JP3197471B2 - Base station call connection control method in mobile communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a portable telephone (PH)
S) and a call connection control method of a base station in a mobile communication system such as a cellular mobile phone.

[0002]

2. Description of the Related Art In a base station type mobile communication system, such as a PHS or a cellular type mobile phone, a fixedly assigned radio frequency is used as a radio channel in each base station. The number of lines through which a plurality of mobile terminals within the service area can simultaneously talk is finite, and the number of PHS base stations is as small as three to several lines.

[0003] For this reason, with the remarkable increase in portable telephones and PHS telephones in recent years, a large number of mobile stations may be concentrated in a communication zone of one base station, and congestion of a communication channel may occur. In addition, in the vicinity of a station, at an intersection of a downtown area, or on the premises of a subway, communication requests or location registration requests (hereinafter referred to as traffic) are concentrated during commuting rush hours or return times, and congestion of communication channels may occur.

For this reason, conventionally, a plurality of base stations are installed in places with high traffic to increase the number of communication channels. However, the current method of using a radio channel in base station type mobile communication is to start communication. Depending on the installation status of the base station, a call (communication request for incoming or outgoing call) may be made to a specific base station depending on the installation situation of the base station, since the communication channel with the highest radio wave intensity among the communication channels that can be used sometimes is used preferentially. May concentrate.

[0005]

In such a case, not only cannot the effective use of the base station installed for making a call be achieved, but also the call requester (user, mobile terminal holder or public line user) cannot use the base station. Looking at it, it is easy to be misunderstood as if the other party is talking on the phone, and even if it is not misunderstood, PHS
It is easy to get dissatisfied with the service contents such as.

In order to solve such a drawback, for example, as disclosed in Japanese Patent Application Laid-Open No. 6-69860, the transmission power of the broadcast channel from the base station is controlled in accordance with the change in the usage rate of the communication channel of the base station. There is disclosed a technique for controlling congestion of a communication channel.

However, controlling the transmission power in accordance with the variation in the usage rate of the communication channel not only complicates the circuit configuration but also makes it possible to grasp the status of the variation unless the communication channel is used to some extent. It is difficult to respond promptly.

In view of the drawbacks of the prior art, the present invention provides a call connection control method for a base station which makes it possible to easily distribute calls to other base stations even when calls are concentrated on a specific base station. The purpose is to do. The present invention makes it possible for a base station, which is a connection partner specified by a mobile station, to connect to a base station with as low traffic as possible when the mobile station is located in a service area of another base station. It is an object of the present invention to provide a call connection control method for a base station.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for directly connecting base stations.
In a call connection control method of a base station in a mobile communication system including a large cell base station and a small cell base station having a column structure ,
The large cell base station is specified in advance as a base station with a lot of traffic (hereinafter, referred to as an A base station), and if a small cell base station having an area overlapping with the service area covered by the A base station is available, the traffic is low. To communicate with a small cell base station (hereinafter referred to as a B base station) using a dedicated line so as to connect a call, and issue a response to the connection request from the B base station which is a small cell base station. The connection of a call is controlled by the following.

[0010] More specifically, such a control method is, more specifically, when the A and B base stations receive a link channel establishment request signal of the mobile terminal PS including the unique number of the A base station, the dedicated line is set up. From the B base station to the A base station side,
After receiving the reception report of the unique number of the A base station and the connection permission, the B base station transmits a link channel assignment signal together with the unique number of the A base station to the mobile terminal PS side, and performs the connection operation of the B base station. What is necessary is just to carry out with the unique number of the A base station.

According to the invention, A having a large traffic
If both the base station and the B base station with low traffic are available, the call is first connected from the B base station, so that the probability that the base station with high traffic becomes busy is reduced.

Further, according to the present invention, the connection operation of the B base station is performed using the unique number of the A base station.
Since the connection operation is performed using the CS-ID (unique number) of the A base station as if it were a base station, the mobile terminal P
There is no need to add any special control on the S side, and the base station side requires only software processing for the lines other than the dedicated lines, so that the circuit configuration is not complicated at all. In addition, since the connection between the base stations is controlled via a dedicated line without using a public line, the service cost does not increase at all.

[0013]

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, a location registration or communication area (service area) of a base station is provided with a plurality of base stations (CS) in order to minimize an empty area (an area where location registration or communication cannot be performed). Thus, the service areas of the respective base stations are arranged so as to overlap. There are also base stations with a wide service area depending on the installation conditions of the base stations. In this case, the base station with a wide service area has a stronger radio wave intensity of the communication channel than the base station with a narrow service area. Calls are concentrated at the station.

For example, as shown in FIG. 4, around a base station having a wide service area (hereinafter referred to as a large cell base station CS3), base stations CS1, CS2, CS4 and C4 having a narrow service area are provided.
When S5 (hereinafter referred to as a small cell base station) synchronizes with a large cell using a dedicated line and has a service area overlapping each other, and the mobile terminal PS is at the point A, the connection partner is a base station. Although any of the stations CS3 and CS4 may be used, the radio wave intensity of the communication channel of the large cell base station CS3 is often strong, and the mobile terminal PS inevitably synchronizes with the large cell base station CS3. Large cell base station CS
3, and the overlapping service area B of the small cell base station CS5
The same applies to the mobile terminal PS located at the point.
Synchronize with

On the other hand, when the mobile terminal PS is at points C and D, only the large cell base station CS3 can be connected,
Assuming that the number of communicable channels of the large cell base station CS3 is 3, when the mobile terminals PS use the communication channels of the large cell base station CS3 in A, B, and C, the mobile terminal PS If you try to make a call, you already have a large cell base station CS3
Is busy, that is, the communication channel is congested.

Normally, each mobile terminal PS operates in synchronization with the timing of a radio frame signal received from the base station CS. Further, since each base station CS is synchronized based on the system reference clock supplied from the wired line, each base station CS constantly monitors the control channel, so that a connection request to another base station CS can be made. Can be received. For example, mobile terminal P of A
When S issues a connection request, both base stations CS3 and CS4 can receive the connection request. Base stations CS3, CS4
Perform a pull-in process at the timing of simultaneously receiving this request and determine that there is no problem in connecting to the base station CS4, and send a response to this request to the base station CS4.
To control call connection.

Each base station CS has a unique ID number called CS-ID, and transmits this CS-ID as data when transmitting a control channel. The mobile terminal PS carries this CS-ID in the connection request and specifies the connection partner. Normally, each base station CS has its own CS-ID
If there is no request, no response is made, and even if a response is returned, no connection is made in order to recognize that the mobile terminal PS has a different CS-ID.

For this reason, when the above-described base station CS3, CS4 is pulled in, the CS-ID included in the connection request transmitted from the mobile terminal PS is exchanged via the dedicated line, and as if the base station CS4 is The connection operation is performed using the CS-ID of the base station CS3 as if it were the station CS3. This allows control between base stations for call connection.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. It's just FIG. 3 shows a schematic configuration of an internal circuit of the base station CS. CS3 functions as a large cell base station, and CS4 functions as a small cell base station connected to the large cell base station CS3.

The large cell base station CS3 has an RF unit,
A main control unit having a TDMA / TDD processing unit and the like and performing signal transmission control with the mobile terminal PS via an antenna, and a built-in communication channel switching unit, radio synchronization establishment unit, pull-in processing unit, etc. And a line control unit 3 for controlling signal transmission with a PHS control station or the like via an ISDN line, a PHS connection device, and a switch (all not shown).

On the other hand, the small cell base station CS4 is provided with a radio control unit 4, and the radio control unit 4 and the main control unit 2 on the side of the large cell base station CS3 are connected to each other via a large / small cell communication line (dedicated line 5). To perform synchronization and pull-in processing of large and small cell base stations.

Next, a description will be given of a pull-in operation between the base station CS and the mobile terminal PS with reference to FIGS. First, the base stations CS3 and CS4 of the large cell and the small cell are set up, the control channels of the base stations CS3 and CS4 are opened, and the CS-I required for call connection via the radio control units 1 and 4.
Transfer of control information including D is performed. (S1)

On the mobile terminal PS side, the two base stations CS
After activating the connection in synchronization with the control channel of the large cell base station CS3 having a strong radio wave intensity among the control channels, the link channel establishment request signal SC of CS-ID3
The channel is transferred to the base station CS3 via the wireless control unit 1.

The base station C of each of the large cell and the small cell
In S3 and S4, if there is a free line, the establishment request is received and recognized. (S2) The base stations CS3 and CS4 wait until receiving the link channel establishment request signal SCCH.

Next, the base station C of either the large cell or the small cell
In S3 and S4, when the establishment request is received, the process shifts to a pull-in operation process shown in FIG. First, when the small cell base station CS4 receives the link channel establishment request signal SCCH of CS-ID3, the small cell base station CS4 transfers the reception report of CS-ID3 to the main control unit 2 of the large cell base station CS via the dedicated line 5. In addition, a connection permission signal is received from the main control unit 2 of the large cell base station CS3 to the small cell base station CS4 via the dedicated line 5. (S3)

In response to the connection permission signal, the small cell base station CS4 changes the ID number from CS-ID4 to CS-ID3, and transmits the link channel assignment signal SCCH together with the ID number of CS-ID3 to the radio control unit 4. Via the mobile terminal PS.

On the mobile terminal PS side, the assignment signal SCCH
After the reception, the synchronization burst signal is transmitted to the large cell base station CS3, and the large cell base station CS3 transfers the synchronization burst signal from the main control unit 2 to the small cell base station CS4 via the dedicated line 5. .

After transmitting the synchronization burst from the small cell base station CS4 to the mobile terminal PS, signal transmission such as call setting / acceptance, definition information request / response, function request / response, authentication request / response, etc. is performed. After establishing the L2 and the service channel, the operation shifts to a predetermined communication operation. Note that FIG.
The operation shown in FIG. 3 is performed for any of the large cell and small cell base stations CS.
FIG. 2 also shows a case where CS-ID3 is received. As shown in FIG. 2, when only large cell base station CS3 receives CS-ID3, large cell base station CS3 receives (S4) and small cell base station C
When only S4 receives CS-ID4, it draws each into the small cell base station CS4 (S5).

[0030]

As described above, according to the present invention, even when calls are concentrated on a specific base station, it is possible to easily distribute the calls to other base stations. Further, according to the present invention, when a mobile station is located in a service area of another base station with respect to a base station as a connection partner specified by the mobile station, a call is first transmitted from a base station with low traffic. Since the connection is made, the probability that the base station with high traffic becomes busy can be reduced.

[Brief description of the drawings]

FIG. 1 shows a control sequence of a pull-in process of a base station according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation procedure of FIG. 1;

FIG. 3 is a system configuration diagram of a base station applied to FIG. 1;

FIG. 4 shows a state of a service area between base stations.

[Explanation of symbols]

 Reference Signs List 1 radio control unit 2 main control unit 3 line control unit 4 radio control unit 5 leased line PS mobile terminal CS base station CS3 large cell base station CS4 small cell base station

Claims (3)

(57) [Claims] A large cell base station having a serial structure and a small cell are connected between base stations.
In a call connection control method of a base station in a mobile communication system including a cell base station , a large cell base station is specified in advance as a base station having a large traffic (hereinafter, referred to as an A base station), and a service covered by the A base station is provided. If the small cell base station having an area overlapping the area is available, low-traffic small cell base station to (hereinafter referred to as base station B), the communication between the base station using a dedicated line to connect the call A base station call connection control method, wherein a call connection is controlled by sending a response to the connection request from a B base station which is a small cell base station . 2. The connection operation of the B base station is performed using a unique number of the A base station, as if the B base station were an A base station. Base station call connection control method (3)Base station call in mobile communication system
In the connection control method, Base stations with high traffic (hereinafter referred to as A base stations)
To the service area covered by the A base station.
If base stations with overlapping areas are available,
For base stations with low traffic (hereinafter referred to as B base stations)
Communication between base stations using dedicated lines to connect calls.
And responds to the connection request with low traffic
It controls call connection by issuing from B base station.
So,  A connection request signal of the mobile terminal including the unique number of the base station APrevious
Via the dedicated lineWhen the signals are received by both the A and B base stations,,
AReceived report of base station unique number and received connection permission
Then, the B base station side and the channel together with the unique number of the A base station
The base station transmits a base station assignment signal to the mobile terminal side.
The feature is that the work is performed with the unique number of the A base station
Base station call connection control method.