JPS648939B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mobile radio communication system in which mobile objects having a plurality of radio frequencies move between a plurality of radio zones and communicate with each other.

In order to communicate with mobile objects that move over a wide area, as seen in the car telephone system, multiple fixed wireless base stations are installed, each with a different frequency assigned to them, and as the mobile object moves, it communicates with the other party. A method is adopted in which the closest fixed base station is selected at any time for communication. Generally speaking, a method for a mobile device to switch radio frequencies with these fixed base stations is to select a fixed base station with which to communicate while comparing the S/N ratio of the radio line.
If N comparison alone is used, there is a possibility that the frequency of a fixed base station located far away from the fixed base station originally installed to handle that wireless zone may be selected due to radio wave overreach or abnormal radio wave propagation. In addition, in general mobile communication systems, in order to improve the calling efficiency when calling a mobile unit from a base station, the location of the mobile station is registered in the radio control station one after another, and the mobile unit is called only from the fixed base station to which the mobile unit belongs. However, in order to reduce the frequency of location registration, a method is used in which a plurality of fixed base stations are collectively configured as one location registration unit. At this time, in the conventional frequency switching method that relies only on determining the S/N ratio mentioned above, the frequency of a nearby fixed base station is not necessarily selected as the mobile object moves; This method has the drawback that the frequency is selected, which actually defeats the purpose of reducing the frequency of location registration. Furthermore, if there is a possibility for a mobile communication party to communicate via a fixed base station far away from the actual location of the mobile body, it is often used to communicate via a fixed base station In a rate system in which communication charges differ depending on the location of the station, there was a problem in which users were not satisfied with the rationality of the rate system.

It is an object of the present invention to eliminate these drawbacks and ensure the continuity of the geographical locations of fixed base stations selected during frequency switching between fixed base stations as a mobile body moves.

Figure 1 is an example of a conceptual diagram of the configuration of a fixed base station to realize the present invention, and each circle indicates the range where radio waves from each base station can be received with a good S/N value (hereinafter referred to as wireless zone). The line from X=1 to X=6 is the abscissa and the line from X=1 to Y=4 is likewise the ordinate for indicating the geographical location of the radio zone. In Figure 1, Z(1, 2), Z(1,
3) to Z(6,3) are names assigned to the wireless zones located at each coordinate. The name assigned to the wireless zone includes information on the geographical positional relationship, and it is clear from the diagram that wireless zones whose X or Y values differ by 1 are geographically adjacent to each other. It is.

FIG. 2 is another example of assigning coordinates to a honeycomb zone arrangement that is often used when configuring wireless zones. Here, X and Y are horizontal and vertical coordinates as in FIG. 1, and Z (1, 2) to Z (11, 2) are wireless zones located at each coordinate. In this example, those whose Y values differ by 1 or whose X values differ by within 2 are adjacent to each other. Furthermore, depending on the application, if the wireless zone expands in the height direction, it is also possible to add another coordinate axis u to represent the three-dimensional positional relationship.

In any of these cases, a range is set for the difference in the values of X, Y, and u, and it can be guaranteed that wireless zones within the range are adjacent to each other.

In the present invention, the coordinate values described above are transmitted as position identification signals from the fixed base stations of each wireless zone, and the mobile radio equipment decodes the position identification signals from each fixed base station to determine the location of the wireless zone. When moving from one wireless zone to another, priority is given to selecting the frequency of a wireless zone adjacent to the wireless zone to which the user previously belonged.

FIG. 3 shows an embodiment of a frequency switching device for a mobile radio to which the present invention is applied, and this embodiment will be explained below.

In the figure, 1 is an antenna of a mobile object, 2 is a transmitting/receiving circuit that has a function of demodulating a received signal and creates a transmitting signal, 21 is an S/N detection section, 3 is a position identification signal detection circuit that detects position information, and 4 is a frequency selection circuit that compares the newly received location information of the radio base station with the location information of the radio base station with which it was previously communicating, and outputs the result to output terminal B. 5 is a variable frequency oscillation circuit that oscillates at a frequency specified by the frequency selection circuit 4, and its output is applied to a terminal C as a local oscillation frequency.

Further, the frequency selection circuit 4 includes a frequency designation circuit 41,
Frequency code table 42, position information comparison circuit 4
3, a position information storage circuit 44, and a gate circuit 45. Further, the position identification detection circuit 3 is composed of a model demodulation circuit 31, a serial/parallel conversion circuit 32, a frame synchronization circuit 33, a position information code decoder 34, and a temporary storage circuit 35, as shown in FIG.

Next, the operation of this embodiment will be explained.

