JPH0124450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a line for selecting and communicating with a specific partner station between a plurality of communication terminal stations that share a multi-channel half-duplex line (unidirectional during communication). This invention relates to a connection control method.

Conventionally, when multiple communication terminal stations communicate using a multi-channel half-duplex line by specifying a single or multiple parties that are not currently communicating, a switching relay station was set up separately from the communication terminal stations. This switching relay station constantly monitors the lines of all channels, accepts calls from communication terminal stations using a specific line control channel, and allocates free lines to the calling station and the called station. Methods such as these are used. However, although this method is suitable for large-scale systems with an unspecified number of communication subscribers in wide-area communications that require relaying and amplification of communications, it is economically disadvantageous for local communications in relatively small areas. For example, in the case of a wireless line, the transmission and reception lines between the switching relay station and the communication terminal station cannot be separated spatially like wired lines, so the transmission frequency from the calling station to the switching relay station is The transmission frequency from the switching relay station to the called station cannot be the same since both transmissions can occur simultaneously. Therefore, although each communication terminal station performs half-duplex communication, it is necessary to prepare different frequency waves for transmission and reception, which is unfavorable in terms of frequency utilization efficiency, and the communication terminal station becomes expensive. There were flaws.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional technology, and is easy to use when a plurality of communication terminal stations share multiple channels for communication within a communication area that does not require communication relay amplification. It is characterized by being an economical method, and has the advantage of being applicable to a wide range of fields, such as frequency-division multi-channel personal wireless and in-premises low electric field wireless. Next, an overview of the present invention will be explained, followed by a more detailed explanation based on examples.

First, the outline of the present invention is as follows. In the present invention, in a plurality of communication terminal stations that share a multi-channel half-duplex line, one specific channel among the multi-channels is designated as a control channel C exclusively for line connection control, and the other channels are used for information after line connection. It is assigned to the information channel S for transmission. Before connecting the line, the reception is monitored, and the control channel and information channel are set alternately, and the information channel is set to receive data at regular intervals while sequentially visiting all channels. If call data reception is started during the call data reception, control channel C is put on hold until the reception of the call data is completed. However, the monitoring time of the information channel S is assumed to be shorter than the length of one frame of call data.

When setting information channel S, reception is detected to determine which channel is free, a list of free information channels is created, and if the call data received on the control channel is addressed to another station, the specified information channel included therein is sent to the above information. Exclude from the free channel list obtained by channel monitoring. Based on the line operation configured as described above, if the data received on the control channel C is addressed to the local station, a specified information channel contained therein is opened. In addition, when the own station makes a call without receiving data on the control channel, first keep it on the control channel side, select the information channel closest to the time of the call from the above free information channel list, and send it to the called station. A feature of this system is that it is configured to perform line connection control such as opening a line using the same information channel after transmitting the address and calling data two or more times in succession. Next, the above will be explained in more detail.

FIG. 1 is a diagram showing an example of the configuration of a communication terminal station implementing the present invention. In the figure, 1 represents a transmitting section, 2 a receiving section, 3 a switching gate, 4 a frequency synthesizer, and 5 a (communication) terminal station. First, the functions of each section will be explained. The transmitter 1 modulates a predetermined carrier wave using the modulation signal MOD from the terminal station 5 and transmits it.
TX is turned on and off by the transmission activation signal PRESS from the terminal station. Line switching gate 3 is signal PRESS
is on and transmitting, the transmit carrier TX is sent to the line.
Connect to LINE, and if it is off and receiving data, the line
Connect LINE to the input of receiving section 2.

The receiving section 2 inputs the modulated received carrier wave RX, detects the arrival of the carrier wave, and demodulates it. The outputs to the terminal station 5 are a demodulated signal DEM and a reception detection signal SQ (squelch). The frequency synthesizer 4 inputs the channel setting signal CH from the terminal station 5, and gives an oscillation output of a frequency corresponding to the set channel to the transmitter 1 and the receiver 2 in common. The channels set in the CH include one channel exclusively for line connection control (the control channel described above), and a finite N number of channels for transmitting information such as voice and data between the calling station and the called station after the line is connected. (The above-mentioned information channel).

The terminal station 5 is a transmission/reception control unit for controlling the line connection and the transmission of voice and data information, and performs monitoring operations in the line connection control operation.
While the control channel and information channel are alternately switched at regular intervals using the CH output, the presence or absence of reception of call data is detected from the demodulated signal DEM input during the control channel set time, and the line is switched during the information channel set time. Detection of the vacant state of the vehicle is performed by squelch signal SQ input.

Next, when the local station makes a call, it moves to connection operation, sets the output CH to the control channel, turns on the transmission start signal PRESS output, modulates the call data from the modulation signal MOD output, and sends it to the transmitter 1 and sends it to LINE. .
However, a modem for changing and demodulating the data is built in the transmission/reception control section 5. In addition, in the control operation of voice and data information transmission, the free information channel determined at the end of the line connection operation is output CH.
Hold this channel until the transmission is finished. Note that the terminal station 5 has interfaces with the outside for inputting and outputting voice and information data, inputting a call request, and outputting an incoming call communication, but these are not shown.

FIG. 2 is a time chart of an example of the monitoring operation for line connection among the operations of the transmission/reception control unit 5. The upper part of the figure shows the channel designation signal CH, and each rectangular frame shows the channel setting contents at that time. Among them, C is a control channel, S ₁ , S ₂ ,...S _i ,
...S _N-1 and S _N indicate N information channels, respectively. Further, let T _C and T _S be the respective setting (allocation) times of the control channel C and the information channel S. The lower part of the diagram shows the squelch signal SQ of the same station, and its H level indicates that there is a signal and is being received, and its L level indicates that there is no signal and that it is not receiving. Now, as shown in the figure, the transmission/reception control section 5 alternately switches between the control channel C and the information channel S using the channel setting signal CH, and switches each channel from S ₁ to S ₂ for the information channel.
→...→S _N →S ₁ →S ₂ →... is set to go around in the order of..., the free status of all information channels is identified by the SQ signal, and a list of free information channels is created. In the example shown in Figure 2, SQ is on (that is, the line is blocked) for each information channel S ₁ , S _i , and _SN , and S ₂ ,
SQ off (line open) is detected in each S _N-1 , and all idle lines are added to the idle information channel list.

Next, the timing of the calling data transmission operation at the calling station (referred to as station a) and the operation of the other station, that is, the called station b, which is in the monitoring operation state shown in FIG.
This will be explained using figures. CHa and CHb in Figure 3
are the channel setting signals of station a and station b, respectively.
CH is shown in the same format as in Figure 2, but with the time scale enlarged. Further, TXa is a transmission carrier wave of station a, and each section 1...k represents a carrier wave transmission time period of one frame time length of data. During this time period, the transmission activation signal shown in Figure 1 is
PRESS is now on. 1~k of TXa
The blank time other than that is a time period in which carrier waves are not transmitted, and the PRESS signal is turned off due to reception monitoring status. Note that the D shown in each data frame indicates the content of the modulation data included in the modulation signal MOD in Fig. 1, and the symbols 1, 2,...k represent the order of data to be sent, so if station a is transmitting the same data. D to k
You can see that it is being sent twice.

Let us now consider a case where, as shown in FIG. 3, station a monitors an information channel (for example, S _j ), sets up a control channel C, starts a calling operation, and successively transmits calling data D k times. At this time, station b is in a reception monitoring state asynchronously with station a, for example, as shown in the figure, S _i-1 ,
C, S _i , and C are alternately switched between the information channel and the control channel, and when the information channel is set, there is a portion (the shaded portion of TXa in the figure) in which calling data on the control channel cannot be received. That is, in this example, up to the (k-1)th data is undelivered.
If station B switches to control channel C during the (k-1)th channel, the carrier wave of TXa is detected (SQ
After that, station b is held on control channel C until it finishes receiving the k-th call monitor (time length T' _c in the figure).

Here, at least one out of k call data is successfully transmitted to the called station without being affected by the shift in the switching point between the control channel and the information channel due to the asynchrony of the monitoring operations of stations A and B. The conditions for
As shown in the figure, if the beginning of all call data from 1st to (k-1)th is not included in the control channel specified time period T _c of the called station, at least the final k-th It is sufficient that the _beginning of
T _D > T _s . Generally, the monitoring time T _s of the information channel S is shorter than the length of one frame of call data T _D , so it is sufficient to set k=2 (two consecutive transmissions of call data frames).

As explained above, each communication terminal station always performs the line monitoring operation shown in Fig. 2, and receives transmitted carrier waves from other calling stations during control channel setting according to the operation example shown in Fig. 3. If detected, the control channel is put on hold and a subsequent call monitor is received. In addition, when the own station makes a call first, the communication terminal station itself controls the line connection by setting a control channel at any time and transmitting the call data a plurality of k times in succession.

