JP2002232928A - Hand-off control system and hand-off control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately execute hand-off independently of a wireless communication state. SOLUTION: When a mobile phone MS 100 making wireless communication with any of base stations BS21-BS27 installed in cells C21-C27 respectively moves between the cells, the mobile phone M100 transmits position data D11 representing its own current position detected by a GPS reception section 41 to the base station BS21, the base station BS21 informs a switching control station 12 about a prediction result of a moving direction by the mobile phone M100 on the basis of the position data D11, the switching control station 12 decides a base station object BS23 in the moving direction to which the mobile phone M100 executes the hand-off on the basis of the prediction result, and the mobile phone M100 makes hand-off to the base station object BS23 in a prescribed timing to avoid hand-off to a base station of a cell in mistake not in a substantial moving direction independently of the state of wireless communication so as to execute accurate hand-off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a handoff control system and a handoff control method, and is suitably applied to, for example, a cellular radio communication system.

[0002]

2. Description of the Related Art Conventionally, in a cellular radio communication system, an area for providing a communication service is divided into cells of a desired size, a base station as a fixed station is installed in each cell, and a base station as a mobile station is installed. The mobile phone is made to wirelessly communicate with a base station having the best communication state.

At this time, various communication systems have been proposed between a mobile phone and a base station.
A code division multiple access system called a (Code Division Multiple Access) system is used, and has many advantages such as being resistant to interference waves and enabling high-speed data communication.

[0004] Regarding this cellular radio communication system,
This will be specifically described below with reference to FIG. In FIG. 5, the cellular radio communication system 1 divides a service area into, for example, a plurality of cells C1 to C7 and
7, base stations BS1 to BS7 are arranged respectively, so that any of the base stations BS1 to BS7 and the mobile phone MS1 are located within the service area.
Wireless communication with the user.

[0005] In this case, the base stations BS1 to BS7 arranged in the cells C1 to C7 are connected to the upper layer switching control station 2, and the switching control station 2 is connected to the base stations BS1 to BS7.
7 is controlled, and a signal path (channel) of a signal transmitted from each of the base stations BS1 to BS7 and a signal transmitted to each of the base stations BS1 to BS7 is controlled by circuit switching.

Here, a mobile phone MS1 as a mobile station
When the mobile phone MS1 communicates within the service area of the cellular radio communication system 1, the mobile phone MS1 is connected to the base station BS1.
~ Select the base station with the best communication condition from BS7,
The selected base station is connected to a wireless line (communication channel) to communicate user information such as a voice signal.

[0007] For example, the mobile phone MS1 is connected to the base station BS1.
, The communication state with the base station BS1 is the best, so that the base station BS1 and the wireless line are connected. At this time, the base station BS1 is connected to the mobile phone MS1.
Is transmitted to the upper-layer switching control station 2, and conversely, the transmission signal received from the switching control station 2 is transmitted to the mobile phone MS1.

The switching control station 2 transmits the data received from the base station BS1 to the terminal device 4 of the communication partner via the public network 3 and the terminal of the communication partner transmitted via the public network 3 The data from the device 4 is transmitted to the base station BS1, whereby the mobile telephone MS1 communicates with the terminal device 4 of the communication partner via the base station BS1, the switching control station 2, and the public network 3. Can be.

[0009] By the way, when the mobile phone MS1 moves, there is a case where the base station to which the mobile phone MS1 is to be wirelessly connected is changed. For example, mobile phone MS
This is the case where the mobile station 1 moves from the cell C1 serving as the service area of the base station BS1 to the cell C2 serving as the service area of the base station BS2.

At this time, the mobile phone MS1 is connected to the base station BS.
1 to a newly connected base station BS2 to perform wireless connection connection switching so-called handoff to perform wireless communication with the base station BS2. By performing such a handoff, the mobile phone MS1 moves. Even in this case, the wireless communication is continued by sequentially switching the base stations BS1 to BS7.

In practice, in order to perform handoff in the cellular radio communication system 1, it is necessary to always search for "to which base station a mobile station should connect" even during communication.

In general, in cellular radio communication system 1, mobile phone MS1 receives pilot signals of a control channel (hereinafter, referred to as control channel CCH) transmitted from base stations BS1 to BS7, and reduces the received power of each signal. The base station that has measured and received the highest received power is determined as a handoff destination base station candidate, and the mobile phone MS1 mainly searches for a handoff destination base station candidate.

The right to determine whether or not to actually perform a handoff is left to the base station. The flow up to performing the handoff is as follows. In accordance with the search result, the base station that has received the handoff request from the mobile phone MS1 determines whether or not to perform the handoff, and performs the handoff when it is determined that the handoff should be performed. "

That is, the base station constantly monitors whether or not the received power of the pilot signal transmitted from the mobile phone MS1 currently communicating is not insufficient to maintain a good communication state. If a good communication state cannot be maintained due to the shortage of mobile phones, it is determined that the currently communicating mobile phone MS1 is to be handed off to another base station, and a handoff destination candidate base station notified from the mobile phone MS1 is determined. Perform handoff for.

[0015]

However, in such a conventional cellular radio communication system 1, a portable telephone M
When S1 moves between cells C1 to C7, in a multipath environment such as an urban building county, the received power is unstable, and the direction of arrival of radio waves from the base station is also affected only by the influence of the multipath from the forward direction. However, there is a problem that the mobile phone MS1 cannot necessarily search for a correct base station candidate and performs an erroneous handoff due to various types such as from behind or from the side.

Further, in the cellular radio communication system 1, when an erroneous handoff is performed, a call between the base station and the portable telephone set MS1 is easily interrupted, and a good communication state cannot be maintained. there were.

The present invention has been made in view of the above points, and proposes a handoff control system and a handoff control method capable of executing a handoff accurately even in an unstable communication state such as in a multipath environment. It is assumed that.

[0018]

In order to solve this problem, according to the present invention, a mobile station that wirelessly communicates with one of base stations installed in a plurality of areas obtained by dividing a communication area into a predetermined size is provided. When moving between multiple areas,
In order to control handoff by the upper switching control station of the base station, the mobile station transmits position data obtained by detecting its current position by predetermined positioning means to the communicating base station, and the base station moves. A higher-order switching control station is notified of a prediction result indicating a moving direction of the mobile station predicted based on the position data received from the station, and the higher-order switching control station performs next handoff based on the prediction result notified from the base station. A base station candidate in a moving direction to be determined is determined, and at a predetermined timing, a command to connect a wireless line with the mobile station is output to the candidate base station, and a command to disconnect the wireless line with the mobile station is sent to the base station. To perform the handoff.

Thus, handoff can be performed to the base station candidate in the moving direction predicted based on the position data, so that even in a multipath environment, the next base station to be handed off is not mistaken. The handoff can be performed more accurately.

Further, in the present invention, the received power value data supplied simultaneously with the position data from the mobile station is reduced below a predetermined threshold level, and the received power value data from the base station candidates is increased above the threshold level. In some cases, handoff is executed by outputting an instruction to connect a wireless line with a mobile station to a base station candidate and outputting an instruction to disconnect a wireless line with a mobile station to a base station.

[0021] With this, when the radio communication state with the next base station candidate surely becomes good, the radio line with the base station is disconnected and the handoff is completed, so that the call with the mobile station is terminated. Instantaneous interruption can be reliably prevented.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) Overall Configuration of Digital Cellular Radio Communication System In FIG. 1 in which parts corresponding to those in FIG. 5 are assigned the same reference numerals, reference numeral 11 denotes a digital cellular radio communication system as a handoff control system as a whole according to the present invention. And base stations BS21 to BS21 arranged in cells C21 to C27 each of which is a plurality of areas obtained by dividing a service area.
Of the BS 27, the base station BS21 of the cell C21 where the mobile phone MS100 is currently located and the mobile phone MS10
0 is wirelessly connected.

