JPH09247744A - Spread code arrangement method for pilot channel, base station equipment and mobile station equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pilot channel use spread code arrangement method, a base station equipment and a mobile station equipment by which an in-zone cell/sector is quickly and surely discriminated without extending the pilot channel spread code for discriminating an in-zone sector for a mobile station in sector processing and without increasing a rising time of the mobile station. SOLUTION: The same spread code is assigned to plural sectors S1, S2, S3 in the same cell. Simultaneously as the pilot channel to the sector S1, a spread code whose spread code phase is 0 is assigned to a reference timing signal, a spread code phase P is assigned to the sector S2 and a spread code phase 2P is assigned to the sector S3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread code arrangement method for a pilot channel, a base station apparatus and a mobile station apparatus in a code division multiple access (hereinafter abbreviated as CDMA) type mobile communication system using a spread spectrum code. Regarding

[0002]

2. Description of the Related Art In a CDMA mobile communication system, a service area is divided into a plurality of unit cells, one base station is provided in each cell, and a mobile station existing in a cell in the service area is divided into cells. Communicates with the base station of the cell via a wireless line.

In the CDMA mobile communication system, the base stations of each cell are assigned different spreading codes of the same frequency, spread by the spreading codes, and constantly transmit pilot channels with constant transmission power. . For example, as shown in FIG. 5A, base stations B1 to B5 are provided in a plurality of cells 1 to 5 provided in the service area, and the base stations B1 to B5 are for different pilot channels. Spreading codes C1 to C5 are assigned, and the base station of each cell constantly transmits the pilot channel spread by the assigned spreading code.

When the mobile station is turned on, the mobile station receives a pilot channel transmitted from the base station in order to determine the serving cell, and determines the serving cell from the received pilot channel. More specifically, each mobile station stores a plurality of spreading codes for the pilot channel of each cell in the memory, and sequentially measures the reception level for the pilot channels of all the stored spreading codes,
The measured reception levels are compared with each other, the pilot channel with the highest reception level is identified, and the cell of this pilot channel is determined to be the serving cell.

The reception level measuring process of the pilot channel is performed by using a matched filter, for example. When a signal that has been spread and modulated with a spreading code is input to this matched filter, as shown in FIG.
A peak signal is output every cycle, and the output level of this peak signal is used as the reception level. In the actual reception level measurement process, in order to improve the normal measurement accuracy, the output level at the timing of the peak signal detected in the first one cycle is measured over a plurality of cycles and averaged.

Therefore, although the reception level measuring process for one spreading code requires a time which is a multiple of the period of the spreading code, the mobile station spreads all the pilot channels stored in the memory as described above. Since it is necessary to perform the reception level measurement processing for the code, the larger the number of pilot channels of this spreading code, the longer the startup time by the reception level measurement processing.

On the other hand, in the mobile communication system, one cell is divided into a plurality of sectors in order to increase the capacity of the radio channel, and the number of sectors per cell is increased. For example, FIG. 5 (b) shows the cell 1 shown in FIG. 5 (a) as the first sector S1, the second sector S2, and the third sector S3.
Although the example of dividing into three sectors is shown, even in the case where the sectorization is performed in this way, it is necessary to perform the serving sector determination process for determining in which sector the mobile station exists. Therefore, for example, it is necessary to arrange a pilot channel for each sector.

[0008]

As described above, a pilot channel is arranged for each sector in order to perform the serving sector determination process in the sectorization in which one cell is subdivided into a plurality of sectors. If different spreading codes are assigned to the respective channels, the number of spreading codes for the pilot channel necessary for the system increases as the number of sectors per cell increases.

[0009] The mobile station is designed to start up when the power is turned on by sequentially performing reception level measurement processing on the pilot channels of all spreading codes stored in the mobile station. When the number of spreading codes for pilot channels is increased due to sectorization, each mobile station needs to perform reception level measurement processing for all of the increased spreading codes. This reception level measurement processing is performed as described above. Since it is necessary to multiply the number of code cycles, there is a problem that the start-up time of the mobile station becomes longer as the number of spreading codes increases.

The present invention has been made in view of the above,
The purpose is to increase the number of spreading codes for the pilot channel for determining the serving sector of the mobile station in sectorization, and to increase the start-up time of the mobile station without increasing the serving cell. / Providing a spreading code arrangement method for a pilot channel, a base station apparatus and a mobile station apparatus that can perform sector determination quickly and accurately.

