JP3442320B2 - Communication system switching radio terminal and communication system switching method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to, for example, PDS, P
The present invention relates to a communication system switching wireless terminal and a communication system switching method for automatically switching and using a plurality of mobile communication services of different types such as HS and CDMA-ONE during a call.

[0002]

2. Description of the Related Art Mobile communication services such as PDS, PHS, and CDMA-ONE are provided by various communication carriers independent of each other, and therefore the communication methods and communication protocols of the respective services are not the same.

Therefore, the model of the wireless terminal used by the user when using the mobile communication service differs depending on the service used. Each wireless terminal generally conforms to the communication system and communication protocol of one mobile communication service. There are also wireless terminals that can support two types of mobile communication services, PDS and PHS.
This wireless terminal incorporates two sets of hardware adapted to the respective communication systems and communication protocols of the two types of mobile communication services. Also, the communication method and communication protocol can be switched by switching the switch.

[0004]

[Problems to be Solved by the Invention] At present,
It is not always possible to obtain satisfactory communication quality for users by simply using one mobile communication service. For example, when communicating at a position far from the base station or when there is an obstacle between the base station and the base station, the line may be disconnected or the call quality may be deteriorated if it goes out of the communicable area. become. In addition, the user may feel that the communication charge is high.

Even today, various telecommunications carriers use PDS, P
Since mobile communication services such as HS and CDMA-ONE are provided, if the mobile communication service to be used can be switched according to the environment at that time, user satisfaction can be obtained by selecting the optimum service. Can be improved. However, in order to use various mobile communication services, each user must have a plurality of communication terminals of different models. Also, PDS and P
A wireless terminal capable of supporting two types of HS mobile communication services is not practical because it is large and expensive. Furthermore, it is necessary to switch the switch at the discretion of the user, and it is impossible to switch the mobile communication service used during the call, so the switching operation is very troublesome.

The present invention is applicable to PDS, PHS, CDMA-O.
An object of the present invention is to provide a communication system switching wireless terminal and a communication system switching method capable of automatically switching a plurality of mobile communication services of different types such as NE during a call.

[0007]

According to a first aspect of the present invention, there is provided a communication system switching wireless terminal capable of wireless communication with wireless base stations of a plurality of mobile communication systems of different types by switching software. A multimode transmission / reception means having an antenna and a power supply line corresponding to transmission / reception of radio signals to / from a plurality of radio base stations respectively belonging to a plurality of mobile communication systems having different communication systems and frequencies, and the multimode transmission / reception means A programmable device that is connectable and capable of programming various functions such as modulation / demodulation and filters necessary for communication, and controls the programmable device to receive radio signals from radio base stations of a plurality of mobile communication systems almost simultaneously. And a quality signal reception control means for receiving from each radio base station under the control of the quality signal reception control means. A plurality of mobile communication systems calculates a communication quality QoS corresponding to each mobile communication system based on characteristic data related to a propagation environment detected based on the signal and characteristic data unique to each mobile communication system. Quality information sending means for sending the communication quality QoS of the mobile station to the wireless base station in communication, and when it is necessary to switch the mobile communication system used for communication to another system, Module addition control means for adding control of a software module for realizing a communication function corresponding to a communication system to control of the programmable device, and a module for releasing a software module for realizing an unnecessary communication function from control of the programmable device Release control means is provided.

The multimode transmission / reception means is provided with an antenna and a power supply line which are compatible with transmission and reception of radio signals of various mobile communication systems having different communication systems and frequencies. For example, (Reference 1: A. Strugatsky, CHWalter “Multimode
Multiband Antenna ”, Tactical Communications Confer
ence, Vol.1, pp.281-295, 1992), a multi-band antenna that can be used in a wide frequency band can be realized. Such a multi-band antenna can be used for multi-mode transmitting / receiving means.

The programmable device is a DSP (Digit
al Signal Processor) and FPGA (Field Programmable)
It is hardware that can be programmed with various functions such as modulation and demodulation and filters required for communication such as Gate Array. For example, (Reference 2: J. Mitola, “The Software Radio
Architecture ”, IEEE Comm. Mag. Vol.33, No5, pp.26-
38, 1995) by adopting the technology shown in
It is possible to implement the main function of the wireless communication device by software using a programmable device such as P or FPGA.

That is, in the communication system switching wireless terminal according to claim 1, various communication systems (PDC, PHS, etc.) can be obtained by changing the software controlling the programmable device.
You can communicate with. The quality signal reception control means controls the programmable device to receive radio signals from radio base stations of a plurality of mobile communication systems almost at the same time.

The quality information transmitting means is characteristic data relating to a propagation environment detected based on a signal received from each radio base station under the control of the quality signal reception control means, and characteristic data unique to the system of each mobile communication system. Based on the communication quality QoS corresponding to each mobile communication system
(Quality of Service) is calculated, and the communication quality QoS of the plurality of mobile communication systems is transmitted to the wireless base station in communication.

On the basis of the information on the communication quality QoS, the base station side can specify the communication system which can provide the mobile communication service most suitable for the communication. For example, if the communication quality of a communication system that provides a mobile communication service different from the communication system currently used for communication is higher (for example, the reception level of the terminal is higher), if switching is possible It is better to use another high quality communication system.

The module addition control means is a software module that realizes a communication function corresponding to the mobile communication system of the switching destination when the mobile communication system used for communication needs to be switched to another system. Control is added to the control of the programmable device. By this addition, the function necessary for communicating with a system different from the system currently used for communication is added.

When the function is added by the module addition control means, the communication system switching radio terminal according to claim 1 is substantially connected to the mobile communication system before switching and to the mobile communication system to be switched. Communication becomes possible at the same time. Therefore, the mobile communication system used for communication can be instantly switched without interrupting the call.

Switching the communication system When the mobile communication system used by the wireless terminal for communication is switched, the communication function corresponding to the mobile communication system before the switching becomes unnecessary. Therefore, the module release control means releases the software module that realizes the unnecessary communication function from the control of the programmable device. A second aspect of the present invention is a communication method switching method for switching a mobile communication system used by a wireless terminal capable of wireless communication with wireless base stations of a plurality of mobile communication systems of different types. In the wireless terminal, based on a plurality of received signals respectively received from a plurality of wireless base stations belonging to a plurality of mobile communication systems of different types that can be used, propagation related to a propagation environment with each wireless base station. Measuring environmental data,
The wireless terminal calculates a communication quality QoS of each mobile communication system based on the propagation environment data and system characteristic data unique to the mobile communication system, and the wireless terminal uses the wireless terminal to calculate the communication quality QoS. Report the communication quality QoS for each of the plurality of mobile communication systems to the first radio base station used for communication by
In the first radio base station, based on the communication quality QoS of each mobile communication system reported from the radio terminal,
The communication quality QoS of each mobile communication system is ranked, and in the first radio base station, the rank of the communication quality QoS of each mobile communication system is the first mobile barrier of the mobile communication system to which the own station belongs. The switching center reports to the switching center, and the first mobile barrier switching center identifies the mobile communication system of the switching destination in the order according to the rank of the communication quality QoS reported from the base station, and moves to the switching destination. A second mobile gateway exchange station belonging to the mobile communication system is queried as to whether or not the second wireless base station belonging to the mobile communication system of the switching destination and the wireless terminal can be connected, and the first mobile barrier exchange station. Then, as a result of the inquiry, when the connection between the second wireless base station and the wireless terminal is possible, the second wireless base station is requested to switch the mobile communication system by inter-system handover. It is characterized in.

In the second aspect, the wireless terminal receives signals from a plurality of wireless base stations belonging to the available mobile communication systems in order to measure the propagation environment data regarding each mobile communication system. Further, the wireless terminal calculates the communication quality QoS of each mobile communication system based on the propagation environment data and the corresponding system characteristic data unique to the mobile communication system. Then, the wireless terminal reports the communication quality QoS for each of the plurality of mobile communication systems to the first wireless base station used for communication.

The first radio base station receiving this communication quality QoS ranks the communication quality QoS based on the reported communication quality QoS of each mobile communication system, and the own station ranks the order. Report to the first mobile gateway switching center of the mobile communication system to which it belongs. That is, multiple Qo
By comparing S, it is possible to identify at least whether or not there is another mobile communication system capable of providing a service having a higher quality than the communication quality of the mobile communication system currently used by the wireless terminal for communication.

In the first mobile gateway switching center, the switching destination mobile communication system is specified in the order corresponding to the rank of the communication quality QoS reported from the base station. Normally, the mobile communication system having the highest communication quality QoS may be selected as the switching destination. However, there may be no channels available in the selected switching destination mobile communication system.

Therefore, the first mobile gateway exchange station is connected to the second mobile gateway exchange station belonging to the switching destination mobile communication system and the second radio base station belonging to the switching destination mobile communication system. Queries the availability of connection with the wireless terminal. As a result of this inquiry, when the connection between the second wireless base station and the wireless terminal is possible, the second wireless base station is requested to switch the mobile communication system by the inter-system handover.