In this case, the base stations BS21 to BS27 arranged in the cells C21 to C27 are connected to the upper-layer switching control station 12, and the switching control station 12 manages the base stations BS21 to BS27. With each base station BS
Signals transmitted from 21 to BS27 and each base station BS
Signal paths (channels) of signals sent to the BS 21 to the BS 27 are controlled by circuit switching.

Here, the mobile phone MS1 as a mobile station
When 00 performs communication within the service area of the cellular radio communication system 11, the mobile phone MS100 selects a base station having the best communication state (reception electric field strength of radio waves) among the base stations BS21 to BS27, and A radio circuit is connected to the selected base station to communicate user information such as a voice signal.

For example, when the mobile phone MS100 is in the cell C2
1, the communication state with the base station BS21 should be the best, so that the mobile phone MS1
00 connects a wireless line to the base station BS21. At this time, the base station BS21 transmits the received signal received from the mobile phone MS100 to the upper-layer switching control station 12,
Conversely, it transmits the transmission signal received from switching control station 12 to mobile phone MS100.

The switching control station 12 transmits the data received from the base station BS21 to the terminal device 4 of the communication partner via the public network 3 and the terminal of the communication partner transmitted via the public network 3. The data from the device 4 is transmitted to the base station BS21.
100 can communicate with the terminal device 4 of the communication partner via the base station BS21, the switching control station 12, and the public line network 3.

In the digital cellular radio communication system 11, when the mobile phone MS100 moves to the direction of the arrow, that is, the cell C23 or the cell C25, with the base station BS21 of the cell C21 connected to the radio line, for example, the multi-path The switching control station 12 can perform the handoff accurately even under the environment, and the configuration for that will be described in detail below.

(2) Circuit Configuration of Mobile Phone As shown in FIG.
0 received signal S1 from the base station BS21
Is transmitted to the receiving unit 32 via the antenna sharing device 31.

The receiving section 32 amplifies the received signal S1 and performs frequency conversion processing by multiplying the received signal S1 by the local frequency signal supplied from the frequency synthesizer 33, and then performs filtering processing and analog-to-digital conversion processing to obtain the received data D1. And sends it to the baseband modulation / demodulation unit 34 and the received power measurement unit 42.

The baseband modulation / demodulation section 34 performs a predetermined demodulation process on the received data D1 to generate a baseband signal D2 and, based on the baseband signal D2, outputs the voice of the communication partner via the speaker 35. The output has been made.

The baseband modulation / demodulation unit 34 includes a memory 36, an operation unit 37 such as operation buttons, and a microphone 3
8, and stores the demodulated baseband signal D2 and various data in a memory 36, modulates a command or the like input by an operation unit 37, and
The communication data D3 is generated by modulating the voice signal of the user collected by the communication device, and is transmitted to the transmission unit 39.

The transmission section 39 generates a transmission signal by performing filtering processing and digital-analog conversion processing on the communication data D 3, and multiplies the transmission signal by a local frequency signal supplied from the frequency synthesizer 33. By performing frequency conversion processing, a transmission signal S4 of a predetermined frequency channel is generated, amplified to a predetermined power, and then transmitted via the antenna duplexer 31 and the antenna 30.

In addition to the above configuration, the mobile phone MS100
Receives a satellite signal S10 from a GPS (Global Positioning System) satellite via a GPS antenna 40, and analyzes the satellite signal S10 at a predetermined time interval (for example, 5 seconds) by a GPS receiving unit 41, so that the mobile phone MS
The current position (latitude, longitude, and altitude) of 100 itself is detected, and the resulting position data D11 is sequentially transmitted to the baseband modem 34.

At this time, the reception power measurement unit 42 simultaneously measures the reception electric field strength of the reception data D 1, and sends the reception power value data D 2 obtained as a result to the baseband modulation / demodulation unit 34.

The baseband modulation / demodulation unit 34 generates modulation data D12 by multiplexing and modulating the position data D11 and the reception power value data D2, and sends the modulation data D12 to the transmission unit 39.

