JPH0918437A - Two-way communication equipment - Google Patents

Abstract

PURPOSE: To simplify center facility by disusung an exchange by interposing a means switching the communication time slot of an incoming data string sent from a terminal to a prescribed communication time slot of an outgoing data string on a transmission line in two-way communications having TDMA and delay control combined together. CONSTITUTION: An incoming/outgoing time slot switching device 18 is provided in an interface with the external network of two-way communication equipment. Synchronous data is arranged at the head of the slot of each of the incoming and outgoing data strings, and information to perform switching control between terminals such as variable slot constitution, three party speech and broadcasting designation, etc., in addition to general control information such as an opposite party address is attached behind the synchronous data. The time slot switching device 18 switches time slots among the terminals A, B and C as designated to perform the switching control based on the control information. In this way, the center facility is simplified by disusing the switching device when communication control is performed between the terminals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a bidirectional communication device using, for example, a coaxial cable or an optical fiber cable as a transmission line.

[0002]

2. Description of the Related Art As is well known, in a bidirectional communication apparatus such as the one described in recent years, delay control and TDMA (Time
It is under consideration to provide a two-way communication service in combination with a division multiple access (time division multiple access) method. As an example of such a two-way communication service, FIG. 8 shows a schematic configuration of a two-way communication device that provides a telephone service using a network of a CATV (Cable Television) broadcasting system.

In FIG. 8, reference numeral 11 is a PBX for performing exchange control for an external network and telephone service.
(Private Branch Exchange) equipment installed in the center. Further, reference numeral 1 in FIG.
Reference numeral 2 denotes a delay control PBX having a delay control function for the terminal and an interface function for the PBX device 11.
It is an interface device.

The delay control PBX interface device 12 is provided with a PCM (Puls) to the PBX device 11 in order to realize an interface function for the PBX device 11.
e Code Modulation) Connected via a highway. The delay control part of the delay control PBX interface device 12 will be described later.

Further, in FIG. 8, reference numeral 13 is a digital modulation circuit for subjecting the binary downlink data output from the delay control PBX interface device 12 to digital modulation processing and frequency conversion processing. The digital modulation circuit 13 is, for example, a low-speed FSK (Frequency Shift Keyi).
ng; frequency shift keying method, medium speed QPSK (Quadratu)
A modulation method suitable for the transmission line or system is adopted, such as a re-phase shift keying method, a high-speed multi-level QAM (Quadrature Amplitude Modulation) method, or the like.

The downlink modulation data output from the digital modulation circuit 13 is sent to the network after passing through the mixing / branching circuit 14. As this network, at present, a plurality of (two in the case shown) terminals A and B are connected via a transmission line 15 made of a coaxial cable, and an optical fiber cable is used up to a halfway point and a coaxial cable is used at the end. Is used, that is, a form in which a plurality of (one in the illustrated case) terminals C are connected via a transmission line 16 of an optical coaxial hybrid type used when the transmission distance is long.

In this case, the downlink modulation data has a transmission band of 70 MHz to 1 GH as shown in FIG. 9 (a).
z is used, and in the case of the CATV broadcasting system, it is transmitted together with the downlink video signal. The downlink digital modulated wave shown in FIG. 9 (a) is modulated by a modulation method within 6 MHz which is the bandwidth of one channel of the analog video signal. An amplifier for correcting data attenuation is inserted in the middle of the network to compensate the data level up to the terminals A, B and C. Also, transmission line 1
The data on the terminals 5 and 16 are transferred to the terminals A, B and C by the branching device.
Distributed to

On the other hand, the upstream signals sent from the terminals A, B, and C, after passing through the transmission lines 15 and 16 and the mixing / branching circuit 14, are supplied to the digital demodulation circuit 17 to be demodulated. Is converted to binary upstream data by
After that, the delay control PBX interface device 12 and P
It can be sent to an external network via the BX device 11.

In this case, the upstream data transmission band is 10 MHz to 50 MHz as shown in FIG. 9 (b).
Is used. The upstream digital modulated wave shown in FIG. 9B is a format in which four modulated waves are transmitted in a 6 MHz bandwidth as in the case of downlink, and the modulation method is the same as the downlink, that is, the low speed is FSK, Speed adopts the QPSK method. Further, as the demodulation method of the digital demodulation circuit 17, since TDMA is used, the differential detection method is generally adopted.

Here, FIG. 10 (a) shows the format of the downlink data. That is, the downlink data string has an FS (frame SYNC) bit string indicating the start of a frame at the beginning, and each terminal A, B, C
By detecting this FS, the downlink data is synchronized.

In addition, delay control data for instructing the terminals A, B and C about the delay time and the transmission level is arranged next to the FS in the downlink data sequence. Although not shown at the head of this delay control data, each terminal A,
Addresses B and C are set, and only terminals A, B and C corresponding to these addresses receive the downlink data and perform processing.

Further, call control data is arranged next to the delay control data in the downlink data string. This call control data is composed of data (communication frequency designation, communication slot designation, etc.) for assigning communication slots in response to communication requests from terminals A, B, and C.

The remaining area of the downlink data sequence is allotted to a communication time slot, and one frame (between FS and FS) is divided at a bit rate that meets the communication specifications. For example, one frame is T (ms),
The transmission speed is H (bps), the number of bits of the above control information is K (bits), and the communication speed of one communication slot is L (bp).
s), assuming that the control information in each slot is J (bit), the number n of time slots that can be secured is n = (T · H−K) / (T · L−J).

Next, FIG. 10B shows the format of the upstream data. This upstream data string is not transmitted continuously from each terminal A, B, C,
Transmitted from different terminals A, B, C in each slot unit,
It becomes a continuous data string when it reaches the center. However, since the modulated waves of the individual time slots are discontinuous, it is not possible to use demodulation means such as synchronous detection, and it is necessary to perform demodulation processing by differential detection.

First, delay control data is arranged at the beginning of the upstream data string. This delay control data corresponds to the terminal A designated by the downlink delay control data,
It is transmitted from B and C to the center. Then, as will be described in detail later, the center measures the delay based on the synchronization pattern included in the upstream delay control data.

In addition, in the upstream data string, next to the delay control data, delay window data indicating the range in which the center measures the delay is arranged. Further, in the upstream data string, call control data for allocating a communication slot is arranged next to the delay window data, and the remaining area after that is all allocated to the time slot for communication.

FIG. 11A shows the format of the upstream delay control data string. In this upstream delay control data string, unmodulated data is arranged at the beginning, and an alternating pattern called a preamble is arranged after that. At the center, the data obtained by demodulating the preamble is clock-synchronized, and the position is detected by the FS arranged next. In the preamble and FS part, the center measures the delay,
The delay time is notified to each terminal A, B, C.

The delay control data arranged after FS in the upstream delay control data sequence is used to confirm whether or not the delay control instructed by the center is correctly received by the terminals A, B and C. , Terminals A, B, C are used to send back downlink delay control data. The CRC (Cyclic Redunda) is added at the end of the uplink delay control data sequence.
ncy Check (redundancy code check) data and error correction data are arranged for error detection and error correction of communication data.

FIG. 11 (b) shows the format of the time slot data sequence included in the upstream data sequence. That is, guard bits G for avoiding interference with the preceding and following time slots are arranged at the beginning and end of each time slot. Then, in the time slot, control data, transmission data, error correction data, etc. are arranged.

Here, FIG. 12 is a flow chart showing the procedure of the delay measurement. First, start (Step S
1) Then, the center, in step S2a,
The downlink delay control data, and in step S3a, after receiving the uplink delay control data sent from the terminal A,
In step S4a, delay measurement is executed based on the preamble and FS. Steps S2a to S4a described above
Processing is sequentially repeated for all other terminals B, ..., L.

