JPS62109448A - Communication control system - Google Patents

Abstract

PURPOSE:To decrease the crosstalks and to reduce the deterioration of the certainty of communication by setting proviously the number of receiving timings with which a base station receives the discrimination codes and at the same time setting again at random the timing by which each slave station sends back the discrimination code every time a specific code is received. CONSTITUTION:The number of receiving timings with which the discrimination codes sent back after a base station calls an unspecified station (slave station) are received is synchronous with the transmitting timing of the discrimination code of the slave station. However the timing available at the slave station is limited to just one of those receiving timings and this timing is decided at random. In an example shown in the diagram, the discrimination codes of slave stations A and D are coincident with each other by change at the timing '1'. While the discrimination codes of the slave stations B and C are divided at timings '3' and '4' and transmitted. Then no station has transmission at timing '2'. Therefore the discrimination codes of both stations A and D are received with crosstalk at he timing '1'. Then the discrimination codes of both stations B and C are received in a correct way at the timings '3' and '4'.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention attempts to efficiently select a partner station in a system in which a base station communicates with a plurality of unspecified partner stations. It is.

[Conventional technology]

In a system in which a base station and a plurality of slave stations are connected through a common transmission path, whether wired or wireless, the problem is how to select a slave station to communicate with the base station. One method is polling, but this is inefficient because it is performed regardless of whether there is a request from the slave station, and it is not flexible because it requires system changes when the number of slave stations changes.

On the other hand, in a system in which multiple slave stations are placed opposite to a common wireless base station, and the operators of the slave stations respond by voice to calls from the base station, there is no problem or unnecessary fluctuation in the number of slave stations. It is also possible to avoid data transmission from other slave stations.

[Problem that the invention seeks to solve]

However, in the above-mentioned method, interference is unavoidable, and in that case, the probability of establishing communication depends on the magnitude of the transmission output of the slave station, the response timing and modulation intensity of the operator, or the hearing ability and discrimination ability of the base station operator. The disadvantage is that some slave stations have high and some have low values. The present invention attempts to improve this point.

[Means for solving problems]

The present invention transmits a specific code from a base station to a plurality of unspecified slave stations at the same time, causes the slave stations that received the code to return a unique identification code, and furthermore, one of the identification codes received by the base station In a communication control method in which the base station returns an identification code and starts communication with the slave station, the number of timings at which the base station receives the identification code is set in advance, and the timing at which each slave station returns the identification code is set in advance. The feature is that the code is randomly reset each time the code is received.

[Effect]

Figure 1 is a diagram explaining the principle of the present invention, in which the number of reception timings is 4.
This is an example. This reception timing number is the number of timings at which the base station calls an unspecified station (slave station) and then receives the returned identification code, and is synchronized with the identification code transmission timing of the slave station. However, only one of these timings can be used by the slave station, and that timing is randomly determined. In the illustrated example, the identification codes of slave stations A and D coincidentally overlap at timing 1, but the identification codes of slave stations B and C are transmitted separately at timings 3 and 4, and at timing 2, which station is the same? has not been sent either. Therefore, at reception timing 1, it is A.

Although the identification code of station D is received with interference, the identification codes of stations B and C can be correctly received at timing 3.4.

In the illustrated example, the number of timings is 4 and the number of child stations is 4, but this combination is arbitrary. The table below shows the probability (%) of not being able to establish communication with any station due to interference, as a function of the number of stations and the number of reception timings.

Table 1 and FIG. 2 are graphs of this, where ``■'' is the case where the number of conventional timings is 1, and ``■'' to ``■'' are the cases where the number of timings is 2 to 4 according to the present invention. As is clear from these tables and figures, the probability of interference decreases as the number of timings increases. Further, by registering (memorizing) the received identification code on the base station side, it is possible to monitor all communication requesting stations, and by selecting these at random, it is possible to equalize the probability of communication confirmation for stations with which communication is possible. However, it is also possible to prioritize and select.

This is the case for automatic selection, but there is also manual selection by the operator. The procedure for confirming communication is as follows.

(1) Confirm that the transmission line is unused.

(2) Calling an unspecified station. --→0 Unspecified station call received.

I at the Nth timing Reception.

(4) Selection of identification code.

(5) Transmission of identification code. --Reception of 1→0 identification code.

(6) Communication confirmation is received ←---. If the identification is the same as your own station, it is a normal communication mode code.
If so, send a communication confirmation.

(7) No confirmation of communication received If so, follow steps (4) or (1) Go back.

〔Example〕

3 to 6 are explanatory diagrams showing one embodiment of the present invention, taking as an example a system in which digital image data is transmitted from a base station to a plurality of mobile stations. Figure 3 is a block diagram of the base station, where 1 is an image input device, 2 is an input/output port, 3 is a modem, 4 is a CPU (central processing unit), 5 is a RAM, and 6 is a R
OM, 7 is a CRT for monitoring. If the image input device 1 is excluded, the configuration becomes a mobile station.

FIG. 4 is a time chart on the base station side, and the number of reception timings is three. FIG. 5 is a program for a communication confirmation procedure executed by the CPU 4 on the base station side, and FIG. 6 is a corresponding program executed by the CPU on the mobile station side. On the base station side, storage areas ANSI to ANS3 and CARAD are set in the registers in the RAM 5 or the CPU 4, and the program shown in FIG. 5 is executed. ANSI to ANS3 are vehicle number data received at reception timings 1 to 3 (tgI
CARAD is used to store vehicle number data to be sent back to the mobile station. On the other hand, on the mobile station side, only the station that has the communication key, in other words, the station that requests communication, responds to the unspecified vehicle address (specific code) from the base station. Then, only the station that receives the CARAD and detects its own car number receives and displays the image data from the base station. Note that detailed procedures regarding transmission and reception of image data are omitted.

〔Effect of the invention〕

As described above, according to the present invention, there is an advantage that interference when establishing communication between a common base station and a plurality of unspecified partner stations and the superiority or inferiority of communication establishment can be reduced as much as possible.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is an explanatory diagram of interference probability, FIGS. 3 to 6 are diagrams illustrating an embodiment of the present invention, and FIG. 3 is a block diagram of a base station. FIG. 4 is a time chart thereof, FIG. 5 is a flowchart 1-1 showing the communication confirmation procedure on the base station side, and FIG. 6 is a flowchart on the mobile station side. In the figure, 1 is an image input device, 3 is a modem, 4 is a CPU, and 5
is a RAM, 6 is a ROM, and 7 is a CRT. Diagram explaining the principle of the present invention Figure 1; Kun (8s (r) I) upper level Rom Roa Figure 2 Pros of Xit station... Figure 3 Figure 3 Guim ÷ Yard Figure 4 Figure 5 No. Flow + Yard Figure 6

Claims (1)

[Claims] A base station simultaneously transmits a specific code to multiple unspecified slave stations, causes the slave stations that received the code to return a unique identification code, and further transmits one of the identification codes received by the base station.
In a communication control method in which the base station returns an identification code and starts communication with the slave station, the number of timings at which the base station receives the identification code is set in advance, and the timing at which each slave station returns the identification code is set in advance. A communication control method characterized by randomly resetting a code each time it is received.