JP5058779B2 - Location registration method and mobile station - Google Patents

Description

  The present invention relates to a location registration method and a mobile station for registering its own location with respect to a wireless communication system.

  In a wireless communication system using a mobile station such as a PHS (Personal Handy phone System) or a mobile phone, location registration with surrounding base stations is required to receive an incoming call to the mobile station. The mobile station establishes wireless communication with the base station having the best communication quality, and performs location registration with the base station. The relay server in the wireless communication system specifies the position of the mobile station based on the position registration, and performs a mobile call to the base station or base station group whose position is registered.

  After the location registration is completed, when a base station with higher communication quality enters the communication range than the registered base station, the mobile station switches the communication target to a new base station with higher communication quality and re-positions at that base station. Carry out registration. However, depending on the communication environment, the superiority or inferiority of communication quality in a plurality of base stations changes from time to time, and position registration is frequently repeated, resulting in wasted power.

  In order to avoid such complicated location registration, the density of the base station is analyzed, and the number of location registrations of the mobile station within a predetermined time is controlled according to the density of the base station, and the base station exists only sparsely By the way, a technique for reducing wasteful power consumption by reducing the number of location registrations is known (for example, Patent Document 1). A technique for limiting the number of location registration requests to a predetermined number is also disclosed (for example, Patent Document 2).

  Not only the limitation of the number of times of position registration, but also complicated position registration can be avoided by using, for example, a received signal strength indicator (RSSI). When the radio field intensity falls below a predetermined value, the mobile station starts searching for a new base station, and switches when a base station having a higher radio field intensity than the currently communicating base station is found. Also disclosed is a technique for finding a new optimum base station and registering a location with the base station even if the radio field intensity does not fall below a predetermined value (for example, Patent Document 3).

Furthermore, a method of imposing a certain amount of offset on the radio field intensity of the destination base station is also adopted. Here, the mobile station further adds an offset of, for example, 12 dB to the radio field strength of the base station with which the radio communication is established, and only the base station having the radio field strength higher than that becomes a new location registration destination. When the mobile station is stopped, a difference of 12 dB is rarely generated as a radio wave intensity, so that a new location registration hardly occurs.
Japanese Patent Application Laid-Open No. 7-212827 JP-A-9-18934 JP-A-10-94032

  However, in a weak electric field where communication errors occur frequently, simply applying the above technology will cause the mobile station to search a wide range of base stations if for some reason the radio waves of the registered base station cannot be received. Thus, there is a risk of starting communication with a base station at a distance where location registration is not possible. This operation will be described with reference to FIGS.

  When an interrupt occurs in the flowchart of FIG. 10, first, it is determined whether the current state is at the time of start-up or the state in which the base station has been lost (S10). A base station search is performed for all surrounding ranges (S12). In such a base station search, communication qualities of a plurality of base stations are measured, and priorities are set for the plurality of base stations.

  Then, a communication start request (S14) is made from a base station with high communication quality among the searched base stations. Here, when the communication start request is not normally completed (S16), it is determined whether the communication start request is made for all the searched base stations (S18), and the communication start request is made at all the base stations. If the communication start process fails, the process is restarted from the beginning. If all the base stations have not ended, the base station with the next highest communication quality is selected (S20), and the communication start request (S14) is repeated.

  Further, if the current state is not a state of starting or disappearing of the base station, it is determined whether or not the radio field intensity of the current base station has decreased below a predetermined value (S22). A base station search is performed (S24). Therefore, it is determined whether or not there is a base station whose communication quality is higher than that of the current base station by an offset, for example, a radio field strength of 12 dB is higher (S26). S28). Here, when the communication start request is normally completed (S30), the base station as the communication target is changed to a new base station that has made the communication start request (S32). In this way, at least communication synchronization can be established between the mobile station and the base station.

  In the communication start process described above, when a base station other than the base station group whose position has already been registered is detected as a communication target (S34), the position registration process is performed. Such a situation may occur when the mobile station moves or when the power is turned on (if it is different from the base station group registered when the power is turned off). Here, the base station group refers to one or a plurality of base stations for securing a communication area serving as a position registration unit, and the one or a plurality of base stations perform equivalent functions in specifying the position.

  In the location registration process, a base station search is performed only for the base station group to which the base station subjected to communication in the communication start process belongs (S36), and a base station with a high communication quality among the searched base stations. The location registration request is executed (S38). If the location registration request is not normally completed (S40), it is determined whether or not the location registration request has been made for all the searched base stations (S42), and the location registration request is made at all base stations. If so, the process is restarted from the beginning, assuming that the position registration process has failed. If all the base stations have not ended, the base station having the next highest communication quality is selected (S44), and the process from the location registration request (S38) is repeated after a timer count of several tens of seconds.

  The problem of the present invention will be described by applying the location registration process as shown in the flowchart of FIG. 10 to the communication environment of FIG. In FIG. 11, the mobile station 50 straddles both the communication area 52 and the communication area 54 under a weak electric field. In each of the communication areas 52 and 54, a group of base stations 60a, 60b and 60c and a group of 62a and 62b connected to the communication network 56 form a base station group. The base station group that supplements communication in the communication areas 52 and 54 is a location registration unit in the wireless communication system.

  In the state of FIG. 11, since the mobile station 50 has established communication with the base station 60 a with a short communication distance, location registration is also performed for the base station group in the communication area 52. At this time, the mobile station 50 receives the radio wave of the base station 62a even though it is weak, but since the difference in radio wave intensity from the current base station 60a does not reach 12 dB, the communication target is not transferred to the base station 62a. Absent.

  However, if the communication with the base station 60a fails continuously several times due to instability of the communication environment due to the weak electric field, the mobile station 50 has lost the base station 60a as shown in FIG. Search for. Then, the base station with the best communication quality at that time is detected regardless of the offset of 12 dB. If the radio wave of the base station 62a happens to be received at this time, the mobile station 50 starts communication with the base station 62a.

  Here, since the base station 62a that started communication is different from the registered base station groups 60a, 60b, and 60c, as shown in FIG. 13, the mobile station 50 has a communication area 54 that includes the base station 62a. The location registration request is made only to the base station group (base stations 62a and 62b) (masking the other base stations 60a, 60b and 60c). This is because a base station group including a base station that has started communication by a base station search is considered to be optimal for location registration. However, when both of the base stations 62a and 62b have a communication distance from the mobile station 50, the mobile station 50 cannot establish communication with the base stations 62a and 62b. Therefore, the location registration will eventually fail.

  Under this circumstance, the base station 60a to be originally communicated is excluded from communication targets, and even if the radio field strength of the base station 60a returns to normal and exceeds the base station 62a, the difference must exceed 12 dB. It will not be subject to communication.

  Thus, even if the mobile station 50 is not moving, the base station to be communicated may change depending on the surrounding radio wave environment, and the newly detected base station should not be detected originally If so, a situation occurs in which the mobile station 50 cannot make an incoming call by repeatedly making a location registration request. Here, although it is possible to fix the base station to be communicated to the base station whose location has been registered, it becomes impossible to cope with the case where the mobile station 50 has actually moved.

  By falling into such a situation, location registration is frequently attempted to a base station that cannot perform location registration, and the mobile station 50 consumes power wastefully. Also, during this location registration process, a link channel cannot be established and incoming calls cannot be made, resulting in a reduction in incoming call rate.

  In view of such a problem, the present invention reduces a useless location registration request to a base station that cannot perform location registration, suppresses wasteful consumption of power, and improves an incoming call rate. And to provide a mobile station.

  In order to solve the above problems, a typical configuration of the location registration method according to the present invention is to perform a base station search for receiving a control channel of a plurality of base stations and detecting a base station with high communication quality as a wireless communication target. When a base station other than the base station group in which the location of the mobile station has been registered is detected in the communication start step, the communication start step for starting the wireless communication with the detected base station is performed for all the surroundings. If the base station detected by the communication start step is included in the base station group to which the base station detected by the base station search belongs, the location registration is performed and the base station is not included And a position registration step re-executed from the communication start step.

  In the location registration step, since the base station search is performed again not only for the base station group to which the base station to be communicated belongs but also for the entire periphery, the radio waves of the base station that happens to be unable to receive radio waves in the communication start process The possibility of receiving is increased. Accordingly, it is possible to perform location registration with respect to a base station group that should originally register the location. By reducing useless location registration requests to base station groups that cannot perform location registration in this way, wasteful power consumption is suppressed, and processing that prevents incoming calls is eliminated, thereby improving the incoming call rate even in weak electric fields. It becomes possible.

  The base station group may be one or a plurality of base stations for securing a communication area serving as a location registration unit, and the identifiers of the base station group may have the same number of digits. With this configuration, the mobile station can quickly determine the base stations belonging to the same base station group. Therefore, even when position registration is performed for each base station in a specific base station group, the target base station can be specified only by the identifier.

  A typical configuration of a mobile station according to the present invention is to detect a base station search that receives a control channel of a plurality of base stations and detects a base station having a high communication quality as a wireless communication target for all surroundings. If a communication start unit that starts wireless communication with the base station and a base station other than the base station group that has registered its position is detected by the communication start unit, the base station search is performed again for the entire periphery, and the base station A position that performs location registration when the base station detected by the communication start unit is included in the base station group to which the base station detected by the station search belongs, and when the base station is not included, the position at which the communication start unit is operated again And a registration unit.

  The components corresponding to the technical idea in the location registration method and the description thereof can also be applied to the mobile station.

  As described above, according to the location registration method of the present invention, it is possible to reduce useless location registration requests to base stations that cannot perform location registration, suppress wasteful consumption of power, and improve the incoming call rate. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Wireless communication system 100)
In order to receive an incoming call to the mobile station, the mobile station registers its own position with respect to surrounding base stations in the wireless communication system. The present embodiment aims to eliminate useless location registration requests in such a wireless communication system, to reduce power consumption and to improve the incoming call rate. Here, for easy understanding, the location registration operation will be described using the configuration of the wireless communication system 100, and then the specific configuration of the mobile station will be described in detail.

  FIG. 1 is a block diagram illustrating a schematic configuration of a wireless communication system 100. The wireless communication system 100 includes a PHS terminal 110 (110a, 110b) as a mobile station, a base station 120 (120a, 120b, 120c), a communication network such as an ISDN (Integrated Services Digital Network) line, the Internet, and a dedicated line. 130 and the relay server 140. Here, the PHS terminal 110 is cited as a mobile station, but the present invention is not limited to such a case. A mobile phone, a notebook personal computer, a PDA (Personal Digital Assistant), a digital camera, a music player, a car navigation system, a portable TV, a game device. Various electronic devices capable of registering the position, such as DVD players and remote controllers, can also be used as mobile stations.

  In the wireless communication system 100, the PHS terminals 110a and 110b perform location registration with the communicable base stations 120a and 120b, respectively.

  When a user attempts to connect a telephone line from the PHS terminal 110a to another PHS terminal 110b, wireless communication with the base station 120a in the wireless communication available area is established according to the operation of the user's PHS terminal 110a. The base station 120 requests the relay server 140 to establish a communication connection with the PHS terminal 110b via the communication network 130, as indicated by (1) in FIG.

  Then, the relay server 140 specifies the base station 120b in the communication area 150b of the PHS terminal 110b based on the registered position information. Then, as shown in (2) in FIG. 1, a simultaneous call is made to the location-registered communication area 150b including the base station 120b. Thereafter, the relay server 140 sets a voice call with the PHS terminal 110b for the base station 120b. When the setup of the voice call at the base station 120b is completed, the relay server 140 passes the voice call processing between the base stations, and as shown in (3) in FIG. 1, the user-side and communication partner-side base stations 120a, The audio signals are directly transmitted and received mainly by 120b. Thus, a call between the PHS terminals 110a and 110b is established.

  In the wireless communication system 100, as indicated by the white arrow in FIG. 1, when the PHS terminal 110b moves, the communication area is changed accordingly. At this time, the PHS terminal 110b must perform location registration with the base station 120c in the new communication area 150c. Accordingly, the PHS terminal 110b has to determine whether or not to perform a new location registration by searching for the radio field strength of the surrounding base stations.

  For example, when the PHS terminal 110b performs a base station search, if the base station 120c has higher radio field strength than the base station 120b and the difference is 12 dB or more, the PHS terminal 110b The location is changed from 120b to the base station 120c, and location registration is performed with respect to the base station 120c. However, under a weak electric field, a base station detected as a communication target is not necessarily a base station that should register the location. If location registration is performed for a base station that happens to receive radio waves, location registration It takes a long time to process and causes a phenomenon of failure. In this embodiment, such a phenomenon is avoided.

(PHS terminal 110)
FIG. 2 is a functional block diagram showing a hardware configuration of the PHS terminal 110, and FIG. 3 is a perspective view showing an appearance of the PHS terminal 110. As shown in FIG. The PHS terminal 110 includes a terminal control unit 210, a terminal memory 212, a display unit 214, an operation unit 216, a voice input unit 218, a voice output unit 220, and a wireless communication unit 222.

  The terminal control unit 210 manages and controls the entire PHS terminal 110 using a semiconductor integrated circuit including a central processing unit (CPU). The terminal control unit 210 also performs a call function, a mail transmission / reception function, an imaging function, a music playback function, and a TV viewing function using the program in the terminal memory 212.

  The terminal memory 212 includes a ROM, a RAM, an EEPROM, a non-volatile RAM, a flash memory, an HDD (Hard Disk Drive), and the like, and stores a program processed by the terminal control unit 210, audio data, and the like.

  The display unit 214 includes a liquid crystal display, EL (Electro Luminescence), PDP (Plasma Display Panel), etc., and is stored in the terminal memory 212 or from an application relay server (not shown) via the communication network 130. The GUI (Graphical User Interface) of the provided Web browser or application can be displayed.

  The operation unit 216 includes switches such as a keyboard, a cross key, and a joystick, and receives a user operation input.

  The voice input unit 218 includes voice recognition means such as a microphone, and converts the user's voice input during a call into an electrical signal that can be processed in the PHS terminal 110.

  The voice output unit 220 includes a speaker, and converts the voice signal of the call partner received by the PHS terminal 110 into voice and outputs the voice. Further, a ring tone, an operation sound of the operation unit 216, an alarm sound, etc. can be output.

  The wireless communication unit 222 performs wireless communication with the base station 120 in the communication network 130. As such wireless communication, a time-division multiplexing method is employed in which communication is performed by allocating a plurality of time slots obtained by time-dividing frames in the base station 120 to channels of the PHS terminal 110, respectively.

  In the present embodiment, the terminal control unit 210 also functions as a communication start unit 230 and a location registration unit 232.

  The communication start unit 230 receives a control channel (CCH) of a plurality of base stations 120, and detects a base station having a high communication quality, for example, a high radio wave intensity or a low error rate as a wireless communication target. A search is performed for the entire periphery, and wireless communication is started with the base station 120 detected there. Here, the base station search is a process for detecting a base station to be communicated from a plurality of base stations, obtains an identifier for identifying the base station from the control channel of each base station, and receives the radio wave of the received radio wave at that time Prioritize base stations according to their strength.

  If the base station 120 other than the base station group whose location has already been registered is detected by the communication start unit 230, the location registration unit 232 performs the base station search again for the entire periphery. If the base station 120 detected by the communication start unit 230 is included in the base station group to which the base station detected by this base station search belongs, location registration is performed. The unit 230 is operated again.

  Since the location registration unit 232 performs the base station search again not only for the base station group to which the base station 120 to be communicated belongs but also for the entire periphery, the communication start unit 230 could not receive the radio wave by chance. The possibility that the radio waves of the base station 120 can also be received increases. Therefore, it is possible to perform location registration with respect to a base station group that should originally register location. By reducing useless location registration requests to base station groups that cannot perform location registration in this way, wasteful power consumption is suppressed, and processing that prevents incoming calls is eliminated, thereby improving the incoming call rate even in weak electric fields. It becomes possible.

  The identifiers of the base station group may have the same number of digits. The predetermined number of digits may be a predetermined number from the upper part, a predetermined number from the lower part, or a predetermined number partially dispersed. With this configuration, the PHS terminal 110 can quickly determine the base stations 120 belonging to the same base station group. Accordingly, even when location registration is performed for each base station 120 in a specific base station group, the target base station 120 can be specified only by the identifier.

  In addition, when the identifier of the new base station 120 is acquired, such as when the power is turned on or when moving from outside the communication range to the communication range, the base station that finally registered the location last time (when the power was turned off or moved outside the communication range) Since it is possible to easily determine whether the base station belongs to a group, the location registration process can be started quickly.

  With the PHS terminal 110 as a mobile station described above, it is possible to reduce useless requests to base stations that cannot perform location registration, suppress useless consumption of power, and improve the incoming call rate. The specific processing operation of this embodiment will be described below with reference to the processing flow of the location registration method according to this embodiment.

(Location registration method)
FIG. 4 is a flowchart showing a processing flow of the location registration method. In the communication start process, the PHS terminal 110 performs a base station search, receives control channels of a plurality of base stations 120, detects a base station with high communication quality as a wireless communication target, and detects the detected base station 120. And start wireless communication. Since the configuration of the communication start process is substantially the same as the process of the flowchart of FIG. 10, the description thereof is omitted here.

  When the base station 120 other than the base station group whose location is already registered is detected as a communication target in the communication start process (S300), the PHS terminal 110 is only the base station group to which the detected base station belongs. Instead, a base station search is performed for the entire periphery (S302).

  When the base station group detected by the above-described communication start process is included in the base station group to which the base station detected by the base station search belongs (S304), the location registration process is performed. In the location registration process, a base station search is performed only for the base station group to which the base station 120 to be communicated in the communication start process belongs (S306), and a base having a high communication quality among the searched base stations. A location registration request is executed from the station (S308). If the location registration request is not normally completed (S310), it is determined whether or not the location registration request has been made for all the searched base stations (S312), and the location registration request is made at all base stations. If so, the process is restarted from the beginning, assuming that the position registration process has failed. If all the base stations have not ended, the base station with the next highest communication quality is selected (S314), and the process from the location registration request (S308) is repeated after a timer count of several tens of seconds.

  If the base station group to which the base station detected by the base station search belongs does not include the base station 120 detected by the communication start process described above (S304), the process is restarted from the beginning assuming that the location registration has failed.

  5-8 is explanatory drawing for demonstrating the position registration process mentioned above. In FIG. 5, the PHS terminal 110 straddles both the communication area 352 and the communication area 354 under a weak electric field. In each communication area 352, 354, a group of base stations 120d, 120e, 120f and a group of 120g, 120h connected to the communication network 130 form a base station group. In the state of FIG. 5, since the PHS terminal 110 has established communication with the base station 120 d having a short communication distance, location registration is also performed for the base station group in the communication area 352. At this time, although the PHS terminal 110 receives the radio wave of the base station 120g even though it is weak, the difference in radio wave intensity from the current base station 120d does not reach 12 dB, so that the communication target shifts to the base station 120g. Absent.

  Here, if communication with the base station 120d fails continuously several times due to instability of the communication environment due to the weak electric field, the PHS terminal 110 disappears from the base station 120d as shown in FIG. Search for a station. Then, the base station with the best communication quality at that time is detected regardless of the offset of 12 dB. If the radio wave of the base station 120g happens to be received at this time, the PHS terminal 110 starts communication with the base station 120g.

