JPH1169406A - Mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm synchronization establishment between a base station and a mobile station and to prevent the waste of a communication channel even when synchronization is not established with the mobile station by making the mobile station receive a first synchronization burst from the base station and transmit a second synchronization burst to the base station. SOLUTION: A mobile station 10-i during reception is moved from the area of a base station 30-j to the area of a base station 30-k, a reception level degradation judgement means 12-i detects reception level degradation and reports it to a channel switching means 14-i and simplex communication channel allocation is requested to the base station 30-j by originating a call again during the reception. When a communication channel specifying means 32-j discriminates that no outgoing communication channel allocation is present in the mobile station of the same group as the mobile station 10-i, a free communication channel is specified for a control channel control signal and the first synchronization burst is sent from a first synchronization burst transmission means 34-j to the mobile station 10-i. It is received by a second synchronization burst transmission means 18-i and returned to the base station 30-j further. When it cannot be received within a fixed time, it is defined that the synchronization cannot be established and the communication channel is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly to a digital mobile communication system for public service which groups mobile stations and provides a group communication mode for communicating between mobile stations belonging to the same group. The present invention relates to channel switching control of a mobile station communication system.

[0002]

2. Description of the Related Art A digital mobile communication system for public service such as a fire department assigns a group number to each mobile station, groups each mobile station into a group such as an organization, and communicates between mobile stations belonging to the same group. It is possible.

In this group communication, a mobile station requests a base station to set up a simplex call by transmission, and thereby allocates an uplink communication channel to perform communication as a talker. In this case, there is a case where communication is performed as a listener by assigning a downlink communication channel, and a case where a communication channel is assigned as an uplink and a downlink by requesting a return call setting by transmission / reception.

FIG. 10 is a configuration diagram of a mobile communication system. As shown in this figure, the mobile station communication system includes a plurality of base stations 2-1 to 2-3, a base station control device 4, a communication console 6
And mobile stations 8-1 to 8-3. In order to perform group communication between the mobile stations 8-1 to 8-3, the mobile station numbers and the belonging group numbers of the mobile stations 8-1 to 8-3 are set using the communication console 6 or the like. Register in the home location register of.

[0005] The base stations 2-1 to 2-3 have their own zone Z.
According to the call setting requests from the mobile stations 8-1 to 8-3 within the range of 1 to Z3, communication is performed between the mobile stations 8-1 to 8-3 by allocating communication channels and the like.

[0006] For example, the mobile station 8-1 receiving a signal from the zone Z
When the mobile station moves from 1 to the zone Z2, the base station 2-2 sets the other mobile stations 8-2 and 8-
3, a TCH (voice) is transmitted to the mobile station 8-1 using the communication channel already allocated from the viewpoint of the efficiency of the communication channel, and the other mobile station 8-2 is used. , 8-3, the communication channel is newly assigned to the mobile station 8-1.

FIG. 11 is a flowchart showing conventional channel switching control. FIG. 12 is a flowchart showing conventional channel allocation control. FIG.
FIG. 9 is a diagram showing a conventional channel switching sequence.

[0008] Hereinafter, the mobile station 8-1 that is receiving data is transmitted to the zone Z1.
A description will be given of control of channel switching and channel assignment when moving from the zone to the zone Z2. The mobile station 8-1
Deterioration of the reception level accompanying the zone shift from zone Z1 to zone Z2 is determined, and the frequency is switched to the control channel of zone Z2 by a perch channel search during communication.

In step S2 in FIG. 11, a re-call-in-reception setting signal is transmitted to the base station 2-2 to request channel switching from the base station 2-2. In step S20 in FIG. 12, the base station 2-2 receiving this does not have the mobile stations 8-2 and 8-3 belonging to the group of the mobile station 8-1 in the zone Z2. Therefore, in order to newly assign a communication channel, the assigned communication channel is selected, and transmission of the first synchronization burst SB1 is started on the assigned communication channel.

In step S22, the transmission timer (TRB1) of the first synchronization burst SB1 is started.
In step S24, the wireless channel designation signal is set to the control channel and transmitted to the mobile station 8-1.

[0011] The mobile station 8-1 having received the request proceeds to step S 4.
In, the frequency is switched to the designated wireless channel. In step S6, the reception waiting timer of the synchronous burst SB1 is started, and the apparatus enters a reception waiting state.

In step S26, the base station 2-2 transmits the synchronization burst SB1 and the radio channel designation until the synchronization burst transmission timer (TRB1) times out.
Proceed to. In step S28, the first synchronization burst S
The transmission of B1 is stopped, and the audio is transmitted by TCH (audio data).

On the other hand, if the mobile station 8-1 receives the synchronization burst SB1 in step S8, the mobile station 8-1 proceeds to step S1.
If the process proceeds to step S6, and the first synchronization burst SB1 is not received, the process proceeds to step S10.

In step S10, if TR1 times out, the process proceeds to step S12, where the synchronization burst SB
If the one waiting timer (TR1) has not timed out, the flow returns to step S8 to confirm reception of the first synchronization burst SB1. In step S16, when the first synchronization burst SB1 is received and synchronization is established, TCH (voice) is received.

Since synchronization could not be established in step S12, the mobile station 8-1 switches back to the old channel and starts up. In step S14, the TCH of the old channel is started.
Receive.

As described above, conventionally, the synchronization establishment control has been performed by the continuous transmission of the unidirectional synchronization burst SB1 from the base station 2-2 (standard STD-39A).

[0017]

FIG. 14 is a diagram for explaining a conventional problem. Hereinafter, the conventional problems will be described with reference to FIG.

As described above, conventionally, in channel switching of a mobile station during reception, the first synchronization burst SB1 for establishing synchronization is unilaterally transmitted from the base station 2-2 for a certain period of time, and the mobile station 8- 1 receives the first synchronization burst SB1,
This is a system that is expected to establish synchronization.
No response signal is sent from 1.

As shown in FIG. 14, when the mobile station 2-2 cannot receive the first synchronization burst SB1,
The mobile station 2-2 determines that the channel switching has failed, and switches back the frequency to the communication channel of the old zone.

