JPH0244823A - Line switching system - Google Patents

Abstract

PURPOSE:To prevent the lack and overlap of transfer information by providing a buffer for absorbing that a burst reception period or a burst length is not fixed in an equipment which executes conversion connection that is to receive user data before and after switching when a line is switched between different radio line terminal equipments. CONSTITUTION:For restoring user data, the buffer for transmission system alteration and time correction 12 in an exchange 9 previously gives a restoration single the initial delay of a prescribed time. The period of inter-burst due to the switching of the line is adjusted by using the initial delay, and a system is altered to the information transfer system of a line conversion type on a communication line 13 for the other station so as to transfer user data. Thus, data which a user has transmitted can be restored as it is without the lack of information and the time space of information.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a line switching system between a wireless line termination device and a switching device in a car phone that performs a circuit-switched connection for digital communication, and particularly relates to a line switching system for transferring information. This invention relates to a line switching method that avoids loss or duplication of transfer information that occurs when lines are switched and used.

[Prior art and problems to be solved by the invention] In mobile communications, the range in which radio waves from a wireless line terminal station can be received is limited, so it is necessary to change the receiving frequency according to the movement of the mobile terminal. In other words, it is necessary to switch lines to ensure communication.

In this case, in the conventional line switching method, multiple lines are simply switched without paying particular attention to the continuity of transferred information, and depending on the line switching time and transmission delay difference, the transferred information that becomes user data There was a momentary interruption.

As a way to prevent such instantaneous interruptions, a buffer is installed at the switching center,
Conventionally, a method was considered to use the buffer to absorb instantaneous interruptions during line switching, but this method either transfers the line switching notification on a separate line or requires synchronization of the line itself that sends the information. /Asynchronization requires recognition of the line through which information is being transferred at that time, making control complex and likely to be incomplete.

In particular, when switching lines across exchanges, it is necessary to perform strict timing control and transfer the information necessary for line switching between exchanges, and special equipment for line switching across exchanges is required. equipment is required.

The present invention has been made in view of the above problems, and uses a simple control procedure to prevent the loss or duplication of transfer information that occurs when there are multiple lines and the line for transferring information is switched and used. The purpose is to provide a line switching method that can avoid this problem.

[Means to solve the problem]

According to the invention, the above-mentioned object is achieved by the means specified in the claims.

That is, the present invention is a car telephone system that performs circuit-switched connections for digital communications, in which user data is transferred in bursts in predetermined units on a wireless line, and line interruptions due to line switching are avoided. In a line switching system that is configured to transfer user data between devices using means that makes the data transfer rate variable, and to transfer all of the user data without any loss, an exchange connection is made with a device that terminates the wireless line. On the two lines between the device and the device, user data is transferred in bursts just like the wireless line above,
In addition, when switching lines between different wireless line termination devices, a buffer is installed in the device that performs the exchange connection to receive user data before and after switching to absorb the fact that the burst reception period or burst length is not constant. This is a line switching system in which the user data in each burst is retrieved and edited using the buffer, and the user data is restored without causing information loss or time gaps.

[For production]

In the mobile communication system used for automobiles, etc., the range in which the automobile, etc. can receive radio waves from one wireless line terminal station is limited, so when moving from place to place, it is necessary to change the frequency of the received radio waves, That is, it is necessary to switch line i to ensure communication.

In this case, on the wireless line between the car, etc. and the wireless line terminal station, user data is transferred in bursts in relatively large units, and the user data is transferred during the line downtime due to line switching. Data is transferred using some means such as making the transfer speed variable, and the configuration is such that it is possible to transfer virtually all user data, and in addition to the above-mentioned wireless line. , the user data on the land line from the device that terminates the wireless line to the device that performs the exchange connection is also in the same burst configuration as on the wireless line above, and in the case of line switching between different wireless line terminating devices. In this case, a buffer installed for the purpose of absorbing the fact that the burst reception period or pars (ft) is not constant is installed in the device that performs the exchange connection to receive user data before and after switching, and recognizes the burst and recognizes the user data in each burst. By extracting data and arranging it seamlessly, the data sent by the user is restored as is, without any missing information or time gaps.

〔Example〕

FIG. 1 shows a device configuration diagram of an embodiment of the present invention, in which 1 is a mobile communication terminal before line switching, 2 is a mobile communication terminal after line switching, 3 is a wireless line used before line switching, 4 is the wireless line in use after line switching, 5 is the wireless line terminating station before line switching, 6 is the wireless line terminating station after line switching, 7 is the wireless line terminating station in use before line switching.
8 is the line between the wireless line terminal station and the switching center used after line switching; 9 is the switching station; 10 is the line terminal H position used before line switching; 11 is the line terminating device used after line switching; 12 is a buffer 7 for changing the transmission method and for time correction.
．． 13 represents a communication line to other stations.

In the figure, when the mobile communication terminal 1 moves to the position of the mobile communication terminal 2, the location of the mobile communication terminal changes from the accommodation area of the radio line termination station 5 to the wireless line termination station 6.
An example is taken where the area changes and line switching occurs.