[0011]

In order to achieve the above object, the present invention according to claim 1 is such that a base station is provided in each of a plurality of cells, each base station is modulated at the same frequency, and the base stations are different from each other. A spreading code allocation method for a pilot channel in a mobile communication system of a code division multiple access system, which transmits a pilot channel spread by an allocated spreading code, and a mobile station determines a serving cell by receiving the pilot channel. Then, the same cell is divided into a plurality of sectors, and as a pilot channel for identifying each of the divided plurality of sectors, the same spreading code is applied to the plurality of sectors and a different spreading code phase for each sector. The point is to assign.

According to the present invention of claim 1, as a pilot channel for identifying each of a plurality of sectors dividing the same cell, the same spreading code is applied to the plurality of sectors and each sector is Since different spreading code phases are assigned to the pilot channel, the number of spreading codes for the pilot channel does not increase, and the pilot channel with the highest reception level among all the sectors in the same cell in one cycle of the spreading code. Detection can be done 1
It is possible to make the start-up time of the mobile station constant without increasing the start-up time regardless of the number of sectors in the cell.

The present invention according to claim 2 provides the invention according to claim 1.
In the invention described above, the process of assigning a different spreading code phase for each sector provides a common reference spreading code phase in the cell, and a different spreading code with respect to the reference spreading code phase for each sector in the same cell. The gist of the present invention is to allocate a phase difference, and each sector transmits a pilot channel with a spreading code phase having the spreading code phase difference with respect to a reference spreading code phase.

According to the second aspect of the present invention, each sector in the same cell transmits a pilot channel with a spreading code phase having a different spreading code phase difference from the reference spreading code phase.

Further, the present invention according to claim 3 provides the invention according to claim 2.
In the invention described above, the code length of the spreading code assigned to the pilot channel is X chips, and the number of a plurality of sectors configured by dividing the same cell is Y.
, The spreading code phase difference assigned to each sector is 0, X / Y, 2X / Y, 3X / Y, ...
(Y-1) X / Y is the gist.

According to the present invention of claim 3, when the spreading code length for the pilot channel is X chips and the number of sectors in the same cell is Y, the spreading code phase difference assigned to each sector is 0. , X / Y, 2X / Y, 3X /
Y, ..., (Y-1) X / Y are arranged at equal intervals.

Further, the present invention according to claim 4 is such that a base station is provided in each of a plurality of cells, each base station is modulated at the same frequency, and is spread by spreading codes assigned differently from each other. In the mobile communication system of the code division multiple access method, in which the mobile station determines the serving cell by receiving the pilot channel, the base station device provided in the cell divided into a plurality of sectors has the cell Storage means for storing the spreading code for the pilot channel assigned to each and a plurality of different spreading code phase information respectively corresponding to each of the plurality of sectors, and a pilot channel spread with the spreading code stored in the storing means. Transmission means for transmitting to each sector while shifting with different spreading code phases corresponding to each sector And summarized in that with.

Further, the present invention according to claim 5 is such that a base station is provided in each of a plurality of cells, each base station is modulated at the same frequency, and is spread by spreading codes assigned differently from each other. In the mobile communication system of the code division multiple access method, in which the mobile station determines the serving cell by receiving the pilot channel, the same cell is divided into a plurality of sectors, and the plurality of divided sectors are As a pilot channel for identifying each of the plurality of sectors, the mobile station device stores a plurality of spreading codes for pilot channels when the same spreading code is assigned to the plurality of sectors and different spreading code phases are assigned to the respective sectors. Storage means and read-out means for sequentially reading the spreading code for pilot channel stored in the storage means A matched filter for receiving a spread modulation signal transmitted from a base station as a pilot channel, despreading the spread modulation signal with a spreading code sequentially read from the reading means, and outputting a despread signal; and the matched filter. All the spreading signals sequentially read from the reading means for receiving the despread signal from the despreading signal and detecting the maximum level of the despreading signal within one cycle of the spreading code and the timing within the one cycle where the maximum level is reached. Corresponds to the maximum level detection circuit that performs the maximum level for all the spreading codes and detects its timing and the largest maximum level among the maximum levels for all the spreading codes detected by the maximum level detection circuit. Select the spreading code to be used and select the cell that transmits the pilot channel of the spreading code. Spreading code selection means for determining a cell, a spreading code selected by the spreading code selection means is read from the storage means and supplied to the matched filter, and the matched filter is despread and the despreading is performed. A control means for controlling to output a signal, and a maximum level for receiving the despread signal output from the matched filter under the control of the control means and detecting the maximum level within one period for each spreading code and its timing. The maximum level signal component in the despread signal is selected from the timing detection means, the timing detected by the maximum level timing detection means, and the despread signal from the matched filter output under the control of the control means. Maximum level component selection circuit and demodulates the maximum level signal component selected by the maximum level component selection circuit The gist is to have demodulation means.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a base station for implementing a spread code arrangement method for pilot channels according to an embodiment of the present invention. In the base station shown in the figure, the cell in which the base station is arranged is sectorized into a plurality of sectors S1, S2, S3 as shown in FIG. The mobile station transmits a pilot channel for efficiently performing the serving cell / sector determination process.

