JP4727396B2 - Wireless communication system, wireless communication method, communication terminal and program in wireless communication system - Google Patents

Description

  The present invention relates to a radio communication system and a radio communication method in which a base station and a communication terminal perform radio communication, a communication terminal in the radio communication system, and a program thereof.

Conventionally, in a wireless communication system in which a base station and a communication terminal perform wireless communication using a communication method such as a CDMA digital mobile communication method, the occurrence of a communication failure or congestion of transmitted / received data in the base station The base station performs processing for prompting the communication terminal that has shifted to the standby state for the base station to switch the standby destination to another base station. This process is called redirection. When the base station transmits redirection information to the communication terminal, the communication terminal performs a process of switching the standby destination to another base station by receiving the redirection information. In a wireless communication system in which a base station and a communication terminal perform wireless communication using a CDMA (Code Division Multiple Access) digital mobile communication system, a technique for instructing portable terminals of redirection information as needed is disclosed in Patent Literature. 1 is published.
JP 2004-297480 A

  By the way, in the redirection process as described above, the communication terminals that receive the redirection information receive the redirection information all at once. Then, each communication terminal completes the acquisition process for the other base station by the redirection process associated with the reception of the information, shifts to the standby state for the base station, and then simultaneously stores it in its own terminal after a predetermined time has elapsed. A base station having a high priority is selected, and acquisition is performed toward the base station. This processing of the communication terminal is called reselection. When the acquisition process by the reselection process is successful, each communication terminal enters a standby state with respect to the base station and requests location registration all at once.

  Here, the communication terminal stores in advance a predetermined time interval in the memory or the like until the reselection process is started after the redirection process is completed, but since this time interval is a fixed value, The plurality of communication terminals that have performed the process simultaneously start the reselection process. Therefore, if the location registration request to the base station, which is the processing of the communication terminal after reselection, increases, the system load increases at the standby switching destination base station, which may cause a failure. .

  Therefore, the present invention aims to reduce the base station system load due to the location registration request that occurs during the reselection process because there are many communication terminals that simultaneously perform the reselection process after the redirection process. An object of the present invention is to provide a radio communication system, a radio communication method, a communication terminal in the radio communication system, and a program thereof.

In order to achieve the above object, a wireless communication system according to the present invention includes a plurality of base stations and a plurality of communication terminals awaiting at a predetermined base station among the plurality of base stations. but for the plurality of communication terminals in the waiting state with respect to the base station, according to a predetermined condition, the redirection information transmission means for concurrently transmitting the redirection information indicating an instruction of capturing to other base stations comprises a wireless communication system, the communication terminal, the simultaneously based on receipt of transmitted redirection information, and acquisition processing means for performing a capture process to listen to the other base station, receiving the redirection information and a counting means for counting an elapsed time after the acquisition process based on the acquisition processing means, a random number onset by said counting means When it counted up the generated counter value by, characterized in that <br/> performing acquisition processing for high base station priority over other base stations the waiting.

  In the invention, it is preferable that the communication terminal includes a counter value generation unit that generates the counter value by generating a random number.

Also, the present invention is characterized in that the base station includes counter value generation means for generating the counter value by generating a random number, and transmits the counter value together with the redirection information to the communication terminal.
In addition, it further includes acquisition priority storage means for storing the priority of the base station that performs acquisition processing, and the acquisition processing means has a higher priority than the other base stations that are waiting based on the stored priority. The acquisition processing is performed for a high base station.

The wireless communication method according to the present invention includes a plurality of base stations and a plurality of communication terminals waiting for a predetermined base station among the plurality of base stations , and the predetermined base station is in a standby state with respect to its own base station. for a plurality of communication terminals, according to a predetermined condition, a radio communication method in a radio communication system comprising a redirection information transmission means for concurrently transmitting the redirection information indicating an instruction of capturing to other base stations , the communication terminal based on the reception of the redirection information, the other performs a capture process to listen to the base station, and counts the elapsed time after the acquisition process based on reception of the redirection information, said counting means when it counted up the generated counter value by a random number generated by the priority over other base stations the waiting And executes the acquisition processing for high base station.

Communication terminal according to the present invention transmits, to the plurality of communication terminals in the standby state with respect to the base station, according to a predetermined condition, simultaneously redirection information indicating an instruction of capturing to other base stations a communication terminal which can wait for the base station which includes a redirection information transmitting unit, based on the reception of the redirection information, and acquisition processing means for performing a capture process to listen to the other base station, the redirection information counting means for counting an elapsed time after the acquisition process based on the reception, wherein the acquisition processing means, when it is counted until the generated counter value by the random number generated by said counting means, the other that the waiting It is characterized in that acquisition processing for a base station having a higher priority than that of the base station is executed.

A program according to the present invention includes a plurality of base stations and a plurality of communication terminals waiting for a predetermined base station among the plurality of base stations , and the predetermined base station is in a standby state with respect to its own base station. respect of the communication terminal, according to a predetermined condition, a program to be executed in a wireless communication system comprising a redirection information transmission means for concurrently transmitting the redirection information indicating an instruction of capturing to other base stations, the redirection based on the received information, and acquisition processing for performing acquisition process to listen to the other base station, a counting process for counting the time elapsed after the acquisition process based on reception of the redirection information, the acquisition process, when counted up the generated counter value by the random number generated by the counting process, the waiting received Than other base stations are and performing the acquisition process for high base station priority.

  According to the present invention, since the reselection start timing is different for each communication terminal based on the counter value generated by the random number generation, it is less likely that the position registration process after the supplement process accompanying the reselection process overlaps. Thereby, the system load of the base station due to the location registration request generated after the reselection process can be reduced.

Hereinafter, a wireless communication system according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the overall configuration of the wireless communication system according to the embodiment.
In this figure, both the radio base station A and the radio base station B perform radio communication with the communication terminal 2 using a CDMA digital mobile communication system. The radio base station A and the radio base station B perform radio communication with each communication terminal 2 using radio signals in different frequency bands (or frequencies), and the radio base station A and the radio base station B communicate with each other. A system is configured, and the entire wireless communication system is configured by the plurality of wireless communication systems. Here, the radio base stations A and B constituting each radio communication system are shown one by one for convenience of explanation. However, each radio base station may have a plurality of radio base stations. In addition to the radio communication system by the stations A and B, more radio communication systems may exist. Further, the communication terminal 2 establishes a wireless communication connection with the wireless communication system having the wireless base station A or B and a wireless communication connection with each base station in each wireless communication system according to the radio wave strength or an instruction from the wireless base station. Thus, a process for always maintaining good wireless communication connection standby with the wireless communication system or the wireless base station is performed.

  In the process of switching the wireless communication connection destination (standby destination) from the wireless base station to another base station, the wireless base station waits for its own base station for a Global Service Redirection Message (hereinafter referred to as redirection information). By transmitting to the communication terminal 2 in the received state, the communication terminal 2 that has received the redirection information performs a capture process for switching the standby destination of the wireless communication to another wireless base station (wireless communication system), and then performs a certain time After the elapse of time, the communication terminal 2 that has performed the redirection processing has received another wireless base station <wireless base station (wireless communication system) connected before the redirection processing, or other wireless base station (wireless communication system)> By performing the reselection process, the wireless communication standby destination is switched again. A process for reducing the processing load in the radio base station to which the standby destination is switched during the reselection process will be described below.

FIG. 2 is a functional block diagram of the communication terminal.
The communication terminal 2 inputs a control unit 21 that controls each processing unit in its own terminal, a radio communication unit 22 that establishes a radio communication connection with a radio base station using a CDMA digital mobile communication system, and inputs characters and operation instructions. Receiving key input unit 23, sound output unit 24 for outputting sound, display unit 25 for displaying a character string and other information input on a liquid crystal screen, redirection processing unit 26 for performing redirection processing, and reselection for performing reselection processing A processing unit 27 and a storage unit 28 for storing various information such as a PRL (Preferred Roaming List) are provided.

FIG. 3 shows the data structure of the PRL.
Next, the PRL will be described.
The PRL is a list holding identification information of radio base stations (wireless communication systems), and is stored in advance in the storage unit 28 of the communication terminal 2. As shown in FIG. 3, the PRL includes a plurality of combination information such as BandClass (used frequency band: hereinafter referred to as BC), channel (used frequency, hereinafter referred to as CH), SID (system identifier), NID (network identifier), and priority. Is retained. Here, in order to configure different radio communication systems, different BC, CH, SID, and NID information is assigned to the radio base station A or B. And the communication terminal 2 receives the signal (pilot signal) transmitted from the radio base station, compares the information included in the signal with the information held in the PRL, and holds it in the PRL, for example. It is a signal including BC, CH, SID, and NID information, and a radio base station that transmits a signal having a radio wave intensity of a predetermined level or higher is captured. Then, the communication terminal 2 waits for information from the radio base station that has succeeded in the acquisition process toward the terminal. The priority held in the PRL indicates a radio communication base station (wireless communication system) that preferentially captures, and is indicated in the PRL with a priority “high” or “low”. For example, the priority of the communication terminal 2 when the communication terminal 2 is in a state of waiting for the radio base station of the radio communication system having the high priority is when the communication terminal 2 is used frequently. This is used for processing to make a wireless communication system with a low priority “low” stand by.

  In addition, when the communication terminal 2 waits for information from the radio base station to the self terminal, the communication terminal 2 performs the location registration process of the self terminal on the radio base station that has captured it. In response to the reception of the connection start information (Sync) received from the radio base station, the location registration process returns identification information (terminal ID, etc.) of the terminal itself to the radio base station, and the radio base station communicates with the communication terminal 2. The identification information is held.

  In addition, information of Access Overload Class (hereinafter referred to as “ACCOLC”) is stored in advance in the storage unit 28 of the communication terminal 2. This ACCOLC is information for grouping the communication terminals 2 and is used for radio base station switching processing. For example, when a wireless base station requests switching of a wireless communication connection to another wireless base station, this ACCOLC information is stored in the switching request information. Then, the communication terminal 2 confirms the information of ACCOLC, and when the information is the same as the information of ACCOLC, the communication terminal 2 starts a process of switching the connected radio base station.

FIG. 4 is a first diagram showing an outline of processing of the wireless communication system.
FIG. 5 is a second diagram showing an outline of processing of the wireless communication system.
FIG. 6 is a diagram illustrating a processing flow of the reselection processing unit.
FIG. 7 is a third diagram illustrating an outline of processing of the wireless communication system.
FIG. 8 is a fourth diagram illustrating an outline of processing of the wireless communication system.
Next, a processing flow of the wireless communication system according to the present embodiment will be described with reference to FIGS.
From FIG. 4, it is assumed that the three communication terminals 2 of the communication terminals 2a, 2b, and 2c are in a standby state first in the radio base station A (wireless communication system). It is assumed that the communication terminals 2a, 2b, and 2c hold ACCOLC information indicating the same class in the storage unit 28. Note that the communication terminal 2 storing different ACCOLC information may be in a standby state in the radio base station A. In such a situation, when the radio base station A detects a communication failure (data congestion or the like) in its own base station or the like, in order to maintain a good communication environment of the standby communication terminal 2, Alternatively, redirection information indicating switching of the standby destination of the wireless communication connection to the wireless communication system) is transmitted. In this redirection information, at least ACCOLC information and information (BC, CH, SID, NID, etc.) of the switching destination radio base station (wireless communication system) B are stored. The switching-destination radio base station B by redirection is a radio base station (radio communication system) with a “low” priority.

  Next, the plurality of communication terminals 2 connected (standby) to the radio base station A receive the redirection information transmitted from the radio base station A. At each communication terminal 2 that has received the redirection information at this time, the redirection processing unit 26 reads the information of ACCOLC stored in the redirection information. Then, the redirection processing unit 26 compares the read ACCOLC information with the information stored in the storage unit 28 of the terminal itself, and determines whether or not they are the same. Here, it is assumed that the ACCOLC information stored in the communication terminals 2a to 2c matches the ACCOLC information stored in the redirection information. Then, the redirection processing unit 26 of the communication terminals 2a to 2c starts a redirection process according to the reception of the redirection information. That is, the communication terminal 2 belonging to the group specified by the ACCOLC information starts the redirection process.