The inter-system handover can be started by such a procedure. That is, when there is another mobile communication system capable of providing a service of higher quality than the communication quality of the mobile communication system currently used by the wireless terminal for switching, to switch to the high quality mobile communication system. Inter-system handover control is performed.

According to a third aspect of the present invention, in the communication method switching method according to the second aspect, in the first radio base station, regarding the communication quality QoS of the mobile communication system to which the own station belongs, system characteristic data held by the own station. It is characterized in that the received communication quality QoS is corrected in consideration of the above. Even if the communication quality detected by the wireless terminal is good, the actual communication quality may subsequently deteriorate if the device resources (available memory, CPU processing capacity, etc.) in the base station are low. There is a nature.

In claim 3, since the communication quality QoS of the system is modified in consideration of the system characteristic data held by the first radio base station, it is possible to more appropriately determine whether or not the intersystem handover should be performed. it can. Claim 4
3. The communication system switching method according to claim 2, wherein the wireless terminal has a reception level, a multipath delay characteristic, a bit error rate,
At least one of a frame error rate and a packet error rate is used as the propagation environment data to calculate the communication quality QoS.

According to a fifth aspect of the present invention, in the communication method switching method according to the second aspect, the wireless terminal uses at least one of transmission rate, security characteristic, communication charge, device resource and power consumption as the system characteristic data for communication. Quality Q
It is characterized by calculating oS. According to a sixth aspect of the present invention, in the communication method switching method according to the third aspect, the first radio base station uses at least one of a channel capacity, a device resource, and power consumption as the system characteristic data held by the own station. It is characterized in that the communication quality QoS is corrected.

According to a seventh aspect of the present invention, in the communication method switching method according to the second aspect, the first mobile gateway switching center requests the second radio base station to switch the mobile communication system by intersystem handover. At the time, while the communication between the first wireless base station and the wireless terminal is being continued, the line connected to the communication partner station is moved to the second mobile terminal under the control of the first mobile barrier switching station. Connecting to the second wireless base station via a gateway exchange, and securing a switching destination wireless communication line between the second wireless base station and the wireless terminal;
After the switching destination wireless communication line is secured, the mobile communication system used by the wireless terminal for communication is switched, and the second mobile gateway switching center performs the above-mentioned switching to the first mobile gateway switching center. A request for releasing the connection between the first wireless base station and the wireless terminal is made, and in response to the request, the first mobile barrier switching center causes the first wireless base station and the wireless terminal to communicate with each other. It is characterized by releasing the connection of.

In claim 7, the line of the mobile communication system before switching is disconnected after the wireless terminal and the communication partner station are connected in parallel by two lines. Therefore, it is possible to prevent the call from being interrupted due to the switching of the mobile communication system.

[0026]

FIG. 1 is a block diagram showing an embodiment of a communication system switching wireless terminal and a communication system switching method according to the present invention.
~ It demonstrates with reference to FIG. This form corresponds to all the claims.

FIG. 1 is a block diagram showing the configuration of the wireless terminal of this embodiment. FIG. 1 shows the configuration of a wireless terminal embodying the communication system switching wireless terminal of claim 1. FIG. 2 is a block diagram showing a configuration example of a communication system. FIG. 3 is a flowchart showing the inter-system handover control sequence (1). FIG. 4 is a flowchart showing the inter-system handover control sequence (2).

FIG. 5 is a flow chart showing a process for the mobile terminal to obtain the QoS. FIG. 6 is a block diagram showing the QoS calculation processing of the mobile terminal. FIG. 7 is a flowchart showing a process in which the base station in communication corrects the QoS. FIG. 8 is a block diagram showing a process in which the base station in communication corrects the QoS. In this mode, the multimode transmission / reception unit, the programmable device, the quality signal reception control unit, the quality information transmission unit, the module addition control unit, and the module release control unit of claim 1 are the multimode transmission / reception unit 10, the programmable processing unit 20, and the programmable processing unit 20, respectively.
It is embodied as a communication quality detection program 36, a system switching program 35, a module addition program 37, and a module release program 38.

Further, the radio terminal, the first radio base station, the first mobile gateway exchange station, the second mobile barrier exchange station and the second radio base station of claim 2 are a mobile station MS and a base station, respectively. B
S-A, mobile barrier exchange MGS-A, mobile barrier exchange M
Corresponds to GS-B and base station BS-B. The wireless terminal shown in FIG. 1 includes a multi-mode transmission / reception unit 10, a programmable processing unit 20, a display unit 31, an operation board 32, a voice processing unit 33, and a communication control unit 3.
4, a system switching program 35, a communication quality detection program 36, a module addition program 37, a module release program 38, and a software module library 39.

Further, the multimode transmission / reception unit 10 is equipped with a multiband antenna 11, a power supply line 12, a reception high frequency amplifier 13 and a transmission power amplifier 14. The multi-band antenna 11 and the feeder 12 are compatible with a wide frequency band and various wireless communication modes.

Therefore, the multimode transmission / reception unit 1
0 is capable of transmitting and receiving radio signals to and from various mobile communication services such as PDC, PHS and CDMA-ONE. Multimode transceiver unit 10
The programmable processing unit 20 connected to the DS
It contains P21 and FPGA22. The multimode transmission / reception unit 10 is hardware that can be flexibly realized by a program that incorporates various functions required for communication (modulator / demodulator, synthesizer, voice codec, communication protocol, etc.) into the DSP 21 and the FPGA 22.

The display unit 31 is a display device for displaying character information such as the telephone number of the other party. The operation board 32 is an input device including a numeric keypad used for inputting the telephone number of the other party. Voice processing unit 33
Is equipped with a microphone for inputting transmitted voice and a speaker for outputting received voice. Communication control unit 34
Is a control device including a microcomputer and the like, and controls the entire wireless terminal.

The system switching program 35 is a program used when performing handover control between a plurality of communication systems that provide different mobile communication services, and is executed by the communication control unit 34. The communication quality detection program 36 uses the communication quality Qo regarding each communication system when performing handover control between communication systems.
It is a program for detecting S and is executed by the communication control unit 34.

The module addition program 37 is a program for performing control for adding to the programmable processing unit 20 and the communication control unit 34 the functions necessary for communicating with a communication system which provides a mobile communication service different from the conventional one. And is executed by the communication control unit 34. The actual function is realized by the additional software module 40.

The module release program 38 is a control for releasing from the programmable processing unit 20 and the communication control unit 34 the function corresponding to the communication system before switching which becomes unnecessary after switching the communication system with which this wireless terminal communicates. And is executed by the communication control unit 34. The software module library 39 holds a large number of software modules 40 including programs and data associated with various mobile communication services.

One software module 40 is connected to the programmable processing unit 20 and the communication control unit 34.
Incorporation into the mobile communication service enables communication corresponding to one mobile communication service. In this form, two software modules 40 are simultaneously installed in the programmable processing unit 20 and the communication control unit 34,
Wireless communication can be performed simultaneously between two types of communication systems.

Mobile station MS (Mobile Station) shown in FIG.
As the above, the wireless terminal shown in FIG. 1 can be used. In FIG. 2, a base station BS (Base Station) -A and a base station BS-B belong to a communication system that provides different mobile communication services. For example, the base station BS-A
Provides PDS services and base station BS-B provides PHS
It is possible to envision the case of providing the service of.

In addition, a mobile gateway exchange MGS (Mobile Gat
eway Switch) -A belongs to the same communication system as the base station BS-A. A large number of base stations belonging to the same communication system as the base station BS-A are connected to the mobile gateway switch MGS-A. Similarly, the mobile gateway switch MGS-B belongs to the same communication system as the base station BS-B. A large number of base stations belonging to the same communication system as the base station BS-B are connected to the mobile gateway exchange MGS-B.

The mobile gateway exchange MGS-A and the mobile gateway exchange MGS-B are mobile inter-system gateway MISGS (Mobile Inter-System Gateway), respectively.
Switch) is connected. Further, a fixed network 53 connected to a fixed telephone is connected to the gateway switch MISGS between mobile communication systems. Here, it is assumed that the mobile station MS in FIG. 2 is using the mobile communication service (A) to talk to the correspondent station 51 of the fixed telephone. That is, the mobile station MS and the base station BS-A are connected by a wireless line, and the mobile station MS is connected to the base station BS-A, the mobile gateway switch MGS-A, and the mobile communication system barrier switch M.
It is connected to the communication partner station 51 via the ISGS, the fixed network 53, and the subscriber line 52.

In the example of FIG. 2, since the mobile station MS is also located in the radio zone of another mobile communication service (B) different from the mobile communication service (A) in communication, the mobile station MS is Can switch the mobile communication service to be used for communication. The wireless terminal of FIG. 1 is replaced by the mobile station M of FIG.
When used as S, the mobile communication service can be automatically switched during a call by performing inter-system handover control. The control sequence of this inter-system handover will be described with reference to FIGS. 3 and 4. In this example, it is assumed that the mobile communication service (A) shown in FIG. 2 is used to perform a handover to the mobile communication service (B) during a call.

The mobile station MS calculates the communication quality QoS of all available services in step S10 of FIG. Specifically, the processing shown in FIG. 5 is performed. this is,
This means that the communication control unit 34 executes the processing of the communication quality detection program 36 of FIG. In step S70 of FIG. 5, radio signals from all communication systems (base stations) of all available (receivable) services are received. In step S71, the reception level and bit error rate of each communication system are measured based on the received wireless signal.

In step S72, the type (PDC, PHS, etc.) of the communication system transmitting the radio signal is specified based on the frequency of the received radio signal. Step S
At 73, system-specific characteristic data (transmission rate, power consumption, communication charge, etc.) regarding each communication system is input. Further, in step S74, the data of the weighting coefficient (w (1) to w (n) in FIG. 6) of each characteristic data is input. The communication control unit 34 holds system-specific characteristic data of various systems and the weighting factor data in advance.

In step S75, the communication quality QoS for each communication system is obtained by the calculation processing as shown in FIG. Communication quality QoS for each communication system by the above processing
After obtaining the value, the processing of the mobile station MS is performed in step S1 of FIG.
Go to 1. In step S11, the information of the communication quality QoS of each communication system obtained in step S10 is reported to the base station BS-A currently communicating.

When the base station BS-A receives this report,
The process of the base station BS-A proceeds from step S20 to S21. In step S21, the communication quality QoS is corrected using the system characteristic data held by the own station. The communication quality QoS to be modified is only for the communication system including its own station. The contents of the actual processing are as shown in FIG.

In step S80 of FIG. 7, the communication quality QoS of all communication systems transmitted from the mobile station MS is received. In step S81, the communication quality Q of the communication system to which the authority belongs is selected from the plurality of received communication quality QoS.
Extract oS (1). In step S82, the system characteristic data (channel capacity, device resource, power consumption, etc.) of the authority is input. In step S83, the weighting coefficient data of each characteristic data is input. The data of the weighting coefficient is held in the base station BS-A as fixed data in advance.

In step S84, the communication quality QoS (1) of the communication system to which the authority belongs is recalculated and corrected. Specifically, the calculation as shown in FIG. 8 is performed. Next, the process of the base station BS-A proceeds to step S22 of FIG. In step S22, the values of the communication quality QoS of all services detected as the services available to the mobile station MS are compared with each other to identify the order of their magnitude relationship.

Then, as a result of step S22, the mobile station M
If another service having a higher QoS than the service currently used by S can be used, the order of magnitude relation of communication quality QoS is set in step S23 to the mobile gateway switch MG.
Report to S-A. When the mobile gateway exchange MGS-A receives the report from the base station BS-A in step S23, the processing of the mobile gateway exchange MGS-A proceeds from steps S30 to S30.
Proceed to 31. In step S31, it is identified whether or not another service having a higher QoS than the service currently used by the mobile station MS can be used. If another service with a large QoS can be used, steps S31 to S3
Go to 2.

In step S32, the mobile gateway switch M belonging to the communication system providing the maximum QoS service.
The GS-B is inquired whether or not there is an empty channel in the wireless zone to which the current position of the mobile station MS belongs. This inquiry is sent from the mobile gateway exchange MGS-A through the mobile communication inter-gateway exchange MISGS.
Forwarded to GS-B.

When the inquiry about the free channel is received, the processing of the mobile gateway exchange MGS-B is performed from steps S50 to S50.
Proceed to 51. In step S51, the mobile barrier exchange MG
S-B checks the base station BS-B that manages the radio zone to which the current position of the mobile station MS belongs for the presence of an empty channel, and reports the result to the mobile gateway switch MGS-A.

When the mobile gateway exchange MGS-A receives a reply from the mobile gateway exchange MGS-B that there is no empty channel, the process of the mobile gateway exchange MGS-A is step S3.
Return from 2 to S31. In this case, it is identified whether another service having the second highest QoS can be used. If there is no free channel, the presence or absence of other services is sequentially checked according to the order of the size of QoS.

When the mobile gateway switch MGS-A receives a reply from the mobile gateway switch MGS-B that there is an empty channel, the process of the mobile gateway switch MGS-A is step S3.
It progresses from 2 to S33. In step S33, a system switching request is sent to the gateway exchange MISGS between mobile communication systems. Further, in step S34, the mobile gateway switch MGS-A notifies the mobile station MS of the idle channel of the base station BS-B via the base station BS-A.

On the other hand, when a system switching request is received from the mobile gateway exchange MGS-A, the processing of the mobile communication inter-gateway exchange MISGS proceeds from step S40 to step S41. In step S41, the subscriber line 52 of the communication partner communicating with the mobile station MS is connected to the mobile gateway exchange MGS-B of the communication system of the switching destination. In this case, the process of the mobile gateway exchange MGS-B proceeds from step S52 to step S53. In step S53, the connected subscriber line 52
Is extendedly connected to the base station BS-B.

When the subscriber line 52 is extendedly connected to the base station BS-B, the process of the base station BS-B proceeds from step S60 to step S61. On the other hand, when the notification of the idle channel sent by the mobile gateway switch MGS-A reaches the mobile station MS in step S34 of FIG. 3, the process of the mobile station MS proceeds to step S12.
To S13.

In step S13, a specific software module 40 for realizing the communication function of the mobile communication service (B) is loaded into the communication control unit 34 and executed by the control of the module addition program 37.

Further, the program of the programmable processing unit 20 is rewritten using the software module 40 to add the communication function of the mobile communication service (B). With the addition of this communication function, the mobile station MS can simultaneously use two mobile communication services (A, B). Then, the process proceeds to the next step S14. Base station BS-B
Processing of step S61 and step S1 of the mobile station MS
And the processing of No. 4, the base station BS-B and the mobile station M.
A wireless line with S is secured.

When the wireless line between the base station BS-B and the mobile station MS is connected, the mobile station MS is connected to the communication partner station 51 by using two types of lines in parallel at the same time. Become. That is, the mobile station MS to the base station BS-A, the mobile gateway exchange MGS-A, and the mobile communication inter-gateway exchange M.
A line connecting the communication partner station 51 via the ISGS, the fixed network 53, and the subscriber line 52, the mobile station MS to the base station BS-B, the mobile gateway exchange MGS-B, the mobile communication system-gateway exchange MISGS, and the fixed network. 5
3. A line connecting the communication partner station 51 via the subscriber line 52 is formed at the same time.

Therefore, the mobile station MS temporarily uses two types of mobile communication services at the same time to communicate with the communication partner station 51. Base station BS-B and mobile station MS
When the wireless line between and is connected, the process of the mobile station MS proceeds from step S14 to step S15. In step S15, the mobile station MS switches the system to be used.

Actually, the mobile station MS already has the communication functions of two types of systems, and therefore, the communication function corresponding to the communication system before the switching which becomes unnecessary by the switching is released. This process is performed by the module release program 38 of FIG.
It is realized by executing. This release allows the addition of other communication functions again.

In step S16, since the system switching in the mobile station MS is completed, the base station BS-
Report completion of switching to B. Upon receiving the notification of completion of switching from the mobile station MS, the process of the base station BS-B proceeds from step S62 to step S63. In step S63, the base station BS-B makes a completion report to the mobile gateway exchange MGS-B.

When the completion report is received from the base station BS-B,
The process of the mobile gateway switch MGS-B proceeds from step S54 to step S55. In step S55, the mobile gateway exchange M
The GS-B reports completion to the gateway exchange MISGS between mobile communication systems. When the completion report is received from the mobile gateway exchange MGS-B, the process of the mobile communication inter-gateway exchange MISGS proceeds from step S42 to step S43.
In step S43, the gateway switch M between mobile communication systems
ISGS sends a completion report to the mobile gateway switch MGS-A.

Mobile communication inter-gateway switch MISGS
Upon receipt of a completion report from the mobile gateway exchange MGS-A
The process proceeds to step S36 from step S35. Step S
At 36, the mobile gateway switch MGS-A is the base station BS-A.
Disconnect the line connection with. In addition, the mobile gateway exchange MGS
When the line with the terminal -A is disconnected, the processing of the base station BS-A proceeds from step S24 to step S25. Step S25
Then, the base station BS-A releases the radio channel with the mobile station MS.

Characteristic items used by the mobile terminal to obtain the communication quality QoS (reception level, bit error rate, frame error rate, packet error rate, device resource, power consumption, communication charge, sound quality, security, transmission rate) Such)
Can be added or reduced as needed. Also, each weighting factor used when calculating the QoS may be changed for each terminal according to the request of the user of the terminal, the communication environment, the propagation environment, and the like.

A simulation was carried out using a computer in order to examine the effect when the wireless terminal performs communication while performing the inter-system handover in which the wireless terminal adaptively selects a plurality of types of mobile communication systems. In this simulation, the following conditions were assumed. Regarding the selection condition of the inter-system handover, the reception level of the wireless terminal is used as the characteristic data of the propagation environment, and the transmission rate (communication speed) is used as the characteristic data unique to the system. Then, the reception level is continuously measured, and the system having the maximum transmission rate is selected from the systems having the reception level equal to or higher than the threshold.

