JPH0834628B2 - Mobile communication system - Google Patents

Description

The present invention relates to a mobile communication system using a zone system,
In particular, the present invention relates to a mobile communication system for covering a service area with a micro zone in an urban area and a service area with a small zone in a suburb.

[Conventional technology]

Conventional mobile communication systems have been variously improved with the problem of how to handle a large traffic volume in a limited frequency band as a primary purpose. As a result, a small zone system car telephone system, which is currently called a cellular system, has been put into practical use. However, the car telephone system of this small zone system has shown remarkable growth after the start of service, and the lack of frequencies is being cried out in countries all over the world. This is especially true in urban areas where traffic is concentrated. For example, looking at the distribution of car phone traffic in Tokyo,
An intense concentration of traffic is observed around Chiyoda Ward and Aoyama. For this reason, the normal 3-4
It takes twice as long (20-30 seconds). This is due to the lack of communication channels, and to address this, telecommunications carriers have subdivided the zones in Tokyo to increase subscriber capacity. This situation is detailed on pages 91 to 104 of Nikkei Electronics No. 401.

In addition, as a new movement of the car telephone system, introduction of a portable terminal that can be carried by a subscriber has been realized. Since such portable terminals are strongly required to be small and lightweight, the transmission power of the wireless device cannot be increased so much. For this reason, zone subdivision, that is, micro-zone formation, is also required from this aspect. Therefore, in future mobile communication systems, at least in urban areas where the number of subscribers is large, a micro zone system with a very small zone radius is required.

However, in the micro zone system, since the number of radio base stations increases significantly, the system cost increases. In urban areas with a large number of subscribers, system costs may be slightly higher, but in suburbs where the number of subscribers is not so large, such micro-zone systems are not economically attractive, so services with the current small-zone system are not possible. Will continue.

That is, a system that uses both the microzone in the urban area and the small zone in the suburbs in combination can construct an efficient system for a service area in which the areal density of subscribers varies.

[Problems to be Solved by the Invention]

In the conventional mobile communication method described above, when a mobile terminal is introduced by using a micro zone and a small zone together, a mobile terminal having a small transmission power has a transmission distance between the mobile terminal and the wireless base station within the micro zone area. Although the service can be received because it is short, the small area in the suburbs has a large zone area and the transmission distance between the mobile terminal and the wireless base station may be long, so if the mobile terminal is located in the small zone area, The service can be obtained only in a very limited area, that is, near a radio base station. Therefore, it is necessary to provide an in-vehicle relay that relays and amplifies a signal from the mobile terminal and transmits the amplified signal to the wireless base station in response to the low transmission power problem of the mobile terminal in the small zone area.

However, in order for the mobile terminal to make a call via the vehicle-mounted repeater, the mobile terminal and the vehicle-mounted repeater need to switch from the random access channel to the call channel. Specifically, the mobile terminal switches from a first random access channel in which a plurality of mobile terminals transmits control information to the same wireless channel, to a first call channel assigned to each mobile terminal, The repeater is a second call channel assigned to each in-vehicle repeater from a second random access channel that relays control information received by a plurality of in-vehicle repeaters from a mobile terminal to the wireless base station on the same wireless channel. Need to switch to. That is, the vehicle-mounted repeater cannot receive the call signal transmitted by the mobile terminal unless the reception channel is switched from the first random access channel to the first call channel. Furthermore, the onboard repeater must switch the transmission channel from the second random access channel to the second call channel,
The wireless base station cannot receive the call signal transmitted by the mobile terminal.

An object of the present invention is to provide a mobile communication system that solves the above problems when providing a service within a small zone.

[Means for solving the problem]

The present invention relates to a mobile communication system including at least a radio base station that covers a service area in which traffic is concentrated in a micro zone and a service area in which traffic is not concentrated in a small zone, an in-vehicle repeater, and a mobile terminal. In the small zone, the vehicle-mounted repeater is a mobile communication system that amplifies the received signal and transmits it to a wireless base station when receiving a signal transmitted from the mobile terminal to the wireless base station, The in-vehicle repeater and the mobile terminal are controlled by the mobile terminal while the in-vehicle repeater and the mobile terminal are located in at least a small zone.

[Action]

As described above, in a system using both a micro zone and a small zone, in order to be able to accommodate a mobile terminal having a small transmission power, the zone area is large and the transmission distance between the mobile terminal and the wireless base station may be long. It is necessary to provide a repeater in a car and provide a mobile communication system that can provide a service if a subscriber's range of action is within a certain distance from the car in a small zone with a possibility.

