Sunday 5 February 2012

Contents of module

Broadband and Convergence

The delivery of broadband services, such as digital terrestrial and satellite television, cable television and cable modem services, interactive television over telephone lines, fast Internet services over digital subscriber lines, or over fixed wireless broadband to the building, or through packet-switched mobile networks to different handheld devices, poses new challenges for regulators and spectrum management besides the obvious one of allocating frequency to different services.

Indeed, the problem of allocating new frequencies to new services and issuing new licences is nothing new at all, just an extension of the regulator's traditional tasks. What is new is the degree of attention that now must be placed upon customer access networks for the delivery of broadband services.

Customer access networks are often bottlenecks in the delivery chain, either because of a lack of capacity or because of interference problems when many users, for example in a residential building, wish to access different delivery channels.

The policy of the Hong Kong Government is that consumers should enjoy the widest possible choice at reasonable prices, and it is the regulator’s job to ensure that comes about. Difficulties arise because the technologies used to deliver broadband content are still evolving, and standards have yet to be established between manufacturers, network operators and service providers, for example set-top box standards and cable modems.

For an OFTA discussion of the latter, see TSAC paper 14/2000 Technical Standards of Cable Modems for connection to In-building Coaxial Cable Distribution Systems Additionally, the problems of interference that may arise in the local access network or in the traditional in-building wiring systems from high speed transmissions of data remain unknown.

Diagram 1 illustrates access by the ITU standard G 992.2, otherwise known as G-Lite or Discrete MultiTone (DMT). A splitter in the exchange seperates PSTN traffic from broadband traffic which is routed to the ATM through fibre and then onwards towards the Internet and a Web-based environment. The characteristic of G-Lite is the delivery of up to 1.5 Mbps over a twisted copper wire pair at the customer access end. The question is how much interference from cross-talk may arise between neighbouring pairs serving different customers? If this proves a problem, it becomes initially an issue of spectrum management for the network operator and customer access provider, but what implications may this have for regulatory issues such as interconnection and unbundling of the local loop? Incumbents often resist interconnect, and offer virtual co-location rather than physical co-location, and physical co-location rather than local loop unbundling, in that order of preference. If spectrum management proves to be a serious issue for broadband transmissions in the local loop, then regulators may find themselves having to take a cautious approach.

In-building Coaxial Cable Distribution Systems

In-building Coaxial Cable Distribution Systems (IBCCDSs) are the block wiring systems inside multi-storey buildings that provide connectivity for a variety of broadcast and multimedia networks. Cable television is one system which is distributed through a hybrid fibre coaxial network to the building basement and channels are then relayed through the IBCCDS to individual subscribers.

There are a number of free satellite television signals that are relayed by Satellite Master Antenna Television (SMATV) systems using receiver dishes on rooftops and signals are fed down through IBCCDS. Two free-to-air broadcasters use Communal Aerial Broadcast Distribution (CABD) systems that make use of the IBCCDS, as do Closed Circuit Television (CCTV) systems.

The four terrestrial television channels in Hong Kong are transmitted in the frequency band 470 – 790 MHz and they are commonly distributed through the CABD system at the same frequency, although there are variations around the territory. For this reason these has been no territory-wide frequency plan for the distribution of terrestrial television programmes in the CABD.

Similarly, because CCTV systems, which use one of the channels in the same band and are mainly used to provide building security, are exempt from licensing there is no central record of them. SMATV systems do require licences, but use different television formats, PAL or NTSC, and occupy bandwidths of either 6 MHz or 8 MHz.

Satellite television services which carry only a few programmes use non-adjacent channels in the IBCCDS, whereas systems that carry many programmes use filters so that adjacent channels can be used.

The cable television network has a capacity to offer 31 channels, transmits in VHF and uses adjacent channels with filters at the headend. It also offers 20 channels over MMDS, but the MMDS frequency is to be returned by May 2001.

Only HKT’s interactive television and Video-on-Demand service is offered over twisted pairs to the customer, but Hutchison Telecom/Global Crossing also offer broadband services to some business and residential districts, while New T&T will be offering telecommunications services over Hong Kong Cable Television Limited’s cable network. Hong Kong has also licenced four BSS services, each capable of transmitting up to 40 channels, and more BSS frequency could become available.

Diagram 2 illustrates the issue of inbuilding or block wiring. The ultimate bottleneck here is the last horizontal cable drop into the residential premises.

The challenge is to squeeze more channels into the IBCCDS for the delivery of a growing number of broadband services. In March 1999 OFTA issued a Consultation Paper ‘Frequency Layout Plan of In-Building Coaxial Cable Distribution Systems’ which discusses these issues in detail. In June 1999 OFTA published the results of the public consultation and in July 1999, OFTA published a summary of the industry’s views and OFTA’s initial response which lays the groundwork for the next step. Among the issues that arose were the following:

  1. If consumers in a building decide they want to buy new services then the providers of these new services shall be required to use digital compression in a ratio of at least 6:1 and use 8 MHz channelling even when 6 MHz NTSC signals are being distributed. This will gradually increase the level of harmonics across Hong Kong.
  2. The cost of upgrading the IBCCDS will be left to commercial arrangement, and will not apply where new services are not being supplied. A central database of all new systems will be maintained and will be published.
  3. A timetable for the digitalization of all IBCCDS will be reviewed when terrestrial digital broadcasting begins, probably in 2002 2003.
  4. The allocation of frequency for IBCCDS, spanning VHF and UHF (54 – 470 750 MHz) is to be increased up to 862 MHz, and adjacent channels will be used to increase capacity when required. Some adjacent channels will be reserved for telecommunications.
  5. Set-top boxes are the means of conditional access consumers have to many of these new services. (See below). OFTA recognizes the difficulty the industry has in the absence of accepted standards, but also has an obligation to protect the consumer’s right to access the services of their choice.

    Most set-top boxes have two functions, an access function and security functions, such as locking, and their combination can obstruct customer access to other service providers. OFTA will review the possibility of separating these functions, and requiring disclosure of interface specifications and related issues after digital terrestrial transmission of television has begun.

Set-Top Boxes

OFTA will require the following:

  1. Set-top boxes should not distort, restrict or prevent competition in broadcasting or telecommunications services.
  2. Set-top boxes should be equipped with by-pass outputs so that signals within the frequency range 50-862 MHz can by-pass the set-top boxes with minimum attentuation.
  3. Set-top boxes should be capable of operating on adjacent channels so that they will be compatible with the new channel plan. (See Annex 12C and 12D)
  4. Set-top boxes should be tunable in the range of 54-862 MHz
  5. Set-top boxes should be equipped with audio/video (A/V) outputs to simplify the connection with the television set and other A/V equipment.
  6. None of these requirements apply to set-top boxes used by existing licensees or for digital terrestrial transmissions, which will be determined later.

It is clear that broadband and conditional access issues are difficult to resolve in the short term because many older buildings are not well equipped and have ancient wiring, while standards issues continue to hold back developments in modern buildings.

The demands upon frequency assignments are likely to grow rather than diminish, so every advantage needs to be taken of technologies such as digital compression techniques, but these in turn may cause as yet unknown issues of interference unless handled with foresight and planning. For that reason, a reliable and up-to-date database covering IBCCDS systems is essential.

Third Generation (3G) Public Mobile Radio Services

A major development in mobile communications is taking place, the shift from circuit to packet switched networks. This has been called second-and-a-half generation mobile phone or 2.5G, but so far as the issuing of new frequencies are concerned it is the development of UMTS or 3G that is important.

There are many complex policy issues surrounding the issuing of 3G licences, for example whether they should be auctioned, and if so what method of auctioning is preferable. This debate has been vigorous in Hong Kong, and focuses on OFTA’s two Consultation Papers, issued in March and October 2000.

OFTA has allocated frequencies at 1920 – 1980 MHz and 2110 – 2170 MHz per second FDD and 20 MHz for unpaired TDD, and WRC2000 recommended additional frequencies become available. Managing spectrum allocations and assignments for 3G and future generations of broadband mobile services will clearly be a major role for regulators in the coming years.