spread-modulated by the long code from At this time, the inverted long code is generated at the head position of the long code cycle, for example, for the short code cycle. As a result, the spread modulation by the long code is canceled, and during that period, the spread modulation is performed only by the short code. Then, the signal is transmitted from the transmission unit 22 via the antenna 21.

Therefore, as shown in FIG. 13, the spread data S using only the short code is transmitted, for example, at the head position of the long code period. In addition, the spread data S using only the short code can be provided at a plurality of locations at a predetermined timing within the long code cycle, thereby speeding up the identification process for the short code in the mobile station.

FIG. 3 is an explanatory view of a main part of a mobile station according to an embodiment of the present invention, wherein 31 is an antenna, 32 is a reception amplification processing unit, 33 is a matched filter (MF), 34 is a timing detection unit, and 35 is Short code generator (SCG), 3
6 is a synthesis unit, 37 is a sliding correlator (SCR),
38 is a correlation value judgment unit, 39 is a long code judgment control unit,
Reference numeral 40 denotes a despreading processing unit.

The matched filter 33, the timing detecting section 34 and the short code generating section 35 constitute the short code identifying section 7 in FIG. 1, and the synthesizing section 36, the sliding correlator 37, the correlation value judging section 38 and the long code The code determination control unit 39 forms the long code identification unit 8 in FIG. Also, the reception amplification processing unit 31
Includes a high-frequency amplifier, a demodulator, an AD converter, and the like, and outputs a digital signal having a plurality of bits so that the reception level can be identified. The sliding correlator 37 may be another correlator already known.

FIG. 4 is an explanatory diagram of a long code determination control unit according to the embodiment of the present invention, wherein 41 is a setting control unit, 42 is a long code generation unit, 43 is a long code table,
Reference numeral 4 denotes a reception level table. For example, as shown in FIG. 12, when each of the cells 1 to N corresponding to the base station is divided into six sectors 1 to 6, as shown in FIG.
SC16, SC21 to SC26, ..., SCn1 to SC
It stores the initial value of n6.

In the long code identification process, the setting control section 41 sequentially reads out the initial values of the long codes from the long code table 43, and
The long code generation unit 42 generates a long code according to the initial value, adds the long code to the synthesis unit 36, and synthesizes the long code with the short code from the short code generation unit 35 (see FIG. 3). It is input to a sliding correlator 37, and performs identification processing of a long code on received spread data that has been double-spread modulated by a short code and a long code, and determines whether or not the correlation value exceeds a threshold value in a correlation value determination unit 38. Is stored in the reception level table 44 when the reception level is exceeded. If the value does not exceed the threshold value, the fact that the threshold value is not exceeded may be stored in the reception level table 44.

The reception level table 44 is configured to store, for example, the number of the initial value of the long code when the correlation value exceeds the threshold value and the reception level (correlation value) in correspondence with each other. The long code corresponding to the number of the initial value at which the reception level becomes the maximum is adopted, set in the long code generation unit 42, and despread demodulation is performed. The reception level in this case indicates a value corresponding to the reception level of the digital signal subjected to the AD conversion in the reception amplification processing unit 32 (see FIG. 3), and the sliding correlator 37 correlates using the digital signal. Since the value is obtained, the maximum correlation value corresponding to the long code is a value corresponding to the reception level. Therefore, this correlation value can be stored in the reception level table 44 as the reception level.

FIG. 5 is a flow chart of the first embodiment of the present invention. For example, as shown in FIG. 12, a case where a cell is divided into six sectors corresponding to a base station is shown. Assuming that sec. = 6 and the counter value i = 1 (A1), the matched filter 33 (see FIG. 3) identifies the short code from the short code from the short code generator 35.

During this time, a long code timing detection is waited, and when a short code is identified, j = INT (i / sec) for the cell number j and the sector number k.
The processing of (t) +1, k = ((i-1) MODsec) +1) is performed (A2). In this case, INT indicates an integer obtained by truncating the decimal part, and MOD indicates modulo. Accordingly, initially, since i = 1, j = INT (1/6) + 1 =
1, k = ((1-1) MOD sec) +1) = 1. In this case, the cell number j becomes 1 to N and the sector number k becomes 1 to 6 sequentially.

