JPS63296530A - Variable band communication system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] A variable bandwidth communication system that uses a time division multiplex communication method to communicate by changing the communication band of information according to the available bandwidth of the communication path by providing a communication band conversion circuit. do.

[Industrial Field of Application] The present invention relates to a variable band communication system, and more particularly to a variable band communication system in which communication can be performed by changing the communication band in a time division multiplex communication system.

The information handled by current communication systems is diversifying, including not only voice but also facsimile information, still image information, and video information, and the speed of communication systems is increasing accordingly. For example, 512K (bl) 31 to 1M [bps] for still images, 1 for videos
A communication speed (bandwidth) of 00M [bps] (bps is an abbreviation for bits/S) is required. Therefore, there is a need for a system that can communicate such high-speed information while reducing the communication time and making effective use of communication resources.

[Conventional technology J Diagram m6 shows the configuration of a conventional time division multiplex communication system.

It is a figure which shows an example. In the figure, 81 to Sn are transmitting terminals, and R1 to Rwl are receiving terminals (n and m are integers). W1 to Wn are corresponding transmitting terminals 81 to 3n, respectively.
The band (speed) of information transmitted by W is the uplink communication path 11 and the downlink communication path I! 2 band and the unit is [bps
]. The information sent from the transmitting terminals S1 to S3n is time-division multiplexed by the multiplexing circuit 1, and then sent to the upstream communication path l! 1 to exchange 2. Exchange I! 2 is the upstream communication path! 1 and the downlink communication path 42.

Here, the uplink communication path /1 and the downlink communication path I2 are connected by the exchange 2. The information sent via the downlink communication path /2 is separated by the separation circuit 3 and then enters predetermined receiving terminals R1 to Rm.

FIG. 7 is a diagram showing an example of band usage in a communication system configured as described above. The entire band is W, and transmitting terminals 81.83. ...Sk is each transmission band Wl
, W3. ...Transmitting by Wk.

From all bands W, these bands W'l, W3 . ...Wk
The remaining after subtracting is the empty band hi! We are. Then, the exchange 2 exchanges the gouyanelle and sends it to the receiving terminal.

FIG. 8 is an explanatory diagram of a conventional example of a typical digital circuit switching country system using a time division multiplex communication system, where (a) is a block diagram and (b) is an explanatory diagram of operation. In this method, the band W
(called a frame) is generally 64k [bps
] in units called time slots, and T1-Tm in the figure are time slots. Also, upstream communication channel! ! 1 is called the incoming highway as seen from exchange 2, and the downlink communication path/2 is called the outgoing highway. Therefore, in this case, the frame W! , tW=64 x mk [bps]. FIG. 8(b) shows that the transmitting terminal S1 is 64k [b
psco, sending terminal S2 is 256k [bpS] (
64k x4) communication is performed. Sl will communicate using one time slot, and S2 will communicate using four time slots. (2) shows the case where four consecutive time slots T2 to T5 are vacant and these four time slots are used for the transmitting terminal S2. (2) shows a case where four consecutive time slots are not vacant, and therefore slots for the transmitting terminal S2 are allocated to the vacant areas at intervals. In both cases (1) and (2), the data on the outgoing highway side is channel-switched by the exchange Ia2, so the order does not match that of the data on the incoming highway side.

In this way, in conventional time division multiplex communication systems, the communication speed (bandwidth) of the terminal is given first, and if that band can be secured in the band W of the communication channel (highway), it can transmit; If so, the communication status will be established.

[Problems to be Solved by the Invention] In the conventional time division multiplex communication system, the terminal communication band 10I! (arg1> is determined by the terminal or by the media, and communication in that band is considered to be free. Therefore, in Fig. 6, the unused (empty) band is We, and let's transmit in the band Wj. When there is a terminal Sj, if We≧Wj, it can transmit, but if We<Wj, it cannot transmit and becomes stuck, and this free band cannot be used effectively. In addition, this hold state becomes longer as Wj is larger, and the problem that the bandwidth that cannot be used effectively becomes larger also occurs. We as vl
-a x64k [bps], Wj -j x
64k [bps], that is, free time thrower 1-
When there are 8 losses and Sj sends 3 time slots "c-", if a≧j, it is possible to send, but if a<j, it cannot be sent and becomes a hold.

The present invention has been made in view of these points, and
The purpose of this invention is to provide a variable bandwidth communication system that prevents the transmission situation from occurring and makes effective use of H vacant bandwidths.

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the present invention. Items that are the same as in Figure 6 are the same 1! Shown with a bow. In the figure, S
CI to SCn are each connected to a corresponding transmitting terminal,
Band 'a! for which band conversion of the transmitting terminal is performed! Switching circuit, RC1~
RCm is a band conversion circuit that is connected to the corresponding receiving terminals R1 to RIM and performs band conversion in accordance with the receiving terminals R1 to R11.

Note that these band conversion circuits sci to SCn, RC1 to RC
I11 does not necessarily have to be provided separately, and the terminal S
1 to 3n, and R1 to RI11.
Since the J53 location and its configuration depend on the implementation method and protocol, it is not particularly limited to its installation location.

[The free bandwidth of the active communication channel is We [bps 1, and the sending terminal S
It is assumed that the communication band between i (i is any one from 1 to n) and the receiving terminal Rj (j is any one from 1 to -) is Wi[bl)31. Now, assuming that We<VVi, it is not possible to communicate using Wi.

Therefore, the band conversion circuits SC1 and RCj change the band from Wi to W.
Band conversion is performed to X (WX is a certain value that is equal to WO or smaller than We) so that step 3 can be performed seamlessly between Si and Rj. This makes it possible to reduce communication time and make effective use of free bandwidth.

In addition, in the case of We≧Wi, it is possible to pass through the band 1aWi as it is, so the band conversion circuits SC1 and RCj
does not perform band conversion.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Here, an embodiment of the JJI combination in which the present invention is applied to the elastic basket method will be described.

The elastic basket method (hereinafter simply referred to as the EB method) is a method proposed by the applicant, and its principle is shown in FIG. In this method, one frame is not divided into fixed-length time slots, but into variable-length slots (called baskets) as shown in the figure.

In other words, a frame is composed of a plurality of variable length baskets. Each basket consists of a variable length data area and an identifier to distinguish the basket from other baskets. The transmitted information from each of the transmitting terminals 81 to Sn is rearranged in each basket by the four interchange Ig devices 2 and sent to the receiving terminals R1 to R111.

3 to 5 are diagrams showing an embodiment of the present invention, and FIG. 3 shows an example of the configuration of a star network using the EB system. FIG. 4 shows a block diagram of the distribution module used in FIG. 3, and FIG. 5 shows a block diagram of the IIA function of the line circuit used in FIG. First, the configuration of the entire system shown in FIG. 3 will be explained. In the figure, M1~
Mn is a distributed module connected to a plurality of terminals T, and includes a multiplex circuit 2 separation circuit and a band conversion circuit shown in the principle diagram of FIG. 1o is a relay module connected to these plurality of distributed modules M1 to Mn via uplinks and downlinks, and performs operations such as channel switching in the same way as the exchange 2 shown in FIG. 1.

Next, the configuration of the distributed module shown in FIG. 4 will be explained. L1 to 1-m are respectively connected to corresponding terminals T, and line circuits accommodating these terminals, B1 is a control bus, B2 is an upstream switching bus, and B3 is a downstream switching bus. 21 is a link circuit connected to each line circuit L1 to Lu11 via these buses ['S1 to B3 and interfaces with the uplink and downlink; 22 is a link circuit connected to each line circuit L1 to Lu11 via a control bus B1; m
and an ibl control circuit that controls the operation of the link circuit v821.

As is clear from the figure, the terminal T here serves both as a transmitting terminal and a receiving terminal.

In the lζ circuit configured in this way, when communication is performed between a current terminal T and another terminal 1, it is assumed that the communication band between these terminals is Wi[b[)S]. The control circuit 22 checks how much free bandwidth is available on this communication path.

As a result, it is assumed that the free bandwidth is We [bps]. If We≧Wi, the two terminals can communicate in a predetermined band Wi. If, We
<Wi, communication cannot be performed using the current band Wi. Therefore, the control circuit 22 sends a control signal to the corresponding 2g line circuits on the transmitting side and receiving side,
Command band conversion. As a result, the band conversion circuit in the line circuit converts Wi to WX (where WX is equal to We (C) or some value smaller than WQ), and connects the two terminals in the band W×. connect. This allows communication to be performed without waiting time, and free bandwidth can be utilized.

Next, details of the line circuit IIIa will be explained.