Next, an example of line connection control operation based on the basic operation shown in FIG. 2 will be explained with reference to a time chart shown in FIG. 4. The representation style of FIG. 4 is the same as that of FIGS. 2 and 3. First, both the a station and the b station are in the monitoring operation state, and the a station is C, S _i-1 , C, S _i , C, S _i+1 , C, S _i+2
The channel setting signal CHa is sent to station B in the order of C,
It is assumed that the channel setting signal CHb is asynchronously switched in the order of Sj-3, C, Sj-2, C, Sj-1, C, and Sj. When station A makes a call at point A of carrier wave TXa of station A, for example, one free channel closest to the time of call is selected from the list of free information channels obtained from the monitoring results of N information channels in the past. The information channel is selected and sent along with the calling data to the called station (referred to as station b). In the example shown in Figure 4, SQa is on for S _i+1 and S _i+2 and the channels are blocked, but during channel setting for S _i-1 and S _i , the reception detection signal SQa of station a is off. If it is added to the available channel list, the channel S _i that is closest to the time of transmission is selected and included in the calling data, and frames are continuously transmitted to the called station twice. S _i shown below the calling data D in the figure indicates this idle information channel data.

Next, station b cannot receive the first of these two consecutive frames of calling data due to the time zone in which channel _S
Since the call is in the call data, normal reception is possible, and the call is verified to be directed to the call destination by a known method such as referring to a predetermined called station address included in the call data. If it is addressed to the own station, for example, in the case of one-to-one communication, station b activates the transmission carrier TXb as shown in the figure, and transmits the free information channel S _i notified by the calling station to the other station (calling station). I will put it in the data and send it back to you for confirmation. Then, when the response data has been returned at point ○B, both the calling station and the called station set the specified information channel S _i , and the voice on the same channel is transmitted from point ○C to point ○D. Transmission of information such as information and data is performed using half-duplex communication using a known method. The portions of TXa and TXb indicated by I indicate the transmission of this information, and both transmit and communicate alternately. In the case of one-to-multiple communication, the above response data may not be returned at all, or a separate means may be used to shift the response times of the plurality of called stations. When communication on the information channel ends at point d, stations a and b2 return to the monitoring operation state again.

The above is the operation between the two stations a and b, but calls and calls occur close to each other in time between two or more communication terminal stations other than these, and there is no availability information on the calling side. If the closest information channel at the time of the call in the channel list happens to be the same as station a, the same information channel will be set simultaneously on at least four stations including stations a and b, causing interference. If the system is configured to receive outgoing call data that is not addressed to the local station, and to exclude the specified information channel from the free information channel list obtained from the information channel monitoring operation as a blocked information channel, In very rare cases where calls occur almost simultaneously and conflict (in this case, the call data is not delivered)
The line connection can be made without any problems except for.

As is clear from the above explanation, according to the line connection control method of the present invention, each communication terminal station itself can monitor all channels of a half-duplex line and select a channel when a call occurs. To achieve this, channel switching at the communication terminal station, which was previously necessary,
It is only necessary to add a simple monitoring operation function in addition to each data transmission function, and there are great economic advantages such as eliminating the need for a switching relay station. Also control channel,
Since it is completely half-duplex communication regardless of the information channel, it has the advantage of being suitable for effective use of radio frequencies when using a wireless line.

[Brief explanation of drawings]

Fig. 1 is a configuration example diagram of a communication terminal station implementing the present invention, Fig. 2 is a time chart of an example of monitoring operation for line connection of the transmission/reception control unit, and Fig. 3 is an operation of a calling station and a called station. A time chart showing timing. FIG. 4 is a time chart of an example of circuit connection control operation based on FIGS. 2 and 3. 1... Transmission section, 2... Receiving section, 3... Switching gate, 4... Frequency synthesizer, 5... Terminal station, C
...Control channel, S...Information channel,
PRESS...Transmission start signal, MOD...Modulation signal,
DEM...Demodulated signal, CH...Channel setting signal,
SQ...Squelch signal.

Claims (1)

[Claims] 1. A control channel dedicated to line connection control for a specific channel among multiple channels in communication between multiple communication terminal stations that share a multi-channel half-duplex line;
In addition to allocating information channels to other information transmission channels, each terminal station alternates between the control channel and the information channel in a reception monitoring state before connecting the line, and the information channel allocates a certain amount of time to each channel while sequentially visiting all channels. If there is call data received during the time set for the control channel, the control channel will be held on hold until the reception is completed, and at the time set for the information channel, reception will be detected to determine which channel is free and the free information will be sent. Create a channel list, and if the call data received on the control channel is addressed to another station, exclude it from the list of free information channels, and if it is addressed to your own station, open a specified information channel included in it, and also receive data on the control channel. When the local station makes a call without a call, it keeps it as a control channel, selects the information channel closest to the time of the call from the free information channel list, and sends this multiple times in succession along with the address of the called station in addition to the call data. A line connection control method for a multi-channel half-duplex line, characterized by opening a line using the same information channel.