Then, the codes of the cell (j) and the sector (k) are set. That is, from the long code table 43, the long code SC1 with the cell number j = 1 and the sector number k = 1
The initial value of 1 is read out and set in the long code generator 42 (A3).

Next, a correlation value is obtained by the sliding correlator 37, and it is determined whether or not the threshold value is exceeded by the correlation value determination section 38 (A4). If the correlation value does not exceed the threshold value, all are determined. It is determined whether or not a long code has been searched (A5). If all long codes have been searched, for example, even if a search has been performed up to a long code SCn6 having a cell number j = N and a sector number k = 6, the correlation value is obtained. Does not exceed the threshold value, it is determined that there is no corresponding value (A6).

If all long codes have not been searched, i = i + 1 is set (A7), and the routine goes to step (A2). In this case, j = 1 and i = 2, and in step (A3), the cell number j = 1 and the sector number k =
2, the initial value of the long code SC12 is set in the long code generation unit 42.

If the correlation value exceeds the threshold value in step (A4), the reception level (correlation value) is stored in the reception level table 44 (A8), and whether or not all sectors have been searched is determined. (A9), and if all the sectors have not been searched, k = k + 1 is set (A10), and the codes of cell (j) and sector (k) are set (A12).
That is, when the correlation value exceeds the threshold value when the cell number j = 1 and the sector number k = 1, the long code SC1 of the cell number j = 1 and the sector number k = 2 is obtained from the long code table 43.
2 is read and set in the long code generator 42, and the process proceeds to step (A8) where the reception level (correlation value) at that time is stored in the reception level table 44. That is, the reception level (correlation value) corresponding to each sector after the reception level (correlation value) exceeds the threshold value is stored in the reception level table 44.
To be stored.

When all sectors are searched, that is,
When the search is performed up to the sector number k = 6, the sector having the maximum reception level is adopted (A11). That is, for each sector of the same base station, the timing of the long code is the same, and the sectors (or cells) having the same timing of the long code are grouped into the same group, and received within this group. The sector having the highest level (correlation value) is determined as the serving sector, the long code in the sector is adopted, and the sector is set in the long code generator 42. Therefore, even if the reception level (correlation value) exceeds the threshold value in the long code identification process, the reception level (correlation value) may be even higher in the same group.
The sector having the maximum reception level in the same group is determined as the serving sector, and the long code in that sector is adopted. Thereby, erroneous identification can be prevented.

FIG. 6 is a flowchart according to the second embodiment of the present invention. Steps (B1) to (B5) correspond to those in FIG.
Are the same as steps (A1) to (A5). If all long codes have not been searched in step (B5), i = i + 2 is set (B7), and the process proceeds to step (B2). That is, in step (A7) in FIG. 5, the search is performed in the order of the sector number by sequentially incrementing the counter with i = i + 1, but in this embodiment, the search is performed in step (B7). By setting i = i + 2, a search for every other sector is performed. In this case, the initial value is 1
Therefore, the odd-numbered sectors are sequentially searched.

Then, if the correlation value does not exceed the threshold value in step (B4) and if all the long codes have been searched in step (B5), ie, j = I
NT (i / sect) + 1 = N, k = ((i-1) MO
If (Dsect) + 1 = 6, it is determined whether or not the even number of the sector has been searched (B6). If the even number has not been searched, i = 2 is set (B8), and the step (B) is performed.
Go to 2). That is, since the search for the odd-numbered sector is completed, the search for the even-numbered sector is sequentially performed. If the correlation value does not exceed the threshold even after the search of the even-numbered sector is completed, there is no corresponding value (B9).
And

When the correlation value exceeds the threshold, the reception level (correlation value) is stored in the reception level table 44 (B1).
0) and k = 1 (B11). Then, it is determined whether or not all sectors have been searched (B12), and if not searched, it is determined whether or not all sectors have been measured (B1).
3) In the case of a measured sector, k = k + 1 is set (B16), and the process proceeds to step (B12). If the sector is not a measured sector, the initial value of the long code of the sector number k of the cell number j at that time is set in the long code generator 42 (B14), and the reception level (correlation value) at that time is stored in the reception level table. 44 (B15), and k
= K + 1 (B16), and the routine goes to Step (B12).