As shown in FIG. 5, the line circuit includes a terminal interface 30. It is roughly divided into a transmitting section 40 and a receiving section 50. V
Arrow 1 inside indicates the flow of information, and arrow 2 indicates the flow of control signals.

In the transmitter 40, the number of the basket (channel) into which the transmission information of the terminal connected to this line circuit is to be placed is set in advance in a register 41 called "transmission basket number." The first counter 42 is set with a value indicating the number of baskets on which information is currently multiplexed on the upstream switching bus B2. , is counted by incrementing by 1 according to this clock.

The comparator 43 compares the values of the transmission basket numbers of the first counter 42 and the register 41, and if they are equal, outputs a signal to the speed conversion buffer 44, and the information in the speed conversion buffer 44 is output to the uplink switching bus B2. Ru. In this way, baskets are multiplexed on the upstream switching bus B2. The transmission f3 length register 45 is preset with the length of the basket on the path B2, that is, the length of transmission or the bandwidth.

The second counter 46 counts the length set in the transmitter register 45 when outputting information from the speed conversion buffer 44 to the uplink switching bus B2. Clock out. The state control circuit 47 has the role of informing the 20th counter 46 whether or not there is information in the speed conversion buffer 44, and performs controls such as suppressing information transmission to the terminal when the speed conversion buffer 44 is about to overflow. .

Here, the transmission speed (bandwidth) is changed by changing the value of the transfer register 45 according to the available band on the uplink. In this case, there is no need to change the clock; it is sufficient to provide a fixed uplink clock.

In the receiving unit 50, a number indicating which basket (channel) on the multiplexed downlink switching bus B3 is to be received is set in advance in a register 51 called "receiving basket number." The counter 52 counts the number of basket information currently on the downlink switch bus B3, and the comparator 53 compares this value with the value of the register 51. If they are equal, a signal is passed to the speed conversion buffer 54 to take in the information on the downlink switch bus B3. The clock conversion circuit 55 generates a desired clock based on the link speed (clock) and the control signal of the control path B1.

If the information is speed (bandwidth) converted, the read control circuit 56 must read the information from the speed conversion buffer 54 faster than the speed received by the speed + ffi conversion buffer 54 and send the information to the terminal. conduct. And register 51. A counter 52 and a comparator 53 perform demultiplexing, and a clock conversion circuit 55 and a read control circuit 56 perform speed conversion.

In the embodiments described above, the present invention is applied to an EIB type star network. however,
It goes without saying that the present invention is not limited to this, and can be applied to other star networks.

[Effects of the Invention] As described in detail above, according to the present invention, in a star network using a time division multiplex communication system, by providing a communication band conversion circuit, when there is insufficient free communication band, the communication It is possible to perform communication by performing band conversion without waiting until the available band recovers to a predetermined band.

Therefore, according to the present invention, it is possible to create a variable bandwidth communication system that prevents transmission from being delayed and effectively utilizes available bandwidth.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a diagram showing the principle of the elastic basket method, Fig. 3 is a diagram showing a configuration example of a star network, Fig. 4 is a block diagram of a distributed module, Figure 5 is a functional block diagram of the line circuit, Figure 6 is a diagram showing an example of the configuration of a conventional time division multiplex communication system, Figure 7 is a diagram showing an example of band usage, and Figure 8 is a diagram of a conventional digital line system. FIG. 43 in Figure 1, 1 is a five-handed circuit, 2 is an exchange, 3 is a separation circuit, 81 to Sn are two transmitting terminals, R1 to RI11 are receiving terminals, /1 is an upstream communication path, and ! ! 2 is a downlink communication path, SCI to scn, r<C1 to RCml, and a band conversion circuit.

Claims (1)

[Claims] A plurality of transmitting terminals (S1) to (Sn), a multiplexing circuit (1) that receives outputs from these transmitting terminals (S1) to (Sn) and performs time division multiplexing, and the multiplexing circuit. A switch (2) receives the output of (1) via an uplink communication path (l1) and performs channel switching; and a switch (2) receives the output of the switch (2) via a downlink communication path (l2) and performs signal separation. The separation circuit (3) that performs
3) a plurality of receiving terminals (R1) to (
In the communication system configured by Rm), band conversion circuits (SC1) to (SCn), (RC1) to
A variable band communication system characterized by providing (RCm).