JPH03247030A - Channel switching system during busy state - Google Patents

Abstract

PURPOSE:To relieve the load of processing on an exchange station by transiting a channel to a control radio channel (C-ch) automatically when the deterioration in the S/N of a talking radio channel (S-ch) during busy state is detected by a mobile station, sending a talking continuity request signal and allowing a base station to send a mobile station call signal. CONSTITUTION:A mobile station 12 always measures the S/N of S-ch during talking state and interrupts the talking on the S-ch when the measured value goes to a criterion or below and moves the channel to C-ch automatically to send a talking continuity request signal. Then one of base stations 11a-11d receiving the talking continuity connection request signal interrupts the S-ch based on a mobile station call signal to be sent. In this case, the S/N measuring function of a reception signal is provided even to the mobile station 12. Thus, in matching with the S-ch of a frequency used for communication zones 4a-4d before movement, the mobile destination of the mobile station is discriminated without collection of all S/N information of the base stations 11a-11d of adjacent communication zones 4a-4d. Thus, the load of an exchange station at channel changeover during busy state is relieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an in-call channel switching method for switching the radio channel in progress when a mobile station moves within a service area across a plurality of communication zones. It is related to.

[Conventional technology]

FIG. 8 is a block diagram showing a conventional channel switching system during a call, which is disclosed in, for example, Japanese Patent Application Laid-Open No. 52-147903. In the figure, 1 is an exchange, 2a and 2b are base stations connected to this exchange 1, and 3 is a telephone terminal accommodated in the exchange 1.

4a and 4b are communication zones of each base station 2a and 2b,
Reference numeral 5 denotes a mobile station that moves within the service area formed by these communication zones 4a and 4b. 6a and 6b are wired lines connecting each base station 2a and 2b to the switching center 1, and 7a and 7b are the signal-to-noise ratios (hereinafter referred to as S/N) sent from the base station 2a or 2b to the switching center 1. (ratio) information, 8a.

8b is a base station control signal for the exchange 1 to control each base station 2a, 2b. Reference numerals 9a and 9b are communication paths that are set within the switching center 1 and connect the base stations 2a and 2b and the telephone terminal 3.

The base stations 2a, 2b and the mobile station 5 also have a communication radio channel (hereinafter referred to as S-ch) for communication,
Control radio channel for communication of communication control signals (hereinafter referred to as
These 5-ch and C-ch each consist of an uplink channel from the mobile station 5 to the base stations 2a and 2b, and a downlink channel from the base stations 2a and 2b to the mobile station 5. has been done.

Next, the operation will be explained. It is now assumed that a telephone call is established between the telephone terminal 3 and the mobile station 5 in the communication zone 4b via the base station 2b.

At this time, the exchange 1 detects the movement of the mobile station 5 using the following method. That is, the base station 2b constantly measures the S/N ratio of the signal from the mobile station 5, and if the measured value is equal to or higher than the standard value, the S/N ratio information 7b is set to, for example, "1" and the switching station 1 Send to. When the mobile station 5 moves to the communication zone 4a, the measured value of the S/N ratio at the base station 2b becomes less than the standard value, and therefore the S/N ratio information 7b from the base station 2b becomes, for example, 0''.

When the S/N ratio information 7b becomes "0", the switching center 1 detects that the mobile station 5 moves out of the communication zone 4b of the base station 2b, and starts switching the channel during the call. The switching center 1 sends a control signal 8a to the base station 2a whose communication zone is adjacent to the base station 2a, instructing the mobile station 5 to receive the S-ch of the frequency used within the communication zone 4b. The base station 2a
-ch is received, and if the S/N ratio is higher than the standard, S
/N ratio information 7a is set to "1" and sent to the exchange 1. Upon receiving this, the exchange 1 switches the communication path 9a to the communication path 9b, realizes a communication between the mobile station 5, the base station 2a, the exchange 1, and the telephone terminal 3, and restores the base station 2b.

[Problem to be solved by the invention]

Since the conventional channel switching system during a call is configured as described above, the switching center 1 accommodates the busy base station 2a,
For all 2b, the S/N of the received signal from mobile station 5 is always
In addition, when detecting the movement of the mobile station 5 between the communication zones 4a and 4b, all base stations surrounding the communication zone 4b before movement are detected until the movement destination communication zone 4a is found. It is necessary to simultaneously or sequentially collect S/N ratio information according to the 5-channel frequency used by the mobile station 5 and the base station 2b within the communication zone 4b before movement, which imposes a heavy processing burden. There was an issue of becoming.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a busy channel switching system that can reduce the processing burden on an exchange when switching a busy channel.

