JPH0262062B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field to Which the Invention Pertains] The present invention is a mobile radio communication system suitable for an automobile radio communication system, and a method for automatically selecting an optimal base station with which a mobile station should communicate. Regarding the method of

[Description of prior art]

A service area is defined within a range within which a large number of mobile stations can move, a large number of base stations are placed within that service area, and a wireless zone is set for each base station.
Systems are known that are arranged to communicate with mobile stations within the wireless zone. To call a mobile station from a base station, make a call using the paging frequency assigned to each base station, specify the number of a specific mobile station in the call, and prompt that mobile station to respond. It is composed of As a general rule, the same paging frequency is assigned to multiple adjacent base stations, and the base station decides which base station to communicate with among the multiple adjacent base stations based on a response signal from the mobile station. Decide and set.

The mobile station automatically selects a base station group with which to communicate by determining the magnitude of the reception level of the paging frequency. In a specific example, when a mobile station turns on the power, it sequentially switches and receives all paging frequencies, detects their reception levels, identifies the paging frequency that is received at the highest level, and uses that frequency. It is determined that the base station is located in the simultaneous paging area of the base station group.

In this method, if the mobile station moves beyond the paging area after power is turned on, other measures are required. For example, if the level of the received paging frequency falls below the specified value, it is determined that the mobile station is moving out of its respective paging area, and at that point , sequentially receives all paging frequencies, selects the paging frequency that is received at the highest level, and resets the base station with which to communicate.

Although this method is generally good, imperfect operation may occur due to facing, which is specific to mobile communications. For this reason, if the specified value for level judgment is set high, it will frequently be judged that the level is below the specified value at a point inside the zone rather than around the zone, and as a result, all paging frequencies will be below the specified value. As a result, it may be mistakenly determined that there is no base station to communicate with, or the search time for the paging frequency may become long. In this case, the mobile station becomes uncontrollable from the base station, and incoming and outgoing calls during this time have the drawback of being lost. In order to avoid this, the above-mentioned drawback can be solved by lowering the specified level determination value, but conversely, even though the mobile station is in a regionally different paging area, it is determined that there is no level deterioration.
Misidentification may occur if the user is located in the previous paging area. In this case, the paging areas will actually overlap, and if the mobile station is located in the overlapped area, the actual location of the mobile station and the registered area of the base station will be different, resulting in service problems. In addition to this problem, interference with other areas increases, making it impossible to effectively allocate frequencies.

Another example of a countermeasure is to search for all paging frequencies at regular intervals regardless of the reception level of the paging frequencies, but this also has the disadvantage that the search time is long and causes call loss. There is.

[Purpose of the invention]

The present invention solves these drawbacks and aims to provide a mobile radio communication system that does not cause call loss and has little interference between radio zones.

[Features of the invention]

In the present invention, mobile stations are divided into a plurality of groups in advance at the time of joining, and the base station performs the simultaneous paging by assigning a group number to each group at a different time. A mobile station detects whether or not its own number is included in the simultaneous paging of a group to which the mobile station belongs; Since the control device is idle during the time when paging is being performed, the control device uses this time to detect the reception level of each paging frequency and select the optimal base station or base station to communicate with. It is characterized by being configured to select a group.

[Explanation based on examples]

FIG. 1 is a conceptual diagram of a service area S in which the mobile radio communication system of the present invention is implemented. Base stations are placed at positions X in FIG. 1, and wireless zones Z are set up around each base station. In principle, each base station communicates with mobile stations within its own wireless zone. A base station performs paging to call mobile stations. Broadcast paging is performed using a mass paging frequency, but the mass paging frequency is for each mass paging area.
A different frequency is assigned to each of A ₁ , A ₂ , and A ₃ . Moreover, the simultaneous call is in this simultaneous call area A ₁ ,
Commonly done for A ₂ and A ₃ at the same time.

The first feature of the present invention is that each mobile station is divided into a plurality of n groups. The group to which a mobile station belongs is fixed from the time the mobile station joins this mobile radio communication system, and changes with the passage of time or movement within the service area. Never.

The second feature of the present invention is that the simultaneous calling is performed for each group at different times, with group numbers assigned to each group.

The third feature lies in the configuration of mobile stations; when each mobile station receives a paging call, if the group to which the mobile station belongs is receiving a paging call, its own station will be included in the pagination. The mobile station detects whether or not the mobile station's number is included and prepares to respond to the call. The broadcast paging frequencies of the base stations are sequentially selected and received, and the reception level of the broadcast paging frequencies is detected. Then, the base station or base station group transmitting the broadcast paging frequency that can best receive the broadcast paging frequency is selected as the base station or base station group with which communication should be set up next.

For example, when a mobile station is in paging area _A1 , which base station to communicate with is determined by
In this example, it is configured to be controlled on the base station side. In other words, when the mobile station detects that its own number is included in the paging signal transmitted by the base station in paging area A ₁ , the mobile station responds according to a predetermined procedure, but this response signal is received simultaneously by multiple base stations. and detects the reception level of the response signal. The levels received by each base station are compared with each other via wired lines, and the base station where the highest received level is detected establishes communication, assuming that the mobile station is in its own wireless zone.

FIG. 2 is a time chart of signals transmitted to the paging frequency according to an embodiment of the present invention. time T ₁
Paging signals 10 to 12 are transmitted to the first group of mobile stations. At time _T2 , paging signals 13-15 for the second group of mobile stations are transmitted. Similarly, paging signals 16 to 18 to the nth group of mobile stations are transmitted at time Tn. This is repeated.
Fig. 3 shows one calling signal (for example, reference numeral 10 above)
This is a time chart showing an example of the configuration. The paging signal includes a start code 19, a group number 20, and a mobile station number 21.

The mobile station sequentially switches and receives all the paging frequencies during the time τ other than when the paging for its own group is being performed, and detects and stores the reception level. The paging frequency with the highest reception level is selected. If this paging frequency is the same as the paging frequency received before the start of switching, the next self-group paging signal is received at the original paging frequency after waiting for the timer to time out. If this is not the same as the paging frequency before switching, switch to the paging frequency that was received at the highest level, and register your location with the base station to indicate that you are in the wireless zone that uses that paging frequency. , from then on, standby reception will be performed on this paging frequency.

FIG. 4 is a flowchart showing the control procedure of the mobile station.

The time τ is chosen to be equal to or smaller than the time T ₂ +T ₃ +...+Tn in FIG. If there is a difference in the ringing time of each group between different paging frequencies, the mobile station needs to detect the period of its own group paging when switching the paging frequency. Wait until a calling signal can be received, and if it is received, repeat the above operation.

FIG. 6 is a diagram showing an example of the configuration of a portion related to simultaneous paging of the base station apparatus according to the embodiment of the present invention. The main control unit 25 in the central control station 22 sends and receives control signals to and from mobile stations and executes control. Main control section 2
The paging signals from 5 are distributed by a distributor 26 into a number equal to the number n of groups of mobile stations. The decoder 27 decodes the group number of each paging signal, and if it is a signal of the first group, the gate 28 is opened and the signal is input into the waiting circuit 29 and stored. As shown below by dotted lines in the figure, the paging signal for the second group is stored in the waiting circuit 29 of the second column, and the paging signal of the first group is stored in the waiting circuit 29 of the nth column.

The timing generation circuit 30 generates the time shown in FIG.
At _T1 , a pulse is supplied to the waiting circuit 29 in the first row, and while the pulse is being supplied, the waiting circuit 29 in the first row sends out the stored paging signal to the signal synthesis circuit 31. . If there is no stored paging signal, no signal is sent. Similarly, a pulse is supplied to the waiting circuits 29 in the second column at time _T2 , and a pulse is supplied to the waiting circuits 29 in the last n-th column at time Tn.
The waiting circuits 29 in the second and subsequent rows send out the stored paging signals to the signal synthesis circuit 31 in the same manner as above while the pulses are being supplied.

In this way, the output of the signal synthesis circuit 31 is a signal aligned with the unique transmission timing for each group of mobile stations, that is, a paging signal shown in FIG. 2 is obtained.

The output of the signal combining circuit 31 is further divided by a distributor 32 into a number equal to the number of radio base stations, and sent to the radio base stations 23-24. At the wireless base station, a paging channel transmitter 33, a duplexer 3
4. The antenna 35 sends this signal to the mobile station. A response signal to the paging signal from the mobile station passes through the antenna 35 and the duplexer 34, is received and demodulated by the paging frequency receiver 36, and is transmitted to the central control station 22.

FIG. 6 is a diagram showing an example of the configuration of a mobile station according to an embodiment of the present invention. The signal from the base station is antenna 3
7. Control unit 4 via transmitter/receiver 38 and receiver 39
2. The local oscillator signal for receiver 39 is supplied from synthesizer 40 . synthesizer 4
The transmission frequency of 0 is specified by the control unit 42. When transmitting a signal from the mobile station, the signal from the control unit 42 is modulated by the transmitter 41 and sent to the duplexer 38.
The signal is then transmitted to the base station via the antenna 37.
The local oscillation signal of transmitter 41 is supplied from synthesizer 40 . The control unit 42 stores the control procedure for the mobile station, and decodes all received signals and encodes all transmitted signals. The control section 42 is composed of a processor, a read-only memory, and a read-write memory, and the control procedure is stored in the read-only memory, and the reception level is stored in the read-write memory.

The reception level is detected by envelope detection of the intermediate frequency signal of the receiver 39 by a wave detector 44, and the detected signal is supplied to the control section 42. The control unit 42 can be configured to perform operations such as memory and averaging for each channel.

