JP2006109517A - Mobile communication method and base station thereof, and mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile communication system in which a switching time required for switching a mobile communication system is short. <P>SOLUTION: The service area of a base station 1 is included in the service area of a communication satellite 3. The base station 1 transmits line information of a satellite communication system in its own service area and in the neighborhood thereof, and line information of its own communication system received from the communication satellite 3, to a mobile communication terminal 5 in its service area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mobile communication system having a mobile communication terminal capable of communicating with a plurality of communication systems having overlapping service areas, for example, a terrestrial cellular communication system and a mobile satellite communication system. The present invention relates to a mobile communication system that provides and uses information on a line that is selected when a terminal switches communication systems.

FIG. 10 is a configuration diagram of a mobile communication system in which a conventional mobile communication terminal is connected to a plurality of mobile communication systems. In the figure, 1 is a base station of the mobile communication system A, and 2 is a service area provided by the base station 1. 3 is a communication satellite of the mobile communication system B, 4 is a service area provided by the communication satellite 3, and a plurality of service areas 4 are generally provided from one communication satellite 3. 5 is a mobile communication terminal that can be connected to both the mobile communication systems A and B by switching, and 6 is a control line that the base station 1 and the communication satellite 3 transmit.
Next, the operation of a conventional mobile communication system is shown. The base station 1 and the communication satellite 3 control the communication with the mobile communication terminal 5 through a control line. The base station 1 and the communication satellite 3 use the respective control lines to control the line information of each base station in each mobile communication system, for example, the line frequency of the peripheral base station corresponding to the peripheral service cell and the size of the service area. Such information is broadcast.

Switching of service areas within individual mobile communication systems begins when the mobile communication terminal 5 changes the setting of transmission / reception parameters and the like to those of the peripheral service cell based on the line information transmitted on the control line. Thereafter, the processing is completed by executing processing such as location registration.
On the other hand, in the system switching between the mobile communication systems, the line information of the peripheral service cell in the switching destination communication system is not provided, and therefore the mobile communication terminal 5 itself switches the switching destination communication system when switching the communication system. In many cases, the time when the user has to search for a line and the user cannot use is several tens of sands. When the mobile communication terminal 5 switches the line connection between the mobile communication systems, it sequentially receives the lines of the switching destination mobile communication system and searches for a line with a good reception state based on the evaluation based on the reception level or the like. The process will be repeated. This process is necessary for performing stable communication. Usually, since there are many lines to be evaluated, it takes a considerable time to evaluate the lines. During this line evaluation period, the replacement mobile communication system cannot be used.
As a countermeasure, it is conceivable to store line information of all communication systems to which the mobile communication terminal 5 can communicate. However, in the case of a system that uses a communication satellite that is not a stationary satellite among communication satellites such as the mobile communication system B, for example, even if the mobile communication terminal 5 is stationary, a service is provided as the communication satellite moves. The area will also move from moment to moment. For this reason, even if the mobile communication terminal 5 stores the line information of each service area at a certain point in time, the arrangement of the service area changes over time, and the peripheral service area in the switching destination communication system is specified. The communication system cannot be switched.

As described above, in the conventional mobile communication system, when the mobile communication terminal switches the mobile communication system itself, the communication terminal side sequentially evaluates the lines that can be used from many lines of the switching destination mobile communication system. There has been a problem that it is necessary to search for a line in which the communication state is good, and the mobile communication system cannot be switched in a short time.
The present invention has been made to solve the above-described problems, and a switching time required when a mobile communication terminal connected to two or more mobile communication systems performs switching of the mobile communication system. A short mobile communication system is provided.

  In the mobile communication system according to the present invention, the service area of the base station is included in the service area of the communication satellite, and the base station receives its own service area received from the communication satellite and the line information of the satellite communication system in the vicinity thereof. And the line information of the own communication system is transmitted to the mobile communication terminal in the own service area.