If it is determined in step (B12) that all sectors have been searched, the sector having the maximum reception level is adopted (B17). That is, the sector having the largest value among the reception levels (correlation values) stored in the reception level table 44 is determined to be the serving sector, the long code corresponding to the sector is adopted, and the initial value is used as the long code generation unit. Set to 42.

In this embodiment, every other sector is searched to determine whether or not the reception level (correlation value) has exceeded a threshold value. A search is performed for an unsearched sector to identify a sector having the maximum reception level, and a long code corresponding to the sector is identified. Compared to a case where the counter value i is sequentially set to +1, a high-speed search is possible. Become.

In step (B7), i = i + 3
It is also possible to search every second sector. That is, the number of steps of the counter value i is not limited to 1 or 2, and can be set arbitrarily according to the number of sectors.

FIG. 7 is a flowchart according to the third embodiment of the present invention.
1) Then, steps (A1) to (A1) in FIG.
Steps (C2) to (C13) similar to 2) are executed. In step (C13), a sector having the maximum reception level is adopted, and a long code corresponding to the sector is registered as a priority code (C14). ). The registered priority code is used for the next long code identification process.

Further, the identification process using this priority code (C1)
Are performed, steps (B1) to (B1) in FIG.
It is also possible to perform 7). That is, step (C)
In 5), when the correlation value does not exceed the threshold value, the search can be performed in the long code group at the same timing, for example, by sequentially searching each sector of the same base station or every other sector.

FIG. 8 is a flowchart of the identification process using the priority code according to the third embodiment of the present invention, where j = cell of the priority code and k = sector of the priority code (C2
1), the initial values of the long codes of the cell number j and the sector number k are read from the long code table 43 and set in the long code generator 42 (C22), and it is determined whether or not the correlation value has exceeded a threshold value (C22). C23).

If the correlation value does not exceed the threshold value, it is determined whether or not all priority codes have been searched (C24).
If the search has not been completed, the next priority code is set (C31), and the routine goes to step (C22). If all the priority codes have been searched, it is determined that there is no corresponding code (C30), and the process proceeds to step (C2) in FIG. If the correlation value exceeds the threshold, the reception level (correlation value) is stored in the reception level table 44 (C25), and it is determined whether or not all the sectors have been searched (C26). Adopts the sector of the maximum reception level (C27). If the search has not been completed, k = k + 1 is set (C28), and the initial values of the long codes of the cell number j and the sector number k are set in the long code generation unit 42 (C2).
9), and proceed to step (C25). In this case, the reception level (correlation value) is stored in the reception level table 44 without determining whether or not the threshold value is exceeded in step (C24).

Therefore, when the identification process using the priority code is started and the correlation value exceeds the threshold value, all sectors in the cell to which the sector belongs (the long code is in the group with the same timing) are searched, and the maximum reception level is determined. The sector is set as the serving sector, and the initial value of the long code corresponding to the sector is set in the long code generation section, and the reception despread demodulation of the spread data from the base station is performed.

FIG. 9 is an explanatory diagram of a priority code table according to the third embodiment of the present invention, showing a case where a plurality of priority codes are set. FIG. 9A shows, for example, setting of five priority codes. A priority code Code13, Code corresponding to a long code as shown in FIG.
When e22, Code15, Code32, and Code55 are stored in the priority code table, as shown in (b), when a new priority code Code11 is stored, the oldest priority code Code55 is deleted.

That is, as shown in step (C14) in FIG. 7, when registering as a priority code, the previously registered priority code is sequentially shifted, the oldest priority code is shifted out, and the priority code is shifted out. Store the latest priority code at the top of the code table. Then, in the identification process using the priority code in the step (C1), the priority code is read from the top of the priority code table, and the step (C1) in FIG.
21) to (C29) are executed.

In this case, if the correlation value does not exceed the threshold value in step (C23), the process proceeds to step (C21) to start the identification process using the next priority code, and is stored in the priority code table. If the correlation value does not exceed the threshold even after the identification process for the priority code is completed,
It is possible to shift to the step (C2) in FIG.

FIG. 9B shows a priority code Code1.
3, Code22, Code15, Code32, Co
The number of registrations is stored in correspondence with de55, and the identification process using the priority code can be performed in the order of the number of registrations. In the case of the priority code table storing the number of registrations corresponding to the priority code, the configuration may be such that the number of registrations is stored for all the long codes. In some cases, the search time for the order cannot be ignored.

In (C), an auxiliary table shown in (b) is provided for the priority code table shown in (a), and the identification process using the priority code is performed in the order of the number of registrations. If a long code not registered in the priority code table is used, register it in the auxiliary table,
When the number of times of registration exceeds the number of times of registration of the priority code stored in the priority code table, processing can be performed so that replacement is performed.

The auxiliary table is cleared at predetermined intervals, and stored in the auxiliary table when a new long code is used, and stored in the priority code table when the long code is repeatedly used. It is also possible. Further, the number of registrations in the priority code table is configured to be decremented in accordance with the number of times other long codes are used, so that the priority can be changed.

FIG. 10 is an explanatory view of the sliding correlation timing according to the embodiment of the present invention. FIG. 10A shows one example of the long code period when the timing of the long code is determined by the identification of the short code. The long code CD1, CD2, CD
The case where the identification process is performed as in 3,. That is,
The initial value of the long code is sequentially read out from the long code table 43 (see FIG. 4) in accordance with the order of the cell number and the sector number, set in the long code generation unit 42, and the long code is generated from the beginning timing of the long code cycle. The correlation value is obtained by the sliding correlator 37, and the correlation value determination section 38 performs an identification process for determining whether or not the threshold value is exceeded.

(B) starts different long codes CD1, CD2, CD3,... At the timing of T0. For example, for the long code CD1, it is determined whether the correlation value exceeds the threshold value in the period t1. It is determined whether or not the correlation value of the long code CD2 has exceeded the threshold value in the period t2.
The case of No. 3 shows a case where it is repeatedly determined whether or not the correlation value has exceeded the threshold value in the period t3.

FIG. 11 is an explanatory diagram of a long code setting according to the embodiment of the present invention. FIG. 11A shows a long code generating section 51 corresponding to the long codes CD1, CD2,.
, 51-2,..., 51-n, and sets the initial values of the different long codes CD1, CD2,. .. Are input to the sliding correlator 53 after switching to the timings T0, T1, T2,..., And the long code identification process is continued sequentially even after the period t2 when the long code is not the start timing. can do. Therefore, high-speed identification becomes possible.

FIG. 11B shows a code table 55-
, 55-n, and a changeover switch 5
6 shows a case where the initial value of the long code is set in the long code generating section 57 by switching the code table 55.
-1 stores the initial value of the long code CD1, the code table 55-2 stores the value at the timing of T1 after the period t1 of the long code CD2, and the code table 55-3 stores Long code CD3 period t
The value at the timing of T2 after 2 is stored.
Similarly, the value of the long code at each timing is stored in the code table.

Accordingly, at the timing of T0, the initial value of the long code CD1 is set in the long code generating section 57, and the long code CD1 is generated. At the timing of T1, the value of the long code after the period t1 of the long code CD2 is obtained. Is set in the long code generation section 57, and the long code generation section 57 generates the long code CD2 when started at the timing T0. According to this embodiment, if the long code cycle is, for example, 2 ⁴² , the value of the 42-bit long code may be stored as the number of types of the long code. The hardware can be reduced in size as compared with the configuration shown in the above (A).

The present invention is not limited to the above embodiments but can be variously added and changed. For example, as a group of the same timing of a long code, a plurality of groups belonging to a base station are included. The present invention can be applied not only to the sector but also to the case where the long codes in a plurality of base stations connected to the same upper station have the same timing.

[0071]

As described above, according to the present invention, spread data that is double-spread modulated by a long code and a short code and spread-modulated by only a short code at each predetermined position of the long code period is used as a base. The mobile station 1 performs a two-step search in which the short code is identified by the short code identification unit 7 and the long code is identified by the long code identification unit 8 based on the timing. In the same timing group, the identification of the long code is assumed to be a temporary identification,
The reception level (correlation value) within the group is obtained and stored in the reception level table 10, and the long code corresponding to the maximum reception level is adopted as the located long code. The order of the identification processing is arbitrarily selected. Also, there is an advantage that the possibility of occurrence of erroneous identification can be avoided. Also, by setting the order of the identification processing to every other order, there is an advantage that the identification processing can be sped up as compared with the case where the identification processing is performed sequentially.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of a main part of a base station according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a main part of a mobile station according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a long code determination control unit according to the embodiment of the present invention.

FIG. 5 is a flowchart according to the first embodiment of the present invention.

FIG. 6 is a flowchart according to a second embodiment of the present invention.

FIG. 7 is a flowchart according to a third embodiment of the present invention.

FIG. 8 is a flowchart of an identification process using a priority code according to the third embodiment of the present invention.

FIG. 9 is an explanatory diagram of a priority code table according to the third embodiment of this invention.

FIG. 10 is an explanatory diagram of sliding correlation timing according to the embodiment of the present invention.

FIG. 11 is an explanatory diagram of a long code setting according to the embodiment of this invention.

FIG. 12 is an explanatory diagram of cells and sectors.

FIG. 13 is an explanatory diagram of a two-stage search method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mobile station 2 base station 3 host station 4 receiving unit 5 transmitting unit 6 control processing unit 7 short code identifying unit 8 long code identifying unit 9 long code table 10 receiving level table 12 receiving unit 13 transmitting unit 14 control unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuo Obuchi 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Hiroaki Iwamoto 4-chome, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa No. 1 Fujitsu Limited (72) Inventor Yoshiharu Tajima 4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture 1-1 In Fujitsu Limited (72) Inventor Kenji Suda 4-chome, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa No. 1 Fujitsu Limited (72) Inventor Tetsuya Yano 4-1-1 Kamikodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited

Claims (12)

[Claims] In an asynchronous CDMA communication system including a plurality of base stations and a plurality of mobile stations, the base station performs spread modulation using a spread long code and a spread short code, and performs the spread long code. A configuration for transmitting spread data obtained by performing spread modulation using only the spread short code at a predetermined position within a code cycle, wherein the mobile station is configured to transmit the spread long code based on a timing obtained by identifying the spread short code. Identifying the spread long code, performing an identification process with another type of spread long code within the same timing group of the spread long code to form a reception level table. A CDMA communication system having a configuration employing a spread long code corresponding to a reception level. 2. In an asynchronous CDMA communication system including a plurality of base stations and a plurality of mobile stations, the base station performs spread modulation using a spread long code and a spread short code, and performs the spread long code. The mobile station, based on the timing by the identification of the spread short code, the same timing of the spread long code, Is divided into a plurality of groups. When identification processing is performed on one divided group and identification is not performed, identification processing is performed on the other divided groups, and a reception level table for the same group is formed by identifying the spread long code. , A structure adopting a spread long code corresponding to the maximum reception level in the reception level table. DMA communication system. 3. A mobile station in an asynchronous CDMA communication system including a plurality of base stations and a plurality of mobile stations, the mobile station performs spread modulation using a spread long code and a spread short code, and performs the spread. A short code identification unit that receives spread data that has been subjected to spread modulation only by the spread short code at a predetermined position within the cycle of a long code, and performs an identification process of the spread short code; and a short code by the short code identification unit. A long code identification unit that identifies the spread long code based on the timing of: and a reception level table that stores a reception level in the long code identification process by the long code identification unit. Long code is used as the spreading long code corresponding to the maximum reception level Mobile station characterized in that it comprises a circuit which sets the section. 4. The long code identification unit has a setting control unit, a long code generation unit, and a long code table, and the setting control unit reads an initial value of a spread long code from the long code table. When the correlation value by the spread long code from the long code generation unit exceeds a threshold value, the long code generation unit sequentially generates different spread long codes at the same timing. Controlling and storing a reception level corresponding to the spread long code in the reception level table, and adopting a spread long code corresponding to the maximum reception level in the reception level table to set the reception level in the long code generation unit. The mobile station according to claim 3, wherein: 5. The setting control unit divides a group of different spread long codes at the same timing into a plurality of groups,
The initial value of the spreading long code which is sequentially different in the divided group is set in the long code generating unit, and when the correlation value by the spreading long code from the long code generating unit exceeds a threshold, the spreading long code in the group is 4. The apparatus according to claim 3, wherein a corresponding reception level is stored in said reception level table, and a spreading long code corresponding to a maximum reception level of said reception level table is adopted and set in said long code generation section. Mobile station. 6. The setting control unit has a priority code table that stores a single or a plurality of spreading long codes identified in the past, and starts identification of the spreading long code using the spreading long code as a priority code. The mobile station according to claim 3, wherein: 7. The mobile station according to claim 6, wherein the priority code table has a configuration for updating the priority of the stored priority code according to the process of identifying the spread long code. 8. A plurality of long code generators for setting initial values of a plurality of types of spread long codes and generating different spread long codes at the same timing, and a plurality of long code generators. A switch for sequentially switching and outputting the spread long code from the unit within the cycle of the spread long code, and a correlator for adding the spread long code output via the switch. The mobile station according to claim 3, 4, or 5. 9. The long code determination unit includes: a code table storing values at different timings from a head timing of a plurality of types of spread long codes; and a spread table at different timings stored in the code table. 6. The mobile station according to claim 3, further comprising a changeover switch for changing a value of a long code and setting the value in a long code generating unit. 10. A communication control method in an asynchronous CDMA communication system including a plurality of base stations and a plurality of mobile stations, wherein the base station performs spread modulation using a spread long code and a spread short code. And transmitting spread data obtained by performing spread modulation using only the spread short code to a predetermined position in the cycle of the spread long code, wherein the mobile station performs the spread long code based on the timing by identifying the spread short code. Performing the identification process of the code, identifying the spread long code, performing the identification process with different spread long codes for the same timing group of the spread long code, detecting the reception level, and storing the reception level in the reception level table. Store,
A communication control method including a step of performing despread demodulation by employing a spread long code corresponding to a maximum reception level in the reception level table. 11. A communication control method in an asynchronous CDMA communication system including a plurality of base stations and a plurality of mobile stations, wherein the base station performs spread modulation using a spread long code and a spread short code. And, spread data that has been subjected to spread modulation only by the spread short code is transmitted to a predetermined position in the cycle of the spread long code, and the mobile station divides the spread long code into a plurality of groups at the same timing. The identification process is performed for each of the divided groups using different diffusion long codes. When identification is not possible, the identification process is performed for each of the other divided groups using different diffusion long codes. When identification is successful, different diffusion long codes in the group are used. The reception level corresponding to the code is detected and stored in the reception level table. A communication control method characterized by comprising the step of performing employing despreading demodulation spreading long code corresponding to the signal level. 12. In the identification process using the spread long code, the head timings of a plurality of different spread long codes are set to be the same, and identification using the different spread long codes is performed at different timings within the cycle of the spread long code. 12. The communication control method according to claim 10, further comprising the step of: