JP2664830B2 - Switching channels during communication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication channel switching control method suitable for a mobile communication system having a minimum zone configuration.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration diagram of a mobile communication system. 3 is a mobile station, 1 is an old radio zone in which the mobile station is communicating, 2 is a new radio zone in which the mobile station is moving, 4 is a base station in the old radio zone 1, 5 Is a base station in the new radio zone, 6 is an exchange connected to the base station 4 and the base station 5, 8 is a communication line connected between the base station 4 and the exchange 6, and 9 is an exchange for the base station 5. It is a communication line connected between the stations 6. This line includes a control line and a telephone line, but here, only the telephone line may be used. Reference numeral 13 denotes a counterpart subscriber with which the mobile station 3 is communicating, and corresponds to a general subscriber of a fixed network or a mobile station of a mobile communication system. Reference numeral 11 denotes a communication line connected to the other party via the exchange 6 and a fixed network or a mobile communication network. You only have to think about this for calls.

[0005] Next, the lines are connected to the other party 13, the communication line 11, the exchange 6, the communication line 8, the base station 4, and the mobile station 3, and the mobile station 3 shifts to the new radio zone 2 during a call. A conventional method for switching the communication line from the exchange 6 to the mobile station 3 will now be described. FIG. 3 is a diagram illustrating a conventional channel switching procedure during communication. When the mobile station 3 moves away from the base station 4 and approaches the base station 5 in the adjacent zone while communicating with the other party 13 via the base station 4 and the exchange 6, the base station 4
The reception level of the communication signal from the communication device decreases. The mobile station 3 constantly or periodically monitors the reception level during communication. If the reception level drops below a certain value, the mobile station 3 detects that the reception level is lower than the predetermined value and starts the channel switching operation during communication. This is step S1. Next, the mobile station receives a signal from another base station, and recognizes the base station 5 to which the mobile station is approaching based on the level. This is step S2. Step S3 is a step in which the mobile station 3 transmits a channel switching request signal to the base station 4. This signal includes the mobile station identification number and base station information of the switching destination (here, base station 5). This signal is received by the base station 4 and transferred to the exchange 6. When the exchange 6 determines that this signal is a channel switching request signal,
A three-party communication function is set, and a communication channel to be used in the new wireless zone 2 of the transfer destination is requested to the base station 5 based on the switch destination base station information. If the communication channel is free and available, the base station 5 returns a response to that effect to the exchange 6. This is step S4. This step is necessary when the base station manages the communication channel. In the next step 5, when the exchange 6 receives the channel information from the base station 5, the exchange 6 transmits a channel switching instruction signal to the base station 4 in the old radio zone in order to switch the mobile station 3 to the channel. The station 4 transfers the signal to the mobile station 3. As a result, the mobile station 3 and the exchange 6 switch to the new communication channel and continue the call. Finally, in step 7, the exchange 6 instructs the old base station 4 to restore the old radio channel.

[0004]

In the above prior art,
Since the information required for channel switching is transmitted through the communicating base station, the channel to the communicating base station is used in places where the zone is small and radio waves do not reach suddenly at the boundary of the zone, such as a mobile phone. There is a drawback that transmission of switching information becomes difficult and channel switching fails. Also, since the channel switching instruction signal to the mobile station is transmitted via the old base station, the mobile station needs to enter the channel switching operation as soon as possible to secure communication with the old base station while the channel switching procedure is completed. There is also a disadvantage that the number of times of channel switching increases more than necessary.

[0005] It is an object of the present invention to provide a method capable of reliably switching channels even in a place where radio waves suddenly cannot reach a zone boundary.

[0006]

In order to achieve the above object, a channel switching method according to the present invention comprises the steps of:
A channel switching request signal is transmitted to the new base station at the migration destination, and the communication channel is not disconnected for a certain period of time even if the reception level is deteriorated so that the old base station cannot communicate.

[0007]

Since the mobile station transmits a channel switching request signal to the new base station to which the mobile station moves, even if the radio wave does not reach the old base station abruptly at the zone boundary, the channel is reliably transmitted. Switching can be performed. Also, since there is no need to transmit a channel switching request signal to the old base station, the mobile station can continue communication with the old base station until the end of the zone is reached, and the mobile station moves with a low channel switching request operation. It is possible to reduce the load on the processing devices of the office and the exchange.

[0008]

FIG. 2 shows a system as a premise of the first embodiment of the present invention. FIG. 1 shows a channel switching procedure during communication according to the present invention. Steps S1 and S3 are the same as in the prior art. S2 is a timer for suspending a communication channel immediately for a certain period of time even if the reception level at the old base station 4 becomes so low that the mobile station 3 has shifted to the new wireless zone 2 so that communication becomes impossible. Is a step of setting Step 4 is a step in which the mobile station 3 transmits a channel switching request signal to the new base station 5. Steps 2 and 4 are features of the present invention. This signal must include the mobile station identification number. Upon receiving this signal, the new base station 5 searches for a free channel, and if so, transfers a channel switching request signal including the information and the mobile station identification number to the switching center 6.

[0009] Upon receiving the channel switching request signal, the exchange 6 searches the communication management memory to determine whether or not channel switching is possible (step S5), and if possible, connects to the old base station 4. The communication line that was being used is switched to the new base station 5 (step S6), and to that effect, the mobile station 3
Teach to As a result, channel switching is performed. This is step S7. In the last step S8, the exchange 6 sends a command for restoring the communication channel and resetting the timer to the old base station 4.

FIG. 4 shows an operation procedure of the exchange 6 for executing the present invention. This is the operation after receiving the channel switching request signal in step S4. Steps S4, S5, S6, and S8 are the same as those in FIG. S10 is a step of determining whether or not the mobile station is in communication when a channel switching request signal is received, and corresponds to step S5 in FIG. More specifically, the exchange station always stores the communication state for the mobile station identification number in the communication management memory 30, searches the memory based on the mobile station identification number included in the channel switching request signal, and searches for this mobile station. Only when the device can recognize that the communication channel is being used, the process proceeds to step S5. If it is determined that it is not being used, the new base station is instructed to stop the channel switching operation.

As described above, according to the present invention, since the mobile station transmits the channel switching request signal to the new base station, channel switching can be reliably performed even at a location where radio waves do not reach suddenly at the zone boundary. In the above, the embodiment in which both the old base station in communication and the new base station to be switched to are connected to the same exchange has been described.Next, the old base station and the new base station are connected to different exchanges. An embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a system configuration diagram in this case.
The difference from FIG. 2 is that a communication network 10 connecting the exchanges 7 and the exchanges is newly shown. Here, the case where the mobile station 3 shifts from the old wireless zone 1 to the new wireless zone 2 will be described as an example. FIG. 6 shows a channel switching procedure in this case. Steps S1 to S3 are the same as those in FIG. S4
Reference numeral 1 denotes a step in which the mobile station 3 transmits a channel switching request signal to the new base station 5. The difference from the first embodiment is that the signal of the switching station 6 is included in this signal. That is the point. In other words, the mobile station 3 receives from the exchange 6 the information that allows the mobile station 3 to connect to the switching center 6 at the time of the zone change, and transmits this information together with the channel switching request signal. The mobile station 3 can receive the information of the transfer source switching station by notifying or notifying the location information and the switching station information from the base station even during the communication. The new exchange 7 receives the channel switching request signal and recognizes the old exchange 6 (step 42), and transfers the channel switching request signal to the relevant exchange (step S43).
Upon receiving this signal, the old exchange 6 during communication enters a channel switching operation, determines whether or not channel switching is possible, and executes channel switching when possible. Steps S5 and S6 are almost the same as those in the first embodiment. When the old exchange 6 has completed the switching, it notifies the new exchange 7 of that effect (step 71).
Upon receiving this signal, the new exchange 7 transmits a response signal to the mobile station 3. This is Step 7. As a result, the communication line is connected via the route of the mobile station 3, the new base station 5, the new switching device 7, the old switching device 6, and the other party 13, and the channel switching is completed. The line restoration and timer reset of the old base station in step S8 are the same as in the first embodiment.

FIG. 7 is a diagram showing the operation of each exchange in this case, and is a modification of the operation of the exchange shown in FIG.
The difference is the steps S42 and S43. That is, when the exchange receives the channel switching request signal, it uses the mobile station identification number and the communication management memory 30 included in the signal, and
It is determined whether or not the mobile station is communicating. If the mobile station is communicating, the same operation as in the first embodiment is performed. If the mobile station is not communicating, it is determined that the channel is switched to another exchange. The new switching center information included in the switching request signal is detected, and the channel switching request signal is transferred to the switching center. In other words, the exchange identifies whether the channel is switched within the exchange or between the exchanges, so that the former switches the line for the new base station within its own station, and the latter switches the line for the new exchange. Control.

[0014]

According to the present invention, channel switching can be reliably performed even in a place where radio waves do not reach suddenly at a zone boundary.

[Brief description of the drawings]

FIG. 1 is a diagram showing a channel switching procedure according to a first embodiment of the present invention.

FIG. 2 is a system configuration diagram according to the first embodiment of the present invention and a conventional technique.

FIG. 3 is a diagram showing a conventional channel switching procedure.

FIG. 4 is a diagram showing a channel switching operation of the exchange in the first embodiment of the present invention.

FIG. 5 is a system configuration diagram according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a channel switching procedure according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a channel switching operation of the exchange in the first embodiment of the present invention.

[Explanation of symbols]

 3 mobile station 5 new base station (destination base station) 6 exchange 7 new exchange (destination exchange) 30 communication management memory

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-27223 (JP, A) JP-A-4-168816 (JP, A) JP-A-4-119727 (JP, A) JP-A-3-27 108848 (JP, A) JP-A-64-32541 (JP, A) JP-A-4-240931 (JP, A) JP-A-2-164139 (JP, A) JP-A-1-180134 (JP, A) JP-A-3-191623 (JP, A)

Claims (1)

(57) [Claims] 1. A mobile communication system in which a service area includes a plurality of wireless zones, and a base station and a mobile station provided in each wireless zone are connected by a wireless line. When it is detected that the signal reception level from the mobile station has deteriorated, it is determined that the communication has shifted from the first wireless zone to the second wireless zone, and the channel including the mobile station identification number for the second wireless zone. Transmitting a switching request signal, the first base station in the first wireless zone and communicating with the mobile station, when the signal reception level from the mobile station has deteriorated until communication becomes impossible, Set a timer to hold the communication line for a certain time from the time when the exchange connected to the second base station included in the second wireless zone receives the channel switching request signal,
This signal is determined to be a channel switching request signal by comparing it with the contents of the communication management memory based on the mobile station identification number included therein, and the communication line connected to the first base station is connected to the second base station. Switching during communication, wherein switching is performed to connect to a base station and the setting of the timer is canceled.