On the other hand, when viewed from the side of the base station 2-2, the base station 2-2 receives the channel switching request due to the re-call and allocates a new communication channel to the zone Z2 for the mobile station 8-1. Since it is unknown whether the mobile station 8-1 has established synchronization in the new zone Z2 and is located in the new zone Z2 or has failed to establish synchronization and is located in the old zone Z1. In both stations 2-1 and 2-2,
A communication channel must be allocated.

Therefore, the base station 2-2 is connected to the mobile station 8-
There is a problem in that the communication channel assigned to 1 is unused and wasted, and a wasteful process of transmitting voice to the communication channel is also performed.

The present invention has been made in view of the above points, and provides a method capable of determining whether or not synchronization of a mobile station has been established even during channel switching of the mobile station during reception of group communication. As a result, it is an object of the present invention to provide a mobile communication system in which an allocated channel is released in a zone where a mobile station is not located, thereby preventing useless channel allocation.

[0023]

FIG. 1 is a diagram illustrating the principle of the present invention. As shown in this figure, communication is performed between a plurality of grouped mobile stations 10-i (i = 1 to n) and mobile stations 10-i (i = 1 to n) located in a zone. A plurality of base stations 30-j (j = 1 to m)
(J = 1 to m) in a mobile communication system having a control station 40 for performing inter-group communication control between mobile stations 10-i (i = 1 to n) belonging to the same group. The -i means a reception level deterioration determining means 12-i for determining that the reception level of the signal of the communication channel being received has deteriorated, and performs frequency switching to a control channel having a higher reception level when the reception level has deteriorated. Channel switching requesting means 14-i for requesting the base station 30-j to allocate a simplex communication channel due to a re-call during reception; and transmitting a frequency signal to a communication channel indicated by a control channel control signal from the base station 30-j. Channel switching means 16-i for switching
And a second synchronization burst transmitting means 18-i for transmitting a second synchronization burst to the base station when the first synchronization burst is received from the base station 30-j, and receiving the first synchronization burst within a predetermined time. If not, an old channel switching means 20-i for switching back to the old communication channel is provided.

On the other hand, the base station 30-j is connected to the mobile station 10-i.
Receives a simplex communication channel allocation request from the mobile station 1
Other mobile stations 10-1 belonging to the same group as 0-i
If a downstream communication channel has not been allocated to (l ≠ i), an idle communication channel is specified in the control signal of the control channel, and the communication channel specifying means 32 transmits the control signal to the mobile station 10-i. -J and a request to allocate a simplex communication channel from the mobile station 10-i, the mobile station 10-i
And another mobile station 10-1 (l ≠) belonging to the same group as
If no downstream communication channel has been assigned to i),
If the first synchronization burst transmitting means 34-j for transmitting the first synchronization burst on the communication channel specified by the control signal and the second synchronization burst cannot be received within a predetermined time,
Communication channel releasing means 36-j for releasing a communication channel
And characterized in that:

According to the above-described configuration, when the receiving mobile station 10-i moves and the serving area changes to the base station 30-j, the reception level deterioration determining means 12-i uses It detects that the reception level of the reception signal of the base station 30-k (k ≠ j) in the zone in which it is located has deteriorated, and notifies the channel switching requesting means 14-i.

The channel switching requesting means 14-i performs frequency switching to the control channel of the base station 30-j having a higher reception level, and requests the base station 30-j to allocate a simplex communication channel due to a recall during reception. do.

The communication channel designating means 32-j determines whether a downstream communication channel is allocated to another mobile station 10-1 (l ≠ i) belonging to the same group as the group of the mobile station 10-i. If no downlink communication channel has been assigned, an empty communication channel is specified in the control signal of the control channel. First synchronous burst transmission means 34-j
Sends the first synchronization burst to the mobile station 10-i on the designated communication channel.

The channel switching means 16-i is connected to the base station 30.
The frequency is switched to the communication channel specified from the control signal from -j. Second synchronous burst transmission means 18-i
When receiving the first synchronization burst from the base station 30-j, the base station 30-j transmitting the second synchronization burst to the base station 30-j cannot receive the second synchronization burst within a certain time. If so, it is determined that synchronization could not be established, and the communication channel is released. Thereby, the base station 30
-J, by receiving the second synchronization burst from the mobile station 10-i, it is possible to confirm whether or not synchronization has been established at the mobile station 10-i, and if synchronization has not been established at the mobile station 10-i, Since the communication channel can be released, allocation of the communication channel is not wasted.

The mobile station 10-i is connected to the base station 30-j
A fourth synchronization burst transmitting means for stopping transmission of the second synchronization burst when the third synchronization burst is received from the base station and transmitting the fourth synchronization burst to the base station through the communication channel; If you did not receive within
Second old channel switching means for switching back to the old communication channel may be further provided.

In this case, when the base station 30-j receives the second synchronization burst, the base station 30-j stops transmitting the first synchronization burst and transmits the third synchronization burst. A second communication channel release unit for releasing a communication channel when a synchronization burst cannot be received within a predetermined time;

According to such a configuration, the base station 30-j
Transmits a third synchronization burst when the second synchronization burst is received from the mobile station 10-i, and transmits a fourth synchronization burst when the mobile station 10-i receives the third synchronization burst. When the second synchronization burst is received, the synchronization can be more reliably established even if the synchronization of the mobile station 10-i is in an unstable state.

The base station 30-j is connected to the mobile station 10-i.
Are synchronized with each other, and the mobile station 10-i is ready to transmit traffic data.
And a synchronization establishment reporting means for reporting that synchronization has been established with the communication apparatus 0-i.

In this case, the control station 40 has a plurality of mobile stations 1
For 0-i (i = 1 to n), first storage means for storing the group information to which the mobile station 10-i belongs and the zone in which the mobile station 10-i is located, and from the base station 30-j to the mobile station. 1
Upon receiving the report of the establishment of synchronization with the base station 30-k (k ≠ j) for which the assigned communication channel has become unused, upon receiving the report of the establishment of synchronization with the base station 30-k (k ≠ j). First communication channel release instructing means for instructing release of the communication channel, and first storage means updating means for updating the first storage means when receiving a report of establishment of synchronization from the base station 30-j. .