According to the present invention, when the mobile terminal receives the wireless channel switching signal from the wireless base station while the vehicle-mounted repeater and the portable terminal are located in at least the small zone, the portable terminal transmits the wireless channel switching signal to the vehicle-mounted relay. To do. The onboard repeater switches the wireless channel according to the instruction from the mobile terminal, so that the onboard repeater can relay the call signal transmitted from the mobile terminal to the wireless base station.

By doing so, it is possible to realize a high service that can communicate with the wireless base station at any location within the small zone area as long as the mobile terminal is within a certain distance from the car.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sequence diagram showing an example of radio channel use in the present invention, and FIG. 2 is a block diagram showing an example of a mobile communication system to which the present invention is applied.

This mobile communication system is configured as follows.
Microzone radio base stations 11, 12, 13 are provided in the microzones 1, 2, 3 respectively, and small zone radio base stations 21, 22 are provided in the small zones 4, 5. Reference numerals 14 and 23 are mobile terminals, reference numerals 15 and 25 are in-vehicle terminals, reference numerals 24
Indicates an onboard repeater, respectively.

In the mobile communication system as described above, the in-vehicle terminal 15 existing in the micro zone 1 directly communicates with the micro zone wireless base station 11, and the in-vehicle terminal 25 existing in the small zone 4 directly communicates with the small zone wireless base station 21. . In addition, the mobile terminal 14 existing in the micro zone 3 directly communicates with the micro zone wireless base station 13. However, the mobile terminal 23
Unlike the mobile terminal 14, it exists in the small zone 5, so that the signal transmitted from the mobile terminal 23 to the small zone base station 22 is sent via the vehicle-mounted repeater 24.

When the small zone wireless base station 22 switches the wireless channel to talk with the mobile terminal 23, the small zone wireless base station 22 transmits a wireless channel switching signal a to the mobile terminal 23. Upon receiving the wireless channel switching signal a, the mobile terminal 23 transmits the wireless channel switching signal b to the vehicle-mounted relay 24. Next, the mobile terminal 23 switches the reception channel to the radio channel used between the small zone radio base station 22 and the mobile terminal 23, and the transmission channel to the radio channel used between the onboard repeater 24 and the mobile terminal 23.

When the onboard repeater 24 receives the wireless channel switching signal b, the onboard repeater 24 sets the reception channel to the wireless channel used between the onboard repeater 24 and the mobile terminal 23 and the transmission channel to the onboard repeater 24.
And the wireless channel used between the small zone wireless base station 22.

Next, the small zone wireless base station 22 transmits the test signal c to the mobile terminal 23 in order to bring the switched wireless channel into the conducting state. Upon receiving the test signal c, the mobile terminal 23 transmits the test signal d to the vehicle-mounted repeater 24. Upon receiving the test signal d, the vehicle-mounted repeater 24 transmits the test signal d to the small zone wireless base station 22.

〔The invention's effect〕

As described in detail above, according to the present invention, the vehicle-mounted repeater is controlled by the mobile terminal. In other words, since the mobile terminal controls the vehicle-mounted repeater according to the instruction from the wireless base station, even when the wireless base station needs to control the vehicle-mounted repeater, the wireless base station communicates directly with the mobile terminal. Therefore, the control signal may be transmitted to the mobile terminal. For this reason, the communication procedure when the wireless base station is installed in the small zone and the communication procedure when the wireless base station is installed in the micro zone can be made the same. In the suburbs, it is possible to easily provide a mobile communication system using a small zone.

[Brief description of drawings]

FIG. 1 is a sequence diagram showing an example of use of a radio channel in the present invention, and FIG. 2 is a configuration diagram showing an example of a mobile communication system to which the present invention is applied. 1,2,3 …… Micro zone 4,5 …… Small zone 11,12,13 …… Micro zone wireless base station 14,23 …… Mobile terminal 15,25 …… In-vehicle terminal 21,22 …… Small zone wireless Base station 24 ... In-vehicle repeater

Front page continuation (72) Inventor Yoshinori Nagata 5-33-1 Shiba, Minato-ku, Tokyo NEC Electric Co., Ltd. (72) Nozuna Furuya 5-33-1 Shiba, Minato-ku, Tokyo NEC Corporation In ceremony company (72) Inventor Toshihito Kanai 5-33-1 Shiba, Minato-ku, Tokyo NEC Corporation

Claims (1)

[Claims] 1. A mobile communication system comprising at least a radio base station which covers a service area where traffic is concentrated in a micro zone and a service area where traffic is not concentrated is covered in a small zone, a vehicle-mounted repeater, and a mobile terminal. In the small zone, the in-vehicle repeater is a mobile communication system that, when receiving a signal transmitted from the mobile terminal to the wireless base station, amplifies the received signal and transmits the amplified signal to the wireless base station. A mobile communication system characterized in that the on-vehicle repeater and the mobile terminal are controlled by the mobile terminal while at least within a small zone.