JPS62133833A - Method for switching base station during talking - Google Patents

Abstract

PURPOSE:To improve the talking quality by providing a timing making the reception output of a switching sender radio base station and the reception output of a switching destination base station effective. CONSTITUTION:A line control equipment sends a reception start command signal 15 toward the switching destination reception base station, which uses the signal 15 to start the reception of a designated channel and returns a reception start acknowledgment signal 16. The line control equipment, in receiving the signal 16, applies a reception line duplex connection processing 17. Then the communication line between the switching sender base station and an exchange station is connected to a communication line between the switching destination base station and the exchange station and two reception signals are added. Then the superimposed signal is sent to the exchange station.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mobile communication system that performs communication via a base station, and a base station during a call that switches base stations without changing the radio channel during a call. This relates to a switching method.

[Conventional technology]

Although there are various methods of configuring base station equipment for a mobile communication system, here, as a conventional example, a system consisting of a mobile station, a transmitting base station, and a receiving base station will be described. Several forms of such a mobile communication system have been considered, and a typical system is shown in FIG. In FIG. 5, 1 is a transmitting base station, 2 to 6 are receiving base stations, T is a mobile station, and 8 is a switching center. The transmitting base station 1 forms a pair with one of the receiving base stations 2 to 6 and communicates with the mobile station 7. The mobile station received wave is transmitted from the transmitting base station 1, and the mobile station transmitted wave is received by one of the receiving base stations. The receiving communication path and the transmitting communication path are usually paired at the transmitting base station and connected to a switching center 8, and the switching center 8 performs switching connection with the general fixed telephone network. In a normal configuration, a line control device (not shown) is installed in the transmitting base station 1 and performs call connection control in cooperation with the switching center 8. Although FIG. 5 shows a case where there is one transmitting base station, multiple transmitting base stations are arranged within the service area, and each transmitting base station has a plurality of receiving base stations under its control. Of course, zone-based mobile communication systems also exist.

There have been various studies on the configuration of such mobile communication systems and the connection control sequence for incoming and outgoing calls.
Very little research has been done on a method of switching base stations while using the same channel during a call.

There are two types of base station switching during a call. One is to switch both the transmitting base station and the receiving base station, and the other is to switch only the receiving base station. Regarding the former method, almost the same means as in a system consisting only of stations having both transmitting and receiving functions are necessarily applied. In this case, the pre-switching radio channel and the post-switching radio channel are generally different channels, and therefore an unavoidable momentary interruption occurs due to switching. Furthermore, although the latter has not been studied much in the past, almost the same switching sequence as in the former case will be applied. The switching control sequence in this case is shown in FIG. FIG. 6 shows switching control between a mobile station, a transmitting base station, a switching source receiving base station, and a switching destination receiving base station. Here, the switching destination receiving base station is the receiving base station in use, and the switching destination receiving base station is the receiving base station of the zone into which the mobile station 7 will enter from now on. In Fig. 6, 9 is a channel designation signal, 10 is a reception start command signal, 11 is a wireless section lower continuity test signal, 1
2 is a radio continuity test signal, 13 is a radio continuity confirmation signal, and 14 is a reception end signal. In this figure, when the need for base station switching arises due to the movement of the mobile station 7, the transmitting base station 1 first sends a channel designation signal 9 to the mobile station 7.
Send out. At this timing, the communication path of the base station transceiver is disconnected.

The channel designation signal designates the same channel as the channel in progress at that time. When the mobile station 7 receives this signal, it disconnects the transmission path and transmits the continuity test signal 1 under the radio section.
Waiting for 1. On the other hand, the line control device installed in the transmitting base station 1 sends a reception start command signal 1 to the switching destination receiving base station.
Sends 0.

A channel number to be received is added to this signal 10. This channel number is equal to the busy channel number above. Subsequently, the transmitting base station 1 sends out a continuity test signal 11 over the radio section to the channel in use. Upon receiving this signal 11, the mobile station T transmits a continuity test signal 12 over the radio section on the same channel. When the switching destination receiving base station receives the signal 12, the switching destination receiving base station sends the radio continuity confirmation signal 1. to the line control device.
Send 3. Upon receiving this signal, the line control device switches the connection of the upper line going to the switching center 8 from the line of the switching destination receiving base station to the line of the switching destination receiving base station, and also ends the reception towards the switching destination receiving base station. A signal 14 is sent out. The switching destination receiving base station that has received the signal 14 ends receiving the wireless section signal upon receiving this signal 14.

[Problem that the invention seeks to solve]

When the above channel switching algorithm is applied, in order to prevent interference between various test signals and call information, the call path must be cut off while signals are being sent, which causes a momentary interruption in communication as the channel is switched.

Since this instantaneous interruption during a call is on the order of several milligrams, it is clearly noticeable to the caller even in the case of a voice call, and is not a desirable phenomenon. Furthermore, in the case of digital communication, this part of the information is completely lost, so the impact is often more severe than in the case of voice calls.

[Means for solving problems]

In order to solve such drawbacks, the present invention provides timing for validating both the reception output of the switching optical radio base station and the reception output of the switching destination radio base station.

[Effect]

Improves call quality during switching.

〔Example〕

FIG. 1 is a switching control sequence showing a first embodiment of the present invention. This figure shows an embodiment in which the base station equipment is applied to the system of FIG. 5, which consists of a transmitting base station and a plurality of receiving base stations. In FIG. 1, 15 is a reception start command signal, 16
is reception start confirmation signal, 1T is reception line double connection processing, 1
Reference numeral 8 indicates a connection confirmation signal, reference numeral 19 indicates a receiving line-overlapping process, and reference numeral 20 indicates a reception end signal. In this figure, first, the line control device sends a reception start command signal 15 to the switching destination receiving base station. Signal 15 includes the radio channel number to be received;
In other words, the same radio channel number used by the switching destination receiving base station is attached. When the switching destination receiving base station receives this signal 15, it starts receiving the designated channel and returns a receiving start confirmation signal 1B. When the line control device receives the signal 16, it performs a receiving line double connection process 17. This is the switching destination receiving base station and switching center 8.
This process connects the communication line between the switching destination receiving base station and the exchange 8 to the communication line between the switching destination receiving base station and the switching center 8, and adds the two received signals. The concept of this process is shown in FIG. FIG. 2 is a diagram showing the concept of addition for the lines of the base station reception system, where 21 is a space division switch, 22 is a group of incoming lines to the switch 21, 23 is a group of outgoing lines from the switch 21, and 24 is a switching destination. 25 is the receiving line that the receiving base station is paying attention to. Reference numeral 25 is the receiving line that the receiving base station is paying attention to. Reference numeral 26 is the outgoing line that has been connected before the switching for the communication that is being noticed. Such a switch is often located at a transmitting base station. In normal conditions other than when switching channels, a specific incoming line 1
Lines and one specific outgoing line are connected to multiple switches. In FIG. 2, the incoming line 24 and the outgoing line 26 are connected by a switch corresponding to the intersection. In addition to this connection, the receiving line double connection process 17 means connecting the switch corresponding to the intersection of the incoming line 25 and the outgoing line 23. Due to such a double connection, the superimposed signal is sent to the exchange 8 (in the sense of making the sending levels the same, it is necessary to reduce the level of the superimposed signal to 1/2). The above is an example of a space division switch, but the effect is exactly the same even if it is a time division switch. In the case of a time division switch, a time slot signal corresponding to the receiving line of interest from the switching destination receiving base station and a time slot signal corresponding to the receiving line of interest from the switching destination receiving base station It is sufficient to add them together, multiply by 1/2, and use this as the signal of the corresponding outgoing time slot.

After performing the double connection processing 1T described above, the circuit control device waits for a connection confirmation signal 18 from the switching destination receiving base station.

On the other hand, the switching destination receiving base station that started receiving with signal 15,
When a signal at a specified reception level is received, a connection confirmation signal 18 is sent to the line control device.

The line control device that has received the signal 18 returns the double-connected state of the switch to the single-connected state with only the switching destination receiving base station. In the case of FIG. 4, the connection between the incoming line 24 and the outgoing line 23 is released. This process is a reception line type connection process indicated by symbol 19.

The line control device that has performed processing 19 sends a reception end signal 20 to the switching source receiving base station. The switching source receiving base station receives the signal 20 and finishes receiving the corresponding wireless channel, thereby completing all switching processing.

As is clear from the embodiment shown in FIG. 1, the most important feature of the present invention is that there is no momentary interruption associated with switching. As a result, there is no unnaturalness during voice calls or lack of information during digital communications. Furthermore, as is clear from a comparison between FIG. 6 and FIG. 1, the load applied to the line control device is almost unchanged.

In the above description, it is assumed that a switch for switching between receiving base stations exists in the transmitting base station. In the present invention, the fact that this switch is located at the transmitting base station is irrelevant to the essence of the present invention. If all the receiving lines are brought to the switching center and the receiving line is selected at the switching center, the double connection process can be performed within the switching center.

Further, although double connection processing is assumed in processing 1T, this processing can also be omitted. In this case, the line controller uses signal 1B
After receiving the signal, it waits for the signal 18.

