JP3790065B2 - Communication channel control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a channel control method for communication between a base station and a mobile terminal, and in particular, the mobile terminal transmits and positions by selecting any one of a plurality of base stations that overlap at least some service areas. The present invention relates to a communication channel control method for registration.
[0002]
[Prior art]
As a communication method of a mobile terminal such as PHS, multiplexing by time division and bidirectional communication are adopted. A plurality of base stations are installed in the general call area, and each base station is connected to a telephone line network through an exchange control center. Each base station has its own service area, and communicates with mobile terminals in each service area using a time-division multiplexing control channel to keep in constant contact.
[0003]
FIG. 4 is a diagram showing a relationship between a conventional mobile terminal waiting for an incoming call and a control channel signal of the base station.
As the control slots of the base station, four consecutive slots (# 1 to # 4 slots, 1 slot width = 6.25 μs) are alternately used as a transmission slot and a reception slot. The base station constantly transmits a control signal intermittently to the mobile terminal using this transmission slot.
[0004]
As shown in FIG. 4A, when the number of grouping is 8, the logical control channel is a system information broadcast channel (BCCH), 8 incoming information channels (P1 to P8CH), and 3 channel allocation control channels. A total of 12 (SCCH) channels are repeatedly transmitted intermittently at a cycle of 1.2 seconds. (This is called LCCH superframe).
Each mobile terminal calculates an incoming call group to which the mobile station belongs based on the superframe configuration and its own terminal number, and intermittently receives any of the corresponding incoming call information channels P1 to P8.
[0005]
When the mobile terminal is turned on, it first looks for the slot transmitted by the base station with the best wireless communication state, and receives information at the timing when the broadcast channel (BCCH) is transmitted. Then, the content of the broadcast message is confirmed, a link channel establishment request message is transmitted on the channel assignment control channel (SCCH), and when a link channel assignment message is received from the base station, a position registration request message is transmitted from the information channel, Register. Thereby, the location registration area where this mobile terminal is located is recognized. When making a call, a link establishment request message is transmitted on the channel assignment control channel (SCCH). When a link channel assignment message is received from the base station, a call setup message is transmitted in the communication channel to make a call.
[0006]
If no outgoing call is made, an incoming call message or broadcast reception instruction is sent at the timing at which the incoming call information channel ( PCH ) is sent for the simultaneous call made by all the base stations in the registered location registration area. Receive.
When the first link establishment request message is transmitted and the base station communication channel slot use state is all 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 radio communication state. The same procedure is then followed for this base station as for the first base station. Thereafter, the same sequence is repeated.
[0007]
[Problems to be solved by the invention]
However, in such a conventional PHS system, the mobile terminal is notified that the base station is busy only after accessing the base station, and is denied access.
Therefore, a mobile terminal that has been denied access 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 be disabled due to a network timeout. Further, if the communication channel slot of the base station to be switched to is not vacant even at the time of handover, it takes more time because another appropriate base station must be searched. Therefore, there is a possibility that the silent time becomes long and the call is disconnected due to the failure of the handover.
In this way, especially in an area with high traffic, the mobile terminal must repeat access to a nearby base station until it is connected to a base station with a free communication channel. There is a problem in the silent time at the time of over and there is a problem that the service quality is low.
[0008]
As a conventional technique for solving such a problem, there is a communication channel control method disclosed in Japanese Patent 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, all information is displayed in the option area of the restriction information notification message that the base station transmits on the system information notification channel. Information indicating that the channel slot is in use is set. Then, before transmitting a link channel establishment request message on the channel assignment control channel when a mobile station tries to transmit or register a location to this base station, avoid this base station and link to another base station having a free communication channel slot. A channel establishment request message is transmitted to transmit or register a location.
[0009]
However, even in this method, since the base station broadcasts the idle information of the communication channel of its own station using only the system information broadcast channel, the mobile terminal needs to receive this broadcast channel once, and immediately from the standby state, the base station There was a problem that access to the network could not be made and an access delay occurred.
An object of the present invention is to provide a communication channel control method that solves the above-described problems and enables a mobile terminal to selectively access only a base station that can be established.
[0010]
[Means for Solving the Problems]
In the present invention, a plurality of base stations provide control information on a control channel configured to include a system information broadcast channel (BCCH), an incoming information channel (PCH), and a channel assignment control channel (SCCH). Of the communication channel that transmits the link channel establishment request message to the base station in which the communication channel slot is vacant based on the received control information, and performs transmission or location registration. In the control method, each of the plurality of base stations sets information indicating availability of its own communication channel slot in the option area of the system information broadcast channel, the incoming information channel, and the channel allocation control channel, and It is characterized by intermittent transmission.
The system information broadcast channel, the incoming information channel, and the channel allocation control channel have the option area in a common area, and the information indicating the availability is stored in the common area of each channel. It is set in the provided option area.
When the communication channel slot of the base station that is waiting from the received control information is not empty, the mobile terminal changes the standby destination to another base station and transmits a link channel establishment message.
The standby destination can be changed immediately when the control information is received, or can be changed when an outgoing or incoming request is generated.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As described with reference to FIG. 4, in the case of a PHS system, a mobile terminal receives an LCCH superframe transmitted from a base station and obtains information necessary for the system.
In the standby state, the mobile terminal intermittently receives only the incoming information channel (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 report the availability of its communication channel slot on all functional channels (BCCH, SCCH, PCH) on the LCCH superframe.
The notification content 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 availability of its own communication channel slot every 100 ms.
[0012]
1 to 3 are diagrams showing the message structure of each functional channel (BCCH, 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, an option area (area) exists in the 8th bit of the first octet and the 3rd bit of the 7th octet. In this optional area, the base station sets a free state of its own communication channel slot.
In the incoming call information channel (PCH) shown in FIG. 2, an option area exists in the eighth bit of the first octet.
[0013]
Further, in the channel assignment control channel (SCCH) shown in FIG. 3, there are option areas at the 8th bit of the first octet, the 4th bit and the 5th bit of the 2nd octet, and the 6th bit of the 3rd octet.
Thus, the system information broadcast channel (BCCH), the incoming information channel (PCH), and the channel assignment control channel (SCCH) have at least an optional area in the common area (area) of the eighth bit of the first octet. Is present. The base station sets the free state of its own communication channel slot in the option areas of the three functional channels and transmits it to the mobile terminal, so that the mobile terminal can check the free state of the communication channel of each base station. It becomes possible to know without performing the operation of outgoing call, incoming call or location registration. Therefore, the mobile terminal can selectively access only a base station that can be reliably connected.
[0014]
Further, even during a handover operation for switching the connection destination base station, the switching operation time can be shortened by selecting a base station having a free communication channel slot as the switching destination base station. For this reason, the silent time due to switching can be shortened, and communication disconnection due to handover failure can be reduced by suppressing the retry of switching operation.
The communication channel control method according to the present invention does not limit the operation on the mobile terminal side. In other words, when it is detected that the communication channel slot of the base station is not available in the standby state and the base station is busy, the standby destination is immediately changed to another base station, or when a call request is made This is free on the mobile terminal side. Therefore, in the present invention, the service quality can be improved regardless of the operation algorithm on the mobile terminal side.
The present invention has been described based on the communication channel control method of the PHS system. However, the present invention is not limited to this, and the digital portable device that transmits control information using a superframe composed of a plurality of functional channels. It can also be used in a telephone system or the like.
[0015]
【The invention's effect】
As described in detail based on the above embodiments, in the present invention, information indicating the availability of communication channel slots is set in all functional channels on the LCCH superframe and transmitted to the mobile terminal. The mobile terminal can selectively access only to the connectable base station, and the connection delay at the time of outgoing / incoming calls can be reduced and the call can be reliably connected.
In addition, since the mobile terminal does not perform useless access, there is an advantage that radio resources are efficiently used and radio interference is reduced.
Furthermore, since the time until the mobile terminal accesses the base station is short, there is also an advantage that the connection delay at the time of outgoing / incoming calls becomes 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 assignment status of an incoming call 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 waiting for an incoming call and a control channel signal of a base station.
[Explanation of symbols]
BCCH System information broadcast channel PCH Incoming information channel SCCH Channel allocation control channel

Claims (5)

The control information on the configured control channel and a call information channels and channel allocation control channel and system information broadcasting channel intermittently transmitting a plurality of base stations to the mobile terminal, based on the received control information In the communication channel control method in which the mobile terminal transmits a link channel establishment request message to a base station having a free communication channel slot, and performs transmission or location registration.
Each of the plurality of base stations sets information indicating the availability of its own communication channel slot in the option areas of the system information broadcast channel, the incoming information channel, and the channel allocation control channel, and performs the intermittent transmission. A communication channel control method. The communication channel control method according to claim 1,
The system information broadcast channel, the incoming call information channel, and the channel assignment control channel have the option area in a common area,
The information indicating the availability is set in the option area provided in the common area of each channel.
A method for controlling a communication channel. The communication channel control method according to claim 1 or 2 ,
When the communication channel slot of the base station that is waiting from the received control information has no vacancy, the mobile terminal changes the standby destination to another base station and transmits a link channel establishment message. Communication control method. The communication channel control method according to claim 3 ,
The communication channel control method, wherein the standby destination is changed immediately upon reception of the control information. The communication channel control method according to claim 3 ,
A method for controlling a communication channel, characterized in that the standby destination is changed when an outgoing or incoming request occurs.

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