It is assumed that the system to be communicated is a microcell system SA, a cellular system SB, an MEO satellite system SC, and a wireless terminal accesses a base station of each system to perform packet data communication. The characteristics of each system are as follows. Microcell system SA Frequency band: 1.9 GHz Access method: TDMA / TDD Fading: Two-wave Rayleigh (Equal level) Symbol rate: 192 kbaud Modulation method: π / 4 shift QPSK Transmission rate: 32 kbit / s Cellular system SB: Frequency band: 800 MHz Access method: TDMA / FDD Fading: Two-wave Rayleigh (Equal level) Symbol rate: 21 kbaud Modulation method: π / 4 shift QPSK Transmission rate: 9.6 kbit / s MEO satellite system SC: Frequency band: 2.5 GHz (downlink) ) Access method: DS-CDMA / FDD Fading: Rice (C / M = 10 dB) Symbol rate: 3.6 kbaud Modulation method: O-QPSK Transmission rate: 2.4 kbit / s Te can utilize the reception level estimated from the despreading result with a common PN code sequence for control pilot channel.

Here, a transmission path model was created assuming a propagation environment in which the average success rate of packet transmission and the throughput in the downlink of each system when inter-system handover is not performed are as follows. Microcell system SA Average packet transmission success rate: 50.3 [%] Throughput: 16.09 [kbit / s] Cellular system SB Average packet transmission success rate: 39.1 [%] Throughput: 3.75 [kbit / s] ] MEO satellite system SC Average packet transmission success rate: 95.9 [%] Throughput: 2.30 [kbit / s] Also, regarding the micro cell system SA and the cellular system SB, the wireless terminal moves at about 14 km / h. Receiving 2-wave Rayleigh fading, MEO satellite system SC
Was assumed to undergo rice fading.

The results of variations in the reception level of each system and system selection in this simulation are shown in FIG. Regarding the system selection condition, it is assumed that a value of (-10 dB) with respect to the average reception level of the reception level is used as a packet discard threshold value, and a system having a maximum transmission rate is selected from systems having this threshold value or more. However, the packet length is sufficiently smaller than the fade length, and 20 ms is assumed as the time required for system switching.

The average packet transmission success rate and throughput when the inter-system handover was carried out were as follows. Average packet transmission success rate: 91.6 [%] Throughput: 19.64 [kbit / s] As described above, it was confirmed that the average packet transmission success rate and throughput are improved by performing the inter-system handover.

[0068]

According to the communication system switching wireless terminal and the communication system switching method of the present invention, various types of mobile communication services can be used by one terminal, and communication can be interrupted during a call. It is also possible to automatically shift to a mobile communication service with higher communication quality.

Further, since the system is switched by adding and releasing functions by controlling software, it is possible to realize a terminal that can use various mobile communication services without complicating the hardware configuration. Furthermore, since a wireless terminal can effectively utilize device resources such as a base station by selecting a high quality service from a plurality of mobile communication services and communicating with the mobile communication service, a communication carrier can use the network or the base station. It leads to reduction of installation cost and development cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless terminal according to an embodiment.

FIG. 2 is a block diagram showing a configuration example of a communication system.

FIG. 3 is an intersystem handover control sequence (1)
It is a flowchart showing.

FIG. 4 is an intersystem handover control sequence (2)
It is a flowchart showing.

FIG. 5 is a flowchart showing a process in which a mobile terminal obtains QoS.

FIG. 6 is a block diagram showing a QoS calculation process of a mobile terminal.

FIG. 7 is a flowchart showing a process in which a base station in communication corrects QoS.

FIG. 8 is a block diagram showing a process in which a base station in communication corrects QoS.

FIG. 9 is a graph showing a reception level variation of each system and a system selection result.

[Explanation of symbols]

10 Multi-mode transceiver unit 11 multi-band antenna 12 power lines 13 Reception high-frequency amplifier 14 Power amplifier for transmission 20 Programmable processing unit 21 DSP 22 FPGA 31 Display unit 32 Operation board 33 Audio processing unit 34 Communication control unit 35 System switching program 36 Communication Quality Detection Program 37 Module addition program 38 Module Release Program 39 Software Module Library 40 software modules 51 Communication partner station 52 subscriber line 53 Fixed network MS mobile station BS-A, BS-B base stations MGS-A, MGS-B Mobile Gateway Switch MISGS Mobile Communication System Gateway Switch

Front page continuation (72) Inventor Shuji Kubota 2-3-1, Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) Reference JP-A-10-13929 (JP, A) JP-A-11- 205842 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B ^7/ 24-7/26 H04Q ⁷ /00-7/38

Claims (7)

(57) [Claims] 1. A communication system switching wireless terminal capable of wireless communication with wireless base stations of a plurality of mobile communication systems of different types by switching software, the plurality of wireless systems having different communication systems and frequencies. A multi-mode transmission / reception unit having an antenna and a power supply line corresponding to transmission / reception of radio signals to / from a plurality of radio base stations belonging to a mobile communication system, and a modulation / demodulation unit required for communication, connectable to the multi-mode transmission / reception unit A programmable device capable of programming various functions such as a filter, and a quality signal reception control means for controlling the programmable device to receive radio signals from radio base stations of a plurality of mobile communication systems at substantially the same time, Detected based on the signal received from each radio base station under the control of the quality signal reception control means The communication quality QoS corresponding to each mobile communication system is calculated based on the characteristic data regarding the carrying environment and the characteristic data unique to each mobile communication system, and the communication quality QoS of a plurality of mobile communication systems is being communicated. Quality information transmitting means for transmitting to the wireless base station of the above, and a communication function corresponding to the switching destination mobile communication system when the mobile communication system used for communication needs to be switched to another system. The module addition control means for adding the control of the software module for realizing the above to the control of the programmable device, and the module release control means for releasing the software module for realizing the unnecessary communication function from the control of the programmable device are provided. A communication mode switching wireless terminal characterized by the above. 2. A communication system switching method for switching a mobile communication system used by a wireless terminal capable of wireless communication with wireless base stations of a plurality of mobile communication systems of different types. In the wireless terminal, based on a plurality of received signals respectively received from a plurality of wireless base stations belonging to a plurality of mobile communication systems of different types available, propagation related to a propagation environment with each wireless base station. The environmental data is measured, the wireless terminal calculates the communication quality QoS of each mobile communication system based on the propagation environment data and the corresponding system characteristic data of the mobile communication system, In the terminal, the communication quality Q for each of the plurality of mobile communication systems is compared with the first wireless base station used by the wireless terminal for communication. reporting the QoS, the first radio base station ranks the communication quality QoS of each mobile communication system based on the communication quality QoS of each mobile communication system reported from the radio terminal, In the first wireless base station, the order of the communication quality QoS of each mobile communication system is reported to the first mobile gateway switching center of the mobile communication system to which the mobile station belongs, and the first mobile barrier switching center The mobile communication system of the switching destination is specified in the order according to the rank of the communication quality QoS reported from the base station, and the switching is performed with respect to the second mobile barrier switching station belonging to the mobile communication system of the switching destination. Inquiring about whether or not the second wireless base station belonging to the previous mobile communication system can be connected to the wireless terminal, and the first mobile gateway switching center, as a result of the inquiry, the second wireless base station and the wireless terminal. end A method for switching a mobile communication system, comprising requesting the second radio base station to switch a mobile communication system by inter-system handover when a connection with a terminal is possible. 3. The communication system switching method according to claim 2,
Regarding the communication quality QoS of the mobile communication system to which the first wireless base station belongs, the first wireless base station corrects the received communication quality QoS in consideration of the system characteristic data held by the own station. Method switching method. 4. The communication system switching method according to claim 2,
Communication method switching, wherein the wireless terminal uses at least one of a reception level, a multipath delay characteristic, a bit error rate, a frame error rate and a packet error rate as the propagation environment data to calculate a communication quality QoS Method. 5. The communication system switching method according to claim 2,
A communication system switching method, wherein the wireless terminal calculates communication quality QoS by using at least one of transmission rate, security characteristic, communication charge, device resource, and power consumption as the system characteristic data. 6. The communication system switching method according to claim 3,
A communication system switching method, wherein the first radio base station corrects the communication quality QoS by using at least one of a channel capacity, a device resource, and power consumption as the system characteristic data held by the own station. . 7. The communication system switching method according to claim 2, wherein when the first mobile gateway switching center requests the second radio base station to switch the mobile communication system by intersystem handover. While the communication between the first wireless base station and the wireless terminal is being continued, the line connected to the communication partner station is connected to the second mobile gateway switching station under the control of the first mobile gateway switching station. After connecting to the second wireless base station via the network, securing a switching destination wireless communication line between the second wireless base station and the wireless terminal, and after securing the switching destination wireless communication line The mobile communication system used by the wireless terminal for communication is switched, and the second mobile gateway switching center is configured to connect the first mobile gateway switching center to the first wireless base station and the wireless terminal. Request to release another connection In response to this request, the first mobile gateway switching station communication system switching method, characterized in that to release the connection between the said first radio base station radio terminal.