After receiving the signal 18, as a process 19, a process of switching the switch from the switching source receiving base station to the switching destination receiving base station is performed. This process can be performed in several hundred μS or less,
Almost all instantaneous interruptions can be eliminated.

As an application of the embodiments of the invention described so far, a case can be considered where a control signal exists outside the communication signal band. Utilizing the presence of this out-of-band control signal, more accurate switching control becomes possible. First, the concept of the communication signal out-of-band control signal will be described below. FIG. 3 is a diagram showing an example of an out-of-band control signal. In FIG. 3, 2T indicates the frequency band of the out-of-band control signal, and 28 indicates the frequency band of the communication signal. Normally, the band of communication signals is 0.3 to 3KHz,
In this example, the control signal is present in the communication signal lower band.

Out-of-band control signals are normally transmitted and received continuously at all times, and are used to control transmission power and transmit and receive interference information. Various types of signal configurations are possible, but a fixed length frame configuration is common.

If such an out-of-band control signal exists, it may not be possible to simply superimpose the signals described in the embodiment of FIG. 1. This is because a phase difference occurs between the two received signals before they are transmitted to the transmitting base station, and when this phase difference exceeds a certain size (usually 80 degrees or more), the out-of-band control signal This is because there may be cases where it cannot be decoded correctly. Since such a phase difference mainly occurs in the transmission path between the receiving base station and the transmitting base station and within each device, it inevitably occurs even in a transmission system without an out-of-band control signal.

If the communication information is an audio baseband signal, this phase difference would not be of much concern due to the nature of human hearing.

However, when the communication information is a digital signal, the influence of this phase difference becomes significant as in the case of an out-of-band control signal.

In such a case, it is necessary to add an out-of-band control signal to the main signal (communication signal) and apply the same measures to the main signal itself as in the case of the out-of-band control signal described below.

FIG. 4 shows a second embodiment of the invention. In FIG. 4, 29 is an inter-receiving base station channel switching notice signal, 30 is a channel switching control signal, 31 is a channel switching completion first signal,
32 is a second channel switching completion signal. In this figure, the line control device of the transmitting base station first sends a reception start command signal 15 to the switching destination receiving base station, and in response, a reception start confirmation signal 1G is sent back. Upon receiving this signal 16, the line control device performs receiving line double connection processing 17. The process up to this point is the same as the embodiment shown in FIG. However, the demodulated output of the receiver of the switching destination receiving base station is cut off until the timing shown below.

Therefore, even if the receiving line double connection process is performed, the information actually transmitted to the exchange side is only the information from the switching source receiving base station. After performing 1T of processing, the transmitting base station uses an out-of-band control signal to send a channel switching notice signal 2 between receiving base stations.
9 to mobile station T. A specific pattern of an out-of-band control signal may be assigned to the signal 29. Mobile station is signal 2
9, it returns a channel switching control signal 30 to the receiving base station. Signal 30 is also an out-of-band control signal and is assigned a specific pattern. This signal is received by both the switching source receiving base station and the switching destination receiving base station.

When the switching source receiving base station receives this signal, the demodulated output of the receiver is changed from the connected state to the disconnected state. When the switching destination receiving base station receives this signal, the demodulated output of the corresponding receiver is changed from a disconnected state to a connected state. Since the two receiving lines are double-connected at the transmitting base station, they can be switched at the same timing by the above connection and disconnection switching operations.

The subsequent operations are almost the same as in the case of FIG. That is, the channel switching completion first signal 31 is sent from the switching destination receiving base station.
Also, a second signal 3 indicating the completion of channel switching from the switching source receiving base station.
2 is sent to the line control device. When the line control device receives the two signals, it knows that the channel switching has been successful. After this, based on the command from the line control device, the receiving line -
Type connection processing 19 is performed, a reception end signal 20 is sent, and all processing ends.

It is clear that even in the case of this embodiment, the double connection process can be omitted and channel switching can be performed with almost no momentary interruptions.

Although an example of a system configured with a transmitting base station and a receiving base station has been described above, almost the same can be said when the base station side equipment is a wireless base station having a transmitting and receiving function. This is the first
This will be explained using figures. In this case, the receiving base station in FIG. 1 is replaced with a radio base station, and the transmitting base station/line control device is replaced with a line control device. The control procedure is almost the same as in the first embodiment. In other words, the switching destination wireless base station is signal 15.
After receiving , it starts receiving radio waves, but does not transmit radio waves. The switching destination wireless base station transmits the signal 18 when radio waves of the required level are received, and starts transmission at this timing. In addition, in the double connection process of process 17, double connection process is performed for the lines for both transmission and reception. In the single connection process of process 19, the single connection process is performed for both transmission and reception lines. Further, when the switching source radio base station receives the signal 20, the transmission and reception at the corresponding transceiver is terminated. Other points are completely the same as the first embodiment, and there is no instantaneous interruption of received radio waves in this embodiment. Furthermore, with regard to the transmission radio waves, if the transmission start timing at the switching destination radio base station is made earlier than the transmission end timing at the switching source radio base station, instantaneous interruption will not occur. In this case, if momentary interruptions are allowed to occur in mobile station transmission signals, double connection processing may be performed only for base station transmission.

