Mobile station, wireless communication system, mobile station control method, and control program

Abstract

To capture an electric wave determined on the basis of a priority list at the time of a zone mobile.SOLUTION: A mobile station (10) is communicated to any one of a plurality of base stations, acquires frequency information related to a frequency of the plurality of base stations, initializes a priority list (17) so as to list the frequency in order of a high frequency level (S11), repeatedly executes a standby processing containing a processing for determining each frequency whether or not a measurement in each frequency of a received magnetic field strength of an electric wave and a decoding of an encryption signal contained in the electric wave are performed in each frequency indicated by the priority list (17) at the time of the standby, and a processing for updating the priority list (17) so that the frequency of the signal to be decoded of the encryption signal is arranged in order of a large reception magnetic field strength (S12 to S15), and determines the electric wave captured at the time of a zone movement moved to the other base station from a zone of one base station of the plurality of base stations on the basis of the updated priority list (17).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a mobile station, a wireless communication system, a control method for a mobile station, and a control program. [Background technology]

[0002] In a conventional carrier monitoring method in a wireless communication system, a mobile station monitors a received carrier when two conditions are met: the received field strength of a carrier wave (i.e., a carrier) transmitted from a base station in a zone surrounding the zone of the base station with which the mobile station is communicating is above a certain level, and there is meaningful data carried by the received carrier (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-304360 A (see, for example, the Abstract) Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional method has a problem that when there is a source that emits jamming waves, which are fraudulent radio waves that imitate meaningful data carried on a carrier emitted from a base station, the mobile station may mistakenly determine that the jamming waves are radio waves emitted from a base station in the surrounding zone.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a mobile station and a wireless communication system having the same that can capture radio waves determined based on a priority list when moving between zones. [Means for solving the problem]

[0006] A mobile station according to the present disclosure is a mobile station in a wireless communication system having a plurality of base stations that transmit radio waves at frequencies determined for each zone in different zones. The mobile station communicates with one of the plurality of base stations. The mobile station includes a receiving unit that receives the radio waves, a decoding unit that decodes encrypted signals contained in the radio waves, and a control unit. The control unit acquires frequency information about the frequencies of the plurality of base stations, initializes a priority list to sort the frequencies in descending order of priority, and, during standby, repeatedly performs standby processing for each frequency indicated in the priority list, measuring the received field strength of the radio waves for each frequency and determining whether the encrypted signals contained in the radio waves have been decoded for each frequency, and updating the priority list to sort the frequencies of the encrypted signals that have been successfully decoded in descending order of received field strength. The control unit determines, based on the updated priority list, radio waves to capture when moving from a zone of one base station to a zone of another base station among the plurality of base stations. [Effects of the Invention]

[0007] According to the present disclosure, a mobile station can capture radio waves determined based on a priority list when moving between zones. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating a configuration of a wireless communication system according to a first embodiment. [Figure 2] 2 is a functional block diagram showing a configuration example of a mobile station according to the first embodiment. FIG. [Figure 3] FIG. 2 is a diagram illustrating an example of a hardware configuration of a mobile station according to the first embodiment. [Figure 4] 5 is a flowchart showing the operation of the mobile station according to the first embodiment. [Figure 5] FIG. 10 is a schematic diagram illustrating a configuration of a wireless communication system according to a second embodiment. [Figure 6] FIG. 10 is a functional block diagram showing an example of the configuration of a mobile station according to a second embodiment. [Figure 7] 10 is a flowchart showing the operation of the mobile station according to the second embodiment. [Figure 8] FIG. 10 is a schematic diagram illustrating a configuration of a wireless communication system according to a second embodiment. [Figure 9] 10 is a diagram showing an example of a priority list and an interference wave list managed by a mobile station according to the second embodiment. FIG. [Figure 10] FIG. 10 is a diagram illustrating an example of a priority list managed by a mobile station according to the second embodiment. [Figure 11] 11 is a flowchart showing the operation of the mobile station according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A mobile station, a wireless communication system, a method for controlling a mobile station, and a control program according to embodiments will be described below with reference to the drawings. The following embodiments are merely examples, and the embodiments can be combined as appropriate and each embodiment can be modified as appropriate.

[0010] In this application, a mobile station is a mobile wireless terminal. For example, the mobile station is a wireless terminal mounted on a moving object such as a vehicle, or a portable wireless terminal carried by a person. A wireless communication system is a system including a mobile station and a plurality of base stations capable of wireless communication with the mobile station.