In the mobile communication system, different spreading codes for pilot channels are assigned to each cell in order to make a cell determination, and the base station of each cell uses the pilot channels spread by the assigned spreading code. Although it is always transmitted, it is necessary to similarly assign a pilot channel to each sector in order to perform a serving sector determination that determines in which sector the mobile station exists even when the sector is formed.

In the present invention, in the case of such sectorization, as a pilot channel assigned to each sector, a different spreading code is not assigned to each sector, but the same is applied to a plurality of sectors in the same cell. With the spreading code, a different spreading code phase is assigned to each sector so that each sector can be determined by a combination of the spreading code and the spreading code phase. That is, although different spreading codes are assigned to each cell as pilot channels, the same spreading code as that of the cell is used as the pilot channel of each sector in the same cell, and the spreading code phase of this spreading code is different for each sector. Have been assigned.

FIG. 2 is a diagram showing a spreading code for spreading the pilot channel of each sector. In the pilot channel shown in the figure, the cell is subdivided into three sectors S1, S2 and S3 as shown in FIG. 5B, and the three sectors are respectively transmitted from the base station having the configuration shown in FIG. Pilot channels with different spreading code phases are transmitted, and the base station generates a reference timing signal as shown in FIG. 2A as a reference for assigning different spreading code phases to each sector. The reference timing signal is output corresponding to one cycle of one spreading code.

Since the three sectors S1, S2 and S3 constitute the same cell, the same spreading code is assigned to each of them, but the first sector S1 is shown in FIG.
As shown in (b), the spreading code phase of this spreading code is spread with the spreading code phase 0 matching the reference timing signal.
2 is the same spreading code as the first sector S1, but FIG.
As shown in (c), a pilot channel spread by a spreading code whose spreading code phase is shifted by P with respect to the spreading code phase of the first sector S1, that is, the reference timing signal, is transmitted, and further the third channel is transmitted. The sector S3 is shown in FIG.
As shown in (d), a pilot channel spread by a spreading code whose spreading code phase is shifted by 2P from the reference timing signal is transmitted.

In this way, the same spreading code is assigned to each sector in the same cell, and a different spreading code phase is assigned to each sector, which is used as a pilot channel for each sector. By transmitting to each mobile station, the mobile station receiving this can determine the serving cell from the spreading code having the maximum peak output level, and can determine the sector from the peak output timing with the spreading code.

FIG. 3 is a diagram showing an output example of the matched filter of the mobile station when the mobile station receives pilot channels having different spreading code phases for each sector by the spreading code of the pilot channel of the serving cell. This figure shows the output level of the matched filter of the mobile station when one cell is divided into three sectors and the spreading code phase difference between each sector is equally divided as in the above example. At the position corresponding to the code phase, three peak signals higher than the other levels appear. These three peak signals correspond to the respective sectors to which different spreading code phases are assigned, and the peak value K1 corresponding to the sector in which the mobile station is currently present is the largest and the peak value for another sector close to the sector. The second peak value K with the next highest peak value
2 and the peak value for the other sector at a far place appears as a smaller third peak value K3. Therefore, the mobile station can determine the serving sector by detecting the largest peak value among them. After that, the mobile station can stand by in the serving sector by receiving the pilot channel at the timing of the maximum peak value.

It should be noted here that the pilot channel having the highest output level can be detected from the pilot channels from all the sectors in the same cell within one period of the spreading code. Therefore, regardless of the number of sectors, it is possible to determine the pilot channel with the highest reception level among all the sectors in a cell in the time required to measure the reception level of the conventional pilot channel of one sector,
Even when the number of sectors increases, the mobile station startup time can be kept constant.

Based on the above, the configuration of the base station shown in FIG. 1 will be described.

The base station of FIG. 1 is a base station of a cell when it is sectorized into three sectors S1, S2, S3 as shown in FIG. 5 (b) as described above. Directional antenna A for transmitting signals toward S1, S2 and S3, in this embodiment a pilot channel
1, A2, A3, and these antennas A1, A2,
A3 is connected to the transmitters 21, 22, and 23, respectively, and these transmitters are connected to the controller 25.

Each of the transmitters 21, 22, 23 has an amplifier 31,
It has a spread modulator 32 and an encoder 33, and also has a controller 25.
Is an input / output interface 41, a CPU 42, a memory 4
3. It has a reference clock generator 44.

Each antenna A1, A2, A3 transmits a pilot channel with the same spreading code and a different spreading code phase for each sector toward each sector S1, S2, S3, but the antenna A1 is shown in FIG. 2 (b). Transmit the pilot channel with spreading code phase 0 shown in Fig.
2 transmits the pilot channel having the spreading code phase P shown in FIG. 2C, and the antenna A3 transmits the pilot channel having the spreading code phase 2P shown in FIG. 2D.

The memory 43 stores the spreading code, the spreading code phase for each sector, the number of sectors, the number of chips per symbol, etc., which is the information necessary to generate the pilot channel transmitted from each antenna in this way. I remember.
In this case, the spread code phase information for each sector is
For example, in the example shown in FIG. 2, information is stored that the spreading code phase = 0 for the sector S1, the spreading code phase = P for the sector S2, and the spreading code phase = 2P for the sector S3. It will be. Further, the reference clock generator 44 is adapted to generate the reference timing signal shown in FIG.

Spreading modulator 3 of each transmitter 21, 22, 23
2 is supplied with the spreading code for the pilot channel and the spreading code phase information corresponding to each sector stored in the memory 43 under the control of the CPU 42 of the control unit 25, respectively, and the reference timing from the reference clock generating unit 44. The pilot channel spread by the spreading code is shifted by the spreading code phase assigned to each sector with respect to the reference timing signal, amplified by the amplifier 31, and the antennas A1, A2, A3 are supplied.
From each.

More specifically, the spreading modulator 32 of the transmitter 21 spreads the pilot channel spread by the spreading code supplied from the controller 25 with respect to the reference timing signal as shown in FIG. 2B. Amplifier 3 without code phase difference
1 to transmit from the antenna A1 to the sector S1. In addition, the spread modulator 32 of the transmitter 22 includes a controller 25.
Figure 2 shows the pilot channel spread with the spreading code from
As shown in (c), the spread code phase difference with respect to the reference timing signal is P, and the pilot channel with this spread code phase difference P is transmitted from the antenna A2 to the sector S2 via the amplifier 31. Spread modulator 3 of transmitter 23
Similarly, 2 also sets the pilot channel spread by the spreading code from the control unit 25 to 2P as the spreading code phase difference with respect to the reference timing signal as shown in FIG. The signal is transmitted from the antenna A3 to the sector S3 via the.

In the above embodiment, the spreading code phase of the spreading code for the pilot channel is shown in FIG.
As shown in (d), an appropriate value P corresponding to the number of sectors
However, it is not necessary to shift by the same value, and the spreading code phase shift is arbitrary. However,
The spread code length is divided into equal intervals for each sector, and the spread code phase difference for each divided sector is equalized, whereby the amount of information stored in the memory 43 can be reduced.

That is, the spreading code length for the pilot channel is X chips, and the number of sectors in the cell is Y.
, The spreading code phase difference assigned to each sector is 0, X / Y, 2X / Y, 3X / Y, ..., (Y−
1) X / Y, and the spreading code phase for each sector is evenly shifted by X / Y. For example, if one symbol making up the spreading code has 64 chips and the number of sectors is 4, it is possible to equally allocate spreading code phase differences to each sector by 64/4 = 16 chips.

Next, with reference to FIG. 4, description will be given of a configuration of a main part relating to the above embodiment of the mobile station which receives the pilot channel transmitted from the base station as described above.

As shown in FIG. 4, the mobile station moves to the matched filter 51, which despreads the spread-modulated signal from the base station with the spreading code of the mobile station and outputs the despread signal, to the matched filter 51. Spreading code generating circuit 57 for supplying spreading code of station, memory 55 storing spreading code identification numbers of a plurality of spreading codes for pilot channels of peripheral cells, maximum level and maximum of despreading signal from matched filter 51. A maximum level detection circuit 59 for detecting the timing within one cycle of taking a level, a pilot channel spread code identification number stored in the memory 55 and read out and supplied to the spread code generation circuit 57, and other mobile stations as a whole. Control circuit 5 for controlling the operation of the
3. A maximum level component selection circuit 61 for selecting the maximum level signal component in the despread signal from the matched filter 51,
And a demodulation circuit 63 for demodulating the maximum level signal component from the maximum level component selection circuit 61.

Next, the operation of the mobile station configured as described above will be described. When the mobile station receives the signal spread-modulated by the spreading code transmitted from the base station as the pilot channel when the power is turned on, the mobile station inputs this spread-modulated signal to the matched filter 51. On the other hand, the control circuit 53 reads the spread code identification number of the spread code for the pilot channel from the memory 55 and supplies it to the spread code generation circuit 57.

The spread code generating circuit 57 is a control circuit 53.
The spread code corresponding to the spread code identification number from is generated and supplied to the matched filter 51. The matched filter 51 despreads the input spread modulation signal with the spreading code from the spreading code generation circuit 57, outputs a despread signal, and supplies it to the maximum level detection circuit 59.

Upon receiving the despread signal from the matched filter 51, the maximum level detection circuit 59 measures the maximum level of the despread signal within one cycle of the spreading code and the timing within the one cycle where the maximum level is obtained. Then, the maximum level for each spreading code and its timing are supplied to the control circuit 53.

The control circuit 53 executes the above-mentioned processing in the memory 5
The maximum level detecting circuit 59 detects the maximum levels of the spreading codes for all pilot channels in 5 and their timings.
Repeat until received from. Then, the control circuit 53
Selects the spreading code with the highest maximum level from all spreading codes for pilot channels, and determines that the mobile station is in the cell transmitting the pilot channel of this spreading code.

The control circuit 53 notifies the spread code generating circuit 57 of the spread code identification number of the selected spread code again, and supplies the spread code from the spread code generating circuit 57 to the matched filter 51. The matched filter 51 despreads the spread modulation signal with the spreading code from the spreading code generating circuit 57 and outputs this despread signal.

When the despread signal from the matched filter 51 is received again, the maximum level detection circuit 59 measures the maximum level and its timing within one cycle for each spreading code, and notifies the control circuit 53 of the measurement result. To do. The control circuit 53 supplies the notified timing to the maximum level component selection circuit 61.

The maximum level component selection circuit 61 selects only the maximum level component in the despread signal from the despread signal from the matched filter 51 and the timing signal from the control circuit 53, and the maximum level component is demodulated by the demodulation circuit 63. Supply to. The demodulation circuit 63 demodulates this maximum level signal component and outputs demodulated data.

[0046]

As described above, according to the present invention,
As a pilot channel for identifying each of a plurality of sectors dividing the same cell, the same spreading code is assigned to the plurality of sectors, and different spreading code phases are assigned to the respective sectors. It is possible to determine the sector with the highest pilot channel reception level in the same cell in one cycle of the spreading code without increasing the number of spreading codes. Even if the number of sectors increases, the startup time of the mobile station can be lengthened. It can be kept constant without.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a base station that implements a spread code arrangement method for a pilot channel according to an embodiment of the present invention.

FIG. 2 is a diagram showing symbols forming a pilot channel assigned to each sector using spreading codes having different spreading code phases.

FIG. 3 is a diagram showing an output example of a matched filter of a mobile station that has received pilot channels having different spreading code phases transmitted from the base station shown in FIG.

FIG. 4 is a diagram showing a configuration of a mobile station used with the base station shown in FIG.

[Fig. 5] Fig. 5 is a diagram showing a plurality of cells and sectors in the cells that form a service area in mobile communication.

