JPH0748897B2 - Radio base station automatic switching system - Google Patents

Description

The present invention relates to a cellular car telephone system, and more particularly to a wireless base station switching system.

(Prior Art) Conventionally, in this type of wireless base station switching method, the wireless base station communicating with the mobile device during a call constantly monitors the propagation state of the radio wave in the call channel, and the radio wave propagation quality is below a reference value. In this case, the radio base station that has been communicating with the mobile device until now requests the exchange to switch the radio base station.

At any time, the exchange instructs the surrounding radio base stations to measure the electric field strength of the above-mentioned call channel, and as a result of the measurement, a method is known in which the call channel is switched to the radio base station received with the strongest electric field strength. Is.

In such a wireless base station switching method, the mobile station and the wireless base station in a call monitor the propagation state of the radio wave of the call channel, and if the quality of the call channel falls below the reference value, the radio base station The mobile station determines that the mobile station has moved from the service area of its own station to the service area of the surrounding wireless base station, and requests the exchange to switch the wireless base station.

When the exchange receives a switching request from a wireless base station, it instructs the wireless base stations in the vicinity of the wireless base station to measure the electric field strength of the above-mentioned communication channel, and based on the measurement results, the strongest electric field strength is obtained. The method is to switch to the call channel of the received wireless base station and continue the call.

(Problems to be Solved by the Invention) In the above-described conventional wireless base station switching method, when the number of signals transmitted and received between the exchange and the wireless base station increases, the processing capability of the exchange and the wireless base station decreases, The processing is complicated, and there is an influence on the electric field strength measurement due to geographical conditions. For this reason, there is a drawback in that the switching process of the radio base station is not always performed accurately when the number of transmissions and receptions is large.

An object of the present invention is to identify the mobile station within the service area of each radio base station when it moves from the service area of a radio base station to the service area of a neighboring radio base station in the vicinity. A plurality of service area identification signal transmitters are used to transmit a service area identification signal of a single frequency common to all service areas and having low power at all times, and separately from the call channel when the mobile device is in a call. When the service area identification signal is received, the mobile station analyzes the service area identification signal, recognizes itself that it has moved from the service area of a certain radio base station to the service area of an adjacent radio base station, and the mobile station side By transmitting the switching request signal to the wireless base station and switching to the communication channel of another wireless base station, the above drawbacks are eliminated and switching is performed accurately. And to provide a radio base station automatic switching scheme configured to be able to perform the management.

(Means for Solving Problems) The wireless base station automatic switching system according to the present invention is an exchange, a plurality of wireless base stations, a first type service area identification signal transmitting device, a mobile receiving means, and a second type. And a service area identification signal transmitting device.

The first type service area identification signal transmitting device transmits service area identification signals from a plurality of locations within a service area of each radio base station at a frequency common to all service areas.
In addition, it is for transmitting with weak power.

The mobile reception means is for receiving the service area identification signal separately from the call channel.

The second type service area identification signal transmitting device receives a service area identification signal having a content different from that of the service area identification signal received by the mobile receiving means, from the service area of a certain first wireless base station. It is for recognizing that the mobile station has moved to the service area of another second radio base station, and for transmitting the switching request signal from the mobile reception means to the first radio base station to switch the radio base station.

(Example) Next, this invention is demonstrated with reference to drawings.

FIG. 1 is a block diagram of a cellular car telephone system showing an embodiment of a wireless base station automatic switching system according to the present invention.

In FIG. 1, 1 is an exchange, and 2 to 4 are 1 to 1 respectively.
A third radio base station, 51 and 52 are vehicles each equipped with a mobile device, 6 is a public telephone network, A is the service area of the first radio base station 2, and B is the service area of the second radio base station 3. , C is the service area of the third radio base station 4, a is a service area identification signal transmitting device indicating the service area A, b is a service area identifying signal transmission device indicating the service area B, and c is a service indicating the service area C. Area identification signal transmission device, ab is a service area identification signal transmission device indicating overlap between service area A and service area B, bc is a service area identification signal transmission device indicating overlap between service area B and service area C, ac is A service area identification signal transmitter that indicates the overlap between service area A and service area C, fa is a communication channel of the first wireless base station 2, and fb is a second wireless channel. Chikyoku is a 3 of the call channel.

The exchange 1 connected to the public telephone network 6 controls the first to third wireless base stations 2 to 4, and the first to third wireless base stations 2 to 4
An automobile 5 equipped with a mobile device moves inside the service areas A to C respectively covered by.

Inside the service area A, a plurality of service area identification signal transmission devices a that constantly transmit the service area identification signal for identifying the service area A are installed, and the service area A and the service area B are overlapped with each other. Is provided with a plurality of service area identification signal transmitters ab for identifying the overlapping areas of the service area A and the service area B, and the service area A and the service area C are provided in the overlapping area of the service area A and the service area C. A plurality of service area identification signal transmitters ac for identifying the overlapping areas are installed.

Similarly, a service area identification signal transmitter b for identifying the service area B, a service area identification signal transmitter bc for identifying an overlapping area of the service area B and the service area C, and a service area identification signal for identifying the service area C. A plurality of transmitters c are installed.

The service area identification signal transmitters a to c are installed inside the service areas closer to the respective radio base stations than the overlapping areas of the service areas, and the service area identification signal transmitters a to c, ab, ac, bc is transmitted with the same frequency and an FM modulated wave of weak power. Therefore, an automobile 5 having a zone smaller than the service areas of the first to third wireless base stations 2 to 4 and equipped with a mobile device is installed.
Can receive radio waves from the nearest service area identification signal transmitter.

Next, the automobile 5 equipped with the mobile device is connected to the first radio base station 2
A wireless base station switching procedure will be described for the case of moving from the service area A to the service area B of the second wireless base station 3.

First, an automobile 5 equipped with a mobile device is inside a service area A and communicates with a first radio base station 2 by a call channel fa. At this time, since the mobile device simultaneously receives the weak power radio wave from the service area identification signal transmitting device a for identifying the service area A, it is recognized that the mobile device itself is placed inside the service area A. ing.

When the vehicle 5 equipped with the mobile device enters the overlapping area of the service area A and the service area B, the mobile device receives the radio wave from the service area identification signal transmitting device ab, and the mobile device itself receives the radio wave. It recognizes that it is moving from A to the service area B, and sends a radio base station switching request signal for switching to the second radio base station 3 covering the service area B by using the call channel fa. It transmits to the wireless base station 2. The first radio base station 2 transmits a radio base station switching request signal from the mobile device to the exchange 1, and the exchange 1 sends a call channel fb to be used next in the call channel fa via the first radio base station 2. By instructing the mobile device to communicate with the second wireless base station 3 via the communication channel fb, the mobile device communicates with the second wireless base station 3 in the service area B using the communication channel fb. Will continue.

Next, when the automobile 5 equipped with the mobile unit moves further inside the service area B from the overlapping area of the service area A and the service area B, the radio wave from the service area identification signal transmitting device b can be received. , The mobile recognizes that it is completely inside the service area B.

By the same method, even when the automobile 5 equipped with the mobile device moves to another service area, the wireless base station is switched. Here, after the mobile device enters the overlapping area of the service area and the call channel is switched,
When the service area returns to the original service area, the call channel of the radio base station inside the original service area must be switched again. However, even if a mobile station receives a service area identification signal with a different content from the previous one so that such an operation does not occur frequently, it does not request a switching immediately but a fixed time has passed. Later, it is necessary to check the service area identification signal again and recognize that the service area has been moved to another service area before transmitting the radio base station switching signal.

In addition, although many service area identification signal transmitters will be installed, there is no control with others and only a single unit is required to transmit weak electric waves at all times, so the configuration is simple and the price is low. Is.

(Effects of the Invention) As described above, according to the present invention, a mobile station uses a service area identification signal for identifying a service area of a wireless base station at the same frequency and uses weak power radio waves for each service area. , The mobile station received the service area identification signal separately from the call channel, analyzed it, and moved from the service area of a certain radio base station to the inside of the adjacent service area. Recognizing that, by switching the radio base station at the request of the mobile unit, the processing of measuring the electric field strength of the call channel to the surrounding radio base station becomes unnecessary, and the signal between the exchange and the radio base station becomes unnecessary. Since the number of transmissions and receptions is reduced, there is an effect that the reduction of the processing capacity of the entire system is suppressed and the processing becomes simpler.

[Brief description of drawings]

FIG. 1 is a block diagram of a cellular car telephone system showing an embodiment of a wireless base station automatic switching system according to the present invention. 1 ... Switch, 2-4 ... Wireless base station 51,52 ... Car, 6 ... Public telephone network A-C ... Service area a-c, ab, bc, ac ... Service area identification signal transmitter fa, fb …… Call channel

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location 7304-5K H04Q 7/04 K

Claims (1)

[Claims] 1. A switch, a plurality of wireless base stations, and a service area identification signal transmitted from a plurality of locations within each of the service areas of the wireless base stations at a frequency common to all service areas and with low power. A first type service area identification signal transmitting device, a mobile reception means for receiving the service area identification signal separately from the communication channel, and the service area identification signal received by the mobile reception means. Recognizes that it has moved from the service area of a certain first radio base station to the service area of another second radio base station when it receives a service area identification signal having different contents, A service area identification signal transmitting device of a second type for transmitting a switching request signal to the first wireless base station to switch the wireless base station. The radio base station automatic switching system, characterized in that the configuration was.