JP2726312B2 - Wireless channel switching control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a radio channel switching method in a digital mobile communication system using TDMA.

[Problems to be Solved by the Prior Art and the Invention] In a digital mobile communication system using TDMA, a mobile station corresponds to a radio channel allocated to itself (the radio channel here is designated by a frequency and a slot). Transmission of a signal outside the slot interferes with the communication of other mobile stations communicating in that slot, so the transmission timing of the mobile station is subordinately synchronized with the downlink signal from the base station,
It is necessary to prevent a plurality of mobile stations using the same frequency from transmitting radio waves at the same time.

Therefore, when the mobile station switches radio channels, it is necessary to perform a procedure of switching the receiving frequency to the frequency of the switching destination channel for reception until the switching destination channel can communicate, and establishing bit synchronization and frame synchronization of the mobile station. is there.

However, in the conventional channel switching method, the frequency is switched to a new frequency in order to synchronize the reception of the switching destination base station. Therefore, since the radio wave from the switching source base station is not received, the synchronization is lost. About a few slots are spent, and during that time, the communication is interrupted.

Further, when the mobile station switches the radio channel, if the mobile station switches to a radio channel other than the designated radio channel, there is a risk that the mobile station may interfere with another mobile station in communication.

Therefore, after confirming that the wireless channel designation from the base station side is performed accurately, and that the wireless channel that the mobile station is trying to switch to is the switching destination wireless channel,
It is necessary to take a safe method such as starting signal transmission on the switching destination wireless channel. As a specific method of performing this confirmation, it is certain that the mobile station actually switches to the radio channel and receives and confirms it. However, in order to switch to the designated radio channel, the current communication Has to be interrupted, so that there is a disadvantage that the time of the instantaneous interruption increases.

An object of the present invention is to provide a mobile communication system that enables a mobile station to switch a wireless channel without interrupting a line under communication in view of such a conventional problem.

[Means for solving the problem]

According to the present invention, the above objects are achieved by the means as set forth in the claims.

That is, according to the present invention, a mobile station and a base station exist in a service area, and a radio transmission path between the mobile station and the base station is provided with a plurality of slots by time-dividing the frequency, and the mobile station and the base station transmit signals. In a mobile communication system that performs transmission and reception of signals in slots allocated by time compression, the mobile station includes means for maintaining a plurality of bit synchronizations and frame synchronizations, and when switching a radio channel during communication, While maintaining the bit synchronization and the frame synchronization of the slot during communication in the mobile station, the other slots are switched to the frequency of the switching destination radio channel, and received at a bit independent of the slot during communication and frame synchronization timing,
This is a radio channel switching control method in which the mobile station starts transmitting an information signal to the switching destination base station after the reception bit of the switching destination radio channel and frame synchronization are established, and the switching destination base station is newly assigned a radio channel. Means to start transmitting an information signal after the mobile station confirms the signal, or at a time other than the slot where the mobile station is allocated for communication, The wireless channel switching control method includes means for switching to a frequency, transmitting a synchronization signal at least once at a timing of a slot allocated for switching, and then starting transmission of an information signal.

[Action]

The present invention relates to a digital mobile communication system using TDMA, in which a mobile station performing communication performs radio channel switching, a bit synchronization and frame synchronization with a radio of a switching destination base station are performed in advance in a part of a slot not used for communication. In addition to establishing synchronization, a wireless channel is switched after confirming a switching destination wireless channel.

This is different from the conventional technique in that it is possible to establish bit synchronization and frame synchronization with the switching destination base station radio and check the switching destination wireless channel without interrupting the line under communication.

〔Example〕

FIG. 1 shows an example of a system configuration diagram for implementing the present invention. This configuration is the same as the conventional case, and there is no particular change.

In the figure, reference numeral 21 denotes a mobile station that is communicating within the service area, 22 is a base station that is communicating with the mobile station, 23 is a base station adjacent to the base station 22, and 24 is a control station that controls the base station and the mobile station. , 25 is an exchange for switching the line, 26 is a line network, 27 is a control line, and 28 is a communication line.

FIG. 2 shows a signal configuration diagram of a three-channel TDMA system according to an embodiment of the present invention, in which first to third signals are temporally multiplexed.

