JPH08265840A - Mobile radio communication system - Google Patents

Abstract

PURPOSE: To allow a mobile radio terminal equipment of the public mobile communication system to access a radio channel of the private mobile communication system without providing disturbance to the public mobile communication system. CONSTITUTION: A private mobile communication system is provided in a service area of a public mobile communication system, a transmitter-receiver 16 provided to the private mobile communication system uses part of frequency channels used for the public mobile communication system to make transmission reception and the transmission power of the transmitter-receiver 16 is set smaller than the transmission power of a base station in the public mobile communication system. Thus, when a private mobile communication system is newly established, a new frequency resource is not required and the interference and disturbance of the private mobile communication system onto the public mobile communication system is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio communication system, and more particularly to a communication system such as a private mobile radio telephone system used in a closed area of an office or a factory, and more particularly to a mobile radio communication device outside the premises. The present invention relates to a mobile radio communication system suitable for communicating with a wide area public mobile radio that has already been serviced when brought out.

[0002]

2. Description of the Related Art A wide area mobile radio telephone system is known as a slave cellular public mobile telephone system. However, when a mobile radio telephone is brought into a premises and a call is made by connecting to a private telephone line in the premises, a building structure is used. Not only the call quality is deteriorated due to the radio interference due to the above, but there is a drawback that the call charge of the cellular public mobile line is added.

As an example of a cellular mobile telephone system for improving this kind of radio interference, 1984 IEEE-VT is used.
The 162 pages of the conference papers are listed.

[0004]

In the private premises telephone system described in the above document, the installation of a wireless line connecting the cellular public mobile radio telephone terminal and the private premises telephone system to each other is not considered, and the mobile terminal is not considered. There was a problem that it was not possible to directly talk to the wireless line of the private telephone system on the premises from this wireless line. Moreover, in the conventional private premises radio telephone system, in order to interconnect the mobile terminal to the cellular public mobile telephone system, it is expensive because the mobile terminal has both the private radio frequency channel and the cellular public radio frequency channel. There was a problem.

An object of the present invention is to provide a wireless line in a private mobile telephone system on a premises so that a cellular mobile radio telephone can directly access the wireless line of a private mobile telephone system on a premises without disturbing the cellular public mobile telephone system. The purpose is to do.

[0006]

[Means for Solving the Problems] The above object is to install a wireless line in a telephone switch of a wired line in a private telephone system in a premises installed in an area where a wide area public mobile wireless telephone system is implemented, and to use the wireless line. Part of the radio frequency channel of the wide area public mobile radio telephone system used in the area is used for the frequency channel of the transmission / reception system,
The radio field intensity is achieved by making it weak enough not to interfere with the wide area public mobile radio telephone system and other private mobile telephone systems installed in the adjacent area.

That is, within a large area (hereinafter referred to as a cluster) in which the private telephone system is installed, it is used in a small area (hereinafter referred to as a cell or sector) in which a private wireless telephone system is installed. Select a radio channel with less interference from radio channels other than the existing radio frequency channel, and use a telephone with a radio field strength that is not affected by other interfering waves within the service area of the private telephone system.

[0008]

The radio frequency channel of the cellular public mobile telephone system is reused between clusters in units of 12 cells using an omnidirectional antenna as a base station, as discussed in the 1984 IEEE-VT Conference Proceedings, page 322. Then, about 1/12 of the total number of channels is allocated to each cell in the cluster. If a multi-beam antenna is used as a base station, the number of cells is 3 or 6
It is divided into sectors and about 1/20 of the total number of channels is distributed to each sector in the cluster.

The mobile radio telephone system of the present invention is installed in this cell or sector. The radio frequency channel used by the cellular public mobile radio telephone system in this cell or sector has the least interference from adjacent clusters. The suboptimal radio channel having a little more interference than this radio frequency channel is reused in the radio line of the mobile radiotelephone system of the present invention. In other words, this radio channel is located as far as possible from the cell or sector to which the private system belongs, and the radio frequency channels of the cell or sector located on the terrain or terrain where the radio wave propagation path has large radio interference are duplicated in the cluster. Reuse.

The transmission wave radiating system of the mobile telephone system according to the present invention is set to have the above-mentioned radio field intensity, secure a service area on the premises, and have a directivity characteristic which does not interfere with the cellular public mobile telephone system and an adjacent private premises telephone system. . The jamming radio wave is not a problem because it is attenuated by the structure inside the building, but it is a problem at the window of the building or outside the building outside the building. The received wave radiation system of the mobile radiotelephone system according to the present invention may be poised to have a directional characteristic that is sufficiently stronger than the received power of the interfering radio waves from within the cluster.