Thus, the unused base station 3
Since the communication channel of 0-k (k ≠ j) is released, it is possible to avoid wasting the communication channel.
Further, according to the alternative, the mobile station 10-i includes a reception level deterioration determination unit 12-i that determines that the reception level of the signal of the communication channel being received has deteriorated, Channel switching request means 1 for performing frequency switching to a higher-level control channel and requesting the base station to allocate a simplex communication channel due to recall during reception.
4-i, a channel switching means 16-i for switching a frequency to a communication channel indicated by a control signal of a control channel from the base station 30-j, and a first synchronization burst when receiving a first synchronization burst from the base station 30-j. A second synchronization burst sending means 18-i for sending two synchronization bursts to the base station, and an old channel switching means 20 for switching back to the old communication channel when the first synchronization burst cannot be received within a predetermined time. −i
And is provided.

On the other hand, the base station 30-j is connected to the mobile station 10-i.
And a communication channel assignment request notifying unit for notifying the control station 40 of the request when receiving the assignment request for the downlink simplex communication channel, and receiving a communication channel assignment instruction from the control station 40, Upon receiving a communication channel assignment instruction from the control station 40 and a communication channel designation means 32-j for designating an empty communication channel and transmitting the control signal to the mobile station, the first communication channel designated by the control signal First synchronization burst transmitting means 34-j for transmitting a synchronization burst, non-synchronization reporting means for reporting the non-synchronization to the control station 40 when the second synchronization burst cannot be received within a predetermined time; When synchronization with the mobile station 10-i is established and the mobile station 10-i is ready to transmit traffic data, the control station 40 establishes synchronization with the mobile station 10-i. And synchronization establishment reporting means for reporting, when receiving a communication channel release instruction from the control station 40 and configured by including a communication channel releasing means 36-j to release the communication channel.

Then, the control station 40 communicates with the plurality of mobile stations 10
For -i (i = 1 to n), information indicating the zone in which each mobile station 10-i is located and the information indicating whether the communication channel assigned to the mobile station 10-i is simplex or duplex is stored. 2
Upon receiving, from the base station, a notification of a request for allocating a downlink simplex communication channel from the storage unit and the mobile station 10-i, the base station 30-j is referred to as the mobile station 10-i by referring to the second storage unit. Communication channel allocation instructing means for instructing the base station 30-j to allocate a communication channel when it is determined that the downlink communication channel has not yet been allocated to another mobile station 10-1 (l ≠ i) belonging to the group. Communication channel release instructing means for instructing the base station to release the communication channel upon receipt of a report indicating that synchronization is not established from the base station 30-j;
and a second storage means updating means for updating the second storage means when receiving the report of the establishment of the synchronization from j.

With such a configuration, the control station 40 also controls the allocation and release of the communication channel, so that if the mobile station 10-i cannot establish synchronization, the communication channel can be released. Therefore, the assignment of the communication channel is not wasted.

[0038]

FIG. 2 is a configuration diagram of a mobile communication system according to an embodiment of the present invention. As shown in the figure, the mobile communication system includes a plurality of mobile stations 50-i (i =
1 to n), a plurality of base stations 80-j (j = 1 to m), a control station 110, and a communication console 122, and inter-group communication between mobile stations 50-i (i = 1 to n). Is what you do.

The number n of the mobile stations 50-i (i = 1 to n)
The number m of the base stations 80-j (j = 1 to m) is not particularly limited, but for convenience of explanation, in this embodiment, n = 3 and m =
The mobile station 50-i (i = 1 to 3) belongs to the same group.

The mobile station 50-i (i = 1 to 3) issues a simplex call setup request (reception / transmission) or a duplex call setup request to the base station 80-j (j = 1 to 3). And base station 80-j
The reception, transmission, or transmission / reception is performed after the synchronization is established by the synchronization burst from (j = 1 to 3). In particular, the movement of the receiving mobile station 50-j (j = 1 to 3) is performed. When the reception level of the signal from the base station 80-j (j = 1 to 3) is lowered due to and the communication channel is switched,
Synchronization is established according to the following sequence.

Upon receiving the first synchronization burst SB1 from the base station 80-j, the mobile station 50-i transmits a second synchronization burst SB2 to the base station 80-j, and the mobile station 50-i transmits the second synchronization burst SB2 to the base station 80-j as described later. When the third synchronization burst SB3 is received, the synchronization is established by transmitting the fourth synchronization burst SB4 to the base station 80-j.

As described above, the reason why the mobile station 50-i transmits the synchronization burst SB2 is that the base station 80-j needs to release the communication channel when the mobile station 50-i fails to establish synchronization. This is because it is a necessary condition to know that synchronization has been established in the mobile station 50-i.

The base station 80-j is connected to the mobile station 50-i.
, When the second synchronization burst SB2 is received from the mobile station 50-i, it is determined that synchronization has been established.
It is also possible to transmit the first synchronization burst SB1 at that moment, and the first synchronization burst SB1 can be received, and the synchronization establishment is in an unstable state. Therefore, in order to establish the synchronization more reliably, Upon receiving the second synchronization burst SB2, the base station 80-j transmits the third synchronization burst SB2 to the mobile station 50-i.
After transmitting the synchronization burst SB3, the mobile station 50-i receives the third synchronization burst SB3, and then receives the fourth synchronization burst S3.
B4 is transmitted to the base station 80-j.

The base station 80-j (j = 1 to 3) transmits a simplex call setting request (reception / reception) from the mobile station 50-i (i = 1 to 3).
Transmission) or a return call setting request, and the mobile station 50-i
(I = 〜3), the mobile station 50
-I for communication.

The control station 110 sends the mobile station 50-i (i = 1
To 3) to control the group communication between
0-j (j = 1 to 3) indicates which mobile station 50-i (i = 1 to
When a channel not used in 3) is also allocated, it is instructed to be released. The communication console 122 registers the number of the mobile station 50-i (i = 1 to 3) and the group number with the control station 110.