In the example shown in Figure 4, all paging frequencies are sequentially switched while calls other than the own group are being made.
We have shown an example of determining the paging frequency with the highest reception level, but as shown in Figure 7, we receive multiple cycles in which calls are being made from groups other than our own group, and perform the above-mentioned level detection for each of these multiple times. It may be configured such that the average reception level of each paging frequency is calculated a plurality of times, and the paging frequency that allows reception in the best condition is determined. That is, assuming that a certain mobile station belongs to the first group, the times of simultaneous paging for the own group are T ₁₁ , T ₁₂ , T ₁₃ . During the first period T ₂₁ to Tn ₁ , all paging frequencies are sequentially switched, and their levels are received, detected, and stored. Let the number of paging frequencies be M, and the reception level of each paging frequency is
Let L ₁₁ , L ₁₂ ...Lm ₁ . The next period T ₂₂ ~
Similarly, during Tn ₂ , the paging frequencies are sequentially switched and the levels are stored, and these are designated as L ₁₂ , L ₂₂ . . . Lm ₂ . For example, the mobile station repeats this three times, and then for each paging channel: 1/3 (L ₁₁ + L ₁₂ + L ₁₃ ), 1/3 (L ₂₁ + L ₂₂ + L ₂₃ ), ... ... 1/3 (Lm ₁ +Lm ₂ +Lm ₃ ), the maximum value is identified, the paging frequency with the maximum value is selected, the standby reception frequency is switched to this base station, and the location is registered.

In the above example, all the paging frequencies are sequentially switched during one period, and the levels are detected for all of the frequencies.However, during one period, only some of the paging frequencies are detected. A method may also be adopted in which the levels are detected by sequentially switching the frequencies, and the levels are detected by switching and receiving all of the paging frequencies using a plurality of cycles.

Furthermore, although the explanation has been given using the case where a plurality of wireless zones exist in the paging area, the present invention can be applied even if the paging area includes only a single wireless zone, that is, the wireless zone and the paging area coincide. is possible.

The present invention is applicable even if the paging frequency matches the communication channel.

Further, in the above example, the frequency at which mobile stations are called within the paging area, that is, the paging frequency, is a single frequency, but it is also possible that the paging frequency differs from radio zone to radio zone, for example. In this case, the paging frequency is newly specified each time the radio zone is changed, but the only difference is that the location registration is performed only when changing the area, and the present invention can be similarly applied. It is possible. Further, in this case, the present invention is applicable even when there is only one paging area within the service area.

[Explanation of effects]

As explained above, the mobile stations are divided into groups, the time for sending out paging signals to the mobile stations in each group is divided by group, and the wireless zone in which the mobile station is located is searched at a time other than the paging time of the mobile station. The control device operates efficiently. Therefore, call losses are less likely to occur, and it is possible to detect the wireless zone in which the mobile phone is located more frequently. In addition, since wireless zone detection is performed more frequently, the overlap of designated frequency areas becomes shallower, allowing correct increase detection at positions close to the boundaries of regular wireless zones, which improves frequency utilization efficiency. There is.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a service area in which the present invention is implemented. FIG. 2 is a time chart showing an example of sending out a paging signal at a paging frequency. FIG. 3 is a diagram showing an example of the format of a calling signal. FIG. 4 is a flowchart showing the control operation of the mobile station. FIG. 5 is a block diagram of a part related to simultaneous paging of a base station according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of the configuration of a mobile station according to an embodiment of the present invention. FIG. 7 is a time chart showing another example of sending out a paging signal at the paging frequency. 10-18...Paging signal, 19...Start code, 20...Group number of the calling mobile station, 21...Number of the calling mobile station, 22...Central control station, 23, 24
... Radio base station, 25 ... Main control unit, 26 ... Distributor, 27 ... Decoder, 28 ... Gate, 29
...Waiting circuit, 30...Timing generation circuit, 31...Synthesizer, 32...Distributor, 33...
All paging channel transmitter, 34... transmitting/receiving duplexer,
35... antenna, 36... paging channel receiver, 37... antenna, 38... transmitting/receiving duplexer,
39...receiver, 40...synthesizer, 41...
...Transmitter, 42...Control unit, 43...Telephone, 4
4...Detector.

Claims (1)

[Claims] 1. A plurality of base stations are provided within the movable range of a large number of mobile stations, and a wireless zone is set for each base station in a range where good communication with the mobile stations can be established, and one of the base stations Alternatively, a unique paging frequency is assigned to each mobile station, and simultaneous paging is performed for multiple base stations in adjacent wireless zones, and each mobile station uses a paging frequency that can be strongly received in the area it is moving In a mobile radio communication system configured to select a base station with which the mobile station should communicate, the mobile stations are divided in advance into a plurality of groups, and the base station performs the above-mentioned simultaneous paging differently for each group. A group number is assigned to the time, and the mobile station detects the reception level of each paging frequency during the time when paging is being performed for a group other than the group to which the mobile station belongs, and determines the optimal communication frequency. A mobile radio communication system characterized in that the mobile radio communication system is configured to select a base station.