That is, the mobile communication terminal 1 connects the wireless line 11A3, the wireless line termination station 5, and the wireless line termination station-exchange #! From the state where the mobile communication terminal 2 was connected to the switching center 9 via A! 4. The wireless line termination station 6 changes to the state where it is connected to the exchange 9 via the wireless line termination return inter-exchange line 8.

Here, the wireless line terminal station-switching center unit M78 transfers information in burst form.

A line termination device 10 in the switching center 9. il extracts the burst from the bit string on the wireless line terminal station-switching center dark circuit Is7.8, and further extracts the information within the burst and transfers it to the buffer 712.

Here, the exchange 9 normally does not need to know which of the wireless line termination station-exchange exchange units $7.8 is being used, and can simply perform burst processing.

In addition, the transmission delay difference in the radio diagram #I terminal station-switching center line 78 is large, and the radio line terminal station-switching station #! If the order of the bursts received from 7.8 is reversed, necessary editing is further performed depending on the state of the bursts.

Batch 7712 for transmission method change and time correction in exchange 9
When restoring user data, the restoration signal has an initial delay of a predetermined time from the beginning, and this initial delay is used to adjust the period between bursts when the line is switched. Then, on the communication line 13 to other stations, the user data is transferred by changing to a normal line-switched information transfer method.

FIG. 2 is a time chart showing an example of information editing according to the present invention, and (1) in the figure shows the temporal positions of the transfer information 20 to 21 on the radio and terrestrial lines 3 and 7 before line switching; The figure (2) shows the temporal position of the transferred information 22 on the radio and terrestrial lines 4 and 8 after line switching, and the figure (3) shows the temporal position of the received information 23, 24, 25 at the switching center 9. (4) in the figure shows the temporal positions of the user data 26, 27, and 28 restored by the switching center 9.

On the same line, as shown in FIG. 2 (1), user data is usually transferred in bursts as shown in transfer information 20 and 21 at regular intervals.

Here, when line switching occurs, as shown in FIG. 2 (2), the next burst (transfer information 22
) is received later.

In this way, if the burst reception time is delayed, as shown in Figure 2 (
As shown in 3), the switching center recognizes the received information 23, 24, and 25 with different intervals between bursts. In order to absorb this difference, a buffer is prepared in advance that adds an initial delay Td when information is further transferred to a downstream station, and this time is used to restore continuous information to the user. Transfer to the downstream station as data 26, 27, and 28.

In the above description of the embodiment, the case where there is one switching center is used as an example, but even when switching between switching centers, the same procedure can be easily performed by bursting the transmission information between the switching centers. line switching can be performed.

Further, in another embodiment of the present invention, in order to absorb the line switching time and the transmission delay difference before and after switching within the time interval between bursts, the information transmitting side connects the line within the burst sending time. One possible method is to terminate the switching.

In this case, when restoring user data, it is possible to reduce the capacity of the pan 7a in the exchange, which was necessary to absorb the line switching time and the transmission delay difference before and after switching, and to reduce transmission delays.

In addition, especially when the line speed is faster than the transferred information, the buffer for changing the speed can be shared with the buffer 7 that absorbs instantaneous interruptions and delay differences.Furthermore, by burst multiplexing the line and operating it, the line speed can be increased. It can be used effectively.

〔Effect of the invention〕

As explained above, by using the present invention, it is possible to avoid missing or duplicating transfer information that occurs when there are multiple lines and the line for information transfer is switched and used. can.

Additionally, if the time interval between bursts is sufficient, the information sending side can complete the line switching operation within the burst sending time, which reduces the buffers at the switching center and reduces transmission delays. can.

Furthermore, not only when there is one switching center, but also when switching over lines across switching centers, line switching can be similarly performed by bursting information transfer between switching centers.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a time chart showing an example of information editing according to the present invention. 1... Mobile communication terminal before line switching, 2
...Mobile communication terminal after line switching, 3...
...Usage status before line switching #X line, 4...
...Wireless line used after line switching, 5...
・Wireless line terminal station before line switching, 6...
Wireless line termination station after line switching, 7... Line between wireless line termination station and exchange used before line switching,
8... Line between wireless line terminal station and switching center used after line switching, 9... Switching station,
10...Line termination device in use before line switching, 11...Line termination device in use after line switching, 12...Buffer T for transmission method change and time correction, 13...Communication line to other station, 2゜21......Transfer information of user data on the line used before switching,
22... Transfer information of user data on the line used after switching, 23.24.25... Information received at the switching center, 26.27.28... Restored user data

Claims (1)

[Scope of Claims] A car telephone system that performs circuit-switched connections for digital communications, in which user data is transferred in bursts in predetermined units on a wireless line, and line disconnections occur due to line switching. In a line switching system configured to transfer user data during a period of time using means that make the data transfer rate variable, and to transfer all of the user data without any loss, the switch connection is connected to the device that terminates the radio line. On the terrestrial line between the equipment that performs the communication, user data is transferred in bursts as with the wireless line mentioned above, and when the line is switched between different wireless line termination devices, the user data before and after the switch is received. A buffer is provided in the device that performs the exchange connection to absorb the fact that the burst reception period or burst length is not constant, and the buffer is used to extract and edit the user data in each burst, resulting in missing information and time gaps. A line switching method characterized by restoring user data without causing any damage.