JPS6329862B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to a public automobile radio system in which service areas are arranged in a honeycomb pattern.

In conventional systems in which a mobile station identifies the service area it is in and communicates with the corresponding base station, the range in which the base station connects to the mobile station and handles communication, that is, the width of the service area, is limited. The base station transmission power is fixed at a certain value, and the installed capacity of each base station is designed to provide a fixed connection rate depending on the expected call volume within its service area, which has the following drawbacks: was occurring. In other words, the first is that if the call volume is up to the maximum capacity, it is not possible to track and switch mobile stations that are in continuous communication flowing in from adjacent service areas, and the second is that all incoming and outgoing calls exceeding the maximum capacity are disconnected. To become a,
The third problem is that the difference between the designed traffic volume and the actual situation results in a lack of equipment on one side and an excess of equipment on the other, resulting in a lack of flexibility.

Accordingly, an object of the present invention is to provide a mobile radio system that provides flexibility in the equipment of adjacent base stations and has a high connection rate and equipment utilization rate.

According to the present invention, a plurality of mutually adjacent service areas divided according to a predetermined standard;
Consisting of a plurality of base stations that individually take charge of these service areas and a control station that controls these base stations, radio waves transmitted from the base station that reach a mobile station are sent to the base station that satisfies predetermined criteria. In the communication system, the control station detects the usage rate of each base station, and determines whether the usage rate of one base station exceeds a design value and the base station adjacent to the one base station Providing means for transmitting a transmission power control signal for setting the transmission power of the one base station to a changed value when the station line is vacant;
Each of the base stations is provided with means for changing its own transmission power upon receiving the transmission power control signal, thereby changing the range of the service area covered by the base station that has changed the transmission power. A mobile radio system is obtained that is characterized by a high connection rate for the entire system.

Next, a detailed description will be given with reference to the drawings.

FIG. 1 is a diagram showing an outline of the arrangement of an embodiment of a system according to the present invention, showing that the service area can be changed by changing the base station transmission power. In FIG. 1, 1, 2 and 3 are base stations, 4, 5
and 6 is the standard service area, 7 is the reduced service area, 8 is the boundary of the standard service area 5,
Reference numeral 9 indicates a mobile station, 10 a boundary line of the reduced service area 7, 11 a movement path of the mobile station 9, and 12 a control station.

FIG. 2 is a diagram showing the relationship between the mobile station position and the mobile station input electric field in the service area of FIG. 1. In Fig. 2, 13, 14, and 15 are the input electric field strengths in the standard service area, 16 are the input electric field strengths in the reduced service area, and 17 are the input electric field strengths in the reduced service area.
-24 are the positions of each part in Fig. 1, 25-27
represents the input level, respectively.

The general operation of the system will be described below with reference to FIGS. 1 and 2. Furthermore, mobile stations, base stations,
Each control station will be explained later. The standard service areas 4 to 6 shown in FIG. 1 are part of a group of service areas that make up the system, and the electric field strength of the transmitted waves from the base stations 1 to 3 that reach the mobile station moving along the movement route 11 is as follows: The input electric field strength is 13 to 15 in FIG. 2, respectively. In this embodiment, the base station 1 uses wireless channels a1, a2, ... a5,
The base station 2 has wireless channels b1, b2, ... b5, and the base station 3 has wireless channels c1, c2, ... c5, and the transmission power of each channel is assumed to be the same in standard time. Note that the control station 12 constantly detects the line usage rate of each base station, and learns that the line usage rate of a certain base station, that is, the call volume, exceeds the design value and that the line of an adjacent base station has margin. It also has a function to control (lower in this case) the transmission power of that base station.

Next, the operation in standard time will be explained. It is assumed that base stations 1 to 3 have channels that are not currently used for calls (hereinafter referred to as empty channels). When an incoming/outgoing call occurs at the mobile station 9, the mobile station 9 sequentially receives transmission waves from each base station, for example, channels a1, b1, and c1. Input level 2 in Figure 2
6, b1 can be received at an input level of 27, and c1 can hardly be received. Mobile station 9
Since the b1 channel is the largest, the mobile station determines that the mobile station is located within the standard service area 5 of the base station 2, and transmits a signal to the base station using the b1 channel. The base station 2 can receive the b1 channel signal, and the base station 2 allocates one free channel among the b1 to b5 channels owned by the base station to the mobile station 9 and performs a connection operation according to a predetermined procedure. In this situation, the boundaries of the standard service area are boundary points 18 and 23 in FIG. 2, ie boundary 8 in FIG. 1.

Next, the call volume exceeding the design value was concentrated in the standard service area 5, but since there was room in the adjacent service area, the control station 12 controlled the base station 2.
The case where the transmission power is lowered will be explained. The electric field strength of the transmission wave from the base station 2 that reaches the mobile station 9 on the movement path 11 decreases to the input electric field strength 16. Therefore, in the mobile station 9 located at the mobile station position 19, the a1 channel has an input level of 26, and the b
1 channel is received at input level 25, it is determined that the station is within the service area of base station 1, that is, a station that can receive at a high input level, and a signal is transmitted to the base station on the a1 channel. Thereafter, in the same manner as in standard time, an empty channel among a1 to a5 is assigned to the mobile station 9, and communication is performed.

The service area of base station 2 is reduced from standard service area 5 to reduced service area 7 by moving from boundary points 18, 23 to boundary points 20, 22 in FIG. On the other hand, the service areas of base stations 1 and 3 will be expanded to the boundary line 10, and mobile stations existing in the periphery of the standard service area 5 of base station 2 will be dispersed to adjacent service areas, and load is reduced.

Next, the configuration and operation of each station to realize the above operation will be explained.

FIG. 3 is a block diagram showing an example of the configuration of the control station 12 (FIG. 1) used in the system according to the present invention, where 31 is a line control section, 32 is a car telephone line, and 33 is a base station 1. 34 is a line for base station n, and these represent the configuration as a normal control station. 35 is a usage rate detection unit, 36 is a transmission power setting unit, and 37 is a transmission power control unit for base station 1. Signals 38 are base station n transmit power control signals, which are particularly used in the system according to the invention. As can be easily seen from FIG. 3, the usage rate detector 35 detects the line usage rate for each base station from the connection state of the line controller 31, and the transmission power setting unit 36 According to the output of A transmission power control signal (37 in the embodiment) is sent to set the transmission power of the base station (1 in the embodiment) whose usage rate exceeds the design value to a reduced value (in the embodiment).

FIG. 4 is a block diagram showing an example of the configuration of base stations 1 to 3 (FIG. 1) used in the system according to the present invention, in which 41 is an antenna, 42 is a duplexer, 43 is a receiver, 44 is an upstream audio/data signal, 45 is a transmitter, 46 is a downstream audio/data signal, and these represent the configuration of a normal base station; 47 is a transmission power control unit;
8 is a transmission power control signal (corresponding to any one of 37 to 38 in FIG. 3), which is particularly used in the system according to the present invention. As can be easily seen from FIG. 4, the transmission power control section 4
7 reduces the output of the transmitter 45 upon receiving a control signal 48 that reduces the transmission power.

Although the mobile station can be used as is in a conventional conventional system, its structure will be shown below and its operation will be explained.