A radio signal from a fixed base station inputted from an antenna 1 of a mobile body is demodulated by a transmitting/receiving circuit 2 and inputted to a position identification signal detection circuit 3. This position identification signal detection circuit 3 has a function of outputting position information of a fixed base station consisting of X, Y or X, Y, u coordinates. That is, the received output of the transceiver 2 is converted into a temporally serial digital code string by the modem demodulation circuit 31, and is further converted into a serial-to-serial digital code string by the serial-to-parallel conversion circuit 32.
is converted into a parallel code by This parallel code is decomposed into X, Y, and u coordinate information by the position information code decoder 34 by timing with the output of the frame synchronization circuit 33 which receives the output of the modem demodulation circuit and extracts the synchronization timing of the signal. After being latched by the temporary storage circuit 35, it is output to the terminal A.

Fixed base station position information currently being received, which is the output of the position identification signal detection circuit 3, is input to the frequency selection circuit 4.

Next, details of the frequency selection device 4 will be explained. When the S/N of the receiving line deteriorates, the frequency specifying circuit 41 adjusts the S/N of the line provided inside the transmitting/receiving device 2.
Upon receiving the output of the detection section 21, one of the frequency codes registered in the frequency code table 42 constituted by a storage circuit such as a ROM is sequentially selected and outputted to the output terminal B of the frequency selection device 4. Here, the frequency designation circuit 41 is composed of a counting circuit including an interval timer, and is realized by giving the output of the counting circuit, which counts up using the output of the interval timer as a trigger when activated from the outside, as the address of the storage circuit. be done. In this state, when new fixed base station coordinate position information is input to the terminal A within a certain period of time, the position information comparison circuit 43 consisting of a logical subtraction circuit and a group of gates for judgment uses the position information storage circuit 44. If the difference in each coordinate information exceeds a preset value when compared with the content, it is determined that it is not the location information of a neighboring base station, and the frequency designation circuit 41 is activated. The next code is selected from the contents of the table 42 and output.

A similar operation is performed when new position information is not input to terminal A within a certain period of time. Comparing the newly input location information with the previous location information of the wireless base station, if the difference in the values of It is determined that the base station is in the vicinity of the base station, and the frequency code sequential selection operation of the frequency designation circuit 41 is stopped, and the gate circuit 45 is opened to store new base station information in the previous position information storage circuit 44, which is a temporary storage memory. let

Frequency specification circuit 41 is frequency code table 4
If a nearby base station cannot be selected after going through 2 once, select an appropriate fixed base station from among those with a good S/N ratio and store the previous location information of this base station as a new communication partner station. It is registered in the circuit 44.

As a result, in the mobile radio device having the configuration shown in FIG. 3, the frequency selection circuit 4 sequentially switches the communication channel with the fixed base station according to the frequency code outputted as appropriate, and selects the fixed base station that is the other party of new communication. If the position coordinate information differs from the previous one within a predetermined range, the switching operation is preferentially terminated.

As is clear from the above explanation, according to the present invention, when switching wireless zones, a neighboring wireless zone is preferentially selected from among fixed stations with a fixed S/N ratio or higher, thereby ensuring geographical continuity when switching zones. It has the feature of ensuring that

[Brief explanation of drawings]

Figures 1 and 2 are conceptual diagrams of a wireless zone configuration to which the present invention is applied, Figure 3 is a block diagram of a frequency switching device for a mobile radio to which the mobile communication system of the present invention is applied, and Figure 4 is a FIG. 2 is a block diagram showing a detailed configuration of main parts. 3...Position identification signal detection circuit, 5...Variable frequency oscillator, 21...S/N...detection unit, 42...Frequency code table, 41...Frequency designation circuit, 44...
...Previous position information storage circuit, 43...position information comparison circuit.

Claims (1)

[Claims] 1. In a mobile communication system consisting of a plurality of fixed base stations that switch and use a plurality of sets of channel frequencies, and a mobile station that moves between the communication zones of the plurality of base stations and communicates with the base station, a detection unit that receives a transmitted signal adding the position information of the base station as coded coordinates and detects the S/N of each received signal; and a storage circuit that stores a frequency code table in advance; It comprises means for switching the receiving frequency according to the code table, means for storing the previous position information, means for separating the position information of the base station from among the received signals, and a position information comparison circuit, When the S/N of the received signals deteriorates, the receiving frequency is sequentially switched, and the received position information is compared with the above position information, and if the difference between the two falls within the set value, the channel of the mobile device is fixed and the communication path is established. 1. A mobile communication system characterized in that the mobile communication system is established and the stored content of the previous location information is updated.