Broadband CATV network - design and simulation Rudolf Volner, PhD. Associate Professor Department of Telecommunications University of Zilina Ve¾ký diel, 010 26 Žilina Slovak Republic
[email protected] Abstract: The article describes information network and CATV applications, backbone network structure. Cable is a natural network for carrying high-capacity, bandwidth - intense information. In the age of analogue program signals, cable’s capacity was a natural transmission media for broadcast colour TV and high-fidelity stereo sound programs. In the new digital program signal age, cable’s high capacity is a natural network for carrying interactive computer-based, data - intensive multimedia programs. Index: broadband network CATV, design, optics system simulation,
1. INTRODUCTION
Cable television is a technical system for distribution of television by cable (coaxial, twisted pair or fibre optic) with potential for largest bandwidth and integrated return channel for interactive services. With the introduction of new technology, the CATV networks will have more active components than at present. Access of an end-user to services in the CATV network is realised by the help of access network. Access network must be enhanced to carry various multimedia services. There are several options to introduce fibre in the access network, fibre to the cabinet/curb FTTCa/C with a last copper drop based on very high rate DSL on one hand and fibre to the building/fibre to the home FTTB/H on the other. FTTCa/FFTC avoids the installation cost of fibre to the costumer premises, but introduces a high exploitation cost, since network operator personnel will have to travel to the cabinet or curb unit for every alteration or maintenance action. Moreover, the process by which the operator becomes entitled to site a cabinet
or curb unit in suitable position is complex, and powering will require a large investment. Because of these reasons it is assumed here that network operators will make the strategic choice of introducing fibre directly to the costumer premises with FTTB/H. Residential broadband access network technology based on Asynchronous Transfer Mode (ATM) will soon reach commercial availability. The capabilities provided by ATM access network promise integrated services bandwidth available in excess of those provided by traditional networks. Other services such as desktop video teleconferencing and enhanced server-based application support can be added as part of future evolution of the network. 2. DESIGN INTERACTIVE CATV NETWORK
Interactive network CATV consists of network nodes and terminal devices, which are connected hierarchically among them. Control nodes are connected to incomplete lattice network and so the primary network is created. Every control node serves set of distribution nodes, which are connected to star and they create secondary network. For each distribution node, several terminal devices are connected to it, and they create tercial network. The whole CATV network could form an access network to some larger network and transmissions will be possible to other networks and standards.
Network services are communication (audio connection, video connection, conference, ...), distribution (audio distribution, video distribution, ...) and special (remote watching, remote measurement, remote alarm or signalization, ...). Next important classification is according to that is the service provided by: • Directly by terminal device (e.g. time services, alarm clock, appliance control, measurements providing, ...). Services like those are not just network services, but it deals with use machine intelligence of terminal device, it depends on terminal device software. •
By superior distribution node (e.g. user communication in frame of distribution node, videoconnection, audioconnection, conference, data transfers and likewise).
•
By superior control node (e.g. videoprogram distribution, which are situated in databases of superior control node). It needs to focus this services category to interactive CATV design. These services require much more means for application, than previous two categories, software and hardware, and it will be shown in price.
•
By another control node, that mediates its services to respective superior control node by network (e.g. video distribution, that aren’t in databases of superior control node).
•
Service application beside CATV network (e.g. communication services beside area covered by CATV, Internet services and likewise). This service category use CATV as only transmission means, using its lines.
Terminal device is the lowest hierarchical element in network. The idea of terminal device is that it deals with a system, that will provide separation of distributed services to household appliance (television set, projector, hi-fi amplifier and likewise) and data collection for sending to superior (rooms temperature, water, gas or energy consumption, ...). The terminal device can be independent television receiver, which conception is different from present-day’s devices. It will be just decoder and screen unit. Every terminal device need contain certain intelligence, to separate its signals from plenty of another ones, because communication will be like Ethernet for example and transmission rate will be about 10Mb/s in this case. For analogue channel receiving it is sufficient to use classic TV set in respective TV norm (PAL, NTSC) without adaptation, but these users have not any access to other services. Transmission medium is coaxial cable, so existing transmission lines will be utilised. The distribution node is superior node of the terminal device. Its job is mostly to distribute services of the control node to terminal users. The distribution node associates tens of terminal users and communicates to them within its tercial network in star like form. The distribution node secures service group within its subordinate terminal users. Certain multitude of distribution nodes (e.g. in frame of one locality, a habitation or likewise), are connected to control node. Control node contains extensive databases (e.g. films, books, ...) and it has very large memory capacity, it provides wide scale of services. If somebody requires certain group of information or services, which are not included, it offers the request to next control node. These nodes are connected both each other and to their distribution nodes for example by wideband optical network with ATM.
