JPH0287727A - Channel switching system during communication - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides TDMA digital mobile communications, while maintaining the continuity of communication information while taking into consideration the time required to switch carriers of transmitters and receivers. The present invention relates to a channel switching method during communication that switches a communication channel to another channel without momentary interruption.

(Prior art) In TDMA digital mobile communications, when a mobile device moves during communication and a situation occurs where the communication channel must be switched to another radio base station, the communication channel is changed due to a zone change. Channel switching is being performed (hereinafter referred to as channel switching during inter-zone communication). In addition, even though the mobile device remains in the same zone, if, for example, the propagation characteristics of the carrier deteriorate, channel switching is performed during communication (hereinafter referred to as "same zone self-communicating channel switching"). .

FIG. 8 is a block diagram of a conventional mobile communication system, and FIG. 9 is a diagram showing a conventional channel switching sequence during communication.

In FIG. 8, 1 is a mobile communication switching center; 2. ．． 22 is a wireless base station, 3 is a mobile device, 4. ．． 42°43 is a transmitting device,
50,5□,5. is a receiving device, 6 is a terminal, 7, . 72.
73 is a wireless channel control device, 8 is a memory switch, 1
0, , 102.103.104 are control signal circuits, 1
1. .

112 is a communication channel; 12. ．． 122 is a control channel.

13 is a channel switching control device. Next, Figures 8 and 9
A conventional method after channel switching during inter-zone communication will be explained using figures.

Mobile device 3 uses communication channel 110. Using the control channel 121, the wireless base station 2. During communication, the wireless base station 2. When the wireless base station 2 detects a decrease in the signal level, the wireless base station 2
1 transmits a communication channel switching request signal to the mobile communication switching center 1 and notifies it. When the mobile communication switching center 1 receives the communication channel switching request signal, it notifies the wireless base stations in the surrounding zones of the zone 1 to monitor the radio wave level of the channel used by the mobile device 3. The wireless base stations in the surrounding zones notify the mobile communications switching center 1 of the monitoring results. Based on this result, the mobile communication switching center 1 determines the radio base station 22 to which the mobile device 3 will switch channels. The mobile communication switching center 1 determines an arbitrary vacant communication channel among the communication channels held by the channel switching destination radio base station 2□ as the switching destination communication channel +12. The mobile communication switching center 1 transmits a communication channel setting instruction signal to the switching destination radio base station 22. Next, the mobile communication switching center 1 transmits the wireless base station 2
A communication channel switching instruction signal is sent to highway 2, control channel 12 . Transmit via. When the mobile device 3 receives the communication channel switching instruction signal,
The channels are immediately switched to the switching destination communication channel II2 and the switching destination control channel 12□. After the switching is completed, the mobile device 3 transmits a communication channel switching completion signal to the switching destination radio base station 22 and the mobile communication switching center l via the control channel 12□. The mobile device 3 then uses the communication channel 112 . Communication is performed using the control channel 12□. Further, after receiving the communication channel switching completion signal, the mobile communication switching center 1 switches the old communication channel 11. and old system channel 12. to release.

This embodiment presents channel switching during inter-zone communication.

In the above embodiment, the wireless base station 2□
By replacing it with 1, it is possible to easily adapt to the same zone's own communication channel after switching.

(Problems to be Solved by the Invention) In the conventional channel switching method during communication, communication channels are switched according to the above procedure.

Mobile communication switching center 1, wireless base station 2. ．． 22, all mobile devices 3 switch from the communication channel II to the switching destination communication channel 1
Time Tc required to switch channels to 12
(hereinafter referred to as channel switching time), time interval Td between the communication channel and the communication channel after channel switching
(hereinafter referred to as channel interval time) is the relationship Tc≦Td
If so, carrier switching is possible within the Td time, so channel switching can be performed without interruption (Fig. 1O). However, when Tc > Td, channel switching is not completed in time for the switching destination channel of the next frame, resulting in an instantaneous interruption of one frame or more (Figure H).

In the conventional technology, the switching destination communication channel 112 was selected without considering the mutual magnitude relationship between Tc and Td.
A momentary interruption occurs when switching channels during communication. The present invention aims to prevent this instantaneous interruption.