  At this time, the base station 120g that has started communication is different from the base station groups 120d, 120e, and 120f that have already registered their locations, so that the PHS terminal 110 proceeds to location registration processing, but in this embodiment, location registration is executed. Before, further, the base station search is performed all around, that is, as shown in FIG. 7, the base station group (120d, 120e, 120f) of the communication area 352 including the base station 120d and the communication area including the base station 120g. Execute for all ranges including 354 base stations (120g, 120h).

  At this time, if the radio wave of the base station 120d is received again, the current base station search result and the previous base station search result are different (the base station group to which the base station detected by the base station search belongs). Therefore, the location registration is determined to be unsuccessful and is immediately performed again from the communication start process. As described above, there is very little possibility that the base station 120g is detected as a communication target, and the communication target and the location registration target all become the base station 120d and return to the original stable communication environment as shown in FIG. To do.

  Further, as shown in FIG. 8, when the PHS terminal 110 actually moves, the base station group (120g, 120h) detected in the base station search in the communication start process is searched again for the base station search in the position registration process. Therefore, the PHS terminal 110 can appropriately receive an incoming call by newly registering the location with the base station group to which the base station 120g belongs.

  It is possible to reduce useless requests to base stations that cannot be registered even by the location registration method as described above, suppress wasteful consumption of power, and improve the incoming call rate. When the location registration method according to the present embodiment and the conventional method are applied to a PHS terminal and an incoming call rate is tested under a weak electric field, as shown in FIG. In contrast, the location registration method of the present embodiment has achieved a result exceeding 55 times.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  Note that the steps in the location registration method of the present specification do not necessarily have to be processed in chronological order in the order described in the flowchart, but are executed in parallel or individually (for example, parallel processing or object-based processing). Processing).

  INDUSTRIAL APPLICABILITY The present invention can be used for a location registration method for registering its own location with respect to a wireless communication system and a mobile station.

1 is a block diagram showing a schematic configuration of a wireless communication system in the present embodiment. It is the functional block diagram which showed the hardware constitutions of the PHS terminal. It is the perspective view which showed the external appearance of the PHS terminal. It is the flowchart which showed the flow of the process of the position registration method. It is explanatory drawing for demonstrating a location registration process. It is explanatory drawing for demonstrating a location registration process. It is explanatory drawing for demonstrating a location registration process. It is explanatory drawing for demonstrating a location registration process. It is explanatory drawing which showed the Example of the location registration method. It is the flowchart which showed the flow of the process of the conventional location registration method. It is explanatory drawing for demonstrating the conventional location registration process. It is explanatory drawing for demonstrating the conventional location registration process. It is explanatory drawing for demonstrating the conventional location registration process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Wireless communication system 110 ... PHS terminal 120 ... Base station 130 ... Communication network 230 ... Communication start part 232 ... Location registration part

Claims (3)

A communication start step for receiving a control channel of a plurality of base stations and performing a base station search for detecting a base station having a high communication quality as a wireless communication target for all surroundings, and starting wireless communication with the detected base station;
When a base station other than the base station group in which the location of the mobile station is registered is detected in the communication start step, the base station search is performed again for the entire periphery, and the base station to which the base station detected by the base station search belongs If the base station detected in the communication start step is included in the station group, position registration is performed, and if not included, the position registration step re-executed from the communication start step,
The location registration method characterized by including.   2. The base station group is one or a plurality of base stations for securing a communication area as a location registration unit, and the identifier of the base station group has a predetermined number of digits equal to each other. Location registration method described in 1. A base station search that receives a control channel of a plurality of base stations and detects a base station with high communication quality as a target for wireless communication, and a communication start unit that starts wireless communication with the detected base station;
When a base station other than the base station group whose location has been registered is detected by the communication start unit, the base station search is performed again for the entire periphery, and the base station to which the base station detected by the base station search belongs If the base station detected by the communication start unit is included in the group, position registration is performed, and if not included, the position registration unit that operates the communication start unit again,
A mobile station comprising:

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