[Means to solve the problem]

The channel switching method during a call according to the present invention provides not only a base station but also a mobile station with a function to measure the S/N ratio of a received signal, and the mobile station constantly measures the S/N ratio of Sch during a call. When a deterioration of the measured value is detected, it automatically shifts to C-ch and sends a call continuation request signal, and one of the base stations that receives the call continuation request signal sends a mobile station paging signal to the mobile station. It is what you send.

[For production]

The mobile station in this invention has an S/S channel on S-ch during a call.
The N ratio is constantly measured, and when the measured value falls below the standard value, the call on the S-ch is temporarily interrupted, the call is automatically transferred to the C-ch, and a call continuation request signal is sent. By switching the SAH based on the mobile station paging signal transmitted by one of the base stations that received the call continuation request signal, we have realized a mid-call channel switching method that reduces the burden on the switching center when switching channels during a call. do.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 is a switching center, 3 is a telephone terminal, 4a to 4d are communication zones, and 6a to 6d are wired lines, which are the same parts as those in the conventional system with the same reference numerals in Fig. 8, or equivalent parts. . Further, 10 indicates each of the communication zones 4a to 4d.
are overlapping crossover zones, lla to lid are base stations forming each communication zone 4a, 4b, and 12 is a mobile station moving within the service area formed by each communication zone 4a, 4b.

FIG. 2 is a schematic configuration diagram showing only the portions of the base station 11a-1id related to the present invention, and FIG. 3 is a schematic configuration diagram showing only the portions of the mobile station 12 related to the present invention. In the figure, 13a and 13b are base stations 11a-
This is an S/N ratio measuring circuit disposed within the mobile station 12 or the mobile station 12 and having a function of measuring the S/N ratio of a received signal.

14a and 14b are transmitting/receiving circuits including a control section for processing the S/N ratio measured by the S/N ratio measuring circuit 13a or 13b.

Next, the operation will be explained. Here, FIG. 4 is a time chart showing a signal sequence when switching channels during a call. Below, in communication zone 4a, base stations 11a and 5
A case will be described in which the mobile station 12 that has been communicating on channel -ch moves to the communication zone 4b of the base station 11b via the crossover zone 10.

While the mobile station 12 is talking on channel 5, its S/N ratio measurement circuit 13b measures the S/N of the received signal from the base station 11a.
The ratio is constantly measured. The mobile station 12 is in communication zone 4.
As you move from b to the crossover zone 10, S
The S/N ratio measurement value by the S/N ratio measuring circuit 13b deteriorates. If the measured S/N ratio falls below the standard value at point A shown in FIG.
When the control section detects this, it immediately interrupts the call on the S-ch, shifts to the C-ch, and sends a call continuation request signal B requesting continuation of the call onto that C-ch. This call continuation request signal B includes the mobile station identification code of the mobile station 12 in question.

This call continuation request signal B is received by each base station 11b to 11d, and its S/N ratio is measured by each S/N ratio measuring circuit 13a. In each base station 11b to lid, the control section of each transmitter/receiver circuit 14a
The continuation acceptance signal C containing the S/N ratio width information and mobile station identification code of the obtained received signal is generated and sent to the exchange 1.

The exchange 1 receives the S included in each received continuation acceptance signal C.
/N base station that analyzes range information and indicates a value that satisfies the standard value;
For example, the base station 11b is selected and a base station selection signal is transmitted to the base station 11b.

Here, if there are a plurality of base stations exhibiting values that meet the standard values, one base station is selected from among them at random or according to a predetermined priority order. In addition, each base station 11c, li that was not selected
A restoration signal E is sent from the switching center 1 to d, and each base station 11c and lid that receives it restores to its original state and returns a restoration acceptance signal F to the switching center 1.

On the other hand, upon receiving the base station selection signal, the base station 11b sends the mobile station paging signal G including the mobile station identification code and vacant 5-ah information to the mobile station 12, and then
b and the mobile station 12 shift to communication on the designated 5-ch. The mobile station 12 that received the mobile station paging signal G sends a connection confirmation signal H that includes the mobile station identification code and the base station identification code of the base station 11b, and the base station 11b that received this connection confirmation signal H returns a connection confirmation response signal I to the mobile station 12, and transmits a communication path setting request signal J containing the mobile station identification code to the switching center 1.

After this, the base station 11a is restored.

The switching center 1, which receives the communication path setting request signal J from the base station 11b, sets up a communication path between the base station 11b and the telephone terminal 3, and the mobile station 12 enters a communication state with the telephone terminal 3. .

Note that there is a possibility that the call continuation request signal B is also received by the base station 11a, but in this case, the reception of the signal is ignored.

Above, we have explained the case where a base station selection signal is given to a base station that indicates a value that satisfies the S/N ratio information criterion value included in the continuation acceptance signal C. However, the base station that first notified the continuation acceptance signal C A base station selection signal may be given to the base station selection signal.

FIG. 5 is a time chart showing a signal sequence during channel switching during a call in such an embodiment, in which the base station 11b receives the call continuation request signal B from the mobile station 12.
The process is the same as that shown in FIG. 4 until lid sends the continuation acceptance signal C.

Here, this continuation acceptance signal C is first transmitted by the base station 11c, as shown in FIG.
It is assumed that the transmissions were made in the order of b. When the exchange 1 receives this continuation acceptance signal C, the exchange 1 transmits the continuation acceptance signal C to the base station 1 to which it was first transmitted.
1c, and transmits a base station selection signal to the base station 11c. In addition, the base station 11 that was not selected
A restoration signal E is sent to C211d to restore the original state. Thereafter, in the same manner as in the case of FIG. 4, this selected base station 11c and the base station 11C
The mobile station 12 enters into a communication state with the telephone terminal 3 via the communication path set between the base station 11 and the telephone terminal 3.
a is restored.

In this case, the S/N ratio measurement circuit 13a of each base station 11a to lid only performs periodic S/N ratio monitoring unrelated to channel switching during a call, and may be omitted if unnecessary. . Furthermore, the base stations 11a to 11lid that transmit the base station selection signal are not limited to those that first notified the exchange 1 of the continuation acceptance signal C, and may be any base station.

Furthermore, the present invention is not limited to the above-mentioned embodiments; for example, the call continuation request signal from the mobile station is
It is also possible to provide a base station selection signal to the base station that receives the base station.

FIG. 6 is a time chart showing the signal sequence during channel switching during a call in such an embodiment. Until each base station receives the call continuation request signal B from the mobile station, are the same.

Each base station 11 including the base station 11a that is currently on call
When a to lid receive this call continuation request signal B, the S/N ratio measuring circuit 13a of each of the received signals is
/N ratio is measured, and the measured value is processed by the control section of the transmitting/receiving circuit 14a. Next, each base station 11a to lid generates a continuation acceptance signal C that includes the mobile station identification code of the mobile station 12 that sent the call continuation request signal B and S/N ratio information of the received signal, and transmits and receives the continuation acceptance signal C. It is sent to the exchange 1 from the circuit 14a. The exchange 1 that receives the continuation acceptance signal C from each base station 11b to lid analyzes the S/N ratio information included in the continuation acceptance signal C, and selects the base station with the best value, e.g. 11b, and sends a base station selection signal to the base station 11b. Furthermore, the switching center 1 sends a recovery signal E to the base stations 11a11c and lld that were not selected, and each base station 11a and llc receives it.

The lid is restored to its original state and sends the restoration acceptance signal F to the exchange L.
send it back to

On the other hand, upon receiving the base station selection signal, the base station 11b sends to the mobile station 12 a mobile station paging signal G containing the mobile station identification code and vacant S-ch information.

Thereafter, in the same way as in the case of FIG. 3. Enters a conversation state with 3.

In this way, by giving the base station selection signal to the base station that has received the call continuation request signal with the best S/N ratio, the mobile station can increase the S/N with the base station with the best communication condition. -ch can be used to make calls, and more stable and better call quality can be obtained.

Furthermore, the present invention is not limited only to these examples,
For example, it is also possible to check the communication path on the S-ch after switching to 5-ch during a call, and if the confirmation cannot be made, to return to the state before switching.