When the mobile telephone system of the present invention is installed in an area where the subscriber density of the cellular public mobile telephone system is high, the cell radius or sector area becomes small. Area becomes small. In this case, “Personal Communication Pe
As discussed in “Rsonal Comunication”, September 1985, p. 28, the premises is divided into a plurality of cells, and the distant cells can be reused to further secure the premises service area.

[0012]

EXAMPLES The present invention will be described below with reference to examples. FIG. 1 is an example of cell arrangement of a cellular public mobile communication system, in which an omnidirectional transmission antenna is arranged at the center of a hexagonal cell (small area), and 12 cells (numbered from 1 to 12) are arranged. Is used as one cluster (large area) unit, the same frequency is reused between different clusters, and the premises 0 in which the mobile radio telephone system of the present invention is installed in the cell 1 and the cells 2 to 12 around it. And the positional relationship of the cluster (the portion surrounded by the thick line) 13 to which these cells belong.

The number of radio frequency channels corresponding to the traffic of the mobile telephone is allocated to each cell, and these radio waves are f ₁ wave in cell ₁ , f ₂ wave in cell ₂ , f ₃ wave in cell 3,
I will express it with .... The f ₁ wave, ..., The f ₃ wave and the like have a constant bandwidth, and there are a plurality of channels in the band. The position of the cell 1 in the cluster 13 is selected at a position where the intensity of the disturbing f ₁ wave from outside the cluster is minimized.

In the mobile radio telephone system 0 of the present invention, the radio frequency channel which is slightly larger than the interference wave intensity but has the condition of the suboptimal interference wave intensity is reused in the cluster. As a frequency of the radio channel that satisfies this condition, for example, the f ₂ wave of the cell 2 exists. Although the cell 4 is located farthest from the cell 1 in the cluster 13, the disturbing f ₄ wave intensity from the outside of the cluster 13 is larger than the previous f ₂ wave. The f ₃ wave used in cell 3 also satisfies the above condition.

FIG. 2 shows the strength of radio waves used by the mobile radio telephone system of the present invention. In FIG. 2, the mobile radio telephone is displayed as "private system". That is, FIG.
When the mobile radiotelephone system of the present invention is installed in the indoor system 0 in the cell 1, the electric field strength E ₁ of the radio wave radiated from the cell ₁ is represented by the following equation (Equation 1) if there is no radio interference.

[0016]

[Equation 1]

Here, R is the distance from the transmitting antenna to the receiving point, a is the proportional coefficient, and P ₁ is the transmitting power of the antenna. In cellular public system, interference from strength S ₁ and cluster 13 outside the cell boundary of the transmission frequency _one wave f ₁ wave intensity I ₁
The ratio S ₁ / I ₁ is set to a value that maintains a predetermined call quality. Transmission power P of mobile radio telephone system 0 of the present invention
₂ is the transmitted f ₂ wave strength S at the boundary of the service area
₂ and the interference f ₂ wave intensity I ₂

[0018]

[Number 2] _{S 2 / I 2 = S 1} / I 1 and, P ₂ is set to a value that satisfies the conditions of the upper limit value or less that does not interfere with other premises private adjacent (Equation 2).

FIG. 3 shows a block diagram of an embodiment of a mobile radio telephone system according to the present invention. A private branch exchange (PBX) 15 for a wired telephone line is installed in the premises 0, and a wireless line is added to this. Wireless line is transceiver (TRX)
Transmitter / receiver antennas 18, 19 via 16 and booster 17
Is connected to the mobile phone 20, and the mobile phone 20 can receive the f ₂ wave having the intensity that suppresses the disturbing f ₂ wave of the cellular public mobile system. The mobile telephone 20 is also connectable to the public f ₁ wave. The transmission power of the mobile phone 20 is set to a value that satisfies the above condition (Equation 2). This command was set in the PBX15 of the private system of the main campus. It is automatically controlled by the radio network controller.

FIG. 4 shows a case where a large number of mobile radiotelephone systems according to the present invention are installed in each of the cells in the cluster 13, and the f _N wave (N = 1) of the radio frequency channel used in each cell.
.About.12) are shown in relation to FIG. For example, in the cells 4, 2 and _{5 of} FIG. 1, when a large number of private premises systems of the present invention using f ₅ waves, f ₃ waves and f ₆ waves are installed in the service area of the cellular public system, respectively, I am concerned about the total interference strength of the transmitted wave. However, the conditions that prevent interference with adjacent private systems are much more stringent. Radiation from the outdoor antenna 19 in FIG. 3 is particularly severe, and directivity is given to the antenna to suppress interference.

When the private premises mobile radio telephone systems are extremely close to each other because they are in the same adjacent cell, the private premises service area of the present invention is extremely narrow. To solve this problem, use other radio frequency channels for adjacent private premises (eg, alternating f ₂ and f ₃ waves). Further, when the reuse frequency is shifted by 1/2 of the channel interval to reduce the interference, the mobile telephone is also shifted to the frequency corresponding to this.

