JPH01149622A - Automobile telephone exchanging system - Google Patents

Abstract

PURPOSE:To prevent the automobile telephone of a cell site controlling station which is not in an overload state from being controlled and the capability of an entire automobile telephone exchanging system from being dropped by a partial overload by detecting overload states at every cell site controlling station and performing transmission control. CONSTITUTION:An exchange 1 houses automobile telephone sets 6 existing in the area to be controlled by the exchange 1 through the cell site controlling station 21 and 22 of each area and connects the telephone sets 6 to a public telephone network. A data linking device 7 connects the cell site controlling stations 21 and 22 with the exchange 1 through data links 3. An overload detecting circuits 8 are provided in the exchange 1 at every cell site controlling station and discriminates the overload state of one cell site controlling station when the time from the moment when the exchange sends a speech frequency moving request to the cell site controlling station to the moment when the moving completion report to the request is received exceeds a previously fixed standard time and counts the number of moving completion reports within the standard time. The circuit 8 performs transmission control when the number exceeds a fixed number against a prescribed number of speech frequency moving requests and cancels the control when the number goes to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a single exchange, and a plurality of exchanges, each of which is connected to the exchange by a data link, and which relays control signals to and from mobile telephones within each cell site. This invention relates to a mobile telephone switching system consisting of a cell site control station.

[Conventional technology]

Conventionally, this type of car telephone switching system has controlled the outgoing calls of the car based on the load condition of the switch itself, thereby controlling the load.

[Problem that the invention seeks to solve]

The conventional car telephone exchange system described above performs load control based on the load condition of the exchange.
There is a drawback that the load condition under the data link device is not known, and the system capacity is reduced because the car telephone exchange system restricts outgoing calls throughout the area covered by the system.

[Means for solving problems]

The mobile telephone switching system of the present invention includes: overload detection means for detecting an overload state of each cell site control station connected to a data link by monitoring control signals used for call connection control; A transmission load control means for transmitting a transmission restriction signal to a cell site control station in an overload state detected by the load detection means, and transmitting a transmission restriction release signal when the overload state is restored and the normal state is restored. have

[Effect]

By detecting overload conditions for each cell site control station and restricting outgoing calls, the car phones of cell site control stations that are not overloaded will not be restricted, and some overloads will be ignored! It is possible to prevent a decline in the performance of the entire 1JiI 1 story exchange system.

〔Example〕

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

FIG. 1 is a relay system diagram of an embodiment of the automobile telephone exchange system of the present invention, and FIG. 2 is a block diagram of the overload detection circuit 8 in FIG. 1.

In a car telephone switching system, the exchange notifies the cell site control station via the data link device of the frequency assigned to the car phone for voice calls in response to a call frequency shift request, and the cell site control station instructs the car phone to use the frequency. When the frequency shift to the assigned frequency in the mobile phone is completed, the cell site control station detects this state and sends a shift completion report to the exchange via the data link device, so that the call is not congested. Then, queuing occurs at the cell site control station and data link device.

Therefore, in this embodiment, the time required to determine whether the cell site control station is overloaded is determined in advance from the time when the exchange sends a call frequency transfer request to the cell site control station to the time when the transfer completion report in response to the request is received. The number of transfer completion reports exceeding the standard time is counted, and if the number exceeds a certain number for a predetermined number of call frequency transfer requests, calling restrictions are imposed. conduct,
When it reaches 0, the call restriction is canceled.

In this example, exchange! ! ! Cell site control stations 21 and 22 are connected to the data link 3 of 1. The exchange 1 accommodates mobile telephones 6 located within the area under its jurisdiction via the cell site control stations 21 and 22 of each area, and connects them to the general telephone network. The cell site control stations 21.22 transmit and receive call signals via the trunks 52.53 and control signals via the data link device 7 to and from the exchange 1, and control the incoming and outgoing calls of the mobile phone 6 via the control radio channel. The radio channel for communication specified by the exchange 1 is connected to the car telephone 6. The data link device 7 connects the cell site control stations 21 and 22 to the exchange 1 and the data link control device 42, respectively.
．． 43 and a data link control device @41 on the exchange side via the data link 3 to transmit control signals between the exchange 1 and the cell site control stations 21 and 22. The overload detection circuit 8 is provided in the exchange 1 for each cell site control station,
The exchange 1 allocates a radio channel frequency for a call when a call is made to or received from the car phone 6, and sends a call frequency transfer request to the cell site control station 2 to instruct it.
The cell site control station sends a transfer completion report indicating that the mobile phone has finished moving to the assigned frequency from the time the request was sent to the cell site control station. A timer 13 that measures the time T1 from 21 to reception and outputs an overflow signal when T1 exceeds a predetermined standard time To, and a movement completion report that is a reset counter that receives the overflow signal and adds up the number of times. A comparator 14 that sends out an enable signal when the values of the delay number counter 12 and the communication frequency movement request number counter 11 exceed a specified value that is predetermined by the cell site control station 21 and stored in the specified value register 16. When the enable signal is received, the movement completion report delay counter 1 at that time
Read the value of 2, store it in the specified value register 17, and compare it with the specified value.
It consists of a comparator 15 that outputs . The transmission regulation signal circuit 9 is provided in a pair with the overload detection circuit 8, and the initial condition is "0".
When "OII" is received, "1" is subtracted from "OII", "1" is added when "1°'" is received, the lowest value is rOJ, the highest value is displayed, for example, "9", and a new " When it reaches 0, it sends out a call restriction release signal, and when it goes to 1 to 8, it sends out the corresponding restriction level signals 1 to 8, and when it goes to 9, it restricts calls from the cell site within the data link. It sends out a signal, and simultaneously starts sending out the same signal to other cell site control stations 22 within the same data link.

Next, the operation of this embodiment will be explained.

Fig. 3 is a sequence diagram of a call connection made by the car phone 6, Fig. 4 is a sequence diagram of call restriction due to an overload at that time, and Fig. 5 is an example of an incoming call connection, which changes from overload to normal load. Sequence diagram for lifting restriction on calling when
7 is a flowchart of the call regulation of the exchange 1, and FIG.

When the car telephone 6 makes a call and dials, the cell site control station 21 in that area receives the call and reports it to the exchange a1, as shown in FIG. The exchange 1 allocates a frequency for telephone calls, sends a frequency shift request for telephone calls to the cell site control station 21, and
The cell site control station 21 instructs the mobile phone 6 to select a frequency for communication, and simultaneously transmits an audio tone called SAT on the assigned downlink frequency. The mobile telephone 6 shifts the frequency according to the designation of the cell site control station 21, and when it detects SAT on the downlink channel, returns the same tone to the uplink communication channel. When the cell site control station 2 receives the SAT from the uplink channel, it sends a communication frequency shift completion report to the exchange 1. As a result, the exchange 1 makes a call to the telephone network, and transfers the line that is being called to the called subscriber to the car telephone 6.
Connect to and play link back tone. When the called party answers, the call state is entered.

Now, as shown in FIG. 4, from the time when the car phone 6 makes a call and the exchange 1 sends out a call frequency transfer request, until the time when the call frequency transfer completion report is received via the cell site control station 21. The required time ■1 is measured, and if it is greater than To, it is accumulated in the movement completion report delay counter 12, and if the value exceeds a predetermined number, for example 50, the corresponding level of call restriction is imposed from the exchange 1 to the cell site control station 21. A signal is sent out. In addition, restrictions on outgoing calls have been implemented, reducing the number of outgoing calls.
As shown in FIG. 5, when receiving a call to the car phone 6, the time required from the call frequency transfer request to the completion report is T.
2 becomes shorter than the predetermined value To, the number of movement completion report delays decreases, and the value accumulated in the movement completion report delay number counter 12 becomes less than the specified value, replace! The cell site control station 21 sends out a calling restriction signal under the level from fi1, and the cell site control station 21 sends out a calling restriction release signal to the car telephones 6 of the corresponding groups within its assigned area.

The specific processing of the above-mentioned calling restriction will be explained with reference to FIG.

When the exchange 1 receives the call from the mobile phone 6, it sends a call frequency transfer request to the cell site control station 21 (step 21). The transfer request is counted as one and added to the number of transmission frequency transfer requests for communication (step 22), and the timer 13 measures the time since the request was sent (step 23).