In the figure, the transmission signal of the base station is multiplexed by time-compressing each frame of the first to third signals and adding a unique word (UW1 is identification information of the first slot) as slot identification information. It is a thing. The mobile station transmits a signal synchronized with the base station signal. For example, the first mobile station using the slot S1 can synchronize by transmitting a specific time α after the end of the slot S1 one frame before.

FIG. 3 shows a transmission / reception circuit configuration of a mobile station for implementing the present invention.

In the figure, 31 and 32 are speed conversion circuits, 33 is a decoding circuit, 34 is a timing circuit, 35 is an encoding circuit, 36 is a bit / frame synchronization circuit, 37 is a demodulation circuit, 38 is a modulation circuit, 39
Represents a control unit, and 40 and 41 represent local oscillators. Here, since it is necessary to synchronize two base stations between the switching destination and the switching source, the bit / frame synchronization circuit 36 has two independent phase synchronization systems, and is configured to be able to switch according to an instruction from the control unit 39. I have. This is because a means for describing a synchronization state such as a phase difference between a reference clock and a received signal, a frame timing phase difference, and the like built in the bit / frame synchronization circuit 36 allows one synchronization system to be connected to many base stations. It can also be used in a time-sharing manner.

The speed conversion circuits 31 and 32 have the demultiplexing function shown in FIG. 2, and the transmission side converts the transmission signal into one TDMA signal for each frame.
The time is compressed into slots, and the receiving side time-expands the received signal from one TDMA slot to the original frame.

In the following, in the system configuration shown in FIG. 1, the operation when the present invention is implemented when the mobile station switches the radio channel to shift from the switching source base station 22 to the zone of the switching destination base station 23 will be described. .

First, multi-transmission and multi-reception as a premise of the present invention will be described.

After determining that the switching of the radio channel is necessary and determining the switching destination wireless channel F2, the multi-transmission means that the switching station 25 simultaneously transmits the information signal to both the switching source base station 22 and the switching destination base station 23. Call.

At the same time, the switching destination base station 23
In F2, the reception operation is started, and “0000” is transmitted to the exchange in place of the received information signal until the mobile station 21 switches the radio channel and receives a valid signal from the mobile station. I do. That is, at this point, the received information is noise, and is not valid content, so that it is replaced with “0000”. When the mobile station 21 switches the radio channel to F2 and becomes able to receive the information signal at the switching destination base station 23, the switching destination base station 23 stops transmitting "0000" and transmits the received information signal as it is. Since the switching source base station 23 cannot receive the signal, it transmits "0000" instead of the information signal.

This can be realized by a fixed operation of replacing received information with a specific pattern when a reception condition such as a reception level when a signal is received by the base station does not satisfy certain conditions. The switching center 25 restores the information signal by finding the logical wheel of the signals from the switching source base station 22 and the switching destination base station 23. The operation in which the switching destination base station 23 and the switching source base station 22 try to receive signals from the same mobile station at the same time is called multiple reception.

By performing multi-transmission and multi-reception as described above, loss of an information signal due to inconsistency of switching timing between the exchange and the mobile station is prevented.

Hereinafter, the operation of the first embodiment of the present invention when switching to a slot after the slot of the wireless channel under communication will be described.

Change the frequency of the wireless channel of the switching source base station 22 to F1 (hereinafter, referred to as
The uplink frequency and the downlink frequency are collectively referred to as a frequency), the used slot is S1, the frequency of the switching destination wireless channel is F2, and the used slot is S3.

 An example of the signal at this time is shown in FIG.

In the figure, (a) is a transmission signal of the switching source base station,
(B) shows the transmission signal of the switching destination base station, (c) shows the reception signal of the mobile station, (d) shows the transmission signal of the mobile station, and (e) shows the radio frequency of the mobile station.

These indications (a) to (e) correspond to a fifth
The same applies to FIG. 7, FIG. 7, and FIG.

Here, since three-channel TDMA is taken as an example, the configuration is a three-slot configuration, in which the switching source base station uses slot S1 and the switching destination base station uses slot S3.

After starting the channel switching operation and starting multi-transmission and multi-reception of signals at the exchange station and the base station, the base station transmits a radio channel designation signal to the mobile station.

At this time, in FIGS. 4 (a) and 4 (b), the same information signal is transmitted because of multi-transmission.

Since the mobile station receives the signal in slot S1 at frequency F1, it receives, but does not receive. signal,
That is, upon receiving the radio channel designation signal from the base station side in the slot as the mobile station reception signal, the mobile station immediately switches the frequency to F1 (see FIG. 4 (e)),
The operation for establishing synchronization is started while receiving the signal. If the synchronization is established here, the signal of F2 and slot S3 may be received as it is, but if the synchronization has not been established yet, once the F1
Return and receive in slot S1. Before switching to F2 for the first time so that it goes smoothly, the synchronization of slot S1 is stored. That is, the frequency is switched to F2 after storing the reception synchronization with the switching source base station 23, the bit synchronization is established and the unique word is detected from the signal transmitted by the switching destination base station 23. The position of the S3 slot of the switching destination base station 23 is calculated, and the reception bit synchronization and the frame synchronization are established.

FIG. 4C shows a case where the signal is established in the middle of the signal. Then, from the next TDMA frame for which the reception synchronization has been established, the switching destination base station 23 is switched to a new frequency F2 and slot S3.
Communicates with In FIG. 4, this means that a signal has been received.

As described above, after confirming that the wireless channel switching has been completed, the multi-transmission and the multi-reception are terminated to release the switching source line and the wireless channel, and the control of the wireless channel switching is terminated.

Next, an operation for switching to a slot earlier than the slot of the communicating wireless channel, which is the opposite of the above case, will be described.

The frequency of the communicating wireless channel is F1, the slot is S3,
The frequency of the wireless channel to be switched to is F2, and the slot is S2.
And FIG. 5 shows a signal example at this time. The frequency and the slot are the same as in the example of FIG. 4, but the difference here is the same as in the case of the base station transmission signal. That is, the difference is that a signal is sent earlier to the switching destination base station.

After deciding that the radio channel switching is necessary and determining the switching destination radio channel, the exchange and the base station start multi-transmission and multi-reception of the signal as described above, and then specify the radio channel to the mobile station. . F1 for mobile stations,
Although the signal is transmitted from slot S1, the channel designation signal is transmitted here.When the signal is received, the signal is received in slot S1 of the signal and received with the switching source base station as in the previous example. Switch the frequency to F2 while keeping the synchronization. Then, the bit synchronization is extracted from the signal transmitted by the switching destination base station and the unique word is detected,
From the result, the position of the S2 slot of the switching destination base station is calculated, and the operation of establishing the received bit and frame synchronization is performed. Since the signal is transmitted during this time, the signal is returned to F1 and S1 to receive the signal. After receiving, switch to F2 again to perform the synchronization establishment operation. During this time, the signal is not received correctly, so that the signal cannot be received correctly, so that the reception synchronization is stored and returned to F1, S1, and after reception, F2,
Return to S3.

Then, from the next TDMA frame for which the reception synchronization has been established, the wireless channel is switched to perform communication with the switching destination base station. Compared with the case of FIG. 4, the switching destination base station is different from that of FIG. 4 in that the signal is transmitted earlier, so that it is necessary to switch back to F1 one more time.

Then, after confirming that the wireless channel switching has been completed, the multi-transmission and the multi-reception are terminated, the switching source line and the wireless channel are released, and the control of the wireless channel switching is terminated.

By performing the control as described above, it is possible to establish the reception bit of the signal from the switching destination base station, the frame synchronization, and perform the communication with the switching destination base station without interrupting the communication with the switching source base station. it can.

 Next, a second embodiment of the present invention will be described.

In the first embodiment, when it is difficult to establish high-speed reception synchronization at the switching destination base station, and when the first slot cannot be received, reception synchronization is established at the mobile station at the time of wireless channel switching control. An effective method is to transmit a synchronization signal to the base station later, establish reception synchronization at the switching destination base station, and then control the mobile station to switch the radio channel. As shown in FIG. 6, the synchronization signal is composed of a preamble for clock recovery and a unique word (UW) for slot number identification and synchronization signal recognition.

As shown in the figure, a guard time is provided before and after an uplink synchronization signal, and a guard bit is provided before and after a downlink synchronization signal, so that synchronization can be performed even when there is a frame phase difference or frequency switching time between base stations. Can send and receive signals.

Also, when switching the radio channel, if the mobile station starts transmission at the wrong frequency, it may interfere with other communications, so make sure that it is the radio channel designated for radio channel switching. When it is necessary to take such a secure procedure, it is effective to transmit a specific signal indicating that the channel is the switching destination channel from the base station and confirm the specific signal at the mobile station before performing the switching operation. is there.

In this case, the specific signal plays a role as a signal for synchronization. Further, a method is used in which the switching destination base station transmits a mobile station confirmation number for identifying the mobile station transmitting on the switching destination wireless channel, and the mobile station confirms the signal to confirm the switching destination wireless channel. If this is the case, more reliable switching becomes possible.

When the mobile station confirmation number is a mobile station number or a part thereof, or a random value, the mobile station determines one of the base stations and notifies the other on the channel before switching, and if the base station determines the The notification may be made simultaneously with the channel designation signal.

An example of transmitting a specific signal at the time of channel switching will be described below.

First, an operation in the case of switching to a slot after the slot of the communicating wireless channel will be described.

The frequency of the wireless channel being communicated is F1, the slot is S1,
The frequency of the wireless channel to be switched to is F2, and the slot is S3.
And FIG. 7 shows a signal example at this time.

First, the signal is transmitted in F1 of the signal from the switching destination base station and in slot S1. The switching destination base station transmits not the information signal but the synchronization signal in F2 and S3.

That is, after determining that the wireless channel needs to be switched and determining the wireless channel to switch to, the exchange performs multi-transmission and multi-reception of signals as shown in the first embodiment. Until the synchronization is established, instead of the information signal from the exchange, a downlink synchronization signal,
Send…. The switching source base station designates a radio channel to the mobile station in the case of a signal, for example. In mobile stations,
Upon receiving the radio channel designation signal from the base station in the signal slot S1, the frequency is immediately switched to F2 while the reception synchronization with the switching source base station is stored, and the downlink transmission is performed by the switching destination base station. , The frame synchronization is established by detecting the bit synchronization and the unique word, the mobile station confirmation number is confirmed, and the reception synchronization of the switching destination base station is stored. Then, the frequency is returned to F1 in order to receive the information signal before the signal slot S1, and the signal in the reception synchronization of the switching source base station stored earlier is received in the signal slot S1. Switch to F2 immediately after receiving,
And an uplink synchronization signal is transmitted.

When the switching destination base station receives the synchronization signal,
From the TDMA frame, transmission of an information signal from the exchange is started in place of the downlink synchronization signal.

That is, in FIG. 7, the same information signal is transmitted as the signal. The mobile station also communicates with the switching destination base station from the next TDMA frame after transmitting the uplink synchronization signal to the switching destination base station. Then, after confirming that the wireless channel switching has been completed, the multi-transmission and the multi-reception are terminated to release the switching source line and the wireless channel, and the control of the wireless channel switching is terminated.

Next, the operation when switching to a slot before the slot of the communicating wireless channel will be described.

The frequency of the communicating wireless channel is F1, the slot is S3,
The frequency of the wireless channel to be switched to is F2, and the slot is S2.
And FIG. 8 shows an example of the signal at this time.

After determining that the wireless channel needs to be switched and determining the wireless channel to switch to, the switching center performs multi-transmission and multi-reception of signals as shown in the first embodiment, and synchronization is established at the switching destination base station. In the meantime, instead of the information signal from the exchange, a downlink synchronization signal is transmitted, and then a radio channel is specified to the mobile station. The mobile station receives a signal from the mobile station that is communicating on the frequency F1 and the slot S1, but when the channel designation signal is transmitted here, the mobile station receives the signal and receives the signal as in the previous example. The frequency is switched to F2 while receiving the reception synchronization with, and the downlink synchronization signal transmitted by the switching destination base station is received. Then, frame synchronization is established from the detection results of the bit synchronization and the unique word, the mobile station confirmation number is confirmed, and the reception synchronization of the switching destination base station is stored. Then, the frequency is returned to F1 before the signal slot S1, and the signal in the reception synchronization of the switching source base station stored earlier is received in the signal slot S1. At the time of the signal in the slot S3, the mobile station transmits an uplink synchronization signal to the switching destination base station at the timing of reception synchronization of the switching destination base station, and the signal slot S3
Then, the signal of the slot S1 of the switching source base station is received.
When the switching destination base station receives the uplink synchronization signal in slot 3, it starts transmitting the information signal from the exchange instead of the synchronization signal from the next TDMA frame.

That is, in FIG. 8, the signal of slot 1 transmitted from the switching source base station and the signal of slot 3 transmitted from the switching destination base station are the same information signal. The mobile station communicates with the switching destination base station from the next TDMA frame after transmitting the synchronization signal to the switching destination base station. Then, after confirming that the wireless channel switching has been completed, the multi-transmission and the multi-reception are terminated to release the switching source line and the wireless channel.

In the above description, an example in which the synchronization signal is transmitted only once is shown. However, a method of performing switching after performing a predetermined number of times of transmission according to the synchronization method or the signal transmission reliability may be used. . In this case, the switching destination base station transmits an information signal from the exchange in place of the downlink synchronization signal from the next TDMA frame that has received the uplink synchronization signal, and operates the multi-reception circuit, Until the mobile station finishes transmitting the synchronization signal up the specified number of times,
Since “0” is transmitted, the above-described switching control can be performed without strictly managing the switching timing of the mobile station.

Alternatively, a method may be used in which the remaining synchronization transmission frequency is added to the uplink synchronization signal, and the mobile station switching timing is notified to the base station.

When performing the above control, depending on the assigned slot, the slot of the used wireless channel and the slot of the wireless channel assigned for switching overlap on the time axis, and the mobile station cannot receive the downlink synchronization signal. Sometimes.

In such a case, switching between slots in the same transceiver can be performed relatively easily because there is no need to resynchronize, and therefore, the slots are switched at the switching destination base station so that they do not overlap. By opening a slot, or by performing slot switching at the switching source base station and moving to a non-overlapping slot before switching,
The switching control of the second embodiment can be performed.

FIG. 9 is a diagram showing an example in which slot switching is performed in order to perform switchable slot arrangement, in which (a) shows an example in which slot switching is performed in the switching destination base station, and (b) shows an example in which switching source base station is switched. An example in which a station performs slot switching is shown.

In the figure, a slot in which a mobile station performing wireless channel switching is communicating is denoted by A. As shown in FIG. 9 (a), in the case where the currently communicating slot is S1 and the wireless channel of the switching destination is also used other than S1, first switch S3 to S1 on the wireless channel of the switching destination. By leaving S3, a non-overlapping slot can be allocated between the switching destination and the switching source, and wireless channel switching can be performed.

Further, as shown in FIG. 9 (b), if the currently communicating slot is S2 and the wireless channel of the switching destination is other than S2, and S3 of the switching source wireless channel is vacant, First, it is also possible to switch S2 to S3 in the switching source wireless channel, move to a slot that does not overlap with the slot of the switching destination wireless channel, and then switch the wireless channel.

Also, in the method of performing slot switching at the time of wireless channel switching, when the control load is concentrated at the time of wireless channel switching and the processing capacity of the control unit becomes a problem, or when it is necessary to switch immediately after determining switching, The following control method is effective.

That is, when another communication is completed in the same wireless channel during communication, and the mobile station communicating in the last slot of the wireless channel has a vacant slot before the communicating slot. If control is performed to switch to that slot, the mobile station in communication performs communication in the front slot, and the probability of the rear slot becoming an empty slot increases. The probability of overlapping on the axis can be reduced.

Only when the slots are overlapped even when the above control is performed, the method of performing the slot switching at the time of the wireless channel switching is used, so that the control load at the time of the wireless channel switching is reduced, and the high-speed wireless channel Switching can be performed.

FIG. 10 shows an example of slot switching at this time. As shown in FIG. 10 (a), slots S1,
When S2 and S3 are used and communication in S2 ends,
The mobile station in communication with S3 releases S3 by switching the radio channel to S2, and vacates the rear slot. (B)
As shown in the figure, only S1 and S2 are used for communication and S1
When the communication is completed, the last S2 is replaced by S1.
Clear the rear by switching to. Contrary to this method, a method is also effective in which control is performed in such a manner that the subsequent slots are sequentially switched to open the front slot.

Further, when the transmission timings of the respective transmitters in the base station coincide with each other, the switching of the transceivers in the same base station can be relatively easily performed. It is also possible to temporarily switch to another carrier in the same base station (here, the carrier is determined by frequency) and then switch to the corresponding radio channel.

 The switching procedure at this time is shown in FIG.

As shown in FIG. 11, when the slot of the switching source radio channel is also S1 in the slot S1 of the switching source radio channel, S2 and S3 are used for other communication in the switching source radio channel and other carriers in the same base station. If S3 is empty,
First, by switching to the slot of S3 in the same base station, switching to S1 of the switching destination wireless channel can be performed.

When the synchronization between the base stations is not established or the synchronization is incomplete, if the frame timing difference or the transmission delay time difference in the radio section is large, the base station receives the signal of the mobile station before switching in advance and performs switching. Determine possible slots. If it is difficult and the mobile station cannot switch to the slot specified by the base station, the mobile station notifies the base station of a switchable slot, and the base station notifies the base station of the available slot. A method of selecting a channel and assigning it to the mobile station, or notifying the base station that switching cannot be performed, and allowing the mobile station to switch from the position of the slot previously allocated by the base station A switchable slot can be allocated by estimating a proper slot and allocating another wireless channel again.

In addition, while performing the wireless channel switching several times, the base station side can determine the slot arrangement that can be switched by the switching source base station and the switching destination base station from the switching availability information from the mobile station. A switchable slot can be allocated in advance on the side.

Further, by receiving a control channel of the switching destination base station or an appropriate communication channel of the switching destination base station within the idle time slot at the mobile station, determining a switchable slot from the frame timing of the switching destination base station, If a method of notifying a switchable slot from a mobile station before allocating a wireless channel is used, a switchable slot can be allocated in advance from the base station side.

The case where the communication line is switched in the exchange has been described above, but the present invention is also applicable to the case where the transceiver is switched in the base station.

In the above description, an example in which the same slot is used for transmission and reception has been described. However, when transmission and reception are performed in different slots or when the frame timing of a signal from the base station to the mobile station and the signal from the mobile station to the base station are different. Even when the frame timings do not match, the above control can be performed by switching the frequency independently of transmission and reception.

〔The invention's effect〕

As described above, according to the method of the present invention, when wireless channel switching is performed, without interrupting communication with the switching source base station, bits between the switching destination base station and frame synchronization are established, In addition, since the switching destination wireless channel is checked, there is an advantage that the wireless channel can be switched without interrupting the communication.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a system configuration for implementing the present invention,
FIG. 2 is a diagram showing a signal configuration of a three-channel TDMA system.
FIG. 4 is a diagram showing an example of a transmission / reception circuit configuration of a mobile station for carrying out the present invention. FIGS. 4, 5, 7, and 8 show examples of signals when the present invention is carried out. FIG. 6, FIG. 6 is a diagram showing a synchronizing signal for carrying out the present invention, FIG. 9 is a diagram showing an example in which slot switching is performed to perform switchable slot arrangement, and FIG. FIG. 11 is a diagram illustrating an example in which slot switching is performed, and FIG. 11 is a diagram illustrating an example in which carrier switching within the same base station is performed to perform switchable slot arrangement. 21 ... mobile station, 22, 23 ... base station, 24 ... control station, 25 ...
... Exchange, 26 ... Network, 31, 32 ... Speed conversion circuit, 33
... Decoding circuit, 34 timing circuit, 35 encoding circuit, 36 bit / frame synchronization circuit, 37 demodulation circuit, 38 modulation circuit, 39 control unit, 40, 41 Local oscillator

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masaharu Hata Examiner, Nippon Telegraph and Telephone Corporation, Satoshi Sato, 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo (56) References JP-A-2-164141 (JP, A )

Claims (3)

(57) [Claims] A mobile station and a base station exist in a service area, and a radio transmission path between the mobile station and the base station is provided with a plurality of slots by dividing a frequency by time, and a signal is transmitted between the mobile station and the base station. In a mobile communication system that performs transmission and reception of signals within slots allocated by time compression, the mobile station includes means for maintaining a plurality of bit synchronizations and frame synchronizations, and when switching a radio channel during communication, While maintaining the bit synchronization and frame synchronization of the slot being communicated at the mobile station, the other slots are switched to the frequency of the switching destination radio channel, and the bits are received independently of the slot being communicated at the frame synchronization timing, and the switching is performed. A radio channel characterized in that the mobile station starts transmitting an information signal to the switching destination base station after the reception bit and frame synchronization of the destination radio channel are established. Switching control method. 2. A switching destination base station transmits a signal in a corresponding slot of a newly allocated radio channel, and after the mobile station confirms the signal, starts transmission of an information signal.
2. The wireless channel switching control method according to claim 1. 3. A mobile station switches to a frequency of a radio channel to be switched at a time other than a slot allocated for communication and transmits a synchronization signal at least once at a timing of a slot allocated for switching. The wireless channel switching control method according to claim 1, wherein transmission of the information signal is started.