FIG. 5 is a block diagram showing the configuration of a mobile station, in which 51 is an antenna, 52 is a duplexer, 53 is a transmitter, 54 is a receiver, 55 is a synthesizer, 56 is an input electric field detector, and 57 is the control section,
58 is a local oscillator signal, 59 is a channel designation signal, 6
0 represents an upstream audio/data signal, 61 represents a downstream audio/data signal, and 62 represents a transmitter control signal. In this configuration, to first explain the general functions, when a mobile call is made, the control unit 57
Channels such as 1 and c1 are sequentially designated, and the input electric field detection section 56 detects the received input electric field and passes the channel number having the maximum input to the control section 57. At this time, the transmitter 53 is off. With the above steps, the channel to be used for the call is determined, and the transmitter 53 is turned on to send a calling signal to the base station. When calling the base, if the corresponding mobile station number and own number match, the above sequence is started, the maximum input channel number is determined, and a response signal is returned.

The operation of a mobile station having the above configuration and functions when switching zones will be explained. In conventional systems, zone switching is performed when a base station moves out of the service area of the base station with which it was communicating, but in the system of the present invention, zone switching is performed in addition to the above cases. This occurs in mobile stations located in the periphery of the area when a base station in the area lowers its transmission power. However, from the mobile station's point of view, zone switching can be performed with exactly the same operation in the two cases. That is, first, the input electric field detection section 5
When detecting that the reception input has become less than the specified value at step 6, the control section 7 turns off the transmitter 53 and switches a1 and b.
Channels such as 1 and c1 are sequentially designated by local oscillator signals. When the input limit detection section 56 detects a channel with the maximum input, the channel number is returned to the control section 57. The control unit 57 locks the synthesizer 55 using the channel number, turns on the transmitter 3, and sends a line switching signal to the new base station. The new base station transmits this signal to control station 12 (first
(Figure), and the line is switched from the old base station to the new base station by following the prescribed procedure.

In this embodiment, the standard service area 5 is reduced by lowering the transmission power, but it is also possible to expand the standard service area 5 by raising the transmission power. The size control extends to all base stations under the control of the control station 12, and for service areas where the call volume exceeds the installed capacity, mobile stations and connections are distributed to adjacent service areas. The feature is that organic control can be performed by changing the transmission power of each base station, and there are no limitations on the combination of target channels and service areas.

By applying the present invention, the system can flexibly respond to the ever-changing mobile station call volume, which increases the overall call volume that can be handled.If the connection rate is held constant, the system can be operated with less equipment than before. A large economic effect can be obtained by being able to operate the system.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an outline of the arrangement of an embodiment of the system according to the present invention, FIG. 2 is a diagram showing the relationship between the position of a mobile station and the input electric field in the service area of FIG. 1, and FIG. A block diagram showing an example of the configuration of a control station used in a system based on
FIG. 4 is a diagram showing an example of the configuration of the base station,
FIG. 5 is also a diagram showing an outline of the configuration of the mobile station. Explanation of symbols: 1 to 3 are base stations, 4 to 6 are standard service areas, 7 is reduced service areas, 8 is border lines, 9 is mobile stations, 10 is border lines, 11 is mobile routes, 12 is control stations, 13-15 are standard input field strengths, 16 are reduced input field strengths, 17-24
is a position, 25 to 26 are input levels, 31 is a line control unit, 32 to 34 are lines, 35 is a usage rate detection unit,
36 is a transmission power setting unit, 42 is a transmitter/receiver duplexer, 43
45 represents a receiver, 45 represents a transmitter, and 47 represents a transmission power control section, respectively.

Claims (1)

[Claims] 1 Consists of a plurality of mutually adjacent service areas divided according to defined criteria, a plurality of base stations that individually take charge of these service areas, and a control station that controls these base stations. In a communication system in which a mobile station communicates with a base station whose base station transmission radio waves reach a predetermined criterion, the control station detects the usage rate of each base station, and Transmission power for setting the transmission power of one base station to a changed value when the usage rate of one base station exceeds the design value and the line of the base station adjacent to the one base station is vacant. Means for transmitting a control signal is provided, and each base station is provided with means for changing its own transmission power upon receiving the transmission power control signal, whereby the service provided by the base station that changes the transmission power is provided. A mobile radio system characterized in that the connection rate of the system as a whole is increased by changing the range of the area.