JPH01278131A - Demand assign communication device - Google Patents

Abstract

PURPOSE:To simplify the connecting procedure and to improve the overall reliability of a communication network by searching the idle carrier wave pairs that are applicable to the communication out of a real communication circuit via a slave station itself. CONSTITUTION:When a call request is received through a telephone set 5 of a calling station, a switchboard 4 of this station informs the request to a demand assign(DAMA) controller 3 of said station via an interface 7. The controller 3 sets a received carrier wave frequency to a message channel MODEM 16 through a signal line 9 and inspects via a carrier wave detecting status signal 40 whether the set carrier wave is already used by another station or not. If not, another carrier wave frequency paired with said carrier wave is recognized by a table of the controller 3. Thus a pair of carrier waves are decided and informed to a called station. In such a way, the communication circuit allocating procedure can be carried out among the slave stations only. Thus a master station which performs the centralized control can be omitted and the overall system reliability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a demand assignment communication device often used in satellite communication systems.

[Conventional technology]

FIG. 2 shows a conventional demand assignment satellite communication system. In the figure, reference numeral 11 denotes an earth station that centrally controls demand assignment (hereinafter referred to as DAMA) as a system, and is called a parent DAMA station. Reference numeral 12 is an earth station that is responsible for the traffic of station n, and from the perspective of DAMA control, it is in the position of requesting line settings from the master station 11, and the slave D
It is called an AMA station. 13 indicates a satellite.

Furthermore, FIG. 3 shows an example of the frequency allocation used in the DAMA system shown in FIG.
All stations making up the system are required to be able to transmit and receive this carrier wave. Reference numeral 15 indicates an E pair (l is an integer of 1 or more) of two carrier waves each, and for example, one bidirectional line is supplied by fl and f2. Such carrier wave pairs are set up in response to a line connection request from a slave station to a master station each time by a command from the master station, and are canceled when they are no longer needed.

FIG. 4 shows the configuration of a child DAMA station in this conventional system. In the figure, 1 is a transceiver connected to an antenna. 3 is the DAMA control device of the slave station, 4 is the exchange, 5
is a telephone or equivalent, 6 is a telephone band communication path signal, 7 is a signal (signaling) interface with an exchange,
8 is a signal (signaling) interface between the modulator and demodulator for the common signal control line, and 9 is the modulator and demodulator for the communication path.
a signal line for specifying the determined carrier frequency, 10
1 is an intermediate frequency interface serving as an interface with the transmitter/receiver, 16 is a modem for communication path, and 17 is a modem for common signal control line.

Next, the operation will be explained. Figure 5 shows the operating procedure of this system.
, 19, 20.21 indicate the information carried by f, , , 22 respectively, 18.19 is one of the slave stations (referred to as A station), and 21.22 is the slave station of the other party of A station ( Station B), and 20 relates to the master station. Assume that there is a call request from the A-side telephone to Plywood. First A
The station exchange 4 transmits this to the A station's child DAMA! through the interface 7. II outfit? ! ! 3. The device 3 drives the modem 17 using the signal line 8, and transmits a connection request to the master station along with the number of the other station, as shown at 23 in FIG.

The master station selects an unused pair (for example, f and 12) from the available carrier pairs 15 and transmits messages 24 and 25 to stations A and B via f csc. Generally, at this stage, complicated procedures such as confirmation responses may be added between the slave station and the master station to eliminate erroneous connections. Furthermore, as can be seen from the above, since both the master station and slave stations share the same carrier wave, TDMA, random access, and a combination thereof are generally used as the access method for the common signal control line. be. Modulator/demodulator 1 of each slave station
7 receives these commands and notifies the DAMA control device 3 of the allocated carrier wave from the master station. As a result, a bidirectional line is established between the A station and the B station using carrier waves f, , f, and a state is reached in which a call can be started. This is 28 in Figure 5.
It is shown in

Now, when the call ends, a call termination signal (signaling) is output from the exchange 4, and the DAMA device 3 sends a line release request 29 through the same route as the connection request, f c
A request is made to the master station via SC. The master station sends an acknowledgment 30 to slave station A, a release instruction 31 to slave station B, and 32.33
At , the DAMA device of each station provides the necessary call termination processing signal to the exchange and cuts off the waves f, , 'f. The DAMA device of the naori station sends a release confirmation signal 34 to the master station. In FIG. 5, the solid line on the vertical axis indicates the state where the carrier wave is being transmitted or is virtually occupied.
The dotted line indicates that the carrier wave is not used and can be used by other stations.

In this case, the usage status of the communication line 15 is centrally managed in the master station 11, which makes the line connection procedure complicated. In addition, since it is a centralized management method, if a failure occurs in the master station, the failure will affect all stations in the communication network, so the master station is required to be several times more reliable than the slave stations, improving reliability. This will increase the cost of doing so.

This invention was made in order to solve the problems of the conventional ones as described above, and aims to provide a demand assignment communication device that can simplify the connection procedure and improve the reliability of the entire communication network. purpose.

[Means to solve the problem]

The demand assignment communication device according to the present invention is configured such that the slave station itself searches for an empty carrier wave pair that can be used for communication from an actual communication line.

[Effect]

In this invention, by configuring the slave stations as described above, the communication line assignment procedure can be executed only between the slave stations, so the master station that performs centralized control can be abolished, and the reliability of the entire system can be improved. I can do it.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a slave station of a demand assignment communication device according to an embodiment of the present invention, in which 40 indicates a signal vA.
This is a status signal indicating whether or not a carrier wave is being received at the reception carrier frequency set in the modulation/demodulation 816 through 9. The other parts are the same as the device and functions described in FIG. 4.

FIG. 6 is a diagram showing a connection control sequence that makes it possible to implement an embodiment of the present invention. Reference numeral 51 indicates a carrier frequency selection procedure on the side (calling side) that initiates a line connection procedure, and 52 indicates a procedure on the side that initiates release of a connected line. Reference numeral 41 indicates a message for instructing to notify the line-connected partner station of the carrier frequency information selected in step 51, and 42 is an acknowledgment message for step 41.

Further, 43 is a message for notifying and commanding the carrier wave frequency information to be released determined in message 52, and 44 is an acknowledgment message.

FIG. 7 shows an example of the format of a signal message used in the common signal control line, where 61 is the address of the station that should receive this message, 62 is the address of the station that sent this message, and 63 is the address of the station that sent this message. ID code indicating the type of this message, 64 is the parameter of this message,
65 is a check code for checking the validity or invalidity of the message as a whole on the receiving station side.

Here, since a random access method is adopted as the access method within the common signal control line, the common signal control demodulator 17 of each station demodulates all the signal messages and transmits them to the DAMA device 3 through the signal line 8. The DAMA control device 3 checks the check code 65 in FIG. 7 to check whether the received message is valid or invalid. If it is valid, it is checked whether the address 61 is the address of the own station, and the corresponding processing is executed according to the message identification code 63 only when the received message is for the own station.

Next, the operation will be explained using FIGS. 1 and 6. A
When a call request is made from the central office telephone, exchange 4 of office A
notifies this to the DAMA control device 3 of the A station through the interface 7. The operation up to this point is the same as that of the conventional device shown in FIG. The DAMA controller 3 now outputs the signal Tla.
A carrier detection status signal 40 is used to set one receiving carrier frequency to the channel modulator/demodulator 16 through a carrier detection status signal 40 to determine whether the set carrier is already in use by another station.
Verify by. As a result of this verification, if the set carrier wave is unused, the DAM A $+ II controller has predetermined another carrier frequency paired with this carrier wave.
The carrier wave pair is determined using the table in the table. If it is recognized from the status signal 40 that the set frequency is already in use by another station, the set reception carrier frequency is updated to another one, and the same procedure as above is used to check whether the frequency is in use or not. This is verified using the status signal 40.

In this way, the DAMA control device 3 performs step 51 in FIG.
Determine carrier frequency pairs at .

The determined two carrier wave frequency information are notified to the called party in a message 41 as shown in FIG. When the DAMA control device 3 of the called side receiving the message 41 decodes the transmitting/receiving carrier wave frequency information included in the message, if the channel modem 16 is not used for communication with another station, the DAMA control device 3 of the called side receives the message 41, After setting the frequency in the channel modulator/demodulator 16 via the signal line 9, the calling side (station A) is notified of the completion of normal setting by a message 42 shown in FIG. The DAMA control device 3 on the calling station side, which has received the message 42 indicating that the normal setting has been completed on the called station (station B) side, reverses the transmission and reception of the frequency pair determined in step 51 to the called station side and commands 26. , and is also set to the channel modem 1G via the signal line 9.

As a result, a bidirectional line is established between the A station and the B station using the selected frequency bare carrier wave, and a call is started. This is shown at 28 in FIG.

In the above, if the channel modulator/demodulator 16 of the called station (station B) that received the message 41 is not communicating with another station, that is, is the connection normal? Although we explained the case of 1n sequence,
If the channel modem 16 at the called station (B station) is communicating with another station and cannot respond to the connection request from the A station, a message 42 will be sent to the calling side (A The A station then notifies the exchange 4 through the interface 7 in FIG. 4 that the other station is busy, and the connection control sequence ends.

Now, the control sequence at the end of a call will be explained using FIGS. 1 and 6. When the call ends, a call termination signal (signaling) is output from the machine 4 and the DAMA control device 3
recognizes each call completion and notifies the other station (B station) by message 43 to release the carrier frequency pair assigned in step 51 during the connection sequence. The B station instructs the channel modulator/demodulator 16 via the signal line 9 to release the transmit/receive frequency pair specified by the message 43, and replies to the A station via a message 44 that the release has been completed. A
When the station also receives the message 44, it instructs the channel modem 16 to release the frequency pair. DAM of A station and B station
After the A control device 3 is released, it notifies the exchange 4 of a necessary call termination processing signal through the signal line 7, as in the conventional device.

In the above embodiments, the configuration of the station is shown in which a single voice communication path is sufficient. On the other hand, FIG. 8 shows another embodiment in which a plurality of voice communication channels are required.

When a plurality of communication paths exist, there is an advantage that when a connection request is made from the exchange 4, the busy rate is reduced compared to the case of a single line.

The connection/release sequence through the common signal control line can be executed in the sequence shown in FIG. 6 in exactly the same way as in the case of a single line station, and the same effect can be obtained.

Also, in the embodiment shown in FIG. 1, there is a telephone line.

Although both the common signal control line and the frequency division method (FDMA) are shown, FIGS. 9 and 10 show still another example of the present invention when the communication line and the common signal control line are configured in the time division method (TDMA). This figure shows an example of this. In this case, as shown in FIG. 9, an ITDMA frame is composed of a time slot 72 for the common signal control line and m fixed length time slots 73 for the communication line.

TDMA requires a reference burst signal to define the frame reference timing shown at 71 in FIG.
It suffices if one representative station transmits.

It is assumed that this reference burst is used merely for the purpose of generating a reference for a TDMA frame and does not contain any information. Although it is necessary to consider the recovery procedure when this reference burst disappears, the explanation is omitted because it is not directly related to the essence of the present invention.

FIG. 10 shows the configuration of a DAMA station using the TDMA system. In the figure, 83 is a transmission/reception burst control unit that performs burst transmission/reception control on the TDMA frame shown in FIG.
Reference numeral 1 indicates a control line for instructing to change the burst plan, and reference numeral 82 indicates a burst reception status signal indicating whether or not a burst exists for a designated time slot. This TDM
The control sequence shown in FIG. 6 can also be applied to method A. However, instead of selecting a frequency pair in step 51, "1 empty time slot is selected as 81".
．． The same effect as the FDMA system shown in FIG. 1 can be obtained in the sense that the selection is made at step 82 and this information is notified to the partner station.

〔Effect of the invention〕

As described above, according to the demand assignment communication device according to the present invention, the station that has generated the connection request can select and determine the frequency or time slot for the channel by itself. becomes unnecessary.

Therefore, the line connection procedure can be simplified, and because of distributed processing, even if a failure occurs in one station, only that station will be unable to communicate, and the failure will not affect all the system stations, improving the reliability of the system as a whole. It has the effect of improving.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a slave station of a demand assignment communication device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a DAMA system, and FIG. Figure 4 is a configuration diagram of a slave station in a conventional device.
FIG. 5 is a diagram showing a line connection/release control sequence in a conventional device, FIG. 6 is a diagram showing an example of a line connection/release control sequence in the present invention, and FIG. 7 is a diagram showing a common signal control line between stations. FIG. 8 is a block diagram of a slave station according to another embodiment of the present invention, and FIGS. 9 and 10 are TDMA frames according to still other embodiments of the present invention. FIG. 2 is a diagram showing a configuration and a configuration of a slave station. In the figure, 1 is a transceiver, 3 is a DAMA control device, and 4 is a transmitter/receiver.
16 is a communication path modem, and 17 is a common signal control line modem.

Claims (1)

[Claims] (1) Common signal line control is performed by each station in the system sharing one wave or one time slot, and the actual communication path is supplied using a carrier wave or time slot that is set each time according to the communication path connection request. In demand assignment communication equipment, when a line is connected, the station that has issued a connection request controls the allocation of the actual communication path, and when the line is released, the station that has issued the release request also controls the release of the actual communication path. A demand assignment communication device characterized by: