JP2000307473A - Cdma mobile communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time needed for a path search without lowering the precision of the path search. SOLUTION: A group number extraction part 1 decides a group number from a spread code number and synchronous symbol spread code generation part 2 sets the synchronous symbol spread code corresponding to the group number in a matched filter 3. According to the synchronous addition signal obtained by the matched filter 3 by correlating a received signal with the synchronous symbol spread code, a path extraction part 4 extracts (m) path timing points. A path search control part 7, while controlling an information symbol spread code generation part 9 so that information symbol spread codes synchronized with the (m) path timing points are set in an inverse spreading unit 5, decides whether each path timing point is path timing of an object of path search according to the large/small relations between the received electric power value decided by a power decision part 6 based on the inverse spread result of the inverse spreading unit 5 in that state and a threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA mobile communication device used as a mobile station in a mobile communication system for communicating between a base station and a mobile station by a CDMA (Code Division Multiple Access) system.

[0002]

2. Description of the Related Art In a CDMA system, a path search for reviewing a reception path is performed by a mobile station.

[0003] To enable this path search, all base stations transmit signals spread with a common synchronization symbol spreading code.

[0004] The mobile station uses a matched filter to correlate the received signal with the synchronization symbol spreading code, and detects a plurality of path timings resulting in a large correlation value.

Subsequently, the mobile station sequentially sets the information symbol spreading code of the base station to be searched for in the despreader in synchronization with the detected path timing, and in each state, the received power value exceeds a certain threshold. Is determined as the path of the base station to be received.

Here, the number of path timings at which despreading is attempted is determined by, for example, the number of base stations at which a transmission radio wave reaches one point in order to detect all paths from all base stations existing within the communicable range. Is set sufficiently large in consideration of

Therefore, for each of such a large number of path timings, it is necessary to repeat the process of despreading with the information symbol spreading code synchronized with the path timing and obtaining the received power value at that time. It took a long time.

[0008]

As described above, conventionally,
Since the path search is performed for the paths from all the base stations existing in the communicable range, there is a problem that the path search requires a long time.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a CDMA mobile station capable of reducing the time required for a path search without reducing the accuracy of the path search. A communication device is provided.

[0010]

In order to achieve the above object, the present invention provides an information symbol spread code generating means such as an information symbol spread code generator for generating an arbitrary information symbol spread code at an arbitrary phase. A despreading means such as a despreader for despreading a received signal using the information symbol spreading code generated by the information symbol spreading code generating means, and a received power value based on a result of despreading by the despreading means. For example, a reception power detection unit such as a power determination unit to detect, for example, an arbitrary spreading code can be set, and a correlation value between a spreading code used for spreading and modulating a received signal and a set spreading code is calculated. Correlation detection means such as a matched filter for detection, and a group identification code group of information symbol spreading codes to which a base station to be subjected to a path search belongs. Spreading code setting means for setting a symbol spreading code in the correlation detecting means, for example, a group number extracting section and a synchronizing symbol spreading code generating section, and information to which a base station to be subjected to the path search by the spreading code setting means belongs A peak timing detection unit such as a path extraction unit for detecting a predetermined peak timing in a correlation value detected by the correlation detection unit in a state where the group identification synchronization symbol spread code of the symbol spread code group is set; Path timing extracting means for extracting a path timing relating to a transmission signal from only the base station belonging to the information symbol spreading code group to which the base station to be searched belongs; and a phase synchronized with the path timing detected by the path timing extracting means. Information symbol spreading code The information symbol spreading code is generated by the receiving power detecting means, and the path timing is a path timing related to the base station to be subjected to the path search based on the receiving power value detected by the receiving power detecting means. For example, a path detection unit such as a path search control unit.

[0011] By adopting such means, only the path timing relating to the base station belonging to the same information symbol spreading code group as the base station to be subjected to the path search is extracted as the peak timing, and only those path timings are extracted. , Is performed to determine whether or not it is the path timing for the base station to be subjected to the path search.

Therefore, the path timing used for determining whether or not the path timing is related to the base station to be subjected to the path search is limited to the path timing related to some base stations when extracting the path timing.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a main configuration of a CDMA mobile communication apparatus according to the present embodiment.

[0015] As shown in FIG.
The mobile communication device includes a group number extraction unit 1, a synchronization symbol spread code generation unit 2, a matched filter 3, a path extraction unit 4, a despreader 5, a power determination unit 6, a path search control unit 7, a path list memory 8, An information symbol spreading code generation unit 9 is provided.

The group number extracting section 1 receives a spread code number indicating an information symbol spread code used for reception demodulation, and receives an information symbol to which a base station to which the information symbol spread code indicated by the spread code number belongs is assigned. Find the group number of the spreading code group. Then, the group number extracting unit 1 notifies the synchronization group spreading code generating unit 2 of the obtained group number.

[0017] The synchronization symbol spread code generation unit 2 generates a synchronization symbol spread code assigned to the information symbol spread code group of the group number notified from the group number extraction unit 1. And a synchronization symbol spreading code generation unit 2
Sets the generated synchronization symbol spreading code in the matched filter 3.

The matched filter 3 receives a received signal which is received by a well-known radio system (not shown) and is in a baseband. This matched filter 3
A correlation between the received signal and the set synchronization symbol spreading code is obtained, and a synchronization addition signal indicating the correlation is generated. Then, the matched filter 3 supplies the generated synchronous addition signal to the path extraction unit 4.

The path extracting section 4 extracts, as path timings, timings at which m peaks from the larger one of the peaks in the synchronous addition signal supplied from the matched filter 3 exist. And the path extraction unit 4
The path search controller 7 is notified of the extracted m path timings.

The received signal input to the matched filter 3 is branched and input to the despreader 5. The despreader 5 receives the information symbol spread code provided from the information symbol spread code generator 9. The despreader 5 despreads the received signal using the information symbol spreading code. Then, despreader 5 gives the received signal after despreading to power determining section 6.

Power determining section 6 determines the power value of the despread received signal. Then, power determination section 6 notifies path search control section 7 of the determined received power value.

The path search control unit 7 determines whether or not each of the path timings extracted by the path extraction unit 4 belongs to the base station to be searched by the information symbol spread code generation unit 9. Is determined by monitoring the received power value notified from the power determination unit 6 while controlling the power. Then, the path search control unit 7 creates a path list indicating the path search result in the path list memory 8 based on the determination result.

A path list memory 8 stores a path list created by the path search control unit 7. An information symbol spread code generation unit 9 receives a spread code number and generates an information symbol spread code corresponding to the spread code number. , At the phase specified by the path search control unit 7. Then, information symbol spread code generating section 9 gives the generated information symbol spread code to despreader 5.

Next, an operation related to a path search in the CDMA mobile communication apparatus configured as described above will be described.

First, when the spreading code number assigned to the base station to be subjected to the path search is given, the group number extracting unit 1 identifies the base station to which the information symbol spreading code indicated by the spreading code number is assigned. The group number of the information symbol spreading code group is determined.

Now, all base stations belonging to the mobile communication system in which the CDMA mobile communication device is used are transmitting signals spread with a common synchronization symbol spreading code in the system. Each base station is grouped into a plurality of information symbol spreading code groups, and transmits a signal spread with a group identification synchronization symbol spreading code unique to the information symbol spreading code group to which the base station belongs. Each of these synchronization signals is synchronized with an information symbol spreading code for spreading and modulating information transmitted to a mobile station.

The synchronization symbol spread code generation unit 2 generates a synchronization symbol spread code unique to the information symbol spread code group of the group number notified from the group number extraction unit 1, and sets this in the matched filter 3. .

Thus, the matched filter 3 is set in a state of correlating the received signal with the synchronization symbol spread code unique to the information symbol spread code group to which the base station to be subjected to the path search belongs.

Accordingly, the synchronous addition signal output from the matched filter 3 in this state includes the phase timing of the transmission signals from a plurality of base stations belonging to the same information symbol spreading code group as the base station to be subjected to the path search. , A peak will occur in synchronization with each of.

Therefore, the path extracting section 4 extracts timings at which m peaks from the larger one of the peaks in the synchronous addition signal given from the matched filter 3 exist as path timings.

The number m of peak timings to be extracted is
For example, it is appropriately set in consideration of the number of base stations belonging to one information symbol spreading code group among base stations whose transmission radio waves reach one point.

When the path search control unit 7 needs to perform a path search, it executes a path search process as shown in FIG.

In this path search processing, the path search control unit 7 first takes in the m peak timings extracted and notified by the path extraction unit 4 as described above (step ST1).

Subsequently, the path search control unit 7 selects one of the m peak timings taken in, and instructs the information symbol spread code generation unit 9 to generate an information symbol spread code synchronized with the peak timing. (Step ST2).

In response to this, the information symbol spread code generating section 9 generates an information symbol spread code corresponding to the spread code number at the designated phase, and sets it in the despreader 5.

Since the received signal is supplied to the despreader 5, the received signal is despread by an information symbol spreading code synchronized with one of the extracted m peak timings.

Therefore, if the peak timing selected here is the same as the arrival timing of the synchronization symbol spreading code transmitted from the base station of the path search,
A large power value appears at the output of the despreader 5. However, if the selected peak timing is the same as the arrival timing of the synchronization symbol spreading code transmitted from the base station other than the path search target, the power value of the output of the despreader 5 becomes smaller.

The power value of the output of the despreader 5 is determined by the power determination unit 6 and is notified to the path search control unit 7.

Then, the path search control unit 7 checks whether or not the received power value to be notified is equal to or more than a predetermined threshold (step ST3).

Here, if the received power value is equal to or greater than the threshold value, the path search control unit 7 determines that the currently selected peak timing is the same as the arrival timing of the synchronization symbol spreading code transmitted from the path search target base station. Are identical,
That is, it is determined that it is the timing of the path to be searched, and the path timing is written in the path list memory 8 to be recorded in the path list (step ST4).

However, if the received power value is less than the threshold value, the path search control unit 7 determines that the currently selected peak timing is the same as the arrival timing of the synchronization symbol spreading code transmitted from the base station other than the path search target. Is,
That is, it is determined that it is not the timing of the path to be searched, and the path timing is ignored.

Subsequently, the path search control section 7 confirms whether or not despreading has been tried for each of the m extracted path timings (step ST5). If the path timing is selected, the process from step ST2 is repeated.

When the despreading has been tried for all of the extracted m path timings, the path search control unit 7 ends the current path search processing.

As described above, according to the present embodiment, the base station belonging to the same information symbol spreading code group as the base station to be subjected to the path search is transmitted using the synchronization symbol spreading code unique to the information symbol spreading code group. Only the path timing related to the transmission signal is extracted. And only for each of the path timings extracted in this way,
Confirmation processing is performed to determine whether the path timing relates to a transmission signal from the base station to be subjected to the path search.

Therefore, the path timing to be checked for whether the signal is related to the transmission signal from the base station to be subjected to the path search depends on a part of all the base stations to which the transmission radio wave reaches one point. Since it relates to a transmission signal from a base station, the number of transmission timings may be smaller than that of the related art which targets path timings for transmission signals from all base stations at which a transmission radio wave reaches one point.

More specifically, although it depends on the arrangement of base stations, the number of base stations belonging to a single information symbol spreading code group among base stations whose transmission radio waves reach one point is a, and Assuming that the number of all base stations at which a transmission radio wave reaches a point is b and the number of information symbol spreading code groups is c, a = b / c in general.

Therefore, in order to perform a path search with the same level of accuracy as in the prior art, it is necessary to confirm whether the number of path timings to be extracted, that is, the path timing is related to a transmission signal from the base station to be searched. The number of repetitions may be about 1 / c as compared with the related art, and the time required for the path search can be greatly reduced.

The number of path timings extracted by the path extraction unit 4 is a parameter that can be set arbitrarily.
If the number is too small, the path timing for the base station to be subjected to the path search may leak from the extracted path timing, and the accuracy is reduced. In the present embodiment, without such a decrease in accuracy,
The number of path timings to be extracted can be reduced.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention.

[0050]

According to the present invention, an information symbol spreading code generating means for generating an arbitrary information symbol spreading code at an arbitrary phase, and receiving using the information symbol spreading code generated by the information symbol spreading code generating means. Despreading means for despreading a signal, received power detecting means for detecting a received power value based on a result of despreading by the despreading means, for example, an arbitrary spreading code can be set, and the received signal is spread modulated. A correlation detecting means for detecting a correlation value between the spreading code used for setting and the set spreading code, and a synchronization symbol spreading code for group identification of an information symbol spreading code group to which a base station to be subjected to a path search belongs. Spreading code setting means to be set in the correlation detecting means, and the base station to be subjected to the path search belongs to the spreading code setting means. And a peak timing detecting means for detecting a predetermined peak timing in a correlation value detected by the correlation detecting means in a state where a group identification synchronization symbol spreading code of the information symbol spreading code group is set. Path timing extracting means for extracting path timing relating to a transmission signal from only the base station belonging to the information symbol spreading code group to which the base station belongs, and information symbol spreading of a phase synchronized with the peak timing detected by the peak timing detecting means A code is generated by the information symbol spread code generation means, and in that state, is the peak timing based on the reception power value detected by the reception power detection means a path timing related to the base station targeted for the path search? Path detection means for determining whether or not Because with,
The path timing used for determining whether or not the path timing is related to the base station to be subjected to the path search is limited to the path timing related to some base stations at the time of extracting the path timing. A CDMA mobile communication device that can reduce the time required for a path search without lowering the CDMA mobile communication device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of a CDMA mobile communication device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure in a path search process by a path search control unit 7 in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Group number extraction part 2 ... Synchronization symbol spread code generation part 3 ... Matched filter 4 ... Path extraction part 5 ... Despreader 6 ... Power judgment part 7 ... Path search control part 8 ... Path list memory 9 ... Information symbol diffusion Code generator

Claims (2)

[Claims] A mobile station transmits a signal spread by a common synchronization symbol spreading code in a system and a signal spread by a group identification synchronization symbol spreading code unique to an information symbol spreading code group to which the system belongs. In a CDMA mobile communication apparatus used as a mobile station in a mobile communication system in which base stations transmitting respective information in synchronization with an information symbol spreading code for spreading and modulating information to be transmitted are arranged, , An information symbol spreading code generating means for generating a signal at an arbitrary phase, despreading means for despreading a received signal using the information symbol spreading code generated by the information symbol spreading code generating means, and despreading by the despreading means. The received power detection means for detecting the received power value based on the result, and the base station to be subjected to the path search belong to Path timing extracting means for extracting a path timing relating to a transmission signal from only a base station belonging to the information symbol spreading code group; and an information symbol spreading code having a phase synchronized with the path timing detected by the path timing extracting means. It is generated by the spreading code generating means, and in that state, it is determined whether or not the path timing is a path timing relating to the base station to be subjected to the path search based on the received power value detected by the received power detecting means. CDM comprising path detecting means
A mobile communication device. The path timing extracting means can set an arbitrary spreading code, and detects a correlation value between a spreading code used for spreading and modulating a received signal and the set spreading code. Detecting means; spreading code setting means for setting a group identification synchronization symbol spreading code of an information symbol spreading code group to which a base station to be subjected to a path search belongs in the correlation detecting means; A peak timing for detecting a predetermined peak timing in a correlation value detected by the correlation detecting means as a path timing in a state where a group identification synchronization symbol spreading code of an information symbol spreading code group to which a target base station belongs is set. 2. The CDMA mobile communication according to claim 1, further comprising a detection unit. apparatus.