FIG. 7 is a time chart showing the signal sequence during channel switching during a call in such an embodiment. Until the base station 11b sends the mobile station paging signal G to the mobile station 12, It is the same as the case.

The mobile station 12 receives the mobile station paging signal G that includes the mobile station identification code of the mobile station 12 and vacant S-ch information transmitted by the base station 11b, and then starts communication on this new 5-ch. to move to. Here, the mobile station 12 that has received the mobile station paging signal G sends out a connection confirmation signal H that includes the mobile station identification code and the base station identification signal of the base station 11b, but for some reason the base station 11b does not receive it. Assume that it was not.

The mobile station 12 waits for a connection confirmation response signal J from the base station 11b for a predetermined time T1 after transmitting the connection confirmation signal H. In this case, the connection confirmation response signal J during the predetermined time T1
cannot be received, so 5-ch is returned to the channel before time A. Similarly, the base station 11b also waits for a connection confirmation signal H from the mobile station 12 for a predetermined time T2 after transmitting the mobile station paging signal G, but since the connection confirmation signal H cannot be received within the predetermined time T2, the exchange A recovery request signal K is sent to the 1. The exchange 1 that received this recovery request signal K is the base station 1.
1b, and thereby the mobile station 12 and the base station 11
The call between b is restored.

In this way, by checking the communication path on the S-ch after switching to 5-ch during a call, and returning to the state before switching if it cannot be confirmed, even if switching of the channel during a call fails, the call can still be made. There will be no sudden interruptions.

In each of the above embodiments, the communication partner of the mobile station is a telephone terminal, but it may also be a mobile station or other terminal connected via a public network, and the communication partner may receive a connection confirmation signal and a connection confirmation signal. The direction of transmission and reception of the acknowledgment signal may be reversed. In addition, in the above embodiment, the number of base stations in the same communication zone is one, and only one mobile station is shown, but the number of base stations and mobile stations may be arbitrary, and the same communication zone can be connected to multiple base stations. It may also be configured as follows. In any of these cases, the same effects as in the above embodiments can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, the mobile station is also equipped with a function to measure the S/N ratio of the received signal, and when the S/N ratio of Sch is constantly measured during a call and its deterioration is detected, it is possible to 5-ch is configured to temporarily suspend the call, automatically switch to C-ch, transmit a call continuation request signal, and switch to 5-ch in response to a mobile station paging signal sent by one of the base stations that received the signal. This eliminates the need for the switching center to constantly measure and monitor the S/N ratio of the received signal from the mobile station at the base station, and allows the base station to adjust the S/N ratio of the signal received from the mobile station to the 5-ch frequency used in the communication zone before moving. This makes it possible to determine the destination of a mobile station without having to collect all the S/N ratio information of base stations in adjacent communication zones, significantly reducing the burden on switching stations when switching channels during a call. This has the effect of providing a channel switching method during a call that can reduce the amount of noise.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram showing a channel switching system during a call according to an embodiment of the present invention, FIG. 2 is a schematic diagram of the base station, and FIG. 3 is a schematic diagram of the mobile station. Figures 4 to 7 are time charts showing signal sequences during channel switching during a call, and FIG. 8 is a block diagram showing a conventional channel switching system during a call. 1 is a switching center, 4a to 4d are communication zones, lla to 11d
12 is a base station, 12 is a mobile station, and 13a and 13b are functions for measuring the S/N ratio of a received signal (S/N ratio measuring circuit). In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A mobile station comprising: a switching center; a plurality of base stations connected to the switching center; and a plurality of mobile stations moving within a service area formed by a set of communication zones configured by the base station; A mobile station controls a call radio channel for a call and communication of a communication control signal, each consisting of an uplink channel from the mobile station to a base station and a downlink channel from the base station to the mobile station. each base station has a function of measuring the signal-to-noise ratio of a received signal, and switches the communication radio channel of the mobile station moving across the plurality of communication zones based on the measured value; In the channel switching method during a call, each mobile station is also equipped with a function to measure the signal-to-noise ratio of the received signal, and the signal-to-noise ratio of the radio channel is constantly measured during a call, and the measured value is not degraded. When the call is detected, the call on the call radio channel is interrupted, the call is shifted to the control radio channel, and a call continuation request signal requesting continuation of the call is transmitted, and one of the base stations that received the call continuation request signal transmits a mobile station paging signal to the mobile station that sent the call continuation request signal.