The SCTE Spring Lecture Meeting, 2002.

The SCTE Spring Lecture Meeting, held at the IEE in London Wednesday March 27th The Society's Spring Lecture Meeting for 2002 attracted approximately 60 members and guests to hear five interesting and challenging papers covering new developments in broadband engineering. The following is a summary of the presentations.

	Network Access Architecture for On-Demand Cable Television. Nimrod Ben-Natan, Director of Narrowcast Services at Harmonic Inc. By 2005 there could be 37 million subscribers to cable networks in the USA, and approaching 90 per cent of these will have access to on-demand services. The networks are segmented and two-way, thus ready for on-demand services and the impetus for these services arises from the drive from the cable modem market, a phenomenon that is apparent also in the UK. The UK cable market encounters strong competition from the digital satellite services, and this is another factor in the push towards VoD services. The last twelve months have seen the rise of SVoD - Subscription Video on Demand - that can operate over the same system architecture as VoD. From the viewpoint of the subscriber SVoD is, however, an additional service on offer. Centralised architecture using servers that are streaming the video content alongside the existing services from the original head-end is a very good idea and what remains to be determined is the method of transport into the subscriber. The options include moving the QAM modulators out into the hubs and even the nodes depending on the number of services that are required to fit the available bandwidth. Configuring the architecture to network demands requires a very flexible arrangement and the philosophy of a switched network and Gigabit Ethernet was discussed by the speaker.

Planning the Cable Network for Future Digital Loading. Matti Susi, Systems Consulting Manager at Teleste Broadband Cable Networks. Matti Susi set out first to analyse the amplitude properties of DVB-C using QAM, and PAL signals. He went on to analyse the effects and constraints of digital channel loading, with the interesting supposition finally that there would be only digital channels present on the HFC network. The third section of his talk dealt with narrowcast channel allocation in relation to DWDM. The overload characteristics of push-pull, power doubling and Gallium Arsenide amplifiers were very revealing, particularly in the case of GaAs, which showed a rapid onset of overload conditions but an higher output level capability than P-P and PD amplifiers. It was also revealed that narrowcast channels should be grouped together in the spectrum to avoid non-linear distortion causing unacceptable levels of unwanted products. Despite the frequent talk of Fibre to the Home, the general opinion was that HFC networks would remain in the majority for at least another ten years, and the prognosis was that most would carry digital signals with little trouble provided that signal levels were set accurately and maintained.

	Operational Support Systems in a Box for Broadband Networks. Nick Coombes, Director of Technical Support - Imagine Broadband Ltd. With networks growing in size, complexity and subscriber density the need has arisen for an integrated network management and supervisory system. Many alarm presentation methods are ineffective due to their concentration onto one monitor screen, and many systems do not offer a satisfactory service viewpoint of network performance. Frequently, important information is missing, and network operators have to do much of the thinking for themselves in an environment where both time and money are at a premium. Some network management systems create difficulties when existing services are changed or others are added. The Imagine solution to this was an innovative approach to NMS that involved gaining an accurate idea of service performance in a simple manner, no complex arrangements, and keeping Management Systems fully provisioned and up to date. The operator should back up the NMS with an intimate knowledge of his network, a full understanding of the network architecture, and control all services in a unified manner. The NMS should be capable of some analysis of reports to identify the nature and location of faults and what service is affected. It should also allow for remote management of set-top boxes and cable modems.

The Set-Top Box as a Home Gateway. Chris Boyce of Pace Micro Technology PLC. Current contenders for the role of the Home Gateway are the Personal Computer, The CATV Set-Top Box, and the Games Console. Possibly more contenders could appear as technology advances. In the competition for Broadband services into the home are Satellite, Cable, xDSL, Terrestrial broadcasting and Wireless services. The industry has already established phase one of journey to The Networked Home and are now into phase two by adding a set-top box with a broadband modem enabling two-way data to pass between network and home. Phase three will be the realisation of The Home Network. The Set-Top Box envisaged for the Home Gateway role will extend the reach of the cable network into the home network via a wireless connection to computers and telephones, though the link to the television receiver will be best served by a direct cable. NTL and Telewest are trialling this concept at the moment. The design aims of the unit are that it should be customer installable, operator-supervised by a full network management system, and secure. It would offer Internet radio, provide an always-on connection for data (no dial-up) and enable some degree of home automation, the monitoring of appliances, utility meters and detectors for fire and Carbon Monoxide. Further developments would incorporate the home video recorder function, targeted advertising, Video on Demand, enhanced interactive operation and programme storage. Future "just over the horizon" developments would add Games and Music storage and a home information cache.

	Euro-DOCSIS 1.0 and 1.1 Cable Modem Technology and its Certification. Prof. Luc Martens, CEO, tComLabs. Professor Martens spoke of the evolution of the Euro-DOCSIS specification, the certification process and the training provided in six two-day courses. The agreement for the Euro-DOCSIS annexe was co-ordinated by Ghent University in February 2000. tComLabs was founded in May of that year in Ghent to perform testing and certification, and the Certification Board was created at the same time. The first certifications were made in June 2000. tComLabs co-ordinates discussions on the specification, develops testing procedures and performs the certification tests. It then handles the feedback to the vendors and organises training sessions for engineers. The certification is, however, granted by the Certification Board. Professor Martens described the DOCSIS 1.0 and 1.1 specifications, and detailed the Euro-DOCSIS derivative in particular.


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