JP2000324553A - Method for controlling channel for communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely connect to a base station which has a free communication channel without repeating access to nearby base stations until a mobile terminal is connected to a base station having a free channel for communication. SOLUTION: By this control method, multiple base stations intermittently transmit to a mobile terminal control information on an LCCH superframe composed of a channel(BCCH) for system information notification, an incoming information channel(PCH), and a channel (SCCH) for channel assignment control and according to the control information, the mobile terminal sends a link channel establishment request message to a base station having a free communication channel slot to perform transmission or position registration. In this case, each base station performs intermittent transmission by setting information showing the free state of its communication channel slots in option areas of the system information notification channel, incoming information channel, and channel assignment control channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication channel control method between a base station and a mobile terminal, and more particularly to a method for selecting an arbitrary one of a plurality of base stations having at least a part of service area overlapping. To control a communication channel when a mobile terminal performs calling and location registration.

[0002]

2. Description of the Related Art As a communication method of a mobile terminal such as a PHS,
Multiplexing by time division and two-way communication are employed. A plurality of base stations are installed in the paging area, and each base station is connected to a telephone network via an exchange control center. Each base station has its own service area, and communicates with mobile terminals in each service area by a time-division multiplexing control channel to maintain constant contact.

FIG. 4 is a diagram showing the relationship between a conventional mobile terminal in a call waiting state and a control channel signal of a base station. The control slot of the base station has four consecutive slots (# 1 to # 4).
Slot, 1 slot width = 6.25 μs) are alternately used as a transmission slot and a reception slot.
The base station uses this transmission slot to transmit control signals to mobile terminals intermittently.

As shown in FIG. 4 (a), when the number of logical control channels is 8, the system information broadcast channel (BCCH) and the eight incoming information channels (P1 to P8C) are used.
H) three channel allocation control channels (SCC
H), a total of 12 channels are repeatedly and intermittently transmitted in a 1.2 second cycle. (This is called an LCCH superframe). Each mobile terminal calculates the incoming call group to which the mobile station belongs based on the superframe configuration and its own terminal number,
One of the corresponding incoming information channels P1 to P8 is intermittently received.

[0005] When the mobile terminal is turned on, it first searches for a slot transmitted by the base station having the best radio communication condition.
Information is received at the timing at which the broadcast channel (BCCH) is transmitted. Then, the contents of the broadcast message are checked, and the channel allocation control channel (SCCH) is used.
Transmits a link channel establishment request message, and upon receiving a link channel assignment message from the base station, transmits a location registration request message from the information channel to perform location registration. Thereby, the location registration area where this mobile terminal is located is recognized. When transmitting a call, a link establishment request message is transmitted on a channel assignment control channel (SCCH), and when a link channel assignment message is received from a base station, a call setup message is transmitted in a communication channel and transmission is performed.

[0006] When no call is made, for a general call performed simultaneously by all base stations in the above-described registered location registration area, an incoming call message or broadcast reception is performed at the timing when a BCH is transmitted. Receive instructions, etc. Then, when the first link establishment request message is transmitted, if all the communication channel slot use states of the base station are in use, the base station transmits a link channel assignment rejection message. The mobile station receives this message and searches for a slot transmitted by the base station having the second best wireless communication condition. Then the same procedure is taken for this base station as for the first base station. Hereinafter, the same sequence is repeated.

[0007]

However, in such a conventional PHS system, when a mobile terminal accesses a base station, it is notified that the base station is busy, and the access is denied. Therefore, the mobile terminal whose access has been rejected must find another base station and perform access again, resulting in a connection delay. In the case of an incoming call, the incoming call may not be able to be made due to a timeout on the network side. If the communication channel slot of the switching destination base station is not vacant even at the time of handover, more time is required because another suitable base station must be searched. For this reason, there is a possibility that the silence time becomes long and the call is disconnected due to a handover failure. As described above, particularly in an area with high traffic, the mobile terminal must repeatedly access the base station in the vicinity until it is connected to a base station having a vacant communication channel. There is a problem in the silence time at the time of overrun and the service quality is low.

As a conventional technique for solving such a problem, there is a communication channel control method disclosed in Japanese Patent Application Laid-Open No. 6-121371. According to this control method, when all the communication channel slots of a certain base station are already in use, the base station transmits all information in the option area of the regulation information broadcast message transmitted on the system information broadcast channel. Information indicating that the channel slot is being used is set. Before transmitting a link channel establishment request message on the channel allocation control channel in order for the mobile station to transmit or position-register to this base station, avoid this base station and link to another base station with a vacant communication channel slot. A channel establishment request message is transmitted to transmit or register a location.

[0009] However, even in this method, the base station broadcasts the vacant information of its own communication channel only through the system information broadcast channel, so that the mobile terminal needs to receive this broadcast channel once. In this case, there is a problem that the access to the base station cannot be performed and an access delay occurs. SUMMARY OF THE INVENTION It is an object of the present invention to provide a communication channel control method which solves the above-mentioned problem and enables a mobile terminal to selectively access only a base station connectable to establishment.

[0010]

The present invention provides a system information broadcast channel (BCCH) and a terminating information channel (PC).
H) and a plurality of base stations intermittently transmit control information on an LCCH superframe composed of a channel allocation control channel (SCCH) to the mobile terminal, and the mobile terminal communicates based on the received control information. Transmitting a link channel establishment request message to a base station having a vacant channel slot, and performing a communication or a location registration in a communication channel control method, wherein each of the plurality of base stations has its own communication channel slot vacant. The intermittent transmission is performed by setting information indicating a status in an option area of the system information broadcast channel, the termination information channel, and the channel allocation control channel. If there is no vacancy in the communication channel slot of the base station waiting from the received control information,
The mobile terminal changes a standby destination to another base station and transmits a link channel establishment message. The change of the standby destination may be performed immediately upon receiving the control information,
It can also be performed when an outgoing or incoming call request occurs.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As described in FIG. 4, in the case of the PHS system, the mobile terminal transmits the L transmitted by the base station.
The CCH superframe has been received and information necessary for the system has been obtained. In the standby state, the mobile terminal intermittently receives only the incoming call information channel (the P1 channel in the example of FIG. 4) corresponding to the incoming call group to which the mobile terminal belongs. Therefore, in the present invention, the base station is configured to broadcast the vacant state of the communication channel slot of the base station on all functional channels (BCCH, SCCH, PCH) on the LCCH superframe. The content of the notification changes in real time according to the availability of the communication channel slot of the base station. In this way, the base station notifies the mobile terminal of the vacant state of the communication channel slot of the base station every 100 ms.

FIGS. 1 to 3 show functional channels (BCCH,
FIG. 3 is a diagram showing a message configuration of PCH, SCCH). Each channel is assigned a predetermined message, but has several optional areas. For example, in the system information broadcast channel (BCCH) shown in FIG. 1, the eighth bit of the first octet and the third bit of the seventh octet
An option area (area) exists at the bit position. The base station sets the availability of its own communication channel slot in this optional area. In the terminating information channel (PCH) shown in FIG. 2, an option area exists in the eighth bit of the first octet.

In the channel allocation control channel (SCCH) shown in FIG. 3, the 8th bit of the first octet,
An option area exists at the fourth and fifth bits of the second octet and at the sixth bit of the third octet. In this way, the base station sets the vacancy status of its own communication channel slot in the option area of the three function channels and transmits the vacancy status to the mobile terminal. Can be known without performing the operation of calling, receiving or location registration. Therefore, the mobile terminal can selectively access only the base station that can be reliably connected.

[0014] Also, at the time of a handover operation for switching the connection-destination base station, the switching operation time can be shortened by selecting a base station having a vacant communication channel slot as the switching destination base station. Therefore, the silence time due to the switching can be reduced, and the disconnection of the communication due to the failure of the handover can be reduced by suppressing the retry of the switching operation. The communication channel control method according to the present invention does not limit the operation on the mobile terminal side at all. That is, when it is detected that the communication channel slot of the base station is not vacant in the standby state and the base station is busy, the standby destination is immediately changed to another base station, or the request is transmitted or received when an outgoing / incoming call is generated. Is free on the mobile terminal side. Therefore, according to the present invention, the service quality can be improved regardless of the operation algorithm on the mobile terminal side. Although the present invention has been described based on the communication channel control method of the PHS system, the present invention is not limited to this, and the present invention is not limited to the digital mobile phone that transmits control information using a superframe composed of a plurality of function channels. It can also be used in telephone systems and the like.

[0015]

As described in detail based on the above embodiments, according to the present invention, information indicating the availability of communication channel slots is set in all the functional channels on the LCCH superframe, and the information is set to the mobile terminal. Since the transmission is performed, the mobile terminal can selectively access only the connectable base station, thereby reducing the connection delay at the time of calling and receiving and can surely connect the call. In addition, since the mobile terminal does not make useless access, there is an advantage that radio resources are used efficiently and radio interference is reduced. Furthermore, since the time required for the mobile terminal to access the base station is short, there is also an advantage that the connection delay at the time of calling and receiving is shorter.

[Brief description of the drawings]

FIG. 1 is a diagram showing a message allocation status of a system information broadcast channel.

FIG. 2 is a diagram showing a message allocation status of an incoming information channel.

FIG. 3 is a diagram showing a message assignment status of a channel assignment control channel.

FIG. 4 is a diagram showing a relationship between a mobile terminal in a call waiting state and a control channel signal of a base station.

[Explanation of symbols]

 BCCH Channel for system information broadcast PCH Termination information channel SCCH Channel for channel allocation control

Claims (4)

[Claims] 1. A system information broadcast channel (BCC)
H), an incoming information channel (PCH), and a channel for controlling channel allocation (SCCH).
A plurality of base stations intermittently transmit control information on a superframe to a mobile terminal, and the mobile terminal transmits a link channel establishment request message to a base station having a vacant communication channel slot based on the received control information. In the method of controlling a communication channel to perform transmission or location registration, the plurality of base stations each indicate information indicating the availability of its own communication channel slot, the system information notification channel, the termination information channel and A communication channel control method, wherein the intermittent transmission is performed by setting the intermittent transmission in an option area of the channel allocation control channel. 2. The communication channel control method according to claim 1, wherein when there is no available communication channel slot of a base station waiting from the received control information, the mobile terminal is connected to another base station. And transmitting a link channel establishment message after changing the standby destination. 3. The communication channel control method according to claim 2, wherein the change of the standby destination is performed immediately upon receiving the control information. 4. The communication channel control method according to claim 2, wherein the change of the standby destination is performed when an outgoing or incoming call request occurs.