FIG. 6 is a diagram showing an output example of a matched filter of a mobile station.

[Explanation of symbols]

 1-5 Cell 21-23 Transmission Unit 25 Control Unit 32 Spread Modulation Unit 43, 55 Memory 44 Reference Clock Generation Unit 51 Matched Filter 53 Control Circuit 57 Spread Code Generation Circuit 59 Maximum Level Detection Circuit 61 Maximum Level Component Selection Circuit 63 Demodulation Circuit A1-A3 antenna S1-S3 sector

Claims (5)

[Claims] 1. A base station is provided in each of a plurality of cells,
A code division multiple access method in which each base station modulates the same frequency and transmits pilot channels spread by differently assigned spreading codes, and the mobile station determines a serving cell by receiving the pilot channel. A spreading code allocation method for pilot channels in a mobile communication system according to claim 1, wherein the same cell is divided into a plurality of sectors, and the divided sectors are used as pilot channels for identifying the plurality of sectors. Same spreading code,
A spreading code arrangement method for pilot channels, which is characterized by assigning different spreading code phases to each sector. 2. The process of assigning a different spreading code phase to each sector provides a common reference spreading code phase in the cell, and spreads differently with respect to the reference spreading code phase for each sector in the same cell. The method according to claim 1, wherein a code phase difference is assigned, and each sector transmits a pilot channel with a spreading code phase having the spreading code phase difference with respect to a reference spreading code phase. 3. The spreading code assigned to the pilot channel has a code length of X chips, and the number of sectors formed by dividing the same cell is Y.
, The spreading code phase difference assigned to each sector is 0, X / Y, 2X / Y, 3X / Y, ...
(Y-1) X / Y, The spreading code arrangement method for pilot channels according to claim 2. 4. A base station is provided in each of the plurality of cells,
A code division multiple access method in which each base station modulates the same frequency and transmits pilot channels spread by differently assigned spreading codes, and the mobile station determines a serving cell by receiving the pilot channel. In the mobile communication system, the base station device provided in a cell divided into a plurality of sectors includes a spreading code for a pilot channel assigned to the cell and a plurality of different spreading codes respectively corresponding to the plurality of sectors. And storage means for storing phase information, and transmitting means for transmitting to each sector while shifting the pilot channel spread by the spreading code stored in the storage means by different spreading code phase corresponding to each sector. A base station device characterized by the above. 5. A base station is provided in each of the plurality of cells,
A code division multiple access method in which each base station modulates the same frequency and transmits pilot channels spread by differently assigned spreading codes, and the mobile station determines a serving cell by receiving the pilot channel. In the mobile communication system, the same cell is divided into a plurality of sectors, and the same spreading code is applied to the plurality of sectors as a pilot channel for identifying each of the divided plurality of sectors.
When different spreading code phases are assigned to the respective sectors, the mobile station device stores the reading means for storing a plurality of pilot channel spreading codes, and sequentially reads the pilot channel spreading codes stored in the storing means. Means for receiving a spread modulation signal transmitted from the base station as a pilot channel, despreading the spread modulation signal with a spreading code sequentially read from the reading means, and outputting a despread signal, and the matched filter. All the processes for receiving the despread signal from the filter and detecting the maximum level of the despread signal within one cycle of the spreading code and the timing within the one cycle when the maximum level is reached are sequentially read from the reading means. The maximum level for all spreading codes and its A maximum level detection circuit for detecting imming and a spreading code corresponding to the largest maximum level among the maximum levels of all spreading codes detected by the maximum level detection circuit are selected and a pilot channel of the spreading code is transmitted. Spreading code selection means for determining a cell as a serving cell, and a spreading code selected by the spreading code selection means is read from the storage means and supplied to the matched filter,
Despreading the spread modulation signal to the matched filter,
Control means for controlling so as to output a despread signal, and receiving the despread signal output from the matched filter under the control of the control means, and detecting the maximum level and its timing within one period for each spreading code. From the maximum level timing detection means, the timing detected by the maximum level timing detection means, and the despread signal from the matched filter output by the control of the control means, the maximum level signal component in the despread signal is calculated. A mobile station apparatus comprising: a maximum level component selection circuit to be selected; and demodulation means for demodulating the maximum level signal component selected by the maximum level component selection circuit.