FIG. 3 is a configuration diagram of the mobile station, the base station, and the control station in FIG. As shown in FIG.
j has a radio unit 52 and a channel switching control unit 53. The radio unit 52 performs transmission or reception by performing modulation or demodulation such as π / 4 shift QPSK. The reception level deterioration determination unit 54 measures the output power of the radio unit 52.

The channel switching control unit 53 controls switching of the communication channel during reception, and includes a reception level deterioration determination unit 54, a channel switching request unit 56, a channel control unit 58, a frequency switching unit 60, and a synchronization establishing unit. 62, a synchronization burst generation unit 64, timers 66, 68, 69 and a synchronization establishment success / failure determination unit 70.

The channel switching request unit 56 requests the frequency switching unit 60 to switch the frequency of the control channel of the base station 80-j having the strongest reception level, and allocates a communication channel using this control channel. Is required.

The channel control unit 58 recognizes the frequency channel specified by the control channel from the base station 80-j, and requests the frequency switching unit 60 to switch the frequency. The frequency switching unit 60 includes the channel switching request unit 5
6 or a frequency synthesizer for switching to a frequency designated by the channel control unit 58.

Upon receiving the first synchronization burst SB1 or the third synchronization burst SB3 from the base station 80-j, the synchronization establishment unit 62 notifies the synchronization establishment success / failure determination unit 70. The synchronization burst generation unit 64 generates the second synchronization burst SB2 or the fourth synchronization burst SB4 according to an instruction from the synchronization establishment success / failure determination unit 70.

The timer 66 is started by the channel control unit 58 and notifies a timeout to the synchronization establishment success / failure determination unit 70 after a predetermined time has elapsed. Timer 6
8, 69 are activated by the synchronization establishment success / failure determination unit 70,
When a certain time has elapsed, a timeout is notified to the synchronization establishment success / failure determination unit 70.

The synchronization establishment success / failure determination unit 70
When receiving the report of the reception of the first synchronization burst SB1 from 0, the timer 66 is stopped, the timer 68 is started, and the generation of the second synchronization burst SB2 is instructed to the synchronization burst generation unit 64, and the third synchronization burst SB3 is generated. When the reception report is received, the timer 68 is stopped, the timer 69 is started, the generation of the fourth synchronization burst SB4 is instructed to the synchronization burst generation section 64, and the TCH (voice) reception section (not shown) receives the voice. When the reception is instructed and the timers 66 and 68 time out, it is determined that the synchronization establishment has failed, and the frequency switching unit 60 is instructed to switch back to the communication channel of the old base station 80-k (k ≠ j). When the timer 69 times out, the communication channel switching retry is controlled.

On the other hand, the base station 80-j includes a radio unit 82,
It has a channel assignment control unit 83 and an I / F unit 104.
The radio unit 82 performs transmission or reception by performing modulation or demodulation such as π / 4 shift QPSK.

The channel assignment control unit 83 controls the assignment of a communication channel when the mobile station 50-i receiving a request to set up a simplex call due to a recall during reception. 84, control channel signal generation section 86, synchronization burst generation section 88, time alignment calculation section 90, synchronization establishment section 92, synchronization establishment success / failure determination section 9
4. It has timers 96 and 98, a channel release unit 100, and a synchronization establishment result report unit 102.

The channel switching request receiving section 84 receives the channel switching request specified by the control channel, and allocates a free time slot of the communication channel to the mobile station 50-i to the control channel signal generating section 86. Are generated, and the synchronization burst generation unit 90 is instructed to generate the first synchronization burst SB1.

Here, when the mobile station 50-i issues a simplex call setting request due to a re-call, the transmission of the first synchronization burst SB1 and the third synchronization burst SB3 to the mobile station 50-i and the mobile station 50-i The transmission of the second synchronization burst SB2 and the fourth synchronization burst SB4 from 50-i to the base station 80-i is performed using the communication channel, but the downlink synchronization burst SB1,
It is necessary to control so that SB3 and the uplink synchronization bursts SB2 and SB4 do not collide with each other.
It is assumed that different time slots are assigned to 0-i at the same frequency in the uplink and downlink.

The control channel signal generating section 86 generates a control signal for designating a communication channel to be allocated to the mobile station 50-i by a control channel in accordance with an instruction from the channel switching request receiving section 86.

The synchronization burst generation unit 88 is connected to the mobile station 50-
i, the first synchronization burst SB
First, a third synchronization burst SB3 is generated. The synchronization establishing section 92 establishes synchronization between the second synchronization burst SB2 and the fourth synchronization burst SB4 from the mobile station 50-i.

The synchronization establishment success / failure judging section 94 includes a synchronization establishment section 9
When the notification of the reception of the second synchronization burst SB2 is received from the second synchronization burst SB2, the timer 96 is stopped, the timer 98 is activated, and the synchronization burst generation unit 88 is instructed to generate the third synchronization burst SB3. Is received, the timer 98 is stopped and TCH (voice) not shown
When the transmission unit is instructed to transmit audio, and the timers 96 and 98 time out, it is determined that synchronization establishment has failed.
It instructs the channel release unit 100 to release the communication channel allocated to the mobile station 50-i.

The timers 96 and 98 are provided for the synchronous burst generator 8.
8 and notifies the synchronization establishment success / failure judging unit 94 of a time-out when a predetermined time has elapsed.
The channel release unit 100 releases a channel in response to a channel release instruction from the synchronization establishment success / failure determination unit 94 or the I / F unit 104.

The synchronization establishment result reporting unit 102 notifies the control station 110 via the I / F unit 104 when synchronization is established. The I / F unit 104 is an interface circuit that interfaces with the control station 110.

The control station 110 includes an I / F section 112, a synchronization establishment result receiving section 114, a channel allocation release control section 116,
It has an empty channel management unit 118 and a home location register (hereinafter, referred to as HLR) 120.

The I / F unit 112 is an interface circuit that takes an interface with the base station 80-j. The synchronization establishment result receiving unit 114 receives the result of the synchronization establishment from the I / F unit 112, and reports that fact to the channel release control unit 11.
6 is notified.

The vacant channel management unit 118 allocates the unused communication channel to the base station 80-
j is notified to the channel release control unit 116.
The HLR 120 manages a group to which the mobile station 50-i belongs and a zone in which the mobile station 50-i belongs, controls group communication, and manages a communication channel assigned to the mobile station 50-i by the base station 80-j. Mobile station number of the station 50-i,
Group number to which mobile station 50-i belongs and mobile station 5
It is constituted by a zone in which 0-i is located.

FIG. 4 is an operation flowchart of the channel switching control section in FIG. FIG. 5 is an operation flowchart of the channel assignment control unit in FIG. FIG. 6 is a diagram showing a control sequence according to the embodiment of the present invention.

FIG. 7 is a diagram showing a control sequence according to the embodiment of the present invention. Hereinafter, referring to these figures,
The switching of the communication channel and the control of the assignment of the communication channel by the re-calling during reception by the mobile station 50-i will be described.

In this example, the mobile station 50-1 that is receiving data is moved from the zone Z1 of the base station 80-1 to the zone Z of the base station 80-2.
2, the mobile station 50-2 enters the zone Z of the base station 80-1.
1 and transmitting, the mobile station 50-3 is in zone Z3 of the base station 80-3 and receiving.

(1) Operation of Mobile Station 50-1 (a) Switching of Frequency Channel The reception level degradation judgment unit 54 performs an idle channel search even during reception of the voice channel (TCH) from the base station 80-1. Using the time, the other base station 80-2
From the base stations 80-1, 80
The average of the reception level of −2 is calculated, and the result is notified to the channel switching request unit 56.

Here, mobile station 50-1 moves from zone Z1 to the boundary of zone Z2, and the average value of the reception level of base station 80-2 is higher than the average value of the reception level of base station 80-1. Suppose it was higher.

The channel switching request section 56 is connected to the base station 80-
The reception level of the signal from the base station 80-2 is compared with the reception level of the signal from the base station 80-2. If the reception level of the signal from the base station 80-2 is higher, the base station 80 -2, and instructs to switch to the frequency of the control channel, and switches the frequency to the control channel. The channel switching request unit 56 switches the frequency to the control channel, specifies (recalling during reception,-, simplex recall setting) and the mobile station number, and then, through the radio unit 52, 80
-2.

Here, (recall during reception,-, simple recall setting) is a recall during reception and indicates a request for setting a downstream recall. The information in the parentheses is the setting information of the radio management (RT), the mobility management (MM) (-is not set), and the call control (CC). The same applies to the following cases.

(B) Reception of Control Channel In step S40 in FIG. 4, the channel control unit 58 receives a radio channel designation (channel frequency) from the base station 80-2 on the control channel.

In step S42, the channel control unit 58 instructs the frequency switching unit 60 to switch the channel frequency to the specified radio channel. The frequency switching unit 60 switches to the designated wireless channel. In step S44, the channel control unit 58 starts the synchronization burst SB1 wait timer 66.

(C) Reception of First Synchronization Burst SB1 The synchronization burst establishing unit 62 synchronizes the first synchronization burst SB1 set to the assigned communication channel,
Upon receiving the first synchronization burst SB1, the synchronization establishment success / failure determination unit 70 is notified.

In step S46, the synchronization establishment success / failure determination section 70 determines whether or not the first synchronization burst SB1 has been received. When the first synchronization burst SB1 has been received, the process proceeds to step S48, where the first synchronization burst SB1 is transmitted. If not, the process proceeds to step S76.

(D) Transmission of Second Synchronization Burst SB2 In step S48, the synchronization establishment success / failure determination unit 70
The synchronous burst wait timer (TR2) 68 is started. In step S50, the synchronization establishment success / failure determination unit 70
Is transmitted to the synchronization burst generation unit 64 by the second synchronization burst SB2.
Is generated.

Synchronous burst generation section 64 transmits to base station 80-
The second synchronization burst SB2 is generated on the communication channel allocated by the base station 2 and transmitted to the base station 80-2 via the radio unit 52.

(E) Reception of Third Synchronization Burst SB3 The synchronization burst establishment unit 62 synchronizes the third synchronization burst SB3 set on the assigned communication channel,
When the third synchronization burst SB3 is received, the synchronization synchronization success / failure determination unit 70 is notified.

In step S52, the synchronization establishment success / failure determination section 70 determines whether or not the third synchronization burst SB3 has been received. If the third synchronization burst SB3 has been received, the process proceeds to step S56, where the third synchronization burst SB3 is determined. If not, the process proceeds to step S70.

(F) Transmission of Fourth Synchronization Burst SB4 In step S54, the synchronization establishment success / failure determination unit 70
The timer 66 is stopped, and the synchronous burst generator 64
The transmission of the synchronization burst SB2 is instructed to stop. The synchronization burst generation unit 64 stops transmitting the second synchronization burst SB2.

In step S56, the synchronization establishment success / failure judging section 70 starts a synchronization burst waiting timer (TR3) 68. In step S58, the synchronization establishment success / failure determination unit 70 instructs the synchronization burst generation unit 64 to generate the fourth synchronization burst SB4.

Synchronous burst generating section 64 transmits base station 80-
A fourth synchronization burst SB4 is generated on the communication channel allocated by No. 2 and transmitted to the base station 80-2 via the radio unit 52.

(G) Voice Reception In step S60, the TCH (voice) receiver (not shown) synchronizes the voice (TCH) from the base station 80-2 and receives the voice (TCH). Proceed to step S66 if audio can be received.

In step S62, the timer 69 is stopped, the transmission of the fourth synchronization burst SB4 is stopped,
H (voice) is received. Thereby, the mobile station 50-1
Can receive the voice from the mobile station 50-2 in the zone Z2, and the inter-group communication is performed.

(H) Retry of Assignment of Communication Channel In step S66, it is determined whether the timer (TR3) 69 has timed out. If the timer 69 has not timed out, the process returns to step S60. Proceed to step S68. In step S68, the transmission of the fourth synchronization burst SB4 is stopped, and the process returns to step S40 to retry allocation of the communication channel.

(I) Switching back to the old channel In step S76, the synchronization establishment success / failure determination unit 70
It is checked whether the timer (TR1) 66 has timed out. If not, the process returns to step S46, and if it has timed out, the process proceeds to step S78.

In step S78, the synchronization establishment success / failure determination section 70 instructs the frequency switching section 60 to switch to the frequency of the old channel. The frequency switching unit 60 switches to the old frequency channel. In step S80, TCH (voice) is received on the old channel.
In step S70, the synchronization establishment success / failure determination unit 70
It is checked whether or not the timer (TR2) 68 has timed out.
Proceed to 2 and if timer 68 has not timed out,
It returns to step S52.

In step S72, synchronization establishment success / failure judging section 70 instructs frequency switching section 60 to switch to the frequency of the old channel. The frequency switching unit 60 switches to the old frequency channel. In step S74, TCH (voice) is received on the old channel.

(2) Operation of Base Station 80-2 (a) Channel Switching Request Acceptance Channel switching request accepting section 84 receives a channel switching request from mobile station 50-1, and obtains a group number from a mobile station number. It is checked whether a downlink communication channel has already been assigned to a mobile station belonging to the same group number as this group number.

If a downlink communication channel is still assigned to a mobile station belonging to the same group, the communication channel is set as a control channel, a control signal is transmitted to the mobile station, and the communication channel is used. , Voice (TC
H).

In step S90, channel switching request receiving section 84 determines whether mobile station 50-
If no downlink channel has been assigned to 2, 50-3, an empty frequency channel is searched to select an assigned channel.

Then, the channel switching request receiving section 84
The synchronization burst generation unit 88 is instructed to generate the first synchronization burst SB1, and the control channel signal generation unit 86 is instructed to generate (−,
-, Re-call setting), and instructs to sequentially generate a control signal and a (radio channel designation,-,-) control signal.

Upon receiving the instruction from the channel switching request receiving unit 84, the synchronous burst generating unit 88 generates a first synchronous burst SB1 on the assigned channel, and
To the mobile station 50-1 via the
The waiting timer (TRB1) 96 is started.

In step S92, the control channel signal generating section 86 receives the instruction from the channel switching request receiving section 84, sets (-,-, recall setting) to the control signal, and sets After transmitting to the mobile station 50-1 via the communication unit 82, (radio channel designation,-,-)
Is set as a control signal, and the radio unit 8
2 to the mobile station 50-1 for a certain period of time. still,
If there is no free communication channel, (return request,-,
Recall setting rejection) to the control signal of the control channel,
It transmits to mobile station 50-1.

In this example, mobile station 50 belonging to the same group as mobile station 50-1 is located in zone Z2 of base station 80-2.
-2 and 50-3 are not present, so the mobile station 50-1
Is assigned a communication channel.

(B) Reception of the second synchronization burst SB2 The synchronization establishing unit 92 synchronizes the second synchronization burst SB2 set in the communication channel allocated to the mobile station 50-1, and converts the second synchronization burst SB2. When the synchronization is established upon reception, the synchronization establishment success / failure determination unit 94 is notified.

In step S94, the synchronization establishment success / failure determination section 94 determines whether the second synchronization burst SB2 has been received. If the second synchronization burst SB2 has been received, the process proceeds to step S96, where the second synchronization burst SB2 is transmitted If not, the process proceeds to step S112.

(C) Transmission of Third Synchronization Burst SB3 In step S96, the synchronization establishment success / failure judging unit 94
The SB2 wait timer (TRB1) 96 is stopped, and SB4
The wait timer (TRB2) 98 is started.

In step S98, the synchronization establishment success / failure judgment section 94 instructs the synchronization burst generation section 88 to generate the third synchronization burst SB3. Synchronous burst generator 88
Is the third synchronization burst S on the assigned communication channel.
In order to establish B3 and superframe synchronization, a superframe synchronization counter (SSC) is set according to the standard STD-39A, and a third synchronization burst SB is set.
3. Generate an SSC and transmit it to the mobile station 50-1 via the radio unit 82.

Here, the SSC is set because the voice information is set, for example, after three bursts.
This is because it is necessary to know the head of the slot from 0-1.
The reason that the SSC is not set in the first synchronization burst SB1 is that a repeated burst pattern may be received.
This is because it is possible to receive the synchronization burst without necessarily knowing the beginning of the slot.

In this example, since the mobile station 50-1 does not transmit the uplink TCH (voice), it is not always necessary to set the time alignment (TA) indicating the transmission time lag. Set.

(D) Reception of Fourth Synchronization Burst SB4 The synchronization establishing unit 92 synchronizes the fourth synchronization burst SB4 set to the communication channel allocated to the mobile station 50-1, and obtains the fourth synchronization burst SB4. Is received and synchronization is established, the synchronization establishment success / failure determination unit 94 is notified.

In step S100, the synchronization establishment success / failure determination section 94 determines whether or not the fourth synchronization burst SB4 has been received. If the fourth synchronization burst SB4 has been received, the process proceeds to step S102, where the fourth synchronization burst SB4 is transmitted. If not, the process proceeds to step S106.

(E) Voice transmission In step S102, the synchronization establishment success / failure judging section 94
Instructs the synchronization burst generation unit 88 to stop transmission of the third synchronization burst SB3, and reports to the control station 110 that the synchronization has been established with the mobile station 50-1 to the synchronization establishment result reporting unit 102. Instruct

The synchronization burst generation section 88 stops transmitting the third synchronization burst SB3. Synchronization establishment result reporting unit 10
2 reports to the control station 110 via the I / F unit 104 that synchronization has been established with the mobile station 50-1.

In step S104, T (not shown)
The CH (voice) transmitting unit receives the voice from the mobile station 50-2 from the control station 110, and transmits the TCH (voice) to the mobile station 50-1.

(F) Channel release In step S112, synchronization establishment success / failure judging section 94
Determines whether the TRB1 timer 96 has timed out, and if not, returns to step S94, and if timed out, proceeds to step S114.