  According to the present invention, the service area of the base station is included in the service area of the communication satellite, and the base station receives the line information of the satellite communication system and the own communication in the service area received from the communication satellite and in the vicinity thereof. Since the line information of the system is configured to be transmitted to the mobile communication terminal in its own service area, the mobile communication terminal can promptly use the other communication system based on the line information of the other communication system. It is possible to perform switching. In addition, the time required for the communication line search of another communication system performed when the mobile communication terminal switches to another communication system is shortened.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing the entire system of a mobile communication system according to the present invention. Reference numeral 1 denotes a radio base station of the communication system A, and reference numeral 2 denotes a service area provided by the radio base station 1. 3 is a communication satellite of the communication system B, and 4 is a service area provided by the communication satellite 3. A mobile communication terminal 5 can be connected to both communication systems A and B by switching. 7 is a control line transmitted from the communication system A and the communication system B to the mobile communication terminal 5, and transmits the line information of its own communication system and the line information of the other communication system to the mobile communication terminal 5. is doing. For example, the communication system B provides line information of its own communication system and line information of the communication system A on this control line 7. Although FIG. 1 shows a terrestrial cellular system as the communication system A and a mobile satellite communication system as the communication system B, the communication systems A and B are both terrestrial cellular systems or satellite communication systems. The present invention also applies.

  FIG. 2 is a configuration diagram showing the configuration of the communication system of the first embodiment. In the base station 1 of the communication system A in FIG. 2, 8 is an antenna, 9 is a transceiver, 10 is a SysA line information storage unit for storing line information of the communication system A, and 11 is a communication system different from the communication system A. This is a SysB line information storage unit for storing line information of the communication system B. In the base station 3 of the communication system B, 12 is an antenna, 13 is a transceiver, 14 is a SysB line information storage unit that stores line information of the communication system B, and 15 is a communication system that is a communication system different from the communication system B. It is a SysA line information storage unit that stores line information of A. In the communication system B, the satellite is a base station or relay station in FIG. 1, and when the satellite is a base station, the base station 3 in FIG. 2 represents the satellite, and the satellite is a relay station. The base station 3 in FIG. 2 represents a ground station. Reference numeral 16 denotes, for example, a public line network. The communication system A and the communication system B are both connected to a terrestrial public line, and a user of a mobile communication terminal can communicate with a user such as a public line network. Further, in the mobile communication terminal 5, 17 is an antenna, 18 is a transceiver, 19 is a line information storage unit for storing line information from the base station 1 or 3, 20 is a control unit for controlling the transceiver 18, 21 Is a user interface consisting of a key search department.

The base station 1 of the communication system A transmits the line information of its own system stored in the SysA line information storage unit 10 to the mobile communication terminal 5 via the transceiver 9 and the antenna 8. On the mobile communication terminal 5 side, when the communication system A is received, the line information is received by the antenna 17 and the transceiver 18 and stored in the line information storage unit 19.
Furthermore, in the present invention, since the line information of the communication system B stored in the SysB line information storage unit 11 is transmitted via the transceiver 9 and the antenna 8, the mobile communication terminal 5 is receiving the communication system A. However, the line information of the communication system B can also be stored in the line information storage unit 19. The SysA line information and the SysB line information may be transmitted / received via the same control line, or may be transmitted / received via different control lines.
The line information stored in the SysB line information storage unit 11 of the base station 1 of the communication system A is transmitted from the base station 3 of the communication system B to the base station 1 of the communication system A. The transmission path may be a dedicated line as shown in FIG. 2 or may be via the public line network 16. Although omitted in FIG. 2, an exchange station for exchanging communication methods and procedures is arranged between the base stations 1 and 3 and the public line network.

The line information of the communication system B transmitted to the SysB line information storage unit 11 of the base station 1 of the communication system A is configured to be transmitted from the base station 3 of the communication system B in FIG. It is good also as a structure which transmits to another communication system from the control station (not shown) which controls a group collectively. In this case, in FIG. 2, the control station enters the middle of the dedicated line, or the control station enters between the base station and the public line network. When the line information of the base station group is monitored in the control station, the line information is transmitted from the control station to the control station of another communication system at a time, so that each base station individually The complexity of transmitting line information to the base station of the communication system can be eliminated.
The base station 3 of the communication system B shown in FIG. 2 has the same configuration as the base station 1 of the communication system A, and the communication system line information and the SysA line information of its own communication system stored in the SysB line information storage unit 14. The line information of the communication system A stored in the storage unit 15 is transmitted to the mobile communication terminal 5.

  FIG. 3 is a schematic diagram showing an example of a logical format in a control line for notifying line information of another communication system. In FIG. 3, the number of systems indicates the number of communication systems that can be received by the mobile communication terminal 5, and the system ID is a number uniquely assigned to each communication system. The number of lines represents the number of lines belonging to the communication system indicated by the system ID, and there are parameters that define each line for the number of lines. FIG. 3 shows an example in which frequency and TDM offset are used as parameters. The mobile communication terminal 5 receives this line information from time to time and updates the line information storage unit 19 to the latest one. The mobile communication terminal 5 uses a combination of frequency and TDM offset for line connection. These pieces of information are sequentially read out from the line information storage unit 19, and line connection is attempted based on these values. For example, when the number of systems is 3, take out one system ID and the number of lines, extract the combination of frequency and TDM offset for the number of lines, perform a reception search, and perform a reception search for the number of lines. If the line connection cannot be established even after the completion, the processing is interrupted, or the next system ID and the number of lines are taken out, and the reception search for the number of lines is similarly performed.

In the case of FIG. 3, frequency and TDM offset are used as line parameters, and multiple access of mobile communication is realized by frequency multiplexing and time division multiplexing. In the case of using code division multiplexing as a multiple access for mobile communication, the code code of code division multiplexing is used as a line parameter, and in the case of using multiplexing by frequency hopping, the code of frequency hopping is used as a line parameter. Is used.
Further, the line information transmitted from the base station is usually line information of the base station and surrounding base stations. If the mobile communication terminal 5 obtains the line information of the area where the mobile communication terminal 5 exists, the mobile communication terminal 5 can transfer communication between cells generated by movement. Therefore, the line information of another communication system received by the mobile communication terminal 5 is desirably line information of another communication system in the area where the mobile communication terminal 5 exists, which is necessary when switching the communication system. . That is, the base station may extract and transmit line information of another communication system that can be received within the service area or in the vicinity of the service area. This extraction at the base station is easily determined by the geographical relationship between the service area covered by the base station and the service area covered by the base station of another communication system. If it is complicated to perform extraction for each base station, the control stations that control those base station groups collectively obtain line information of other communication systems that each base station should transmit through the control line, By delivering to each base station, simplification can be achieved. However, in this case, the control station is located on the dedicated line in FIG. 2 to receive the line information of another communication system, or is located between the public line and the base station, What is necessary is just to receive line information.

Next, processing before switching the communication system in the mobile communication terminal 5 and processing at the time of switching will be described. FIG. 4 is a flowchart showing a process flow before switching the communication system, and FIG. 5 is a flowchart showing a process flow when switching the communication system.
In FIG. 4, the mobile communication terminal 5 is in a standby state or a communication state in which a line is connected to one communication system and communication is waited as a state before switching as shown in step S1. . At this time, the control line is received as in step S2, and line information is obtained. In step S3, the obtained line information branches depending on whether the line information of the currently communicating communication system or the line information of another communication system. That is, if it is the line information of the currently communicating communication system, the control line is received again in step S2 while maintaining the communication state of the currently communicating communication system in step S4. If the line information received in step S2 is the line information of another communication system, in step S5, the line information classified and received for each system is stored in the line information storage unit 19, and the current communication is performed in step S4. The communication state of the communication system is maintained, and the control line is received again in step S2.

  Next, the flow of processing when switching the communication system shown in FIG. 5 will be described. Step S6 is a system switching operation from the currently communicating communication system to another communication system. This switching operation may occur in response to a request from the user via the user interface 21 of the mobile communication terminal 5 shown in FIG. For example, the mobile communication terminal 5 has a function of automatically switching to another communication system because the line condition with the currently communicating communication system deteriorates due to radio wave conditions or the like. This is the case. When a system switching operation occurs in step S6, it is confirmed in step S7 whether or not the control line of the designated communication system is stored in the line information storage unit 19 of the mobile communication terminal 5. If the control line is not stored as a result of the confirmation, the process proceeds to step S8, the communication system is determined to be unusable, and the process ends. At this time, the process may be terminated by notifying the user that it cannot be used, or the process of evaluating the next communication system may be repeated. In the former case, switching to the next system is performed by an explicit instruction from the user. In the latter case, the mobile communication terminal 5 automatically advances the line connection process to another communication system based on the contents of the line information storage unit 19 so that the user needs to intervene in the line connection. No user convenience is improved.

  In step S7, when the control line of the designated communication system is stored in the line information storage unit 19 of the mobile communication terminal 5, the process proceeds to step S9 and is identified by the system ID of the communication system. The frequency and TDM offset use candidates stored in the stored area are used as an evaluation target list for line connection. Next, the process proceeds to step S10, where control lines on the evaluation target list are received in order, and it is evaluated whether they can be used. As an evaluation method here, for example, evaluation is performed by measuring and determining so-called reception quality such as a reception power value, a bit error rate, a unique word detection state, and the like. Based on the evaluation in step S10, the process branches in step S11. That is, if a usable control line is found, the process proceeds to step S12, and the line is connected by the usable control line. If not found, the process proceeds to step S8, and the communication system is determined to be unusable. To finish the process. At this time, the process may be terminated by notifying the user that it cannot be used, or the process of evaluating the next communication system may be repeated as described above.

Moreover, the mobile communication terminal 5 can communicate with a plurality of communication systems, and the present invention may not be applied to some of the communication systems. In this case, by not transmitting the system ID of the communication system that is not applicable from the base station, the mobile communication terminal 5 does not need to confirm the line information in the line information storage unit 19 and is not applicable depending on the presence or absence of the system ID. It can be determined whether or not.
The mobile communication terminal 5 includes means for setting and storing the priority connection order of the communication system desired by the user. By switching from the currently communicating communication system to another communication system in this order, the mobile communication terminal 5 is convenient. Can be improved.

Embodiment 2. FIG.
FIG. 6 is a block diagram showing another configuration example of the mobile communication terminal of the communication system according to the present invention. In FIG. 6, 22 is a line parameter table.
In the first embodiment, as an example of transmitting channel parameters such as frequency and TDM offset as channel information of another communication system transmitted from the base station, a logical number mapped to them, The cell number as shown in FIG. 7 may be transmitted, and the mobile communication terminal 5 may obtain the line parameter. In particular, when a cell number is transmitted from the base station, when the mobile communication terminal 5 is connected to the line, the line information corresponding to the cell number stored in the line information storage unit 19 is retrieved from the line parameter table 22 and sent to the control unit 20. The transmitter / receiver 18 is operated based on the line information. The line parameter table 22 is a table for storing line information of the frequency and TDM offset for the cell number, an example of which is shown in FIG. Of course, as the line information, as described in the first embodiment, when code division multiplexing is used as a mobile communication multiple access method, a code code of code division multiplexing is used as the line information, and frequency hopping is used. When multiplexing by is used, a frequency hopping code is stored in the line parameter table 22 as line information.

Embodiment 3 FIG.
FIG. 9 is a block diagram showing another configuration example of the communication system according to the present invention. In the figure, 23 is a terrestrial cellular communication base station, 24 is a cell position storage unit for storing the cell position of a mobile satellite communication system which is another communication system, and 25 is a cell position stored in the cell position storage unit 24. A cell extracting unit for extracting cells located in or near the service area provided by the terrestrial cellular communication base station 23 from the other system line for inputting the cell line information extracted by the cell extracting unit 25 to the transceiver 9 An information storage unit 27 is a self-system line information storage unit in which the terrestrial cellular communication base station stores line information of its own system. 28 is a mobile satellite communication base station, and 29 is a self-system line information storage unit in which the mobile satellite communication base station 28 stores the line information of its own system. 30 is a cell location storage unit that stores the cell location of a terrestrial cellular system that is another communication system, and 31 is a service area provided by the mobile satellite communication base station 28 from the cell locations stored in the cell location storage unit 30. A cell extractor 32 for extracting cells located in or near the cell line information storage unit 32 inputs the line information of the cells extracted by the cell extractor 31 to the transceiver 13. In FIG. 9, the other constituent elements denoted by the same reference numerals are the same as those shown in the first embodiment.

In mobile satellite communications, there is a mode in which communication is performed between a communication satellite in geostationary orbit and a ground mobile body, and a mode in which communication is performed between a communication satellite in orbit and ground and a mobile body on ground. There is a thing. In particular, in the latter case, the position of a cell emitted from the communication satellite toward the ground surface changes from moment to moment as the communication satellite moves relative to the ground surface. Following the change in the cell position, the terrestrial cellular communication base station 23 extracts a mobile satellite communication cell in or near the service area, and transmits line information of the extracted cell to the mobile communication terminal 5. .
The cell position that is changed by the progress of the communication satellite of the mobile satellite communication is stored in the cell position storage unit 24. This cell position changes every moment, and the cell extraction unit 25 extracts cells in or near the service area of the terrestrial cellular communication base station 23. The other system line information storage unit 26 sends the cell line information extracted by the cell extraction unit 25 to the transceiver 9. In FIG. 9, the channel information in the other system channel information storage unit 26 is sent from the mobile satellite communication base station 28. May be sent from a control station or the like that monitors In FIG. 9, the cell position and line information are shown as separate dedicated lines for the sake of clarity, but it is not necessary to provide separate dedicated lines, and both may be combined into one dedicated line. If the frequency of data transmission is low, it is also possible to transmit / receive through a public line. The mobile satellite communication system line information transmitted from the terrestrial cellular communication base station 23 is received by the mobile communication terminal 5, and the mobile communication terminal 5 switches the communication system from terrestrial cellular communication to mobile satellite communication. At this time, it is possible to shorten the time required for line switching by reading out from the line information storage unit 19 and using it. The operation of communication system switching in the mobile communication terminal 5 is as described in the first embodiment.

In addition, a series of cell extraction processes in the cell location storage unit 24 and the cell extraction unit 25 and a process of reading cell line information in the other system line information storage unit 26 by the extracted cells are performed in each base station. This is a common process. By performing these processes collectively from the base station to the control station of the communication system, it is possible to avoid complication of the base station.
In addition, cell location information from the own system line information storage unit 29 of the mobile satellite communication base station 28 due to the fact that a dedicated line cannot be prepared between the mobile satellite communication base station 28 and the terrestrial cellular communication base station 23. Can be received by the terrestrial cellular communication base station 23, the terrestrial cellular communication base station 23 can also calculate the orbit of the communication satellite to obtain cell position information. That is, the orbit information of the communication satellite is given in advance to the cell position storage unit 24 in FIG. 9, and the cell position is calculated. The orbit information is, for example, the altitude of the communication satellite, the orbit inclination angle, the descending intersection time, the orbit flatness, and the like. The current position of the communication satellite in the orbit can be calculated, and the position of the cell emitted from the communication satellite to the ground surface can be calculated. The cell extraction unit 25 extracts a cell in or near the service area of the terrestrial cellular communication base station 23 from the calculated cell positions of the mobile satellite communication system, and transmits the line information corresponding to the extracted cell to other system lines. The processing for sending information from the information storage unit 26 to the transceiver 9 is the same as described above. Thus, the process of calculating the orbit of the communication satellite from the orbit information, and further the process of calculating the cell position of the mobile satellite communication from the calculated current position on the orbit of the communication satellite are duplicated in each base station. Therefore, the processing complexity can be avoided by collectively processing this calculation in, for example, the control station of the terrestrial cellular communication system.

Next, on the mobile satellite communication base station 28 side, the satellite communication base station 28 has a case where the communication satellite is a base station and a case where the communication satellite is a simple relay station and the base station is arranged on the ground.
In a mobile satellite communication system using an orbiting satellite, the position of a cell that the communication satellite radiates toward the ground surface changes from moment to moment as the communication satellite travels in an orbit. Therefore, for example, the cell position provided by the terrestrial cellular communication base station, which is another communication system, changes from time to time with respect to the cell position transmitted from the mobile satellite communication base station 28. In the present embodiment, the mobile satellite communication base station 28 extracts cells of the terrestrial cellular communication system in or near the service area provided by the mobile satellite communication base station 28, and transmits the extracted cell line information to the mobile communication terminal 5. Send.