5 and 6 show a cellular public mobile telephone system 6
It is an example of area allocation when a 60-degree directional multi-beam antenna is used in the center of a rectangular cell. Each cell is divided into 6 sectors, and 4 cells and 24 sectors are used as a unit cluster, and frequencies are reused between the clusters. FIG. 6 shows a mobile radio telephone system of the present invention installed in each sector.
FIG. 6 shows an example of the corresponding sector numbers in FIG. 5 in the case of dual reuse of radio channels within a cluster. Existence other than this example of the sector number is similar to the case of the 12-cell unit sector. The directivity of the antenna is an important factor in considering the interference wave from another sector, and the proportional coefficient a = a ₀ G (θ) and the directivity gain function G (θ) of (Equation 1) are introduced. There is a need.

In an area with many cellular public subscribers, the cell radius is shortened to increase the traffic per unit area.
The mobile radio telephone system of the present invention is designed with this increase in the private premises. Table 1 shows an example of the relationship between the radius of the private private service area and the radius of the public cell of the present invention.

[0024]

[Table 1]

When the premises area is larger than the service area radius of the private system, the radio frequency channel is reused also in the premises private system.

FIG. 7 is a block diagram of another embodiment of the present invention for reusing a radio frequency channel in a premises. Transceiver (TRX) 2 with wireless transceiver and antenna integrated
In the building 1, a transceiver (TRX) 22 is installed outside the premises to set radio frequency channels, transmission power and antenna directivity that do not interfere with each other. The private branch exchange (PBX) 15 is equipped with a radio network controller, and when the mobile terminal 20 moves from the f ₂ wave area to the f ₃ wave area, it automatically detects and switches channels. It is similar to the cellular public mobile telephone system. It is also possible for this wireless line control device to improve the communication quality by using the vacant channels of the cellular public system and the adjacent private system of the premises.

The area in which the mobile radio telephone system of the present invention is installed depends on the hill structure or the unique terrain, as shown in FIGS.
In addition to the ideal cell arrangement described in 1 above, the radio wave propagation is attenuated more severely than the above (Equation 1). The application of the invention is essentially unchanged by this.

In reusing the cellular public wireless channel according to the present invention, the public free channel information is obtained by the transmission / reception installation separately provided in the local system, and if the reuse channel is disturbed, the busy channel is switched to busy. It is also clear that the call quality will be further improved by performing.

[0029]

【The invention's effect】

1) According to the present invention, when the mobile radio telephone system is installed, the radio frequency channel used in the existing cellular public mobile radio telephone system is reused, so that there is an effect that a frequency resource is not newly used.

2) According to the present invention, when a portable telephone terminal is brought into the premises in an area where the cellular public mobile radio telephone service is provided, it is possible to directly access the extension telephone, so that the radio wave can be transmitted from the building structure. There is an effect that the call charges through the cellular public line are not required because of no obstacle.

3) According to the present invention, a mobile terminal capable of directly accessing both the cellular public system and the private premises system can be realized without adding a high frequency line to the mobile terminal.
It has the effect of making mobile terminals smaller, simpler, and more economical.

[Brief description of drawings]

FIG. 1 is a plan view of a cellular public cell arrangement in an area where an embodiment of the present invention is installed.

FIG. 2 is a diagram showing a relationship between radio field intensities in the cell 1 of FIG.

FIG. 3 is a configuration diagram of an embodiment of the present invention.

FIG. 4 is a plan view showing channels used when the present invention is carried out in each cell of FIG.

FIG. 5 is a plan view showing cell configurations of different types in regions where an embodiment of the present invention is installed.

FIG. 6 is a plan view having the same meaning as in FIG.

FIG. 7 is a configuration diagram of another embodiment of the present invention.

[Explanation of symbols]

0 ... A premises in which a private system of the present invention is installed, 1 ... A cell in which an embodiment of the present invention is installed, 2-12 ... A peripheral cell of a cell in which an embodiment of the present invention is installed, 13 ... The present invention The cluster in which the embodiment of the present invention is installed, 14 ... Other adjacent premises in which the present invention is implemented, 15 ... Private exchanges in which the present invention is implemented, 16 ... Transceiver, 17 ... Booster amplifier, 18 ... In a building Antenna, 19 ... Outdoor antenna, 20 ... Mobile terminal,
21 ... In-house transceiver and antenna, 22 ... Outdoor transceiver and antenna.

Claims (1)

[Claims] 1. A private mobile communication system provided in a service area of a public mobile communication system, wherein a transceiver provided in the private mobile communication system has a frequency used in the public mobile communication system. A private mobile communication system, wherein part of a channel is shared for transmission / reception, and the transmission wave power of the transceiver is smaller than that of the base station in the public mobile communication system.