Next, it is determined whether the movement completion report for this request was received within the standard time To (step 24), and if it is not received within the standard time To, it is added to the movement completion report delay number (step 25). If it is received within the standard time To, the process directly proceeds to the next step. It is determined whether the number of call frequency transfer requests has reached a specified value predetermined for each cell site control station (step 26). If the predetermined value has not been reached, the next communication frequency transfer request of 31 is made, but if the predetermined value is reached, it is determined whether the transfer completion report delay number is less than the predetermined value, for example 50 (step 27). If it is below the specified value, determine whether the previous regulation level value is 0 (Step 28); if it is 0, no regulation is required and the process proceeds to Step 33 to reset the current observation; if it is between 0 and the specified value, it is determined whether the previous regulation level value is 0 or not. regulation level value is 1
~ If it is the maximum value, the regulation level is set to be below the previous level (step 29), and a regulation signal of that regulation level, for example 2, is issued (step 32), and this observation is reset in steps 33 and 34. If the movement completion report delay count exceeds the specified value, it is determined whether the previous restriction level has reached the maximum value, for example "9" (step 30), and if it has reached the maximum value, the process proceeds to steps 33 and 34. , reset this regulatory process.

If it is determined that it is below the maximum value, the previous restriction level is raised by one level (step 31), and a transmission restriction signal of restriction level 3, for example, is issued (step 32).

In this way, the regulation level is increased or decreased by a level, and the observations are reset each time (step 3).
3.34>.

On the other hand, when the car phone 6 receives a restriction signal as shown in FIG. 7, it determines whether the signal is for the restriction group to which it belongs (step 51), and then determines whether the signal is a restriction signal or not after determining the restriction group. If it is a restriction signal, refrain from transmitting (step 53).
), in the case of a transmission restriction release signal, transmission becomes possible (step 54).

Note that it is also possible to combine call restriction levels and grouping based on the priority of car phones, or to assign call restrictions and sub-times sequentially to each group, so call restrictions can be set for each group of car phones within the cell site control station. It can also be done as

〔Effect of the invention〕

As explained above, the present invention simplifies load control by detecting the load status of each cell site control station in a mobile telephone switching system without using any special signals and regardless of the data link control protocol. The scope of regulation can be freely changed from a minimum of a group of mobile telephones within one cell site control station to a maximum of data link equipment units, which has the effect of minimizing the decline in the performance of the mobile telephone exchange system. .

[Brief explanation of the drawing]

FIG. 1 is a relay system diagram of an embodiment of the car telephone exchange system of the present invention, FIG. 2 is a block diagram of the overload detection circuit 8 in FIG. 1, and FIG. 3 is a call connection made by the car phone 6. Fig. 4 is a sequence diagram of outgoing call restriction due to overload at that time, Fig. 5 is a sequence diagram of outgoing call restriction release when overload changes to normal load, taking incoming call connection as an example, and Fig. 6 The figure is a flow chart of outgoing call regulation for exchange 1.
FIG. 7 is a flowchart of the process performed by the car phone 6 upon reception of the call restriction signal. DESCRIPTION OF SYMBOLS 1... Exchange, 21.22... Cell site control station, 3... Data link, 41.42.43... Data link control device, 50-
53... Trunk, 6... Car phone, 7... Data link device, 8... Overload detection circuit, 9... Call restriction signal circuit, 11... Frequency transfer request number counter for calls , 12...
・Movement completion report delay number counter, 13...Timer, 14.15...Comparison circuit, 16.17...Specific value register. 2nd cause Figure 3 Figure 5 District 7

Claims (1)

[Scope of Claims] A mobile telephone switching system comprising one switch and a plurality of cell site control stations, each connected to the switch via a data link and relaying control signals to and from the mobile telephones in each cell site, comprising: an overload detection means for detecting an overload state of each cell site control station connected to a data link by monitoring control signals used for call connection control; and an overload state detected by the overload detection means. A car telephone switching system characterized by having a calling load control means that sends a calling restriction signal to a cell site control station that has become overloaded, and sends a calling restriction release signal when the overload state is restored and the normal state is restored. .