  The cell position that changes with the progress of the communication satellite of the mobile satellite communication is stored in the own system line information storage unit 29. This cell position changes every moment. On the other hand, the cell position of the terrestrial cellular communication system is input and stored in the cell position storage unit 30 through a dedicated line or a public line. Since the cell position of the terrestrial cellular communication system is generally fixed, it may be stored in the cell position storage unit 30 in advance, but if it is not fixed, the cell position through a dedicated line or public line Need to be entered. The cell extraction unit 31 extracts, from the cell location storage unit 30, a cell of the terrestrial cellular communication system in or near the service area provided by the cell stored in the own system line information storage unit 29. The cell line information extracted by the cell extraction unit 31 is sent from the other system line information storage unit 32 to the transceiver 13. The other system line information storage unit 32 is previously input with line information corresponding to the cell of the terrestrial cellular communication system. The line information of the terrestrial cellular communication system transmitted from the mobile satellite communication base station 28 is received by the mobile communication terminal 5, and the mobile communication terminal 5 switches the communication system from the mobile satellite communication to the terrestrial cellular communication. At this time, by reading out from the line information storage unit and using it, it is possible to shorten the time required for line switching. The operation of communication system switching in the mobile communication terminal 5 is as described in the first embodiment.

In addition, a series of cell extraction processes in the cell position storage unit 30 and the cell extraction unit 31 and a cell line information read process in the other system line information storage unit 32 by the extracted cells are used for each mobile satellite communication. This is a process common to the base stations. These processes are separated from the base station, and, for example, collectively processed in the control station of the mobile satellite communication system, it is possible to avoid complication of the base station.
In the above description of the present embodiment, the case of terrestrial cellular communication is shown as another communication system, but the present invention can also be applied when the other communication system is a mobile satellite communication system. When the other communication system is a mobile satellite communication system, the position of the cell of this communication system changes as the communication satellite moves. The mobile satellite communication base station 28 acquires the cell position information of the mobile satellite communication system which is another communication system from time to time, or calculates the cell position information based on the orbit information.

1 is a configuration diagram showing the entire system of a mobile communication system according to the present invention (Embodiment 1). It is a block diagram which shows the structure of the mobile body communication system which concerns on this invention (Embodiment 1). FIG. 3 is a schematic diagram showing an example of a logical format in a control line in which a base station of a mobile communication system according to the present invention notifies line information of another communication system (Embodiment 1). It is sectional drawing which shows the state which inserted the duct for deaeration when it loaded with the plastic bag. 3 is a flowchart showing a flow of processing before switching of the mobile communication system according to the present invention (Embodiment 1). 3 is a flowchart showing a flow of processing at the time of switching of a mobile communication system according to the present invention (Embodiment 1). It is a block diagram which shows the other structural example of the mobile communication terminal of the mobile communication system which concerns on this invention (Embodiment 2). FIG. 6 is a schematic diagram showing an example of a logical format in a control line in which a base station of a mobile communication system according to the present invention notifies line information of another communication system (Embodiment 2). It is a schematic diagram which shows an example of the line parameter table of the mobile communication terminal which concerns on this invention (Embodiment 2). FIG. 6 is a configuration diagram showing another configuration example of the mobile communication system according to the present invention (Embodiment 3). It is a block diagram which shows the whole system of the conventional mobile communication system.

Explanation of symbols

  1 wireless base station, 3 communication satellite, 5 mobile communication terminal, 10, 11, 14, 15, 19 circuit information storage unit.

Claims (3)

  The service area of the base station is included in the service area of the communication satellite, and the base station receives the line information of the satellite communication system and the line information of the own communication system in its own service area and its vicinity received from the communication satellite, A mobile communication method for transmitting to a mobile communication terminal in its own service area.   A base station existing in the service area of the communication satellite, receiving means for receiving the link information of the satellite communication system in the service area and its vicinity from the communication satellite, and storing the received link information of the satellite communication system Mobile communication base station comprising: storage means for transmitting and transmission means for transmitting the stored line information of the satellite communication system and the own communication system to the mobile communication terminal in the own service area .   When the service area of the base station is included in the service area of the communication satellite, the line information of the satellite communication system and the line information of the base station communication system in the base station service area and its vicinity are A mobile communication terminal comprising receiving means for receiving from a station and switching means for switching from a communication system of the base station to a satellite communication system of a communication satellite.

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