(Means for Solving the Problems) The characteristics of the present invention are TDMA (Time div
The wireless line terminal device is equipped with a plurality of wireless line terminal devices that transmit and receive information using a communication method (multiple access) and a channel control device that controls the TDMA channels used by the wireless line terminal devices. Alternatively, in a method of seamlessly switching information to channels in different TDMA frames, the time interval (Td) between the currently communicating channel in the currently communicating frame and the channel after channel switching in the next frame is defined as the switching time of the synthesizer, A channel switching scheduling device and a channel switching control device are provided to select a channel after channel switching so that the channel switching time (Tc) including carrier synchronization time, frame synchronization time, and bit synchronization time is longer, and the channel switching time Tc is longer than the channel switching time (Tc). When the channel time interval is greater than Td, the communication channel is temporarily switched to a temporally earlier temporary TDMA channel in the next TDMA frame within the same carrier;
Next, the target T of the carrier that targets the temporary channel is
It is a channel switching method during communication that switches to a DMA channel without momentary interruption.

Another feature of the invention is that TDMA (Timed
It is equipped with a plurality of wireless line termination devices that transmit and receive information using a communication method (multiple access), and a channel control device that controls the TDMA channels used by the wireless line termination devices, and the communication channels are connected within the same TDMA frame. Alternatively, in a method of seamlessly switching information to channels in different TDMA frames, the time interval (Td) between the currently communicating channel in the currently communicating frame and the channel after channel switching in the next frame is defined as the switching time of the synthesizer, comprising a channel switching scheduling device and a channel switching control device that select a channel after channel switching so that it is longer than a channel switching time (Tc) including carrier synchronization time, frame synchronization time, and bit synchronization time,
When the channel switching time Tc is greater than the channel time interval Td, the channel to be switched is first switched to the next T in the same carrier.
First tentative TD in time direction in DMA frame
Switching once to the MA channel; 1) Switching to a second temporary TDMA channel temporally later than the switching destination channel in the TDMA frame of the carrier intended for the first temporary channel; It is a channel switching method during communication in which the channel is switched to the target TDMA channel of the target carrier without momentary interruption.

(Function) The present invention includes a channel switching scheduling device and a channel switching control device, and when the relationship between the channel switching time Tc and the channel time interval Td is Tc≦Td, switching is performed in the same procedure as the conventional method, and Tc>Td. In this case, switch to the temporary channel of the previous time slot of the same carrier, and then switch to the target time slot of the target carrier. Furthermore, if a momentary interruption cannot be avoided even with this method, switch to the first temporary channel of the previous time slot of the same carrier,
Next, it switches to the second provisional channel in the later time slot of the target carrier, and further switches to the [1st temporary channel] of the target carrier.

Note that although the switching time between channels on the same carrier is short, the switching time when switching to a channel on a different carrier is relatively long.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a mobile communication system showing an embodiment of the present invention, and FIG. 2 is a block diagram of a mobile communication switching center.
3 and 5 are diagrams showing a channel switching sequence during communication, and FIGS. 4 and 6 are diagrams showing specific effects of channel switching during communication.

In FIG. 1, 1 is a mobile communication switching center; 2. ．． 22 is a wireless base station, 3 is a mobile device, 45.4□, 43 is a transmitter,
51.5□, 53 is a receiving device, 6 is a terminal, 7. ．． 7. ．．
73 is a radio channel control device; 8 is a memory switch; 9
10. is a channel switching scheduling device; ．． 10□
.

103.104 is a control signal circuit, 111.112 is a communication channel, +2. , +2□ are control channels, and 13 is a channel switching control device. In FIG. 6, 15. ．． 1
52 is a memory switch; 16 is a switch write control circuit (counter); 17. ．． 172 is a switch readout control circuit (counter), 181, 182, 183, 18
4 is a serial/parallel converter, 19 is an input time division multiplex highway, 20 is an output time division multiplex highway, 21
is a control signal processing device.

The uninterrupted channel switching procedure will be explained based on FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. 6. This example shows an inter-zone channel switching procedure.

The intra-zone channel switching procedure is the same if the radio base station 2□ is regarded as 21.

The mobile device 3 connects to the radio base station 2 through the communication channel II, control channel +21. During communication using the wireless base station 2. When detecting a decrease in the signal level, it notifies the mobile communication switching center 1 by transmitting a communication channel switching request signal. When the mobile communication switching center 1 receives the communication channel switching request signal, it notifies the radio base stations in the surrounding zones of the zone 1 to monitor the radio wave level of the channel used by the mobile device 3. The radio base stations in the surrounding zones notify the mobile communications switching center l of the monitoring results. Based on this result, the mobile communication switching center 1 determines the radio base station 22 to which the mobile device 3 will switch channels. The mobile communication switching center 1 is the mobile communication switching center among the communication channels owned by the switching destination wireless base station 22! , the radio base station 21, 22, and the mobile device 3 (channel switching time Tc) are longer than the channel interval time Td from the communication channel II to the switching destination communication channel 11□. The vacant channel is determined as the switching destination communication channel 112. if,
If there is no free channel that satisfies this condition, the free channel with the largest channel interval time Td is determined as the switching destination channel 112.