  When the redirection processing unit 26 of the communication terminals 2a to 2c starts the redirection process, the redirection processing unit 26 first notifies the radio communication unit 22 to perform a capturing process on the radio base station B. In this acquisition processing, the radio base station is searched by searching for a pilot signal transmitted from a radio base station in a radio communication system other than the radio base station A, and synchronizing the short-term PN code of the terminal with the searched pilot signal. The station (wireless communication system) B is supplemented. After that, the radio base station identification information (BC, CH, SID, NID, etc.) included in the signal from the radio communication base station B is read, and a signal that matches the radio base station B identification information is selected. Complete the acquisition process for station B. When this acquisition process is completed, the control unit 21 controls the wireless communication unit 22 and the like so as to perform standby for the supplemented wireless base station B. Thereafter, the redirection processing unit 26 notifies the reselection processing unit 27 to start the reselection process.

  Next, when the reselection processing unit 27 receives a notification of the start of the reselection processing from the redirection processing unit 26 (step S101), it generates a random number to generate one value (step S102). The reselection processing unit 27 registers the generated value as a counter value in a counter memory or the like, and counts the time indicated by the counter value (step S103). The time indicated by the counter value is the time from the start of standby for the radio base station B to the start of the reselection process. The reselection processing unit 27 determines whether or not the counter value is counted (step S104). When the counter value is reached, the reselection processing is started. Here, since the counter value is a value generated by random number generation, the radio base station A is switched to another radio base station (or another radio communication system) in accordance with a redirection instruction (redirection information reception). Each of the communication terminals 2a to 2c starts the reselection process based on different counter values. That is, each timing which starts the reselection of the communication terminals 2a-2c differs.

  From FIG. 5, it is assumed that the communication terminal 2a having the smallest counter value starts the reselection process. The reselection processing unit 27 of the communication terminal 2a that counted the time of the counter value identifies the identification information associated with the priority “high” in the PRL, and the radio base station (radio communication system) A having this identification information A capturing process is performed on (step S105). Specifically, the radio base station (radio communication system) A is searched by searching for a pilot signal transmitted from the radio base station A, and synchronizing the short-period PN code of the own terminal with the searched pilot signal. Complement. Then, if there is no failure in the supplemented radio base station A, the reselection processing unit 27 performs location registration processing on the radio base station A (step S106), and the radio base station A Stand by. Note that the base station supplemented when performing the reselection may be another high-priority radio base station (radio communication system) different from the radio base station A.

  Next, from FIG. 7, it is assumed that the communication terminal 2b having the second smallest counter value starts the reselection process as the count reaches the counter value. This reselection process is the same as the process of the communication terminal 2a described above. Further, as shown in FIG. 8, the communication terminal 2c having the longest counter value starts the reselection process as it counts up to the counter value. This process is also similar to the process of the communication terminal 2a described above.

  With the above processing, since the reselection start timing is different for each communication terminal based on the counter value generated by generating the random number, it is possible to suppress overlap of the location registration processing after the capture processing accompanying the reselection processing. Thereby, the system load of the base station due to the location registration request generated after the reselection process can be reduced.

  Note that the communication terminal and the wireless base station described above have a computer system inside. The process described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

  In the above-described embodiment, the radio communication system including the radio base station A different from the radio communication system that performs the reselection process from the standby state with respect to the radio communication system including the radio base station B is provided. However, the present invention is not limited to this. However, the acquisition priority is set for a plurality of radio base stations in the same radio communication system, and the reselection process is performed in the same radio communication system. You may comprise so that the start timing of the reselection process at the time of supplementing with respect to another radio base station with a high acquisition priority may differ in each terminal.

