JPS626588A - Channel-access control device - 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] Industrial Application Field This invention relates to communication on a communication transmission line (home bus) in the home,
The present invention relates to a channel access control device used in the fields of communication within a limited distance in offices, CATV networks, and home buses in homes.

Conventional technology Data at home, office, and CATV.

A system that simultaneously transmits information on at least one or more pieces of audio and video composite media on the same transmission medium, bi-directionally, and accesses multiple channels using home bus baseband communication control, for example, the subband channels of a coaxial cable. There isn't.

Problem to be Solved by the Invention For example, individual signals of data, voice, and camera signals or a composite signal of multiple signals are received from the CATV network to the home at the CATV termination, and this signal is, for example, a mid-band signal, and is connected to the home bus in the home. In some cases, the information ah can be used only in subbands. Also, IFU in the home
Depending on the long distance between CATVNT and IFU and the carrier frequency for transmission, the attenuation of the transmitted signal may be large and the signal may not be transmitted. Also CATV NT
When communication starts from the IFU of the home bus to the IFU of the home bus, and between at least one IFU, without channel management, channel conflict and poor quality communication will occur.

Therefore, it is necessary to establish channel access control when controlling communication between CATV NT and each IFU.

Means to solve the problem
A frequency converter function that converts the ATV signal frequency to the frequency used in the home bus or converts the home bus frequency to the frequency used by the ATV, and the IFU number and signal that corresponds to CATV mid-band data. Notify the CATv NT of the used frequency and
Communication is established by notifying the IFU of the communication source 9 of the subband frequency and modulation/demodulation channel to be used from the ATV NT, and controlling the modulator frequency and tuner frequency of this IFU.

Function The present invention provides CATV NT (CATV Network Termination), which performs channel management and channel access control for communication control between CATV and IFU in the home bus, as one of the external information networks, and which is managed under CATV NT. Performs IFU modulation and demodulation control.

Example In a system that combines a CATV network and a home bus system, by providing a CATVNT (CATV network terminal) that controls calls from the CATV network and communication control within the home bus system, it is possible to connect the external information network CATV to the home bus system. Can handle call requests from other parties.

Also, optical cables and coaxial cable bare wires can be considered as home buses that can finally make call requests from the IFU on the home bus side to CATV, but here we will take a coaxial cable for example and add baseband signals such as g, e kb, etc.
Channel access in which the frequency of the subband of the information channel is selected using the control data of the pg will be explained.

FIG. 1 is a system configuration diagram for explaining the channel access control method.

There is a CATV network consisting of transmission lines of optical cables and coaxial cables as CATVI &, and CATV NT1.
At least one information outlet 3 is connected to a home bus 2 as a communication transmission path within the home connected to the 0cATV NT1. This information outlet 3 includes an interface unit 4t51e, which has communication control functions, modem control functions, and I10 control functions, and each interface unit (hereinafter referred to as IFU)! 7/.

Voice handsets 7, 8, 9, monitor T as objects of control
v1o, 11, 12, cameras 13, 14, and 15 are connected, respectively.

The functions of the IFU in FIG. 1 will be explained with reference to a block diagram showing the IFU functions in FIG. 2.

The IFU is connected to the information outlet 3 of the home bus 2,
Base band control data from this information outlet 3,
The subband information channel signals are sent to the IFU's transmitter/receiver (hereinafter referred to as T/
R) 16 for transmission and reception.

(E) in Fig. 3 superimposed on the home bus on this T/R1e
A low-pass filter (LPF) 16a extracts the DC power shown in FIG. The signal is supplied to the modulator 21. The baseband control data of the coaxial cable is a band pass filter (BFU).
The baseband communication control unit 1 is separated from other signals by 1sb.
8 has the functions of communication control between each IFU and communication control means with CATV NT. In addition, the baseband communication control unit 18 also controls the subband frequency band (c) shown in FIG.
The selection control of the channels corresponding to the audio video signal (AV signal) for 9 channels and the audio signal for 10 ah shown in
This is done using the control data of N'T1.

Terminals 23, 24, and 25 have audio handsets and monitor TVs.
, cameras are connected to each, and this IFU itself controls the functions of the video phone. 19 is a power tuner 20 which is superimposed on the home bus 2 using a capacitor. It has a function of blocking direct current application to the modulator 21. A tuner 20. Modulator 2
1 is connected.

For example, a coaxial cable is used as the home bus 2, but depending on the transmission distance of the home bus and the frequency used for transmission, the amount of signal attenuation becomes large and communication may not be possible. IFU
Depending on the transmission distance between IFUs, only data/audio signals can be transmitted, and between IFUs where the influence of signal attenuation is small, data/audio/video signals can be transmitted.

Each IFU (!: CATV NTIK) There is a table memory that shows the availability of information media shown on the lower display.
For example, when transmitting information media from IFU4 to IFU6, AV signals and data can be transmitted.

However, it can be seen at the IFU level that only audio data can be transmitted from IFU4 to IFU12. I
When transmitting information from FU4 to IFUe, IFU4
The CATV NT1 makes an inquiry to the CATV NT1 to obtain communication permission and permission to select an information medium, and after obtaining permission from the CATV NT1, a communication link is established with the IFUe.

Next, the functions of CATVNT1 will be explained with reference to FIG. CATVl includes an interface management table 36 for managing whether or not information media can be transmitted between interface IFUs, and an interface management table 36 for managing which IFU is currently controlling communication. Subchannel f→ shown in FIG.

A bus channel usage management table 36 that manages which frequencies of (d) and (e) are used. The communication control agreement shown in FIG. 5 is determined. NT channel/channel management table 3
4, the conditions for controlling communication between the IFUs of the home bus are determined. This management table has the following rules for communication control: (1) giving priority to connections with small IFU numbers; and (2) giving priority to connections with small IFU numbers.
It has functions such as specifying the AV signal channel based on the transmission distance between FUs. From the CATV network to the CATV transmitter/receiver (T/R) 30 of the external information network (Fig.
(a) A mid-band signal is received, and the mid-band information channel is managed in the CATV management table 31. This information ah is converted by the frequency converter 32 into the frequency of the subband on the home bus side. This frequency is managed by the bus channel usage management table 36 and is
A link between the midband of V and the subband of the home bus is established.

When controlling communication with the external information network of CATV NT1 from the home bus IFU, N of CATVNT1
T channel management table 34. In order to determine the information ah in (c) and (b) in FIG. 3 from the interface management table 36, the selection of information media in the table described above,
The frequency of the subband is notified to the IFU side using the channel selection algorithm shown in the figure.

This signal is converted into a mid-band frequency on the CATV side by the frequency converter 32.The CATVNT manages the mid-band frequency on the CATV side as shown in FIG. 3 (b) sent from the CATV side. Mid-band frequencies are assigned by the management table 31 of .

Next, from the outside of CATV NT1 to the IF in the home bus
When CATV NT1 receives a request to communicate with U, transmitter receiver 3o of CATV NT1
receives this signal, the communication control unit 33 detects which frequency, for example, in the mid-band ah in FIG. 3, and this frequency ah is stored in the CATVci management table 31 in CATVNTl. As mentioned above, the CATV NT management table 31 is
This is to avoid duplication of the use of mid-band channels that use the CATV network, since it is also possible to communicate with the ATV network. The ah stored in the CATV channel management table 31 is used to convert the mid-band ah to the subband in the home bus by the frequency converter 32, except for the ah in (c) in Fig. 3, which is already used in the home bus. Also, if the conditions of the NT channel management table 34 are matched, and the interface management table 36 determines whether or not the IFU is on a call, if the IFU is on a call, cATV NT1 (7) OA
'Notify the IFU specified by the baseband control data in FIG. 3(e) that there is a call on the TV network.

When the call of the specified IFU ends, the frequency converter 32 transfers the specified audio/video signal or audio signal from the bus usage management table to the home bus through the bypass filter (HPF) 16a of the T/R3B on the home bus side of the CATV NT1. inject. This bus usage management table is used for each IFU of the home bus as shown in the table above.
It contains a table that enables transmission communication for each IFU, and manages the usage range of the modulator and tuner of each IFU.

When CATV NT1 receives a Data signal from the CATV center, it also receives a CATV signal from CATV'NT1.
When sending a Data signal to the TV center, the home bus contains the control data (E) in Figure 3 (e.g. EVA 9, 6).
kbps). The CATV Senp-Heno transmission data is 9.6 kbps. Data with a speed Xn times as shown in FIG. Transfer the necessary data to CATV NT
The signal is transmitted to the home bus 2 through the bandpass filter (BPF) 1ab of the transmitter/receiver 38 of No. 1. Also, from the home bus side, CATV NT1's CATV-1
When transmitting data to a computer (to an external information network), it is controlled by the reverse sequence of operations described above.

Effect of the invention Coaxial cable will be used as the transmission medium for CATV in the future.

Optical cables can be considered, and these can be used to link with external information centers and communicate various types of service information to homes. In addition to this, it will also be possible to control calls within the home and using the CATV network.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the system configuration of a channel access control device according to an embodiment of the present invention, Fig. 2 is a block diagram for explaining the functions of the interface unit, and Fig. 3 is a block diagram showing the system configuration of a channel access control device in an embodiment of the present invention.
Figure 4 is a block diagram for explaining the functions of CATV NT, and Figure 5 is a diagram of the frequency characteristics of the subband of the information channel used on the home bus side as an example of the frequency allocation transmitted to T. This is an algorithm table for communication control of the interface unit. 1... CATV network terminal, 2...
... Home bus, 3 ... Information outlet, 4,5゜6 ... Interface unit),
7,8.9...Audio handset, 10,11.
12...Monitor TV, 13,14.15...
···camera. Name of agent: Patent attorney Toshio Nakao and 1 other person2-
11 home base 3-) rt adjustment J set> 4, G---IFLJ 7x'? ---T Ha Sending/Receiving (""-'E4TV 13~1.5---Camera 2nd figure 2--One-4 hearth! @ 3 Figure←-CATVNT

Claims (2)

[Claims] (1) Equipped with a system consisting of an external information network and a home bus, an interface unit that controls audio/video data connected to the home bus transmits an audio/video composite signal or audio depending on the number of the interface to communicate with the other party. A channel access control device with the ability to determine whether the signal is signal-only or not. (2) The channel access control device according to claim 1, wherein the system is a CATV network termination and is capable of performing the same channel access control as a home bus for the CATV network termination connected to an external information network. .