Since the baseband modem 34 supplies the position data D11 and the received power value data D2 from the GPS receiving unit 41 and the received power measuring unit 42 at predetermined time intervals, the communication data D3 is supplied at the same time. Is multiplexed together with the communication data D3.

The transmitting section 39 generates a transmission signal by subjecting the modulated data D12 to filtering processing and digital-analog conversion processing, and multiplies the transmission signal by a local frequency signal supplied from the frequency synthesizer 33 to obtain a frequency. By performing the conversion process, a handoff support signal S13 of a predetermined frequency channel is generated, amplified to a predetermined power, and then transmitted via the antenna duplexer 31 and the antenna 30.

(3) Configuration of Base Station and Switching Control Station As shown in FIG.
The hand-off support signal S13 transmitted from 00 is received by the antenna 51 and transmitted to the receiver 52 as a received signal S14.

The receiving section 52 amplifies the received signal S14,
By performing a frequency conversion process, a filtering process, and an analog-to-digital conversion process, reception data D15 is generated and sent to the demodulation unit 53.

The demodulation section 53 performs a predetermined demodulation process on the received data D15 so that the cellular phone MS10
0, position data D11, reception power value data D2, and position data D2 corresponding to communication data D3.
1. Generate the received power value data D22 and the communication data D23 and generate the received power value data D22 and the communication data D2.
3 to the multiplexing unit 55 and the position data D21.
To the movement direction prediction unit 54.

The moving direction predicting unit 54 is provided with a plurality of position data D21 supplied sequentially from the demodulating unit 53 at predetermined time intervals.
, The current position (latitude and longitude) of the mobile phone MS100 is estimated and the moving direction is predicted. For example, the fact that the mobile phone MS100 is moving from the cell C21 to the cell C23 is multiplexed as the prediction result data D24. To the conversion unit 55.

The multiplexing unit 55 outputs the prediction result data D24,
The received power value data D22 and the communication data D23 are multiplexed, and the resulting multiplexed data D25 is output to the upper switching control station 12.

The switching control station 12 inputs the multiplexed data D25 received from the base station BS21 to the demultiplexing unit 61, demultiplexes the multiplexed data D25 in the demultiplexing unit 61, and processes the communication data D23 obtained as a result for audio processing. The received power value data D22 and the prediction result data D22
24 to the channel switching control unit 64.

After converting the communication data D23 into a voice signal, the voice processing unit 62 outputs the voice signal to the terminal device 4 (FIG. 1) via the exchange 63 and the public line network 3.

The channel switching control unit 64 includes the location registration unit 6
5 and is supplied with the location registration data D30 of the mobile phone MS100 from the location registration unit 65.

Here, the position registration data D30 is a cell number indicating the cell C21 in which the mobile phone MS100 itself is located when the mobile phone MS100 first turns on the power switch, and notifies the base station BS21 of the cell number. The current location area of the mobile phone MS100 reported from the BS 21 to the switching control station 12.

Accordingly, the channel switching control unit 64 recognizes the first location registered based on the location registration data D30, and moves to any cell from the first location registration location based on the prediction result data D24. In addition to accurately recognizing the moving direction of the mobile phone, the change of the received electric field strength with the base station BS21 in the moving mobile phone MS100 can be monitored based on the received power value data D22.

At this time, the channel switching control unit 64 also notifies the received power value data of the mobile phone MS100 from the base station BS23 which is a base station candidate in the moving direction at this time. Of the received electric field strength can be monitored at the same time.

Thus, the channel switching control unit 64 recognizes the moving direction of the mobile phone MS100, reduces the reception electric field strength of the mobile phone MS100 with the base station BS21 below a predetermined threshold level, and sets the moving direction destination. If it is determined that the received electric field strength with the base station BS23, which is the base station candidate of the cell C23, has risen above a predetermined threshold level, a handoff control signal S32 for handing off to the base station BS23 of the cell C23 in the moving direction is provided. In addition, the mobile phone MS100 outputs a preparation signal S31 for preparation for disconnection of a wireless line to the channel switching unit 56 of the base station BS21 with which communication is currently being performed.

The channel switching unit 56 of the base station BS21
Based on the preparation signal S31 supplied from the channel switching control section 64 of the switching control station 12, both the base station BS23 of the next cell C23 and the base station BS21 and the mobile phone M
From the state where the wireless line with S100 is connected,
When it becomes difficult to connect the wireless line between S21 and the mobile phone MS100, the base station BS21
The mobile phone MS100 is disconnected from the wireless line.

As described above, the channel switching control section 64 switches the radio channel to the base station BS23 of the next cell C23 and, at the same time, temporarily disconnects the radio channel of the base station BS21 instead of disconnecting the radio channel. BS21 and base station B
By creating a so-called soft hand-off state in which the wireless line is connected to S23, control is performed so as not to cause an instantaneous call interruption.

In practice, the channel switching control unit 64 of the switching control station 12 uses the same spreading code sequence as that spread by the mobile phone MS100 to disconnect the wireless line with the mobile phone MS100 currently communicating. The supply of the Walsh code C50 to the demodulation unit 53 is stopped, and the reception data D15 is not despread, so that the demodulation process is stopped and the wireless line is disconnected.

On the other hand, next, a base station BS for connecting a radio line
The channel switching unit (not shown) of the switching control station 12
Based on the handoff control signal S32 supplied from the channel switching control unit 64, a new Walsh code given by the base station BS23 is supplied to the demodulation unit and despread, thereby starting the demodulation processing and Phone M
A wireless line with S100 is newly connected.

(4) Handoff control processing procedure in the digital cellular radio communication system Here, the portable telephone MS100, the base station BS21 and the switching control station 12 of the digital cellular radio communication system 1
4A, first, as shown in FIG. 4 (A), the mobile phone MS100 enters from the start step of the routine RT1 and proceeds to step SP1.
Move on to

In step SP1, the mobile phone MS1
00 is a GPS receiver 41 for the mobile phone MS100
In addition to detecting position data D11 representing its own current position (latitude, longitude and altitude), received power value data D2 representing received electric field strength of received data D1 is received by received power measuring section 42.
Is detected, and the routine goes to the next step SP2.

In step SP2, the mobile phone MS1
00 transmits the position data D11 and the received power value data D2, which are detection results, to the base station BS21 in the cell C21 currently communicating as the handoff support signal S13, and proceeds to the next step SP3.

At step SP3, the mobile phone MS1
00 next receives the satellite signal S10 and outputs the position data D1.
It is determined whether or not a predetermined time has elapsed until 1 is detected. If a negative result is obtained here, this means that it is not time to detect the next position data D11. At this time, the mobile phone MS100 transmits the next position data D11 after a predetermined time has elapsed. Wait for the detection timing to come.

On the other hand, if an affirmative result is obtained in step SP3, this indicates that the predetermined time has elapsed and the timing for detecting the next position data D11 has come. At this time, the portable telephone MS100 Is Step SP
Returning to step 1, the above-mentioned processing is repeated again, and the position data D11 and the received power value data D2 are detected at predetermined time intervals, and the detection results are sequentially transmitted to the base station BS21.

At this time, as shown in FIG.
In S21, the process starts from the start step of the routine RT2 and proceeds to step SP11. In step SP11, the base station BS21 predicts the moving direction of the mobile phone MS100 using the moving direction prediction unit 54 based on the position data D21 sequentially received from the mobile phone MS100, and proceeds to the next step SP12.

At step SP12, the base station BS21
Is the prediction result data D24 predicted in step SP11
And the received power value data D22 obtained from the mobile phone MS100 are sequentially transmitted to the higher-order switching control station 12 for handoff control processing, and the process proceeds to the next step SP13.

At this time, as shown in FIG. 4C, the switching control station 12 enters from the start step of the routine RT3 and moves to step SP21. In step SP21, the switching control station 12 moves based on the prediction result data D24 received from the base station BS21, indicating that the mobile phone MS100 currently communicating with the base station BS21 is moving to the base station BS23 of the cell C23. Is recognized, and a change in the received electric field strength is monitored based on the received power value data D22, and the routine goes to the next step SP22.

In step SP22, the switching control station 12
Determines whether the monitored received electric field intensity has decreased below a predetermined threshold level. If a negative result is obtained here, this means that the base station BS21 and the mobile phone MS10
This indicates that the communication state with 0 is good. At this time, the switching control station 12 determines that it is not necessary to perform the handoff, and proceeds to the next step SP24 to terminate the processing without issuing a handoff instruction.

On the other hand, if an affirmative result is obtained in step SP22, this means that the received electric field strength is reduced below a predetermined threshold level, and the base station BS21 and the mobile phone MS1
This indicates that the communication state with 00 is degraded and there is a possibility of a momentary interruption of the call. At this time, the switching control station 12 proceeds to the next step SP23.

In step SP23, the switching control station 12
Is the base station BS that is the recognized base station candidate in the moving direction.
Handoff control signal S32 for handing off to 23
Is output to the base station BS23, and a preparation signal S31 is output to the currently communicating base station BS21 to prepare for line disconnection, and the process proceeds to the next step SP24 to switch to the switching control station. The processing of 12 is ended.

Next, step SP13 of the routine RT2
In, the base station BS21 recognizes the line disconnection instruction based on the preparation signal S31 from the switching control station 12, and determines whether or not the soft handoff state has been completed. If a negative result is obtained here, this indicates that the soft handoff state has not been completed, and at this time, the base station BS21 waits until the soft handoff state ends.

On the other hand, if an affirmative result is obtained in step SP13, this indicates that the base station BS23 in the moving direction is located.
This indicates that the line with the mobile phone MS100 has been completely connected and the state in which it is difficult to connect the wireless line with the original base station BS23, that is, the soft handoff state has been completed. The base station BS21 proceeds to the next step SP14 because there is no possibility that the call will be momentarily interrupted by the connection of the next base station BS23 and the mobile phone MS100 via the wireless line.

In step SP14, the base station BS21
Stops the supply of the Walsh code C50 to the demodulation unit 53 and cuts off the line with the mobile phone MS100, thereby changing the communication destination of the mobile phone MS100 from the base station BS21 to the next base station BS23 in the moving direction. Handoff can be performed at the most appropriate timing and accurately,
Moving to the next step SP15, the processing in the base station BS21 ends. Thus, all the handoff control processing procedures in the digital cellular radio communication system 1 are completed.

(5) Operation and Effect In the above configuration, the digital cellular radio communication system 1 first analyzes the satellite signal S10 received by the mobile phone MS100 from the GPS satellite,
In addition to detecting position data D11 representing the current position (latitude, longitude, and altitude) of the mobile phone MS100 itself, the reception power value data D2 is generated by measuring the reception electric field strength of the reception data D1, and the position data D11 and The received power value data D2 is transmitted to the base station BS21 as the handoff support signal S13.

The base station BS21 is connected to the mobile phone MS100.
Of the mobile phone MS100 based on the position data D21 received from the mobile phone MS100, and predicts the moving direction. The resulting predicted data D24 is received from the mobile phone MS100. Data D
22 and the upper-level switching control station 12 is notified.

The switching control station 12 outputs the prediction result data D24
, The mobile station MS100 accurately recognizes the moving direction from the first location registration point based on the received power value data, and monitors the change of the received electric field strength in the moving mobile phone MS100 based on the received power value data D22. Is determined to be lower than the predetermined threshold level and the received field strength with the base station BS23 in the moving direction is higher than the predetermined threshold level, the cell C23 in the moving direction is determined.
And outputs a handoff control signal S32 for handing off to the base station BS23 of the mobile phone MS1.
00 is the channel switching unit 5 of the base station BS21 currently communicating.
Then, a preparation signal S31 for line disconnection is output to 6.

At this time, based on the preparation signal S31 supplied from the channel switching control unit 64 of the switching control station 12, the channel switching unit 56 of the base station BS21 communicates with the mobile telephone MS100 currently communicating after the soft handoff ends. By disconnecting the line connection, instantaneous interruption of the call can be reliably prevented.

As described above, digital cellular radio communication system 1 accurately predicts the moving direction of mobile phone MS100 before handoff, and predicts the moving direction in advance according to the change in the received electric field strength due to the movement of mobile phone MS100. By handing off to the base station BS23 of the previous cell C23, even in a case where the received electric field strength obtained from a base station other than the base station BS23 in the original moving direction becomes large under a multipath environment such as a building county, The handoff can be accurately performed without erroneous handoff destination base station.

As a result, the digital cellular radio communication system 1 does not perform handoff to the wrong base station, so that useless communication channels can be prevented and effective use of the communication channels can be achieved.

Further, in the digital cellular radio communication system 1, the reception electric field strength of the portable telephone MS100 is lower than a predetermined threshold level, and the base station B in the moving direction is used.
When it is determined in step S23 that the received electric field strength has exceeded the predetermined threshold level, the base station B in the moving direction of the mobile phone MS100 is executed by performing handoff.
Handoff can be executed at an optimal timing to S23, and thus instantaneous interruption of a call can be reliably prevented.

According to the above configuration, digital cellular radio communication system 1 can accurately execute handoff to base station BS23 at the destination in the moving direction predicted based on position data D11 obtained from mobile phone MS100. Handoff can always be executed accurately even in an unstable communication state such as under a multipath environment.

(6) Other Embodiments In the above embodiment, G as a positioning means is used.
Although the case where the position data D11 is detected by analyzing the satellite signal S10 from the GPS satellite by the PS receiving unit has been described, the present invention is not limited to this, and various other positioning means such as the Loran system may be used. The positioning may be performed by using this.

In the above embodiment, the position data D
11, the present position of the mobile phone MS100 is recognized based on the latitude and longitude, and the destination of the movement is predicted. However, the present invention is not limited to this, and the altitude information of the position data D11 is used. The destination of the moving direction may be predicted three-dimensionally. For example, the base station BS21
When it is predicted based on the altitude information of the position data D11 that the mobile phone MS100 is moving to the top floor of the building, the mobile phone MS100 may be controlled to perform handoff to a base station whose cell is the top floor of the building.

Further, in the above-described embodiment, the case where the handoff is performed in units of cells has been described. However, the present invention is not limited to this, and the handoff is performed in units of sectors of the cell ahead in the predicted movement direction. You may do it. In this case, the base station switches handover in sector units by switching the radiation direction of radio waves in sector units, and can perform finer handoff to maintain a good communication state.

[0080]

As described above, according to the present invention, a handoff can be performed to a base station candidate in a moving direction predicted based on position data, so that a next handoff is performed even in a multipath environment. Handoff control system and handoff control method capable of performing handoff more accurately without making a wrong base station and thus capable of performing handoff accurately even in an unstable communication state such as under a multipath environment Can be realized.

According to the present invention, the received power value data supplied simultaneously with the position data from the mobile station is reduced below a predetermined threshold level, and the received power value data from the base station candidates is increased above the threshold level. Then, by outputting to the base station candidate an instruction to connect the wireless line with the mobile station, and outputting to the base station an instruction to disconnect the wireless line with the mobile station to execute the handoff, When the wireless communication condition with the base station candidate becomes surely good, the wireless line with the base station is disconnected and the handoff is terminated, so it is ensured that the call with the mobile station is momentarily interrupted. It is possible to realize a handoff control system and a handoff control method that can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a digital cellular radio communication system according to the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration of the mobile phone.

FIG. 3 is a block diagram illustrating configurations of a base station and a switching control station.

FIG. 4 is a flowchart showing a handoff control processing procedure in the digital cellular radio communication system.

FIG. 5 is a schematic diagram showing a configuration of a conventional general cellular radio communication system.

[Explanation of symbols]

1, 11 ... digital cellular radio communication system, 2,
12 switching control station, 3 public telephone network, 4 terminal equipment, 32, 52 receiving unit, 34 baseband modem unit, 39 transmitting unit, 41 GPS receiving unit, 42 …
... Received power measuring section, 53... Demodulation section, 54... Moving direction prediction section, 56... Channel switching section, 64... Channel switching control section, 65... Location registration section, BS1 to BS7, BS
21 to BS27 base station, MS1, MS100 mobile phone.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshimi Abe 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo F-term within Sony Corporation (reference) 5J062 AA08 BB05 CC07 DD12 5K022 EE01 EE21 EE31 5K067 DD20 DD26 DD44 EE02 EE10 EE16 EE24 FF03 GG01 GG11 GG21 JJ39 JJ52 JJ56 JJ66

Claims (6)

[Claims] When a mobile station that wirelessly communicates with any one of base stations installed in a plurality of areas obtained by dividing a communication area into a predetermined size moves between the plurality of areas, a higher level of the base station is provided. In a handoff control system for controlling handoff by a switching control station, the mobile station transmits position data obtained by detecting its own current position by a predetermined positioning means to the communicating base station, Notifies the higher-order switching control station of a prediction result indicating the moving direction of the mobile station predicted based on the position data received from the mobile station, and the higher-order switching control station is notified from the base station. A base station candidate in the moving direction in which the handoff is to be performed next is determined based on the prediction result, and the base station candidate is communicated with the mobile station at a predetermined timing. Outputs a connection command line, the handoff control system and executes the handoff by outputting a disconnection command of the radio channel between the mobile station relative to the base station. 2. The mobile station transmits, to the base station, received power value data obtained by measuring a received power value from the base station in addition to the position data, Notifying the received power value data to the upper switching control station in addition to the result, the upper switching control station reduces the received power value data below a predetermined threshold level, and receives the received power from the base station candidate. When the value data increases above the threshold level, a command to connect the base station to the mobile station is output to the base station candidate, and the base station is disconnected from the mobile station. The handoff control system according to claim 1, wherein the handoff is performed by outputting a command. 3. The base station, when starting wireless communication with the mobile station, performs position registration of the mobile station, and based on the position corresponding to the position registration and the position data, the base station transmits the position information of the mobile station. The moving direction is predicted.
3. The handoff control system according to claim 1. 4. When a mobile station that wirelessly communicates with any of the base stations installed in a plurality of areas obtained by dividing a communication area into a predetermined size moves between the plurality of areas, an upper level of the base station is provided. A handoff control method for controlling handoff by a switching control station, a position data transmitting step of transmitting position data obtained by detecting the current position of the mobile station by a predetermined positioning means to the communicating base station; A prediction result notification step of notifying the higher-order switching control station of a prediction result indicating the moving direction of the mobile station predicted by the base station based on the position data received from the mobile station; and Based on the prediction result notified from the base station, a base station candidate in the moving direction in which the handoff is to be performed next is determined, and the base station candidate is determined at a predetermined timing. A handoff control step of executing a handoff by outputting an instruction to connect a wireless line to the mobile station to the base station candidate and outputting an instruction to disconnect the wireless line to the mobile station to the base station; And a hand-off control method. 5. The position data transmitting step, wherein the mobile station transmits received power value data obtained by measuring a received power value from the base station to the base station in addition to the position data, In the prediction result notifying step, the base station notifies the received power value data to the upper switching control station in addition to the prediction result. And when the received power value data from the base station candidate is greater than the threshold level, the higher-order switching control station outputs to the base station candidate an instruction to connect a wireless line with the mobile station. 5. The handoff according to claim 4, wherein the handoff is executed by outputting a command for disconnecting a radio link with the mobile station to the base station. Your way. 6. The prediction result notifying step includes performing position registration of the mobile station when the base station starts wireless communication with the mobile station, and based on the position corresponding to the position registration and the position data. The handoff control system according to claim 1, wherein the mobile station predicts a moving direction of the mobile station.