It is a block diagram which shows the structure of a radio | wireless communications system. It is a functional block diagram of a communication terminal. It is a figure which shows the data structure of PRL. It is a 1st figure which shows the process outline | summary of a radio | wireless communications system. It is a 2nd figure which shows the process outline | summary of a radio | wireless communications system. It is a figure which shows the processing flow of a reselection process part. It is a 3rd figure which shows the process outline | summary of a radio | wireless communications system. It is a 4th figure which shows the process outline | summary of a radio | wireless communications system.

Explanation of symbols

A, B Radio base station 2 Communication terminal 21 Control unit 22 Radio communication unit 23 Key input unit 24 Audio output unit 25 Display unit 26 Redirection processing unit 27 Reselection processing unit 28 Storage unit

Claims (7)

A plurality of base stations, and a plurality of communication terminals waiting for a predetermined base station among the plurality of base stations,
The given base station transmits to the plurality of communication terminals in the waiting state with respect to the base station, according to a predetermined condition, simultaneously redirection information indicating an instruction of capturing to other base stations A wireless communication system comprising redirection information transmitting means,
The communication terminal includes a capturing processing means based on the received redirection information sent to the simultaneously performs acquisition processing to listen to the other base station,
Counting means for counting an elapsed time after the capture processing based on reception of the redirection information ,
Said acquisition processing means, when it is counted until the generated counter value by the random number generated by said counting means, performs acquisition processing for high base station priority over other base stations the waiting <br / > A wireless communication system characterized by the above.   The wireless communication system according to claim 1, wherein the communication terminal includes counter value generation means for generating the counter value by random number generation. The base station comprises counter value generation means for generating the counter value by random number generation,
The wireless communication system according to claim 1, wherein the counter value is transmitted to the communication terminal together with the redirection information. It further comprises acquisition priority storage means for storing the priority of the base station that performs acquisition processing,
The acquisition processing means performs acquisition processing for a base station having a higher priority than the other base stations waiting based on the stored priority.
The wireless communication system according to claim 1, wherein the wireless communication system is a wireless communication system. A plurality of base stations, and a plurality of communication terminals waiting for a predetermined base station among the plurality of base stations,
For the plurality of communication terminals, wherein the predetermined base station is in a waiting state in the base station, according to a predetermined condition, the redirection information transmission for transmitting simultaneously redirection information indicating an instruction of capturing to other base stations A wireless communication method in a wireless communication system comprising means ,
The communication terminal based on the reception of the redirection information, performs acquisition processing to listen to the other base station,
Count the elapsed time after the capture process based on the reception of the redirection information,
A radio communication method characterized in that , when a counter value generated by random number generation is counted, acquisition processing for a base station having a higher priority than the other waiting base stations is executed. For a plurality of communication terminals in the standby state with respect to the base station, according to a predetermined condition, including a redirection information transmission means for concurrently transmitting the redirection information indicating an instruction of capturing to other base stations the base A communication terminal that can stand by at a station,
Based on the reception of the redirection information, and acquisition processing means for performing a capture process to listen to the other base station,
Counting means for counting an elapsed time after the capture processing based on reception of the redirection information ,
Said acquisition processing means, characterized in that said when it is counted until the generated counter value by the random number generated by the counting means, to execute the acquisition process for the base station a higher priority than the other base stations that the waiting Communication terminal. A plurality of base stations, and a plurality of communication terminals waiting for a predetermined base station among the plurality of base stations,
For a plurality of communication terminals, wherein the predetermined base station is in a waiting state in the base station, according to a predetermined condition, the redirection information transmitting means for transmitting simultaneously a redirection information indicating an instruction of capturing to other base stations A program to be executed in a wireless communication system comprising:
Based on the reception of the redirection information, and acquisition processing for performing acquisition process to listen to the other base station,
A counting process for counting an elapsed time after the capture process based on reception of the redirection information;
The acquisition process, when it is counted until the counter value generated by the random number generated by the counting process, performs acquisition processing to the base station a higher priority than the other base stations that the waiting <br / > A program characterized by

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