[0011] 1. First embodiment 1-1 Configuration FIG. 1 is a schematic diagram showing a configuration of a wireless communication system 1 according to a first embodiment. As shown in FIG. 1, the wireless communication system 1 includes a mobile station 10 and a plurality of base stations (e.g., base stations 100, 200, ...) that can communicate wirelessly with the mobile station 10. The plurality of base stations form a wireless communication network. Different carrier frequencies (e.g., frequencies f1, f2, ...) are assigned to the plurality of base stations, and the plurality of base stations form a plurality of zones (e.g., zones 110, 210, ... that are set around the base stations 100, 200, ...). The base stations 100 and 200 shown in FIG. 1 are legitimate base stations that belong to the wireless communication system 1, and the zones 110 and 210 are legitimate zones formed by the wireless communication system 1. In other words, the wireless communication system 1 includes a plurality of base stations 100 and 200 that transmit radio waves at frequencies f1 and f2 that are determined for each zone in the different zones 110 and 210, and a mobile station 10 that communicates with one of the plurality of base stations 100 and 200.

[0012] 1 shows a source 300 of jamming waves (e.g., illegal radio waves), which are unauthorized radio waves. Base station 100 transmits radio waves C1 (i.e., carrier waves) at frequency f1, and base station 200 transmits radio waves C2 (i.e., carrier waves) at frequency f2. Mobile station 10 can communicate with base station 100 in zone 110 using radio waves C1 at frequency f1, and can communicate with base station 200 in zone 210 using radio waves C2 at frequency f2. FIG. 1 shows a state in which mobile station 10 is moving from zone 110, the base station 100 with which it is communicating, to zone 210, a neighboring zone.

[0013] In the example of FIG. 1, jamming wave source 300 is transmitting jamming waves, which are radio waves of frequency fn2. The radio waves of frequency fn2 are radio waves that imitate radio waves C2 of frequency f2 transmitted from base station 200 and that also imitate the transmission timing of radio waves C2 of frequency f2. Mobile station 10 acquires frequency information of base stations (e.g., base station 200) in surrounding zones of the communicating base station 100 from the communicating base station 100. In addition, the base stations in the surrounding zones transmit encrypted signals obtained by encrypting meaningful data determined for each base station.

[0014] FIG. 2 is a functional block diagram showing the configuration of a mobile station 10 according to the first embodiment. The mobile station 10 is a device capable of implementing the control method according to the first embodiment. As shown in FIG. 2, the mobile station 10 has an antenna 11 for wireless communication, a receiver 12 as a communication circuit for performing wireless communication, a controller 13, a decoder 14, a meaningful data determination unit 15, and a memory 16. The memory 16 stores a priority list 17 and an interference list 18. The controller 13 controls the receiver 12, the decoder 14, the meaningful data determination unit 15, and the memory 16. The memory 16 may be a memory of an external device capable of communicating with the mobile station 10.

[0015] The antenna 11 transmits and receives radio waves. The antenna 11 communicates wirelessly with a base station. The receiver 12 receives a received signal based on the radio waves of the frequency received by the antenna 11 and sends the received signal to the controller 13. The controller 13 manages a priority list 17 and an interference list 18 stored in the memory 16. The decoder 14 decodes the encrypted signal received by the antenna 11. The meaningful data determination unit 15 determines whether the signal received via the antenna 11 and decoded by the decoder 14 contains predetermined meaningful data used in the wireless communication system 1. The priority list 17 is information that lists the received field strength of radio waves captured by the mobile station 10 in order of priority (e.g., in order of received field strength). The number of pieces of base station identification information constituting the priority list 17 is equal to the number of pieces of frequency information of base stations in surrounding zones (e.g., base station 200) received from the currently communicating base station 100. The interference list 18 is information that lists the received field strength of radio waves that the mobile station 10 has determined to be interference waves.

[0016] The mobile station 10 first acquires frequency information about the frequencies of multiple base stations and initializes the priority list 17 so that the frequencies are sorted in descending order of priority. During standby (which may include zone movement), the mobile station 10 repeatedly (e.g., periodically) performs standby processing, including measuring the received field strength of radio waves for each frequency indicated in the priority list and determining whether the encrypted signals contained in the radio waves have been decoded for each frequency, and updating the priority list so that the frequencies of the decoded signals among the encrypted signals are sorted in descending order of received field strength. Based on the updated priority list 17, the mobile station 10 determines which radio waves to capture when moving from the zone of a base station (also referred to as "first zone") with which it is currently communicating to the zone of another base station (i.e., a surrounding zone). The mobile station 10 may add information indicating the encrypted signals that could not be decoded to the interference list 18.

[0017] FIG. 3 is a diagram illustrating an example of a hardware configuration of a mobile station 10 according to the first embodiment. The mobile station 10 includes a processor 91, a memory 92, a storage device 93, a communication circuit 94, and an antenna 11. The mobile station 10 is, for example, an information processing device with a wireless communication function, i.e., a computer. The processor 91 is, for example, a CPU (Central Processing Unit). The memory 92 is, for example, a volatile semiconductor memory such as a RAM (Random Access Memory). The storage device 93 is, for example, a non-volatile storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The communication circuit 94 includes, for example, the receiving unit 12 of FIG. 2. The storage device 93 includes, for example, the storage unit 16 of FIG. 2.

[0018] Each function of the mobile station 10 may be realized by a processing circuit. The processing circuit may be either dedicated hardware or a processor 91 that executes a program stored in a memory 92. The processor 91 may be any of a processing device, an arithmetic device, a microprocessor, a microcomputer, and a DSP (Digital Signal Processor).

[0019] When the processing circuitry is dedicated hardware, the processing circuitry may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or any combination thereof.

[0020] When the processing circuit is a processor 91, the processing of each functional block in FIG. 2 is realized by a program, such as software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in memory 92. The processor 91 can realize the functions of the functional blocks shown in FIG. 2 by reading and executing the programs stored in memory 92. Note that the mobile station 10 may be partially realized by dedicated hardware and partially realized by software or firmware. In this way, the processing circuit can realize the functions of each functional block shown in FIG. 2 by hardware, software, firmware, or any combination thereof.

[0021] 《1-2》Operation First, the main operations of the mobile station 10 will be described. The control unit 13 acquires frequency information regarding carrier frequencies (i.e., carrier frequencies) f1 and f2, which are radio waves transmitted by the multiple base stations 100 and 200, and initializes the priority list 17 so that the frequencies are arranged in descending order of priority. During standby, the control unit 13 repeatedly performs standby processes for each frequency indicated in the priority list 17, including a process of measuring the received field strength of the radio waves for each frequency and determining whether the encrypted signals contained in the radio waves have been decrypted for each frequency, and a process of updating the priority list 17 so that the frequencies of the decrypted signals among the encrypted signals are arranged in descending order of received field strength. Based on the updated priority list 17, the control unit 13 determines the radio waves to capture when moving between zones. In this way, the priority list 17 is updated as needed by repeatedly performing the first and second processes during standby in advance, allowing the mobile station 10 to smoothly move between zones when the strength of the captured field becomes weak. In addition, the control unit 13 creates an interference wave list 18 that lists the frequencies of encrypted signals that could not be decrypted, and does not perform the above-mentioned determination of whether the encrypted signal could be decrypted for radio waves of frequencies on the interference wave list 18.

[0022] 4 is a flowchart showing the operation of the mobile station 10 according to the first embodiment. In step S11, the mobile station 10 communicates with the base station 100 via the antenna 11. The receiver 12 of the mobile station 10 receives, via the antenna 11, frequency information of radio waves transmitted by base stations (e.g., base station 200) in the vicinity of the base station 100 with which the mobile station 10 is communicating, and sends the frequency information to the controller 13. The controller 13 of the mobile station 10 creates a priority list 17 based on the frequency information of the surrounding base stations, and records the list in the memory 16. In step S11, an initial value of the priority list 17 is created.

[0023] In step S12, the mobile station 10 enters standby mode, and repeatedly performs the processes of steps S13 to S16 during standby mode.

[0024] In step S13, the control unit 13 of the mobile station 10 determines the radio waves to capture when moving between zones. That is, during standby (including when moving between zones), the control unit 13 performs a process of assigning priorities to the electric fields of the surrounding zones to which the mobile station 10 will move next when the electric field weakens, and updating the priority list 17. Specifically, the control unit 13 receives an encrypted signal and measures the electric field strength of the carrier wave of this signal.

[0025] In step S14, the decoding unit 14 of the mobile station 10 determines whether the received encrypted signal can be decoded. Furthermore, the meaningful data determination unit 15 determines whether meaningful data is present in the signal decoded by the decoding unit 14. Based on the results of these processes, the control unit 13 determines whether the radio wave of the frequency received in step S13 is a radio wave transmitted from a legitimate base station (e.g., base station 200) of the wireless communication system 2. If it is determined that meaningful data is present, it is determined that the received encrypted signal has been decoded.

[0026] If the decryption unit 14 can decrypt the received encrypted signal (YES in step S14), the control unit 13 determines that the radio waves of the received frequency are radio waves of the wireless communication system 2. If the decryption unit 14 can decrypt the received encrypted signal and the meaningful data determination unit 15 determines that meaningful data is included (YES in step S14), the control unit 13 can also determine that the radio waves of the received frequency are radio waves of the wireless communication system 2. In step S15, the control unit 13 adds frequency information of radio waves transmitted by base stations in descending order of the received field strength of the mobile station 10 to the priority list 17 (i.e., updates the priority list 17). In other words, the control unit 13 may determine that the encrypted signal has been decrypted when meaningful data is detected.

[0027] In step S13, if a jamming wave that is a radio wave of frequency fn2 is received, in step S14, the control unit 13 determines whether the received radio wave can be decoded by the decoding unit 14 and whether meaningful data of the wireless communication system is present by the meaningful data determination unit 15 (NO in step S14), and determines that the received signal is a jamming wave and not a radio wave transmitted by a base station of the wireless communication system. In step S16, the control unit 13 stores frequency fn2 in the jamming wave list 18, and does not perform measurement of frequency fn2 in step S12.

[0028] In embodiment 1, the case where the electric field of an interference wave and the electric field of radio waves transmitted from a base station of a wireless communication system are received is described, but the present invention can also be applied to a case where there are improper radio waves (interference waves of unknown origin) received from a source other than the interference wave source 300.

[0029] Effect 1-3 As described above, according to the first embodiment, the mobile station 10 checks whether it can decrypt an encrypted signal (or whether it can decrypt an encrypted signal and whether meaningful data is present) during standby, and therefore can reliably capture the radio wave field of the wireless communication system without capturing any jamming waves when moving between zones. In other words, according to the first embodiment, even if a third party is transmitting jamming waves that imitate the signals of the wireless communication system with the intent of jamming, it is possible to capture the radio wave field transmitted from the base station of the wireless communication system without capturing the jamming waves. Furthermore, according to the first embodiment, the frequency of the wireless communication system 1 is stored as the priority list 17, and therefore the time required to recapture the radio wave field can be shortened.

[0030] 2. Second Embodiment 2-1 Configuration In the first embodiment, an example has been described in which a mobile station creates and updates the priority list 17, detects interference waves, and creates the interference wave list 18. In the second embodiment, an example will be described in which a mobile station is further provided with a function to calculate its own location information in addition to creating and updating the priority list 17 and creating the interference wave list 18.

[0031] Fig. 5 is a schematic diagram showing the configuration of a wireless communication system 2 according to a second embodiment. In Fig. 5, components that are the same as or correspond to those shown in Fig. 1 are assigned the same reference numerals as those shown in Fig. 1. Fig. 5 shows a state in which a mobile station 20 is located within a zone 110. In Fig. 5, the wireless communication system 2 has a mobile station 20 and a plurality of base stations (e.g., base stations 100, 200, ...) that can communicate wirelessly with the mobile station 20. The plurality of base stations are assigned different carrier frequencies (e.g., frequencies f1, f2, ...), and each form a plurality of zones (e.g., zones 110, 210, ...) that are areas in which the mobile station can communicate.

[0032] Fig. 5 shows an interference wave source 300. Base station 100 transmits radio waves C1 with frequency f1, and base station 200 transmits radio waves C2 with frequency f2. In the example of Fig. 5, mobile station 20 can communicate in zone 110 using radio waves C1 with frequency f1, and can communicate in zone 210 using radio waves C2 with frequency f2. Fig. 5 shows a state in which mobile station 20 is in zone 110 during communication.

[0033] In the example of FIG. 5, the transmission source 300 transmits a jamming wave, which is a radio wave of frequency fn2 that imitates the radio wave C2 of frequency f2 and the transmission timing of the radio wave C2 of frequency f2. The mobile station 20 is located within the jamming wave zone 310. The mobile station 20 acquires location information of base stations (e.g., base station 200) surrounding the communicating base station 100 from the communicating base station 100. The communicating base station 100 transmits, as an encrypted signal, meaningful data determined in the wireless communication system to which the communicating base station 100 itself belongs (i.e., its own system) in addition to the frequency information of the surrounding base stations. The mobile station 20 receives the jamming wave of frequency fn2 and the encrypted signal of frequency f1 transmitted from the base station 100 via the antenna 11.

[0034] FIG. 6 is a functional block diagram showing the configuration of a mobile station 20 according to the second embodiment. The mobile station 20 is a device capable of implementing the control method according to the second embodiment. In FIG. 6, components that are the same as or correspond to those shown in FIG. 2 are assigned the same reference numerals as those shown in FIG. 2. The mobile station 20 according to the second embodiment includes a location information receiving antenna 21 and a distance calculation unit 22 in addition to the configuration of the mobile station 10 according to the first embodiment. The storage unit 16 stores a priority list 17, an interference list 18, distance information 23, and base station location information 24. The location information receiving antenna 21 receives location information of the mobile station 20. The base station location information 24 stores location information data of base stations in the wireless communication system 2 as initial information. The distance calculation unit 22 calculates a distance L1 from the mobile station 20 to the base station 100 with which the mobile station 20 is currently communicating, based on the location information received by the location information receiving antenna 21 and the location information stored as the base station location information 24. The calculated distance L1 is stored in the storage unit 16 as distance information 23. The mobile station 20 may acquire the location information using a known method such as the Global Positioning System (GPS).

[0035] 《2-2》Operation First, we will explain the main operations of the mobile station 20. The control unit 13 acquires frequency information regarding the frequencies f1 and f2 of carrier waves, which are radio waves transmitted by the multiple base stations 100 and 200, and initializes the priority list 17 so that the frequencies are arranged in descending order of priority. During standby, control unit 13 repeatedly performs standby processing, including a process of acquiring location information of multiple base stations and location information of mobile station 20 from a base station currently in communication with the mobile station 20 and calculating distance L (L1 or L2 in FIG. 5) from mobile station 20 to the base station; a process of measuring the received field strength of radio waves for each frequency indicated by priority list 17 and determining, for each frequency, whether encrypted signals contained in the radio waves have been decrypted; and a process of updating priority list 17 so that the frequencies of decrypted signals among the encrypted signals are sorted in descending order of received field strength. Specifically, control unit 13 acquires location information of multiple base stations and location information of mobile station 20 from a base station currently in communication with the mobile station 20 and determines whether the encrypted signals have been decrypted if distance L (L1 or L2 in FIG. 5) from mobile station 20 to the base station is equal to or less than a predetermined threshold La. Control unit 13 determines, for each frequency, whether encrypted signals contained in the radio waves have been decrypted and updates priority list 17 so that the frequencies of decrypted signals among the encrypted signals are sorted in descending order of received field strength. In addition, when the distance L is greater than the threshold value La, the control unit 13 can create an interference wave list 18 that lists the frequencies of the radio waves transmitted by the base station and the frequencies of the encrypted signals that could not be decrypted, and not determine whether the encrypted signals could be decrypted for the radio waves of the frequencies on the interference wave list 18.

[0036] 7 is a flowchart showing the operation of the mobile station 20 according to the second embodiment. In step S21, the mobile station 20 communicates with the base station 100 via the antenna 11. The receiver 12 of the mobile station 20 receives, via the antenna 11, frequency information of radio waves transmitted by base stations (e.g., base station 200) in the vicinity of the base station 100 with which the mobile station 20 is communicating, and sends the frequency information to the controller 13. The controller 13 of the mobile station 10 creates a priority list 17 based on the frequency information of the surrounding base stations, and records the list in the memory 16. In step S21, the controller 13 creates an initial value for the priority list 17. In addition, the base station location information 24 stored in the memory 16 stores initial information on the location information data of the base stations of the wireless communication system 2.

[0037] In step S22, the mobile station 20 enters the standby state and repeatedly executes the processes of steps S23 to S27 during standby.

[0038] In step S23, the control unit 13 of the mobile station 20 determines the radio waves to be captured when moving between zones. That is, the control unit 13 performs a process of updating the priority list 17 by assigning priorities in advance to the radio fields of the surrounding zones to be visited next when the radio field weakens during standby (including when moving between zones). Specifically, the control unit 13 receives an encrypted signal, measures the electric field strength of the carrier wave of this signal, receives position information, and calculates the distance L.

[0039] In step S24, the distance calculation unit 22 calculates the distance L between the base station and the mobile station 20 based on the position of the base station of the wireless communication system 2 stored in the base station position information 24 and the current position information of the mobile station 20 recorded in the distance information 23. The control unit determines whether the base station is at a position below a preset threshold value La (that is, whether La ≥ L or La < L). The threshold value La is the threshold value of the distance between the position of the base station transmitting radio waves at that frequency within the wireless communication system 2 and the current position of the mobile station 20. Note that the calculation of the distance L may also be performed by the control unit 13.

[0040] If La < L in step S24, the control unit 13 determines that the position of the mobile station 20 is not a position where radio waves transmitted from the base station 200 can be received. Therefore, the process proceeds to step S27, and the control unit 13 stores the frequency of the received radio wave in the interference wave list 18, and thereafter, does not measure the interference waves stored in the interference wave list 18 in step S22. The condition for measuring again the frequency determined to be an interference wave is when the mobile station 20 moves and the condition of La ≥ L is satisfied.

[0041] If La ≧ L in step S24, the process proceeds to step S25, where it is determined whether the radio waves received by the mobile station 20 are radio waves from the wireless communication system 2. The determination method is the same as that in step S14 of FIG. 4. If the received radio waves are radio waves from the wireless communication system 2, the process proceeds to step S26, where the control unit 13 adds the radio waves to the priority list 17 in descending order of received field strength as electric fields of radio waves to be captured when moving between zones. If it is determined in step S25 that the received radio waves are jamming waves, the control unit 13 adds information indicating the received radio waves to the jamming wave list 18 in step S27. In this case, since La ≧ L, the received radio waves become a measurement target in step S24. However, since the decryption unit 14 determines whether the encrypted signal can be decrypted, the mobile station 20 can move between zones using only the electric fields of the wireless communication system 2 without capturing jamming waves.

[0042] In the example of Fig. 5, the distance relationship is L2>La>L1. Furthermore, the received field strength E1 of radio wave C1 of frequency f1 and the received field strength E2 of radio wave C2 of frequency f2 have the relationship E2>E1. If the distance L2 from base station 200 to mobile station 20 is greater than threshold La, mobile station 20 cannot receive radio wave C2 transmitted from base station 200. Control unit 13 can determine whether the distance from mobile station 20 to base station 100 is greater than the distance from mobile station 20 to base station 200 based on base station position information 24 and distance information 23 stored in memory unit 16.

[0043] Furthermore, the location where the mobile station 20 received the interference wave imitating the electric field of the base station 200 is not a location where the mobile station 20 can receive the radio wave C2 of frequency f2, and the mobile station 20 can determine in step S25 that the frequency fn2 is the interference wave. In step S27, the control unit 13 adds the frequency fn2 to the interference wave list 18. Therefore, the priority list 17 when moving between zones becomes as shown in FIG. 9, and the mobile station 20 can continue communicating with the base station 100.

[0044] FIG. 8 is a schematic diagram showing the configuration of a wireless communication system 2 according to a second embodiment. FIG. 8 illustrates a case in which the mobile station 20 moves from the position shown in FIG. 5 and approaches the base station 200. In FIG. 8, the distance relationship is L1≧La>L2. Furthermore, the received field strength E2 of the radio wave C2 of frequency f2 is greater than the received field strength E1 of the radio wave C1 of frequency f1. That is, E2>E1. The control unit 13 can determine from the base station position information 24 and the distance information 23 that the distance L2 from the mobile station 20 to the base station 200 is greater than the distance L1 from the mobile station 20 to the base station 100, and can determine that the position where the mobile station 20 received the radio wave C2 of frequency f2 is a position where La>L2. Therefore, the control unit 13 deletes the item "frequency fn2" stored in the interference wave list 18 and stores the frequency f2 corresponding to "frequency fn2" in the priority list 17. Therefore, the received field strength E2 of the radio wave C2 of frequency f2 can be measured again. Since the received field strength is E2>E1, the list in the priority list 17 when moving between zones is as shown in Figure 10. In this case, the received field strength E2 of the radio wave C2 of frequency f2 is measured every time. Therefore, when the received field strength E1 of the radio wave C1 of frequency f1 becomes weak, the zone can be moved and the field of the radio wave C2 of frequency f2 can be captured.

[0045] In the second embodiment, the distance between the base station and the mobile station 20 is used, but instead of the distance, distance information corresponding to the threshold La may be provided for each of the x-coordinate, y-coordinate, and z-coordinate, which are the coordinates of the location information.

[0046] 2-3 Effects As described above, according to the second embodiment, the location information of the base station and the source of the interference wave is stored, so that the electric field priority list and the interference wave list of the wireless communication system 2 can be determined based on the received electric field strength and the distance L, thereby obtaining the effect of further improving the effect of the first embodiment.

[0047] In all other respects, the second embodiment is the same as the first embodiment.

[0048] 3. Third Embodiment 3-1. Structure In the first and second embodiments, the mobile station acquires frequency information of one or more surrounding base stations from the base station 100 with which it is communicating, and measures the received field strength of radio waves of the frequency indicated by the acquired frequency information. In contrast, in the third embodiment, the mobile station does not acquire frequency information of one or more surrounding base stations from the base station 100 with which it is communicating, and the mobile station itself determines the frequency of the radio waves for which it measures the received field strength.

[0049] The configuration of a wireless communication system according to the third embodiment is the same as that shown in Fig. 5 and Fig. 8. The configuration of a mobile station according to the third embodiment is the same as that shown in Fig. 6. Therefore, when describing the third embodiment, reference will also be made to Fig. 5, Fig. 6 and Fig. 8. The mobile station according to the third embodiment differs from the mobile station 20 according to the second embodiment in that the number of lists in the priority list 17 is set as an initial value.

[0050] In urban areas and other areas where there are many base stations, the number of radio waves whose received field strength must be measured is large, which increases the time it takes for a mobile station to measure the received field strength, causing the mobile station's remaining battery power to decrease quickly. Therefore, a mobile station according to the third embodiment repeatedly measures the received field strength during standby (e.g., periodically) and updates a list containing predetermined items of the top received field strengths in descending order of priority. This enables a mobile station in a wireless communication system that does not receive instructions from a base station about the fields to be measured to measure the received field strength more quickly.

[0051] Furthermore, any number of electric fields may be left in the priority list 17. Furthermore, even if an electric field has a high priority in the priority list 17, if the received electric field strength is not sufficiently high, it is necessary to search for an electric field other than that on the priority list. In this case, it is necessary to measure all the received electric field strengths of the wireless communication system 2. However, by adopting a configuration that combines the second and third embodiments, the base stations that should be receivable by the second embodiment are known, and therefore there is no need to search all of them.

[0052] 《3-2》Operation 11 is a flowchart showing the operation of a mobile station according to embodiment 3. The mobile station according to embodiment 3 differs from embodiment 2 in that it receives frequency information of all base stations in the wireless communication system in step S31, and the number of list items included in priority list 17 is a predetermined number, rather than the number of surrounding base stations as in embodiment 1 or embodiment 2. For example, if the number of list items in priority list 17 is set to five, the number of received field strengths stored in priority list 17 in step S26 will be five even if the total number of base stations in wireless communication system 2 is 50.

[0053] 3-3 Effect As described above, according to the third embodiment, the mobile station is configured to be able to determine the priority of the received field strength measured during standby by itself, so that the received field strength can be measured quickly even when there are many base stations. Therefore, even in a system in which the base station in communication cannot instruct the received field strength of radio waves transmitted from surrounding base stations, it is no longer necessary to measure the received field strength of all mobile stations in the wireless communication system, and the measurement time for the received field strength can be shortened.

[0054] In all other respects, the third embodiment is the same as the first or second embodiment.

[0055] 4. Supplementary Note Aspects of the disclosure are described below.

[0056] [Appendix 1] In a wireless communication system having a plurality of base stations that transmit radio waves at frequencies determined for each zone in different zones, a mobile station that communicates with any one of the plurality of base stations comprises: a receiving unit that receives the radio waves; a decryption unit that decrypts an encrypted signal included in the radio wave; A control unit; and The control unit acquiring frequency information regarding the frequencies of the plurality of base stations, and initializing a priority list so that the frequencies are arranged in descending order of priority; During standby, a standby process is repeatedly performed, for each of the frequencies indicated in the priority list, including a process of measuring the received field strength of the radio waves for each frequency and determining for each frequency whether an encrypted signal included in the radio waves has been successfully decrypted, and a process of updating the priority list so that frequencies of signals that have been successfully decrypted among the encrypted signals are arranged in descending order of the received field strength; Based on the updated priority list, a radio wave to be captured when moving from a zone of one of the plurality of base stations to a zone of another base station is determined. A mobile station characterized by: [Appendix 2] The control unit creating an interference wave list that lists the frequencies of the encrypted signals that could not be decrypted; The standby process is not performed for the radio waves of the frequencies in the interference wave list. 2. The mobile station according to claim 1, [Appendix 3] The control unit acquiring location information of the plurality of base stations and location information of the mobile station from a base station currently in communication among the plurality of base stations; When the distance from the mobile station to the base station is equal to or less than a predetermined threshold, the standby process is performed. 3. The mobile station according to claim 1 or 2. [Appendix 4] The control unit If the distance is greater than the threshold, an interference list is created that lists the frequencies of radio waves transmitted by the base station and the frequencies of the encrypted signals that could not be decrypted; The standby process is not performed for the radio waves of the frequencies in the interference wave list. 4. The mobile station according to claim 3, [Appendix 5] The control unit acquires the frequency information from a base station currently in communication among the plurality of base stations. 5. The mobile station according to claim 1, wherein: [Appendix 6] The method further includes a meaningful data determination unit that determines whether or not the encrypted signal contains predetermined meaningful data, When the meaningful data is detected, it is determined that the encrypted signal has been decrypted. 6. The mobile station according to any one of Supplementary Notes 1 to 5,

[0057] [Appendix 7] a plurality of base stations that transmit radio waves at frequencies determined for each zone in different zones; the mobile station according to any one of Supplementary Note 1 to 6, which communicates with any one of the plurality of base stations; A wireless communication system comprising:

[0058] [Appendix 8] 1. A control method for controlling a mobile station communicating with any one of a plurality of base stations in a wireless communication system having a plurality of base stations that transmit radio waves at frequencies determined for each of the plurality of zones, the method comprising: acquiring frequency information regarding the frequencies of the plurality of base stations, and initializing a priority list so that the frequencies are arranged in descending order of priority; During standby, a standby process is repeatedly performed, for each of the frequencies indicated in the priority list, including a process of measuring the received field strength of the radio waves for each frequency and determining for each frequency whether an encrypted signal included in the radio waves has been successfully decrypted, and a process of updating the priority list so that frequencies of signals that have been successfully decrypted among the encrypted signals are arranged in descending order of the received field strength; Based on the updated priority list, a radio wave to be captured when moving from a zone of one of the plurality of base stations to a zone of another base station is determined. A method for controlling a mobile station.

[0059] [Appendix 9] A control program executed by an information processing device that is a mobile station communicating with any one of a plurality of base stations in a wireless communication system having a plurality of base stations that transmit radio waves at frequencies determined for each of the plurality of zones, the control program comprising: acquiring frequency information about the frequencies of the plurality of base stations and initializing a priority list so that the frequencies are arranged in descending order of priority; a step of repeatedly performing standby processing during standby, the step including: a process of measuring the received field strength of the radio waves for each frequency indicated by the priority list and determining for each frequency whether an encrypted signal included in the radio waves has been decrypted; and a process of updating the priority list so that frequencies of signals that have been decrypted among the encrypted signals are arranged in descending order of the received field strength; determining, based on the updated priority list, radio waves to be captured when moving from a zone of one base station among the plurality of base stations to a zone of another base station; a control program for causing the information processing device to execute the above; [Explanation of symbols]

[0060] 1, 2 Wireless communication system, 10, 20 Mobile station, 11 Antenna, 12 Receiving unit, 13 Control unit, 14 Decoding unit, 15 Meaningful data determination unit, 16 Memory unit, 17 Priority list, 18 Interference wave list, 21 Location information receiving antenna, 22 Distance calculation unit, 23 Distance information, 24 Base station location information, 100, 200 Base station, 110, 120 Zone, 300 Source, 310 Interference wave zone.

Claims

1. In a wireless communication system having a plurality of base stations that transmit radio waves at frequencies determined for each zone in different zones, a mobile station that communicates with any one of the plurality of base stations comprises: a receiving unit that receives the radio waves; a decryption unit that decrypts an encrypted signal included in the radio wave; A control unit; and The control unit acquiring frequency information regarding the frequencies of the plurality of base stations, and initializing a priority list so that the frequencies are arranged in descending order of priority; During standby, a standby process is repeatedly performed, for each of the frequencies indicated in the priority list, including a process of measuring the received field strength of the radio waves for each frequency and determining for each frequency whether an encrypted signal included in the radio waves has been successfully decrypted, and a process of updating the priority list so that frequencies of signals that have been successfully decrypted among the encrypted signals are arranged in descending order of the received field strength; Based on the updated priority list, a radio wave to be captured when moving from a zone of one of the plurality of base stations to a zone of another base station is determined. A mobile station characterized by:

2. The control unit creating an interference wave list that lists the frequencies of the encrypted signals that could not be decrypted; The standby process is not performed for the radio waves of the frequencies in the interference wave list.

2. The mobile station according to claim 1, wherein:

3. The control unit acquiring location information of the plurality of base stations and location information of the mobile station from a base station currently in communication among the plurality of base stations; When the distance from the mobile station to the base station is equal to or less than a predetermined threshold, the standby process is performed.

2. The mobile station according to claim 1, wherein:

4. The control unit If the distance is greater than the threshold, an interference list is created that lists the frequencies of radio waves transmitted by the base station and the frequencies of the encrypted signals that could not be decrypted; The standby process is not performed for the radio waves of the frequencies in the interference wave list.

4. The mobile station according to claim 3.

5. The control unit acquires the frequency information from a base station currently in communication among the plurality of base stations.

5. A mobile station according to claim 1, wherein the mobile station is a wireless communication station.

6. a plurality of base stations that transmit radio waves at frequencies determined for each zone in different zones; The mobile station according to any one of claims 1 to 4, which communicates with any one of the plurality of base stations; A wireless communication system comprising:

7. 1. A control method for controlling a mobile station communicating with any one of a plurality of base stations in a wireless communication system having a plurality of base stations that transmit radio waves at frequencies determined for each of the plurality of zones, the method comprising: acquiring frequency information regarding the frequencies of the plurality of base stations, and initializing a priority list so that the frequencies are arranged in descending order of priority; During standby, a standby process is repeatedly performed, for each of the frequencies indicated in the priority list, including a process of measuring the received field strength of the radio waves for each frequency and determining for each frequency whether an encrypted signal included in the radio waves has been successfully decrypted, and a process of updating the priority list so that frequencies of signals that have been successfully decrypted among the encrypted signals are arranged in descending order of the received field strength; Based on the updated priority list, a radio wave to be captured when moving from a zone of one of the plurality of base stations to a zone of another base station is determined. A method for controlling a mobile station.

8. A control program executed by an information processing device that is a mobile station communicating with any one of a plurality of base stations in a wireless communication system having a plurality of base stations that transmit radio waves at frequencies determined for each of the plurality of zones, the control program comprising: acquiring frequency information about the frequencies of the plurality of base stations and initializing a priority list so that the frequencies are arranged in descending order of priority; a step of repeatedly performing standby processing during standby, the step including: a process of measuring the received field strength of the radio waves for each frequency indicated by the priority list and determining for each frequency whether an encrypted signal included in the radio waves has been decrypted; and a process of updating the priority list so that frequencies of signals that have been decrypted among the encrypted signals are arranged in descending order of the received field strength; determining, based on the updated priority list, radio waves to be captured when moving from a zone of one base station among the plurality of base stations to a zone of another base station; a control program for causing the information processing device to execute the above;

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