In step S114, the synchronization establishment success / failure determination section 94 stops the TRB1 timer 96 and instructs the synchronization burst generation section 88 to stop transmitting the first synchronization burst SB1. The synchronization burst generation unit 88 stops transmitting the first synchronization burst SB1.

In step S 116, synchronization establishment success / failure determination section 94 instructs channel release section 100 to release the channel. The channel release unit 100 includes the mobile station 50-1
Release the communication channel assigned to.

In step S106, the synchronization establishment success / failure judging section 94 judges whether or not the TRB2 timer 98 has timed out. If not, the process returns to step S100.
Proceed to 106.

In step S106, the synchronization establishment success / failure determination section 94 stops the TRB2 timer 98 and instructs the synchronization burst generation section 88 to stop transmitting the third synchronization burst SB3. The synchronization burst generation unit 88 stops transmitting the third synchronization burst SB3.

In step S110, synchronization establishment success / failure judging section 94 instructs channel releasing section 100 to release the channel. The channel release unit 100 includes the mobile station 50-1
Release the communication channel assigned to.

(3) Operation of Control Station 110 (a) Receiving Synchronization Establishment Result The synchronization establishment result receiving unit 114 receives a report of the synchronization establishment result from the synchronization establishment result reporting unit 102 through the I / F unit 112. The base station 80-2 notifies the channel assignment release control unit 116 that synchronization has been established between the base station 80-2 and the mobile station 50-1.

(B) Channel allocation release The channel allocation release section 116 notifies the idle channel management section 118 that synchronization has been established between the base station 80-2 and the mobile station 50-1, and releases the idle channel. Instruct the check.

FIGS. 8A and 8B are diagrams showing the contents of the HLR. In particular, FIG. 8A shows the state before the channel switching, and FIG. 8B shows the state after the channel switching. Free channel management unit 118
Updates the serving zone number of the mobile station 50-1 to the zone Z2 of the base station 80-2 from the mobile station number of the mobile station 50-1 of the HLR 120 shown in FIG. 8 as shown in FIG. 8B. At the same time, the mobile station 50-2, 50-3 belonging to the same belonging group 1 as the mobile station 50-1 is searched for the zone in which the mobile station 50-2, 50-3 is located.
If the downlink simplex communication channel has not been allocated in step (a), the channel assignment releasing unit 116 is instructed to release the communication channel to the base station 80-1.

In this example, the mobile station 50-2 is in the zone Z1, but is assigned an uplink communication channel, and the mobile station 50-3 is in the zone Z3. Since no down-link simplex communication channel has been allocated to the mobile stations 50-2 and 50-3, the mobile station 50-2 instructs the base station 80-2 in the zone Z1 to release the communication channel.

The channel allocation release section 116 is connected to the I / F section 1
12, the base station 80-1 is instructed to release the channel. In response to this, the channel release unit 100 of the base station 80-1 releases the communication channel allocated to the mobile station 50-1.

FIG. 9 is an explanatory diagram of an effect according to the embodiment of the present invention. As shown in this figure, the receiving mobile stations 50-1, 50-2, 50-3 located in the zone Z1 are:
When moving to zones Z2, Z3, and Z4, synchronization establishment in the new zones Z2, Z3, and Z4 fails, and the zone Z2 and Z4 are switched back to the old zone Z1.
3, Z4, the communication channel is released and the old zone Z
1, only the communication channel is allocated. Therefore, unlike the related art, the communication channel is not allocated in the zone Z1 and the zones Z2, Z3, and Z4, and the communication channel is not wasted.

According to the embodiment described above, the mobile station 5
0-i is transmitted from the base station 80-j to the first synchronization burst SB1.
Is received, the second synchronization burst SB is transmitted to the base station 80-j.
2, the base station 80-j transmits the mobile station 50-
Since i knows that the first synchronization burst SB1 has been received, if the second synchronization burst SB2 cannot be received within a predetermined time, the channel can be released and the channel allocation is not wasted.

When receiving the second synchronization burst SB2, the base station 80-j transmits the third synchronization burst SB3. When the mobile station 50-i receives the third synchronization burst SB3, the base station 80-j transmits the fourth synchronization burst SB4. Is transmitted, so that synchronization with the mobile station 50-i can be more reliably established.

Furthermore, since the base station 80-j reports the establishment of synchronization to the control station 110, the control station 110 checks an empty channel, and if there is an empty channel, the base station 0-k (k ≠ j ) To release the channel,
No channels are wasted.

In this embodiment, when a request for switching the communication channel is received from the mobile station 50-i, the control of the allocation of the communication channel and the release of the communication channel is controlled by the base station 80.
-J itself, but the base station 80-j notifies the control station 110 of the communication channel switching request from the mobile station 50-i, and reports the success or failure of synchronization establishment to the control station 110. The control station 110 may instruct the base station 80-j to allocate a communication channel and release the communication channel.

[0123]

As described above, according to the first to fourth aspects of the present invention, when the mobile station receives the first synchronization burst from the base station, it transmits the second synchronization burst to the base station. Therefore, since the base station can confirm the establishment of synchronization with the mobile station, the communication channel is not wasted even if the synchronization with the mobile station is not established.

According to the second aspect of the present invention, the base station transmits the third synchronization burst after receiving the second synchronization burst, and the mobile station transmits the fourth synchronization burst when receiving the third synchronization burst. Therefore, synchronization can be more reliably achieved, and improvement in communication reliability can be expected.

According to the third aspect of the present invention, the fact that synchronization has been established between the mobile station and the base station is reported to the control station,
Since the control station instructs the mobile station to release the communication channel to the base station to which the communication channel has been allocated, the old channel is released even when the mobile station moves and allocates the communication channel in a new zone. Communication channel is not wasted.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of a mobile communication system according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a mobile station, a base station, and a control station in FIG. 2;

FIG. 4 is an operation flowchart of a channel switching control unit in FIG. 3;

FIG. 5 is an operation flowchart of a channel assignment control unit in FIG. 3;

FIG. 6 is a diagram illustrating a channel switching sequence according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating a channel switching sequence according to an embodiment of the present invention.