The channel switching scheduling device 9 in FIG. 2 selects one of the following three types of channel switching procedures based on the relationship between the channel switching time Tc and the channel interval time Td.

■Td>Tc: Switch the communication channel using the conventional procedure.

■'rd'>Tc≧: Switch the communication channel according to the procedure shown in FIGS. 3 and 4.

■Td”>Tc≧Td: Communication channels are switched according to the procedure shown in FIGS. 5 and 6.

However, Td' is the communication channel 11. is transferred to a temporally earlier TDMA channel (channel switching channel C+) within the same carrier, the channel interval time between the channel switching channel CI and the switching destination communication channel 112 is shown. Td” indicates the channel interval time between the channel switching channel C3 and a TDMA channel (channel switching channel C2) that is within the same carrier as the switching destination communication channel +12 and is later in time.Channel switching channel C ,, Possible methods for selecting the position of C2 include random selection from available channels, and reserving the temporally leading and final channels of the TDMA frame for channel switching. A method is used in which the first and last channels are reserved as channels C1 and 62 for channel switching.

When the relocation scheduling device 9 selects the procedure (2), the conventional channel switching shown in FIG. 9 is performed.

Next, the procedure (2) will be explained using FIGS. 3 and 4.

If the channel switching scheduling device 9 of the mobile communication switching center 1 or the channel switching procedure of
．． A channel C for channel switching and a switching instruction signal are transmitted to the mobile device 3 via the channel C. When the radio base station 21 and the mobile device 3 receive the instruction signal, they switch the channel to the channel switching channel C1, and the mobile device 3 switches the channel to the mobile communication switching center 1 via the radio base station 21 to the channel switching channel C1. Transmit a completion signal. The mobile communication switching center 1 is a wireless base station 2
．． to old communication channel 11. After transmitting the release request signal, the wireless base station 2. communication channel II to mobile device 3 via
A communication channel switching instruction signal is transmitted to switch the channel to 2. Upon receiving this signal, the mobile device 3 immediately switches from the channel switching channel C3 to the switching destination channel 11□
Switch the channel to . Thereafter, the mobile device 3 notifies the mobile communication switching center 1 of a communication channel switching completion signal via the radio base station 22. The mobile communication switching center 1 notifies the wireless base station 2I of a channel switching channel C8 release request.

In this way, the mobile device 3 connects to the communication channel It2.
Channel switching is performed without interruption via the radio base station 2°.

Finally, the procedure (2) will be explained using FIGS. 5 and 6.

If the channel switching scheduling device 9 of the mobile communication switching center 1 or the channel switching procedure of A channel switching instruction signal [;1 switching instruction signal is transmitted to the mobile device 3 via the station 21. When the radio base station 21 and the mobile device 3 receive the instruction signal, they switch the channel to the channel switching channel C1. , the mobile device 3 transmits a channel switching channel C1 switching completion r signal to the mobile communication switching center 1 via the radio base station 21.The mobile communication switching center 1 requests the radio base station 21 to release the old communication channel II. The mobile communication switching center 1 transmits the channel C2 switching instruction No. 5 for channel switching to the mobile device 3 via the radio base station 21. Upon receiving the switching instruction signal, station 2゜ and mobile device 3 immediately switch the channel to channel switching channel C2, and mobile device 3 sends a channel switching completion signal to mobile communication switching center 1 via radio base station 2□. The mobile communication switching center 1 transmits the channel C for channel switching to the radio base station 21.
5 release request and release the channel switching channel C1. In addition, the mobile communications switching center engineer, J! ! A communication channel switching instruction signal is transmitted from the channel switching channel C2 to the switching destination channel 11□ to the mobile device 3 via the line base station 22. Immediately after receiving this switching instruction signal, the radio base station 2 and mobile device 3 switch the channel to 112, and complete the communication channel switching (transmit No. After receiving the channel switching completion signal, the mobile communication switching center 1 transmits a channel switching channel C2 release request to the radio base station 2□, and releases the channel switching channel C2.

In this way, the mobile station 3 is connected to channel II.

to communication channel l12, channel switching channel C
, , C2 is used to perform channel switching without momentary interruption.

On the other hand, in the present invention, the mobile communication switching center 1 has the configuration shown in FIG. This configuration is obtained by adding a channel switching schedule link device 9 and a channel switching control device 13 to the configuration described in Japanese Patent Application No. 61-215647 (devices surrounded by dotted lines), and the channel switching schedule link device 9 and the channel switching control device 13 are added to This is a switching method that enables switching without interruption. Communication Channel 11. , channel switching channel [;1, channel switching channel C2, and then to the communication channel 112. At the same time, the channels are time-divided into different time slots of the incoming time division multiplex highway 197, and the memory switch 15. , adds to +52. This call,
It is possible to replace them all in the same frame without interruption on the exit time division multiplex highway 20F.

This embodiment relates to inter-zone channel switching, and detects a low signal level at a radio base station to reduce signal quality. It is also applicable to internal channel switching.

Further, in this embodiment, in step 2, a channel switching instruction signal is transmitted each time the communication channel is switched to the channel switching channels C, , C2 and the switching destination communication channel II2. In contrast, the switching channel information and switching timing are transmitted to the wireless station 2. ．． It is also possible to transmit the data all at once to 22 and the mobile device 3, and perform channel switching using a countdown method (FIG. 7).

(Effects of the Invention) As described in 1-1 above, according to the present invention, by switching the TDMA channel once or twice on the same carrier, it is possible to achieve instantaneous interruption of TDMA channel switching.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram showing the configuration of a digital TDMA mobile communication system of the present invention, FIG. 2 is a diagram showing the configuration of a mobile communication switching center of the present invention, and FIG. , FIG. 4 is a diagram showing a channel switching sequence in digital TDMA mobile communication according to an embodiment of the present invention, FIG. 4 is a diagram showing TDMA mobile communication channel switching according to an embodiment of the present invention, and FIG. FIG. 6 is a diagram illustrating a TDMA mobile communication channel switching sequence according to an embodiment of the present invention.
A diagram showing mobile communication channel switching, FIG. 7 is a diagram showing a TDMA mobile communication channel switching sequence using a countdown method, and FIG. 8 is a diagram showing a conventional digital TDM
FIG. 9 is a diagram showing the configuration of mobile communication system A, FIG. 9 is a diagram showing a channel switching sequence in conventional digital TDMA mobile communication, FIG. 1O is a diagram showing TDMA mobile communication channel switching, and FIG. FIG. 2 is a diagram illustrating a case where a momentary interruption occurs in conventional TDMA mobile communication channel switching. 1...Mobile communication switching center, 23.2□...Radio base station, 3...Mobile device, 41,4□, 4,
l-...Sending device, 5I, 5□, 53...Receiving device, 6...Terminal, 71.7□, 73...Radio channel control device, 8...Memory switch, 9. ...Channel switching scheduling device, 01, +
02. +03i04-:l+' control signal circuit, 1,,I
I□...Communication channel, 2, +2□...Control channel, 3...Channel switching control device, 5+, 152...Memory switch, 6...Switch JT reading control circuit (counter) ,7
,,+72...Switch readout control circuit (counter)
, L, 182, 183. IL”・Serial/parallel converter, 9...Person side time division multiplex 1 [Highway, 20
-... Exit time division multiplex highway, 21... Control signal processing device. highway 1

Claims (2)

[Claims] (1) TDMA (Time division multi
It is equipped with a plurality of wireless line termination devices that transmit and receive information using a communication method (please access), and a channel control device that controls the TDMA channels used by the wireless line termination devices, and the communication channel is divided within the same TDMA frame or In a method for switching information to channels in different TDMA frames without momentary interruption, the time interval (T
d), synthesizer switching time, carrier synchronization time,
It is equipped with a channel switching scheduling device and a channel switching control device that select a channel after channel switching so that it is longer than a channel switching time (Tc) including a frame synchronization time and a bit synchronization time, and the channel switching time Tc is a channel time interval Td. When the communication channel is transferred to the next TDMA within the same carrier
A communication channel switching method characterized by switching without momentary interruption by first switching to a temporally earlier temporary TDMA channel in a frame, and then switching from the temporary channel to the target TDMA channel of the target carrier. . (2) TDMA (Time division multi
It is equipped with a plurality of wireless line termination devices that transmit and receive information using a communication method (please access), and a channel control device that controls the TDMA channels used by the wireless line termination devices, and the communication channel is divided within the same TDMA frame or In a method for switching information to channels in different TDMA frames without momentary interruption, the time interval (T
d), synthesizer switching time, carrier synchronization time,
It is equipped with a channel switching scheduling device and a channel switching control device that select a channel after channel switching so that it is longer than a channel switching time (Tc) including a frame synchronization time and a bit synchronization time, and the channel switching time Tc is a channel time interval Td. The switched channel is initially switched to the next T in the same carrier
the temporally forward first temporary TD in the DMA frame;
Switch once to the MA channel, then switch to a second temporary TDMA channel temporally later than the switching destination channel in the TDMA frame of the target carrier for the first temporary channel, and then switch to the second temporary TDMA channel temporally later than the switching destination channel. A channel switching method during communication characterized by switching without momentary interruption by switching a channel to a target TDMA channel of a target carrier.