3. THE STRUCTURE OF THE INTERACTIVE NETWORK
doesn’t deal with system, which transfers the TV and R signals, but with the system transferring whatever information to arbitrary direction. By this new approach, primary sense of CATV fades and the network becomes the universal data network, where it is possible to create and realise almost arbitrary services. In interactive CATV, there are three levels, similarly as in distribution network. Tree structure is shown in figure 1:
At present, the great importance of CATV is in the best transferring of information, mainly in association with satellite transmission of TV and R signals. It indicates that possibilities of CATV are much bigger and they reach to other spheres. Therefore, it is necessary to come nearer CATV from another point of view. This point of vie is the information approach, and new conception of CATV the city
primary network
central
central
central
node
node
node
secondary network
distribution node
distribution node
tercial network
distribution node
terminal user
terminal user
Figure 1 - Structure of interactive network
1. In a city or another larger region, there is a set of mutually connected central nodes, which create the primary network. Each of them serves respective part of the city e.g. and habitation, a street or likewise. Interactive CATVs can be independent networks, which exist simultaneously with other ones. But, it is economically better and efficiently when the primary network of CATV is an access network of certain great national network (WAN, MAN, B-ISDN etc...). Communication in the primary network must be enough wideband and of larger distance than in primary network of distribution CATV. Therefore, there is directly offered using of optical fibres with standard transfer rates here, e.g. 155Mb/s, 622Mb/s or much. 2. The central node is connected to set of distribution nodes and so it is created
the secondary network in star form. Each of distribution nodes covers set of flats or offices in small area, e.g. in multi-storey building. Wideband connection through optical fibres uses standard transfer rates, e.g. 155Mb/s, 622Mb/s or much. Physical layer is the same as in primary network. 3. Distribution node creates its own tercial network in star form, which connects user’s terminal devices. The transfer medium is coax cable, therefore for this subnetwork is possible use the existing lines which were created for distribution CATVs. Tercial network is possible alternative to present LAN with transfer rate 10Mb/s. One connection in tercial network contain several Ethernet channels. So, the connection of terminal user is indeed wideband. In the figure 1, there is shown only
simple tree structure, relay cross connections between distribution nodes can be created too. Secondary and tercial networks have star form, however in the future, more nodes or terminal users. 4. PROPOSAL OF CATV NETWORK
When a new CATV network system is designed, different alternative offering the same functionality have to be compared with respect to performance, reliability, robustness, hardware and software complexity, etc. Interactive communication requires bi-directional transmission. There are several methods by which bidirectional transmission on optical fibres can be realised. The final choice depends on the required upstream and downstream bit rate, network structure and for PON systems also on multiple access method. Cable operators can deploy ATM systems as part of an evolutionary path to a fully integrated multimedia bearer service offering. Conventional AM video transmission will remain attractive for the foreseeable future, because millions of existing analogues TV sets support only AM. Much of CATV networks at the moment consist of analogue transmission services, and the services themselves are analogue. There is a need to gradually introduce digital services without disrupting current analogue programs. The requests for the network design: every end-user has an access to twenty analogue TV channels, radio broadcasting,
bit rate 155 Mb/s for digital signals in both downstream and upstream direction. The main accent is imposed for the providing of digital distributive and interactive services. On the basis of above-mentioned requests we have propose the followed solution - figure 2. In the figures 3 and 4 are depicted blocks schemes of CTKR and RCDS. Solid lines present streams of users signals. Dash lines present the simplified concept of bit stream control signals. ATM is chosen as data-link protocol. The selection of ATM for proposed network has the advantage in that it provides a suitable integrated multiplexing platform capable of supporting a mix of guaranteed (predictive) traffic flows with best-effort (reactive) traffic flows. In addition, the nature of ATM allows other multimedia applications to be added in the future without requiring iterative changes to the basic ATM protocol. The provided services: • distributive – analogue and digital TV (terrestrial, satellite), radio broadcasting, • interactive – narrowband (voice mail, electronic mail, videotext, teleorder, telebank, teleshopping, medicine care, facsimile, telemeasurement, medicine measurement, telecontrol) • broadband (videophone, videocamera, B-videotext, telesecurity, television program, interactive television, telelearning, interactive games).
Figure 2 Topology of proposed network
Figure 3 - Scheme of centre CATV network (CTKR)
Figure 4 - Scheme of centre of home network (RCDS)
5. SIMULATION PROGRAM
If the configuration is over correctly, the program continues and it shows something similar like figure 5. It depends on settings
in configuration files. The structure of network is shown in working windows. At first, the working window shows always the set of central nodes. By left mouse
click we can go into the network structure. From set of central nodes, we can go to set of subordinate distribution nodes, from certain one to its subordinate terminal users and finally from there to set of available distribution services for respective terminal user. Each of descried transitions is done by left mouse single click (when the mouse pointer changes its picture to hand-like form). Each of working windows has a caption. There is
always shown the name or specification of actual object. If you are in the window showing set of central nodes, the caption title is ‘\’ (like a root). If you are inside of any object, its name or path is shown in the caption. In the left top corner of working window, there are two little buttons. The first serves for going to the root (the set of central nodes). The second serve for going up in the structure by one step.
Additional text: Vstupy do CTKR z vonkajších zdrojov - Inputs of CTKR, CTKR - Centre of CATV network, Výstupy do RCDS - Outputs of RCDS, RCDS - Centre of home network, (optické vlákna - fibre optics), Výstupy do EUB - Outputs of EUB, EUB - End unit box
Figure 5 Simulation program - steps
6. CONCLUSION
The question: „What is necessary for improvement of subscriber’s luxury ?“, the answer: „Not so much“. The cable lines of
CATV have already been existed and they are able to carry much greater multitude of information than they really have used. Present cable lines are able to cary
frequency spectrum 1GHz or wider and they are too great capital don’t to use it. I don’t want to say that making all beside cable lines is easy, but I think that putting cable lines into the earth is the greatest effort and after that „the playing“ with terminal devices and software can begin. The quality of subscriber luxury depends mainly on the software. The exact direction in which the utility business is headed in the next several years is uncertain at this time. It is difficult to predict the future marketplace when technology and standards are not fully developed and defined. Some utilities may seek to become „universal providers“ of electric service, demand side management, advanced metering, and fibre provider for telephone, cable TV, and other telecommunication services. Their will probably is many new businesses, such as edutainment and videoon-demand, if the multimedia industries take off as expected. Furthermore, the way we do business will greatly change. Distance learning, work at home, and remote diagnosis and treatment will become commonplace. Finally the importance of global collaboration in the research and development of multimedia technologies and applications, in the establishment of multimedia standards, and in the construction of a global multimedia network should be stressed. REFERENCES [1] Volner, R., Trunkvalter, M.: Interactive CATV and Multimedia, proceedings of The fifth international conference information systems development - isd 96, Gdansk, Poland September 1996, pp. 649 - 652, ISBN 83 - 86230 - 18 - 5 [2] Volner, R.: The Interactive Video - Future Services?; proceedings of International Symposium on Signals, Circuits and Systems SCS ‘97, Iasi, Romania, October 1997, pp. 77 - 80 [3] Volner, R., Boreš, P., Tichá, D.: CATV and PC = Information Network; proceedings of International Symposium on Signals, Circuits and Systems SCS ‘97, Iasi, Romania, October 1997, pp. 81 - 84
[4] Volner, R., Boreš, P., Tichá, D.: CATV architecture and simulation network; conference proceedings, The 6th Biennial Conference on Electronics and Microsystems Technology BEC 98, Tallinn, Estonia, October 1998, pp. 211 - 214 [5] Volner, R., Boreš, P., Tichá, D., Žiak, R.: The computer model of the interactive CATV network, proceedings of 20th International Conference on Information Technology Interfaces, Pula, Croatia, June 1998, pp. 217 - 221 [6] Žilka, Z., Volner, R.: System solution for transmission of interactive services on basis of optical CATV, proceedings of SPIE, 3rd International Conference Photonics Prague 99, Prague, June 1999, pp., and Programme & Book of Abstracts pp. 32, ISBN 80-86114-27-9 [7] Volner, R., Tichá, D.: Proposed applications of acoustic-optic processor in distributed interactive video system, proceedings of SPIE, 3rd International Conference Photonics Prague 99, Prague, June 1999, pp., and Programme & Book of Abstracts pp. 40, ISBN 80-86114- 27-9 [8] Volner, R.: Multimedia systems in interactive customer system, proceedings of 21st International Conference on Information Technology Interfaces, Pula, Croatia, June 1999, pp. 459 - 465, ISSN 13301012 [9] Volner, R.: CATV – gateway between traditional video services and new multimedia applications, proceedings of 22nd International Conference on Information Technology Interfaces, Pula, Croatia, June 2000, pp.253-260 , ISSN 13301012, ISBN 953-96769-1-6, (in English) [10] Volner, R. : Security system for road automobile communication system, proceedings of 22nd International Conference on Information Technology Interfaces, Pula, Croatia, June 2000, pp.73-80 , ISSN 1330-1012, ISBN 953-96769-1-6, (in English) [11] Volner, R., : CATV – Interactive Security and Communication System, proceedings the institute of electrical and electronics engineers, 34th Annual 2000 International Carnahan Conference on Security Technology, October 2000 Ottawa, Canada, pp. 124-136 , IEEE Catalog Number 00CH37083, ISBN 0-7803-5965-8, (in English) [12] Volner, R., Tichá, D.: Security system for road automobile communication system, proceedings the 11th International Conference on Information and Intelligent Systems – IIS 2000, September 2000, Varaždin, Croatia, pp., ISBN, [70%], (in English) [13] Volner, R. : CATV – video and multimedia system, proceedings the 11th International Conference on Information and Intelligent Systems – IIS 2000, September 2000, Varaždin, Croatia, pp. , ISBN , (in English) [14] Volner, R. : CATV – video and multimedia system, conference proceedings, The 7th Biennial Conference on Electronics and Microsystems
Technology BEC 2000, Tallinn, Estonia, October 2000, pp. 211 – 214, poster, (in English) [15] Volner, R., Tichá, D. : Road automobile communication system – telecommunication and security system, National Conference with International participation Automatics and Informatics’2000, October 2000, Sofia, Bulgaria,
pp. 56-58, ISBN 954-9641-19-8, [70%], (in English) [16] Volner, R.,: CATV multimedia system – new video system, National Conference with International participation Automatics and Informatics’2000, October 2000, Sofia, Bulgaria, pp. 59-61 , ISBN 954-9641-19-8, (in English)