FIG. 8 is a diagram showing the contents of an HLR.

FIG. 9 is an explanatory diagram of an effect according to the embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional mobile communication system.

FIG. 11 is a flowchart showing conventional channel switching control.

FIG. 12 is a flowchart showing conventional channel assignment control.

FIG. 13 is a diagram showing a conventional channel switching sequence.

FIG. 14 is a diagram showing a conventional problem.

[Explanation of symbols]

 10-i (i = 1 to n) Mobile station 12-i (i = 1 to n) Reception level deterioration determination means 14-i (i = 1 to n) Channel switching request means 16-i (i = 1 to n) ) Channel switching means 18-i (i = 1 to n) Second synchronous burst transmission means 20-i (i = 1 to n) Old channel switching means 30-j (j = 1 to m) Base station 32-j (J = 1 to m) Communication channel designation means 34-j (j = 1 to m) First synchronous burst transmission means 36-j (j = 1 to m) Communication channel release means 40 Control station

Claims (4)

[Claims] A mobile communication system comprising: a plurality of grouped mobile stations; a plurality of base stations communicating with mobile stations located in a zone; and a plurality of mobile stations belonging to the same group by controlling the base stations. A mobile communication system having a control station that performs inter-group communication control in the mobile station, the mobile station comprising: a reception level deterioration determination unit that determines that a reception level of a signal of a communication channel being received has deteriorated; When is deteriorated, by performing frequency switching to a higher control channel of the reception level, the base station,
Channel switching requesting means for requesting allocation of a simplex communication channel due to recall during reception; channel switching means for switching frequency to a communication channel indicated by the control signal of the control channel from the base station; and A second synchronization burst transmitting means for transmitting a second synchronization burst to the base station when one synchronization burst is received, and switching to an old communication channel when the first synchronization burst cannot be received within a predetermined time. The base station, when receiving the allocation request for the simplex communication channel from the mobile station, performs downlink communication to another mobile station belonging to the same group as the mobile station. If the channel has not been allocated yet, a free communication channel is designated for the control signal of the control channel, and the communication channel for transmitting the control signal to the mobile station. Receiving a request for allocating the simplex communication channel from the mobile station, if the mobile station has not yet allocated a downlink communication channel to another mobile station belonging to the same group as the mobile station, First synchronization burst transmission means for transmitting the first synchronization burst on a designated communication channel; and communication channel release means for releasing the communication channel when the second synchronization burst cannot be received within a predetermined time. A mobile communication system, comprising: 2. The mobile station, upon receiving a third synchronization burst from the base station, stops transmitting the second synchronization burst and transmits a fourth synchronization burst to the base station on the communication channel. A fourth synchronization burst transmitting unit; and a second old channel switching unit for switching back to an old communication channel when the third synchronization burst cannot be received within a predetermined time. A third synchronization burst sending means for stopping transmission of the first synchronization burst when receiving the second synchronization burst, and sending the third synchronization burst; 2. The mobile communication system according to claim 1, further comprising: a second communication channel release unit that releases the communication channel when reception has failed. 3. The base station is synchronized with the mobile station, and when the mobile station is ready for transmission of traffic data, the base station establishes synchronization with the control station with the mobile station. The control station further includes: a first storage unit that stores, for the plurality of mobile stations, group information to which the mobile station belongs and a zone in which the mobile station is located. Receiving a report of the establishment of synchronization with the mobile station from the base station, referring to the first storage means, for the base station in which the assigned communication channel is in an unused state,
First communication channel release instructing means for instructing release of the communication channel; and receiving a report of establishment of synchronization from the base station;
The mobile communication system according to claim 1, further comprising: first storage updating means for updating the storage. 4. A plurality of base stations communicating with a plurality of grouped mobile stations and mobile stations located in a zone, and a plurality of base stations controlling said base station and belonging to the same group. A mobile communication system having a control station that performs inter-group communication control in the mobile station, the mobile station comprising: a reception level deterioration determination unit that determines that a reception level of a signal of a communication channel being received has deteriorated; When is deteriorated, by performing frequency switching to a higher control channel of the reception level, the base station,
Channel switching requesting means for requesting allocation of a simplex communication channel due to recall during reception; channel switching means for switching frequency to a communication channel indicated by the control signal of the control channel from the base station; and A second synchronization burst transmitting means for transmitting a second synchronization burst to the base station when one synchronization burst is received, and switching to an old communication channel when the first synchronization burst cannot be received within a predetermined time. Communication channel assignment request notifying means for notifying the control station that the base station has received the downlink simplex communication channel assignment request from the mobile station. Receiving an instruction to allocate the communication channel from the control station, specifying a vacant communication channel in the control signal of the control channel, Communication channel designation means for transmitting the control signal; first synchronization burst sending means for sending the first synchronization burst on the communication channel designated by the control signal when receiving the communication channel assignment instruction from the control station; If the second synchronization burst cannot be received within a predetermined time, synchronization failure reporting means for reporting the failure of synchronization to the control station; and synchronization is established between the mobile station and the mobile station. When preparation for transmission of traffic data is completed, synchronization establishment reporting means for reporting to the control station that synchronization has been established with the mobile station, and upon receiving a communication channel release instruction from the control station, the communication channel Communication channel releasing means for releasing the communication channel, wherein the control station comprises, for the plurality of mobile stations, a zone in which each mobile station is located and a communication channel allocated to the mobile station. Second storage means for storing information indicating whether the packet is simplex or duplex, and when receiving from the base station a notification of the downlink simplex communication channel allocation request from the mobile station, the second storage means. With reference to the storage means, when the base station determines that the mobile station has not yet allocated a downlink communication channel to another mobile station belonging to the same group as the mobile station, the base station instructs the base station to allocate a communication channel. Communication channel assignment instructing means, and receiving a report of synchronization failure from the base station, a second communication channel release instructing means for instructing the base station to release the communication channel, and a report of synchronization establishment from the base station. Upon receipt, the second
A mobile communication system, comprising: a second storage updating unit that updates a storage unit.