Thereafter, in step S5, the center waits for the preset number of times of polling, which is k times, to be completed, and in step S6, the delay measurement result is sent to each of the terminals A, B, ..., L. Notify and perform alignment. After that, the center repeats polling and corrects the delay time at regular intervals.

FIG. 13 is a timing chart shown for explaining the delay measuring operation. First, the downlink data sequence as shown in FIG. 13A transmitted from the center is delayed by a predetermined time as shown in FIG.
It is received by the terminals A, B, ..., L. Then terminal A,
B, ..., L sees the delay control data included in the received downlink data sequence, and if it indicates the transmission of the uplink delay control data to itself, the next At the FS timing, the uplink delay control data is transmitted as shown in FIG. 13 (c).

The uplink delay control data transmitted from the terminals A, B, ..., L in this way reaches the center after a delay time equivalent to that of the downlink data sequence as shown in FIG. 13 (d). To be done. In this case, the center measures the time from the occurrence of the FS of the downlink data sequence to the reception of the uplink delay control data, and 1/2 of the measured time is measured from the center to the terminals A, B ,. It is determined that the delay time is up to L. Then, the center repeatedly executes such measurement of the delay time for each of the terminals A, B, ..., L according to the procedure of the flowchart shown in FIG. 12, and integrates the result to obtain an average value. Calculate and calculate each terminal A,
Notify B, ..., L respectively.

Therefore, each terminal A, B, ..., L controls the delay based on the notified data by transmitting the uplink delay control data before how long the FS of the downlink data sequence is received. You can determine what you can do. That is, the position shown by the broken line in FIG. 13C is the transmission timing of the uplink delay control data after the delay measurement is completed. This timing is also applied to the communication time slot, and when viewed from the center side, all received uplink data are demodulated without duplication.

Next, the communication time slot allocation control will be described with reference to FIG. That is, in the state where the delay control has already been completed, the terminals A, B, ..., L
When a request to secure a communication time slot is issued to the terminal, the terminals A, B, ..., L transmit the uplink call control data to the center. Then, the center receiving this uplink call control data searches for an empty time slot,
If it is not necessary to switch between the upstream and downstream frequencies, only the time slot allocation instruction is transmitted to the terminals A, B, ..., L while maintaining the current frequency.

As a result, the terminals A, B, ..., L start communication in the communication time slot according to the instruction from the center. In addition, terminals A, B, ..., L
If the time slot of the currently used frequency is full at the time when the communication time slot is requested by the center, the center instructs the terminals A, B, ... It will be output to.

However, in the conventional two-way communication device as described above, when the communication control is performed between the terminals A, B, ..., L, for example, the upstream data transmitted from the terminal A is once transmitted to the center. Is received, and the center performs time slot allocation, frequency allocation, exchange control, etc., and then transmits as downlink data to another terminal B, which causes a problem that the center equipment becomes large in scale. ing.

[0028]

As described above, in the conventional two-way communication device, when performing connection control between terminals,
Since the signal transmitted from the terminal is disassembled once and the communication control is performed by a switching device such as RBX, the facilities of the center become enormous, which is disadvantageous in terms of installation area and economical efficiency. There is.

Therefore, the present invention has been made in consideration of the above circumstances, and is an extremely good two-way communication which can facilitate simplification of center equipment by eliminating the need for a switching device when controlling communication between terminals. The purpose is to provide a device.

[0030]

A two-way communication apparatus according to the present invention performs two-way communication in which TDMA and delay control are combined between a center and a plurality of terminals via a common transmission line. Intended. Then, a predetermined communication time slot of the upstream data string transmitted from the first terminal to the transmission line via the transmission line and a predetermined communication of the downstream data string transmitted to the second terminal are transmitted. It is provided with a transfer means for transferring to a time slot.

[0031]

According to the above configuration, the predetermined communication time slot of the upstream data string transmitted from the first terminal to the transmission line is transmitted to the second terminal on the transmission line. Since the transfer means for transferring the data to the predetermined communication time slot of the data string is interposed, the communication control between the terminals can be performed without using the switching device, and the simplification of the center equipment is promoted. be able to.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. In FIG. 1, the same parts as those in FIG. 8 are designated by the same reference numerals. That is, in FIG.
Reference numeral 18 is an up / down time slot transfer device,
In this example, the process of transferring the upstream communication time slot to the allocated downstream communication time slot is performed as described later.

When the upstream / downstream time slot switching device 18 is connected to an external network including, for example, a center (not shown), the upstream / downstream time slot switching device 18 has a signal processing portion for external connection and decomposes the time slot to the outside. I am trying to convert it to the required signal format for output. Also,
In FIG. 1, reference numeral 19 is a delay control device, which measures the delay amount and signal level between the center and the terminals A, B, and C, and transmits the transmission signals from each of the terminals A, B, and C when reaching the center. The process of aligning is performed.

Here, FIG. 2A shows the format of the upstream data stream, and FIG. 2B shows the format of the downstream data stream. That is, slot 1 of the uplink data sequence is replaced with slot n of the downlink data sequence, and slot 2 of the uplink data sequence is replaced with slot 1 of the downlink data sequence. It is assumed that the slot to be replaced is designated in advance. In this way, by transferring the slots of the upstream data sequence to the slots of the downstream data sequence, the data transfer from the upstream data sequence to the downstream data sequence is completed.

FIG. 2C shows the data format in the slot. That is, at the beginning of the slot,
Synchronous data is arranged, and then control information exists. This control information includes, in addition to the conventional information, terminal A,
Information for enabling exchange control between B and C is added. Then, after this control information, communication data is arranged, and finally the error correction data that was also added to the upstream data is added as it is.

Here, as the contents of this control information, as shown in FIG. 2D, the number of the other party's terminal (for example, address, telephone number, ID number, etc.) is at the beginning, and then the telephone etc. Have the ringing, hooks and inversions needed to control
After that, key data for data scrambling, transfer destination data, etc. follow, and finally, control data for other services are arranged. This service includes, for example, variable slot configuration, three-way calling, broadcast designation, etc. for processing additional functions.

FIG. 3 shows an example of this variable slot configuration. Normally, in the case of digital communication such as telephone, when the coding method is decided, it can be supported only by the decided method, but the present invention does not need to replace time slots, that is, the center function. According to the above, as long as a terminal can be supported, it is possible to realize transmission by various encoding methods. For example, as shown in FIG. 3, PCM and AD (Adaptive Differential;
It is possible to mix and transmit audio data encoded by two methods such as adaptive difference) PCM. Although not shown, it is also possible to mix audio data that has been further highly compressed.

Further, since only the time slot allocation is supported by the center and the individual connection is performed by the terminal, the efficiency of time slot allocation becomes a problem, but as shown in FIGS. 4 (a) and 4 (b). , Both the upstream data sequence and the downstream data sequence have two or more delay control data, call control data, and delay control window data, thereby reducing the probability of time slot allocation conflict and performing efficient communication. be able to.

Further, FIG. 5 shows the principle of supporting a three-way call. Conventionally, the switching device decomposes the time slots and then combines the necessary slots. However, if all the combinations are to be supported, the circuit becomes large in scale. In the example shown in FIG. 5, the three-way call function can be realized by selecting two or more slots returned from the uplink / downlink time slot switching device 18 on the terminal side and combining them. This function is controlled by adding data instructing the three-way calling function to the control information added to each time slot.

FIG. 6 shows an example of a downlink data sequence that can be used for broadcast data transmission, not for communication using an empty area generated by switching up / down time slots. That is, since there is an unnecessary area in the downlink data string such as the area of the delay control window and the guard bit G part of each communication time slot in the uplink data string, the uplink communication time slot is set to the downlink communication time slot. When replaced with, that part becomes an empty area.

Therefore, various services can be made possible by transmitting the data to the terminal by utilizing the empty portion as a broadcasting data area. Examples of services include announcement broadcasting and voice BGM (Back Ground Music).
) Broadcasting, game data broadcasting, etc. are considered.

In FIG. 7, by designating the broadcasting data area described in FIG. 6 from a terminal, broadcasting can be performed from any terminal to all terminals or a designated group. An example of a / downstream data string is shown. Broadcast control data is added to the control data and transmitted in the control information of the upstream time slot. The up / down time slot transfer device 18 only transfers the transmitted time slot to the broadcast area based on an instruction from the added broadcast control data when the time slot is transferred. Now, it is possible to broadcast from any terminal. It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the scope of the invention.

[0043]

As described in detail above, according to the present invention,
It is possible to provide an extremely good two-way communication device that can facilitate simplification of center equipment by eliminating the need for a switching device when performing communication control between terminals.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a bidirectional communication device according to the present invention.

FIG. 2 is a diagram shown for explaining a format of downlink and uplink data of the embodiment.

FIG. 3 is a diagram shown for explaining a variable slot configuration example in the embodiment.

FIG. 4 is a diagram shown for explaining a modification of the delay control data string in the embodiment.

FIG. 5 is a diagram shown for explaining a modified example of the time slot process in the embodiment.

FIG. 6 is a diagram for explaining a modified example in which the broadcast data area of the embodiment is provided.

FIG. 7 is a diagram for explaining an example of a broadcast designation format of the modified example.

FIG. 8 is a block diagram showing an outline of a conventional bidirectional communication device.

FIG. 9 is a diagram for explaining frequency allocation of downlink and uplink data of the conventional device.

FIG. 10 is a diagram shown for explaining a format of the downlink and uplink data.

FIG. 11 is a diagram shown for explaining the details of the uplink data.

FIG. 12 is a flowchart shown to explain a delay control procedure of the conventional apparatus.

FIG. 13 is a diagram shown for explaining a delay measuring operation of the conventional apparatus.

FIG. 14 is a diagram for explaining a time slot allocation operation of the conventional apparatus.

[Explanation of symbols]

 11 ... PBX device, 12 ... Delay control PBX interface device, 13 ... Digital modulation circuit, 14 ... Mixed branch circuit, 15, 16 ... Transmission line, 17 ... Digital demodulation circuit, 18 ... Up / down time slot transfer device, 19 ... delay control device.

Claims (9)

[Claims] 1. A two-way communication device for performing two-way communication in which TDMA and delay control are combined between a center and a plurality of terminals via a common transmission line, the two-way communication device being interposed on the transmission line, A transfer means for transferring the pre-specified communication time slot of the upstream data string transmitted from the terminal of the second terminal to the pre-specified communication time slot of the downlink data string transmitted to the second terminal. A two-way communication device characterized in that 2. The two-way communication apparatus according to claim 1, wherein the communication time slot that is replaced by the replacement means includes error correction data added to the upstream time slot. 3. The two-way communication device according to claim 1, wherein the communication time slot that is replaced by the replacement unit includes key data for scrambling. 4. The two-way communication device according to claim 1, wherein a data area for a transfer service is secured in a communication time slot that is replaced by the transfer means. 5. The length of each communication time slot replaced by the transfer means is changed according to a transmission coding method of data included in each communication time slot. The two-way communication device described. 6. The uplink data sequence and the downlink data sequence are provided with a plurality of areas in which slot designation information for designating communication time slots to be transposed by the transposition means is arranged. Claim 1
A two-way communication device as described. 7. The bidirectional according to claim 1, wherein the second terminal comprises a combining means for combining the data of a plurality of communication time slots included in the received downlink data sequence. Communication device. 8. The broadcast data to be transmitted to a plurality of terminals is arranged in an empty area created in the downlink data sequence due to the replacement of the communication time slots by the replacement means. The two-way communication device described. 9. The two-way communication device according to claim 8, wherein broadcast designation information from the terminal is added to an area in which the broadcast data is arranged.