The same thing as above can be said about the embodiment shown in FIG.

In this case as well, the receiving base station in FIG. 4 is replaced with a radio base station, and the transmitting base station/line control device is replaced with a line control device. The control procedure changes are as follows.

When the switching destination wireless base station receives signal 15, the corresponding transceiver only starts receiving radio waves, but does not transmit them.

11) Upon receiving the signal 30, the switching destination wireless base station connects its transceiver and starts transmitting radio waves.

111) Upon receiving signal 30, the switching source wireless base station turns off its transceiver and ends radio wave transmission.

lv) In the double connection process 17, double connections are made for both transmission and reception lines. - type connection processing 19 is also performed for both sending and receiving lines.

It is clear that instantaneous interruptions can be avoided by the above processing.

〔Effect of the invention〕

As explained above, since the wireless base stations perform reception with temporal overlap, there is no signal interruption, and
This has the effect of improving communication quality.

[Brief explanation of drawings]

FIG. 1 is a sequence explanatory diagram showing an embodiment of the present invention;
FIG. 2 is a diagram explaining a space division switch, FIG. 3 is a diagram explaining out-of-band signals, FIG. 4 is a sequence diagram showing another embodiment of the invention, and FIG. 5 is a diagram showing the system configuration. , FIG. 6 is a sequence explanatory diagram showing an example of a conventional method. 1... Transmitting base station, 2 to 6φ/Φ/receiving base station, 7
... Mobile station, 8 ... Switching station, 9 ... Channel designation signal, 1o ... Reception start command signal, 11 ...
...Wireless section lower continuity test signal, 12...Wireless section upper continuity test signal, 13...Wireless continuity confirmation signal, 1
4...Reception end signal, 15...Reception start command signal, 16...Reception start confirmation signal, 1TΦ...Reception line double connection processing, 18...Connection confirmation signal, 19・
...Reception line-type connection processing, 2o...Reception end signal. Figure 1 Figure 2 Figure 3 Figure 5

Claims (3)

[Claims] (1) A wireless line is set up between the first radio base station and the moving mobile station, and a communication line is set up between the first radio base station and the line control device, so that the mobile station moves. A communication line is set up between the station and the switching center via a line control device, and as the mobile station moves, the active communication line is switched to a communication line via a second wireless base station. In the switching method, the wireless channel of the second wireless base station is made the same as the wireless channel of the first wireless base station, and the communication lines between the first and second wireless base stations and the switching center are connected in duplicate. , a method for switching a base station during a call, characterized in that after a wireless line is established between both the first and second wireless base stations and the mobile station, the communication line of the first wireless base station is disconnected. . (2) A wireless line is set up between the first radio base station and the moving mobile station, and a communication line is set up between the first radio base station and the line control device, so that the mobile station moves. A communication line is set up between the station and the switching center via a line control device, and as the mobile station moves, the active communication line is switched to a communication line via a second wireless base station. In the switching method, the wireless channel of the second wireless base station is made the same as the wireless channel of the second wireless base station, and the first and second wireless After the communication line between the base station and the switching center is double-connected, and a wireless line is established between the first and second wireless base stations and the mobile station, the first wireless base station connects the mobile station to the mobile station. The mobile station transmits a channel switching notice signal using an out-of-band signal to the wireless base station, and the mobile station that receives this signal sends a channel switching signal using an out-of-band signal to the wireless base station. 1. A method for switching a base station during a call, which comprises disconnecting a communication line of a first radio base station after receiving the signal, and connecting the demodulated output of a second radio base station. (3) A wireless line is set up between the first radio base station and the moving mobile station, and a communication line is set up between the first radio base station and the line control device, so that the mobile station moves. A communication line is set up between the station and the switching center via a line control device, and as the mobile station moves, the active communication line is switched to a communication line via a second wireless base station. In the switching method, the wireless channels of the first wireless base station and the second wireless base station are made the same, and the communication lines between the first and second wireless base stations and the switching center are connected in a double manner, After a wireless line is established with the mobile station at both the first and second wireless base stations, transmission starts from the second wireless base station and the first wireless base station's communication line is disconnected. A base station switching method during a call, characterized in that: