JP2000152318A - Mobile unit channel scanning system and method, and recording medium recording control program therefor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the time spent for channel scanning of a new connection destination base station of a mobile station, and to determine the state of the communication channel and the actual communication channel which the mobile station grasps based on the result of the channel scanning. The degree of inconsistency that occurs in the state of (1) is reduced. A channel of a base station which is likely to be selected as a new connection destination by a mobile station by using latest information stored in a storage unit 322 about a base station which has communicated with the mobile station. , The time for channel scanning is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and a method for scanning a channel of a mobile station, and a recording medium storing a control program therefor. The present invention relates to a channel scanning method of a mobile device that can reduce the time.

[0002]

2. Description of the Related Art A channel scanning method of a mobile station in a mobile communication system is used for finding a candidate for a channel to which the mobile station is newly connected. An example of a conventional channel scanning method is described in Japanese Patent No. 2662697. The method described in this publication is a method for reducing the probability that a mobile station fails to allocate a communication channel. A channel under the most advantageous condition is selected as a connection destination candidate from the reception state of each channel and the usage rate of the channel. However, this conventional technique has the following problems.

The first problem is that channel scanning must always be performed for all communication channels in the system because channels to be scanned are not taken into consideration. In this case, the processing time and load spent on channel scanning of the mobile device increase. When the processing time spent for channel scanning of the mobile device increases, the state of all communication channels obtained as a result of the channel scanning by the mobile device has a time difference between the time of scanning each communication channel and the real time, In some cases, there is a discrepancy with the state of the actual communication channel.

[0004] The second problem is that when the state of the communication channel grasped by the mobile unit does not match the actual state of the communication channel, it is determined based on the state of the communication channel grasped by the mobile unit. When the switching of the communicating channel is performed by the mobile device, depending on the degree of discrepancy between the communication channel state recognized by the mobile device and the actual communication channel status, the mobile device changes the communication channel that is not suitable for communication to the communication channel. There is a case where a call is disconnected due to selection as a switching destination.

An example of a channel scanning method capable of solving these first and second problems is described in Japanese Patent Application Laid-Open No. 8-331628. The method described in this publication is a method for reducing the power consumption of a mobile device. In the channel scanning, scanning of all communication channels in the system and scanning of the channel that has performed the latest communication and the peripheral communication channels of the channel are alternately repeated at predetermined time intervals.

[0006]

However, Japanese Patent Application Laid-open No.
The prior art disclosed in Japanese Patent No. 331628 has the following problems. That is, in a mobile communication system in which the network side does not notify the mobile device of information about the peripheral channel of the communication channel of the mobile device, the mobile device cannot obtain information of the peripheral channel of the communication channel. Therefore, in order to specify a peripheral channel of a certain channel, information including the peripheral communication channels for all communication channels in the system must be stored in advance. Therefore, the capacity of the storage device is occupied more than necessary. Further, since it is necessary to previously store a peripheral communication channel of a certain communication channel, there is a problem that it is impossible to cope with a change in the peripheral communication channel due to the addition of a base station or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reduce the time spent for channel scanning of a new connection destination base station of a mobile station, and to reduce the time required for channel scanning. A mobile station channel scanning system and method capable of reducing the degree of inconsistency that occurs between the state of the communication channel recognized by the mobile station and the state of the actual communication channel based on the result, and a method for recording the same, and a recording recording the control program thereof To provide a medium.

[0008]

According to the present invention, a base station history storage means for storing a history of past communication base stations, and a base station history storage means for channel scanning of a new connection destination base station. Channel scanning control means for performing scanning with respect to the channel of the base station.

The channel scanning control means scans all communication channels in the mobile communication system and scans the base station channels stored in the base station history storage means. Further, the channel scanning control means performs scanning by thinning out a predetermined number of channels, instead of scanning all the communication channels.

[0010] Further, as a result of the channel scanning by the channel scanning control means, there is provided a connection destination candidate selecting means for selecting an optimal channel for performing communication as a connection destination candidate. Further, the channel scanning control means scans each channel at the time of scanning the channel of the base station, and updates the order of channels advantageous for performing communication each time. .

According to the present invention, a history storing step of storing the history of the past communication base station in the storage means, and a channel of the base station stored in the storage means at the time of channel scanning of a new connection destination base station. And a scanning control step of performing scanning on the mobile device.

In the scanning control step, in addition to scanning all communication channels in the mobile communication system, scanning of the base station channel stored in the storage means is performed. The control step is characterized in that, instead of scanning all of the communication channels, scanning is performed by thinning out a predetermined number of channels.

[0013] Furthermore, as a result of the channel scanning by the scanning control step, the method further includes a connection destination candidate selection step of selecting an optimal channel for communication as a connection destination candidate. Further, the scanning control step is characterized in that, at the time of scanning the channel of the base station, scanning is performed for each channel and the order of channels advantageous for performing communication each time is updated.

According to the present invention, a history storing step of storing the past history of the communication base station in the storage means, and the channel of the base station stored in the storage means at the time of scanning the channel of a new connection destination base station. A recording medium having recorded thereon a control program for a channel scanning method for a mobile device including a scanning control step of performing scanning.

The operation of the present invention will be described. The mobile station scans for the channel of the base station that is likely to be selected as a new connection destination by using the latest information about the base station that the mobile station has communicated with, and that the mobile station has selected. It is intended to reduce the scanning time.

More specifically, the channel switching processing unit is started up by the management processing unit in response to the radio wave condition monitoring processing unit or other requests, and switches the communication channel of the mobile station. If the switching of the communication channel is successful, the management processing unit starts the base station history creation processing unit, and the mobile station uses the base station and the communication channel that were used before the switching of the communication channel. The information about the base station that is located is organized, and the storage content of the base station history storage unit is updated. The connection destination candidate selection processing unit is periodically activated by the management processing unit, and scans a specific communication channel based on information in the base station history storage unit to determine the most advantageous channel for performing communication. Or the most advantageous in performing communication by scanning all communication channels in the system based on the information in the channel information storage unit, and in some cases, communication channels in which a certain number is thinned out from all communication channels. Channel is selected as a connection destination candidate.

Thus, when selecting a connection destination candidate, a new connection of a mobile station is performed by scanning only a specific communication channel prior to scanning all communication channels in the system. It is possible to reduce the time spent scanning the channel of the destination base station, and prevent the state of the communication channel recognized by the mobile station from being inconsistent with the actual state of the communication channel based on the result of the channel scanning.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a mobile communication system according to an embodiment of the present invention. A mobile device 11 that performs communication while moving and a plurality of base stations 12A and 12B that perform wireless communication with the mobile device 11. , 12C and communication areas 13A, 13B, 13C covered by each base station.
And base station controllers 14A and 14 for controlling each base station.
B and the exchange 15.

FIG. 2 is a block diagram showing a configuration example of the mobile device. Referring to FIG. 2, the mobile device includes an antenna unit 111 for transmitting and receiving a radio wave, an RF unit 112 for converting a radio wave received by the antenna unit 111 into a signal and a transmission signal to a radio wave, A demodulation unit 113 that demodulates the signal from the unit 112, a modulation unit 114 that modulates a transmission signal and passes it to the RF unit 112, a multiplexing / demultiplexing processing unit 115 that multiplexes and demultiplexes a signal, and a voice that performs audio processing. Processing unit 116, RAM 121, ROM 122, CPU 12
The control unit 120 includes a control unit 120 configured to perform various controls and a bus 119 having a function of exchanging signals between components. Further, it has a speaker 117, a microphone 118, a keyboard 124, and a display 125.

FIG. 3 is a functional block diagram of the control unit 120. Referring to FIG. 3, a management process 311 manages activation, interruption, and termination of each process of the processing unit 31 other than the process of the management process 311. The radio wave condition monitoring process 314 measures the reception electric field strength and reception quality of the received radio wave, and when it is determined that the radio wave condition is not suitable for communication during communication,
Issues a request to switch channels during communication.

A channel switching process 315 performs a channel switching process during communication in response to a request from the radio wave condition monitoring process 314 and other requests. The connection destination candidate selection process 313 stores a new connection destination communication channel candidate required for location registration or switching of a communication channel in the channel information storage 321.
The channel scanning is performed based on the information of all the communication channels used in the system stored in the base station or the communication channel information of the base station history storage unit 322, and the channel is selected from the most advantageous conditions for performing communication.

The base station history creation processing 316 arranges information on the base stations used by the mobile station based on the result of switching the communicating channel in the channel switching processing 315, and updates the storage contents of the base station history storage unit 322. . General call processing 312
Performs processes such as call establishment and call disconnection, which are normal processes required for the mobile device to perform communication.

Next, the operation of this embodiment will be described.
FIG. 4 is an operation flowchart of the base station history creation processing 316 in FIG. In FIG. 3, a channel switching process 31 is performed.
5 is completed and the switching of the communicating channel is actually performed, the base station history creation processing 3 is performed as the next processing.
The processing of step 16 is started. In the base station history creation processing 316, based on the processing result of the channel switching processing 315, a base station history table of the base station used before the switching of the communicating channel and the base station used after the switching of the communicating channel. Is present in the base station history storage unit 322 (step 41). If the base station history table does not exist, a base station history table is created for the base station that does not exist (step 42).

When the base station history table is present in the base station history storage unit 322, the base station history table of the base station before the switching of the communicating channel is added to the base station itself before the switching of the communicating channel. In addition to checking whether information about the base station after the switching of the communicating channel is registered, the base station history table for the base station after the switching of the communicating channel is communicating with the base station itself after the switching of the communicating channel. It is checked whether information about the base station before the channel switching has been registered (step 43). If there is any information that has not been registered, the information about this base station is registered in the base station history table (step 4).
4).

For example, in the mobile communication system as shown in FIG. 1, a communicating mobile unit first communicates in the communication area 13A, moves to the communication area 13B while communicating, and further communicates while communicating. Suppose that it moved to 13C. The configuration example of the base station history storage unit 322 in this case is as shown in FIG. In the example of FIG. 8, the base station history storage unit 322 indicates to which base station the base station has switched the channel during communication, or that the base station has switched the base station to each base station during communication. Is stored, and information on which frequency each base station is using is stored.

Next, referring to FIGS. 5 and 6, the processing flow of the connection destination candidate selection processing 313 is shown. When the process of the connection destination candidate selection process 313 for determining the connection destination candidate required at the time of location registration or switching of the channel during communication is started, it is checked whether or not the mobile device has already been registered. Step 5A). If the location has already been registered, it is checked whether or not it is the first time that the processing of the connection destination candidate selection processing 313 has been started after the last communication channel has been switched (step 5B).

If the connection destination candidate selection processing 313 is the first connection destination selection processing 313 after the last communication channel switching, the communication channel scanning count based on the information in the base station history storage unit 322 is set to 0.
(Step 5C). It is determined whether or not the number of communication channel scans based on the information in the base station history storage unit 322 is smaller than an arbitrarily determined threshold value (step 5D), and the number of communication channel scans based on the information in the base station history storage unit 322 is threshold. If the value is smaller than the value, the information of the base station history table for the base station currently in communication is read from the base station history storage unit 322 (step 5E).

The communication channel of the read information of the base station history table and the communication channel selected in the previous connection destination candidate selection processing 313 are set as the channels scanned in the current connection destination candidate selection processing 313 (step 5F). . In this case, among the communication channels selected in the previous connection destination candidate selection processing 313, the most advantageous communication channel is obtained, and the most advantageous communication channel and the communication channel read from the base station history table are determined. , The scan channel in the current process. As the most advantageous communication channel, a channel having the strongest radio wave is selected from the available channels.

Scanning is performed for all the channels set in step 5F (step 5G), and the channel order advantageous for performing communication is updated based on the channel scanning result (step 5H). The number of channel scans based on the information in the base station history storage unit 322 is incremented (step 5).
I), as a result of the channel scanning from the information in the base station history storage unit 322, it is checked whether or not a connectable channel exists (step 5J).

If the mobile station has not registered the location in step 5A, or the base station history storage unit 3 in step 5D.
If the number of channel scans based on the information from 22 is greater than the threshold, the base station history storage
If there is no channel that can be connected to the result of the channel scan based on the information from the base station 22, the number of channel scans based on the information from the base station history storage unit 322 is set to 0 (step 5K), and the channel information storage unit 321 is set. Is set as the channel to be scanned in the current connection destination candidate selection processing 313 (step 5L). Scanning is performed for all the channels set in step 5L (step 5M), and the order of channels advantageous for communication is updated based on the channel scanning result in step 5M (step 5N).

If there is a channel that can be connected in step 5J, or after execution of step 5N, the most advantageous channel is selected as a connection destination candidate from the order of channels advantageous for communication ( Step 50: terminate the connection destination candidate selection processing 313.

For example, as shown in FIG. 8, the registration contents of the base station history storage unit 322 include base station history tables of the base stations 12A, 12B, and 12C, and the base station 12A history table includes the base station 12A itself. Information of the base station 12B is registered, information of the base station 12B itself and information of the base stations 12A and 12C are registered in the history table of the base station 12B, and information of the base station 12C itself and the base station 1C are registered in the history table of the base station 12C.
Consider a case where 2B information is registered. If the mobile station is located at a location where the communication area 13A of the base station 12A and the communication area 13B of the base station 12B overlap and are communicating using the base station 12B, a connection destination candidate selection process 313 is performed.
Performs channel scanning only on two communication channels, the channel of the base station 12A and the channel of the base station 12C.

As a result of the channel scanning, if there is a vacancy in the base station 12A, the channel of the base station 12A is updated to the most advantageous channel for communication, and the channel of the base station 12C is updated to the second channel. The 12A channel is selected as a connection destination candidate. If there is no free space in the base station 12A, the user wants to select the channel of the base station 12C as the most advantageous channel for performing communication and then select the channel as a connection destination candidate channel. 12C
Is not suitable for performing communication, so that neither of the base stations 12A and 12C scans all communication channels in the system without selecting them as connection destination candidates, and there is a communication channel that can be connected. Then, the channel is selected as a connection destination candidate.

However, in the example of FIG. 8, even if all the communication channels in the system are scanned, the base station 12A and the base station 12
Since the mobile device is located at a position where communication can be performed only by B, a channel other than the channel of the base station 12A cannot be selected as a connection destination candidate.

FIG. 7 is a processing flow chart of the channel switching processing 315. When the channel switching processing 315 is activated, the candidate channel of the processing result of the connection destination candidate selection processing 313 is set as the switching destination channel of the communicating channel. (Step 61), and the switching of the communicating channel is performed for the channel set in step 61 (step 6).
2).

Next, another embodiment of the present invention will be described with reference to the drawings. Referring to FIG. 9, this embodiment is different from the embodiment shown in FIG.
Is different from the embodiment of FIG. 3 in that the

The channel state management processing 811 is periodically activated, and is used when registering a location or switching a communication channel based on the communication channel information in the channel information storage unit 321 or the communication channel information in the base station history storage unit 322. The order of the channels advantageous for communication, which is information when selecting a necessary new connection destination channel candidate, is updated.

The channel switching process 812 performs the switching process of the communicating channel based on the result of the channel status management process 811 in response to the request from the radio wave condition monitoring process 314 and other requests. This is different from the switching process 315. The other parts are the same as those in the embodiment of FIG.

The operation of this embodiment will be described with reference to the drawings. The radio wave state monitoring process 314 and the base station history creation process 316 in FIG. 9 are the same as those in the embodiment shown in FIG. 10 and 11 show channel state management processing 8.
FIG. 11 is an operation flowchart of Step 11 in FIG.
A, 5B, 5C, 5D, 5E, 5F, 5H, 5I, 5
J, 5K, 5L, and 5N are the same as the respective steps in the description of the operation of the connection destination candidate selection processing 313 in the previous embodiment.

FIG. 12 shows a channel switching process 812.
FIG. 12 is a processing flowchart of FIG.
Since the channel switching processing 315 is the same as step 62 of the processing flow of FIG. 7, each description thereof will be omitted.

When the channel to be scanned in the current process is set in step 5F, the channel state management process 811 executes channel scanning for one of the set channels that has not been scanned yet (step 9).
A). After updating the order advantageous for performing the communication in step 5H, it is checked whether or not there is a channel which has not been scanned yet among the channels set in step 5F (step 9B). If there is a channel for which scanning has not been executed yet in step 9B, the processing after step 9A is executed again.

After updating the setting of the channel to be scanned in the current processing in step 5L, the channel scanning is executed for one of the set channels that has not been scanned yet (step 9C). After updating the order of the channels advantageous for performing the communication in step 5N, it is checked whether or not any of the channels set in step 5L has not been scanned yet (step 9).
D). If there is a channel for which scanning has not been performed yet in step 9D, the processing after step 9C is performed again. When the scanning of all the set channels is completed, the processing of the channel state management processing 811 ends.

In the channel switching process 812, the most advantageous channel is selected as the switching destination channel of the communicating channel from the order of channels advantageous for performing the communication updated in the process of the channel state management process 811. It is set (step 101). Switching of the communication channel in step 62 is performed for the channel set in step 101,
The processing of the channel switching processing 812 ends.

In this embodiment, every time one channel is scanned, the order of channels advantageous for performing communication is updated. Even when the switching process 812 is activated, the channel scanned before the process of the channel state management process 811 is interrupted is considered, and information on the order of channels that is advantageous for performing communication is used. There is a new effect that the switching destination channel of the channel during communication can be specified.

It should be noted that the above-described procedures of the respective operation processing flows of FIGS. 4 to 7 and FIGS. 10 to 12 can be executed and controlled by a program stored in advance in a storage medium such as a ROM (Read Only Memory). It is obvious.

[0046]

The first effect of the present invention is that the processing time spent for scanning a communication channel of a mobile station is reduced, so that the state of a communication channel grasped by the mobile station based on the result of the channel scan and the actual state of the communication channel are reduced. Is to reduce the degree of inconsistency that occurs in the state of the communication channel. The reason is that information on base stations that have been used by the mobile station is organized and stored, and based on the stored information on the base station, a small number of communication channels to be scanned at the time of channel scanning of the mobile station are used. The mobile station scans one communication channel and the mobile station scans all of the communication channels whose status it wants to grasp, and the mobile station ends the channel state by reducing the processing time spent scanning the channel. This is to reduce the time difference at the moment when all are grasped.

The second effect of the present invention is that the mobile station repeatedly performs communication around the same base station as compared with the case where a new base station candidate is selected in the base station used by the mobile station for the first time. In this case, when a new candidate for a connection destination base station in a base station that has been repeatedly used is selected, the reliability as a candidate for a connection destination base station to be selected is increased. The reason is that by storing information about base stations that have been used by the mobile device, the mobile device can preferentially perform channel scanning only on channels that are likely to be channel switching destinations. It is.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a mobile communication system to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating a configuration of a mobile device.

FIG. 3 is a block diagram illustrating an example of a configuration of a control unit in FIG. 2;

FIG. 4 is a processing flow of base station history creation processing 316.

FIG. 5 is a part of a processing flow of connection destination candidate selection processing 313;

FIG. 6 is a part of a processing flow of a connection destination candidate selection processing 313;

FIG. 7 is a processing flow of a channel switching processing 315.

FIG. 8 is a diagram showing an example of a storage table of a base station history storage unit 322.

FIG. 9 is a block diagram illustrating another example of the configuration of the control unit in FIG. 2;

FIG. 10 is a part of a processing flow of a channel state management processing 811;

FIG. 11 is a part of a processing flow of a channel state management processing 811;

FIG. 12 is a processing flow of a channel switching processing 812.

[Explanation of symbols]

 Reference Signs List 11 mobile station 12A to 12C base station 13A to 13C communication area 14A, 14B base station control device 115 exchange 31 processing unit 32 storage unit 311 management processing 312 general call processing 313 connection destination candidate selection processing 314 radio wave state monitoring processing 315, 812 Channel switching process 316 Base station history creation process 321 Channel information storage unit 322 Base station history storage unit 811 Channel state management process

Claims (12)

[Claims] 1. A base station history storage means for storing a history of past communication base stations, and a base station channel stored in said base station history storage means at the time of channel scanning of a new connection destination base station. A channel scanning system for a mobile device, comprising: channel scanning control means for performing scanning. 2. The channel scanning control means scans all communication channels in a mobile communication system and scans a channel of a base station stored in the base station history storage means. The mobile station channel scanning system according to claim 1. 3. The channel scanning control unit according to claim 2, wherein a predetermined number of channels are skipped instead of scanning all of the communication channels.
A channel scanning system for a mobile device as described. 4. The apparatus according to claim 1, further comprising connection destination candidate selection means for selecting, as a connection destination candidate, an optimal channel for performing communication as a result of channel scanning by said channel scanning control means. The mobile station channel scanning system according to any of the preceding claims. 5. The channel scanning control means according to claim 1, wherein, at the time of scanning the channel of the base station, scanning is performed for each channel and a channel order advantageous for performing communication each time is updated. The channel scanning system for a mobile device according to claim 1, wherein: 6. A history storing step of storing a history of past communication base stations in a storage means, and scanning a channel of a base station stored in said storage means when scanning a channel of a new connection destination base station. And a scanning control step. 7. The scanning control step of scanning a base station channel stored in the storage means in addition to scanning all communication channels in a mobile communication system. A channel scanning method for a mobile device as described in the above. 8. The channel scanning of a mobile device according to claim 7, wherein the scanning control step performs scanning in which a predetermined number of channels are thinned out, instead of scanning all of the communication channels. Method. 9. The method according to claim 6, further comprising the step of selecting a connection destination candidate as a connection destination candidate as a connection destination candidate as a result of the channel scanning by said scanning control step. A channel scanning method for a mobile device as described in the above. 10. The scanning control step is characterized in that, when scanning a channel of the base station, scanning is performed for each channel, and the order of channels advantageous for performing communication each time is updated. The channel scanning method for a mobile device according to claim 6. 11. A history storage step of storing a history of past communication base stations in a storage means, and scanning a channel of a base station stored in said storage means when scanning a channel of a new connection destination base station. A recording medium on which a control program for a channel scanning method for a mobile device, comprising a scanning control step to be performed, is recorded. 12. The scanning control step of the program, wherein scanning of the channel of the base station is performed for each channel and the order of channels advantageous for performing communication each time is updated. The recording medium according to claim 11, wherein: