Infrastructure & Spectrum Compatibility

Infrastructure and spectrum compatibility or, more likely, incompatibility, happens in the case of having:

1. A simulcast period, having both a digital and analogue service in the same geographical areas (as mention in section 2.14.3 it is possible to have no simulcast period and to switch-over from one hour to the other), and;

2. The analogue and digital plan are not compatible (see GE06), i.e. there is a lack of digital spectrum in a certain area, not necessarily the entire country. In some countries there might only be analogue terrestrial television service in Band I/III and non in Band IV/V²¹⁵.

215 Please note that in some countries non-broadcasting services might be operational in Band IV/V.

This situation of infrastructure and spectrum incompatibility is likely to occur in the ASO process and should be addressed in the network planning prior to actual execution of the ASO process.

This section is organized in the following parts:

1. Scoping incompatibility: where can incompatibility occur;

2. Implementation guidelines for resolving incompatibility issues.

2.17.1 Scoping incompatibility

Incompatibility can happen in both the transmitter infrastructure as well as in the available spectrum.

The main incompatibility issues have been listed below:

1. Infrastructure or network facilities, including:

a. Lack of antenna capacity, either:

i. In the case of antenna sharing (two or more service or frequencies on one antenna²¹⁶): the antenna has reached its maximum electrical load (especially occurring at the antenna connectors);

ii. In the case of a new antenna: the new antenna exceeds the maximum wind load capacity or there is a lack of physical space to place the new antenna²¹⁷;

b. Lack of floor space for placing extra transmitters: the additional floor space is technically limited by the maximum length of the feeder cables to the antennas.

Longer cables may allow for the placing of the transmitters in containers outside the the mast premises (depending also on local building regulations);

c. Lack of power/back-up/no-break facilities: the existing power supply facilities might have reached its maximum load. In addition, in rural areas, installing extra power units might be limited by fuel supply logistics;

d. Lack of cooling capacity: see above.

2. Spectrum, i.e. in (a limited) geographical area the digital and analogue frequencies cannot coexist. In such a case the network planner has to trade off two key aspects in its network design:

a. Continuation of the existing analogue services so as to avoid complaints due to degrading service and that, consequently, viewers will migrate to other available (competing) platforms;

b. The largest/best possible coverage for the digital service, ideally as close as possible to the analogue coverage (however 100% is not possible otherwise there would not be an incompatibility problem). Without a good digital signal people cannot switch to the new DTTB service.

2.17.2 Implementation guidelines

For resolving the problems of infrastructure and spectrum incompatibility the following guidance can be provided:

216 Even frequencies/services with different antenna diagrams can technically be facilitated on one single antenna system, a so called ‘multi-pattern’ antenna, however those antennas are relatively complex and expensive and sharing prices will be more complicated (as it has to be combined with mast sharing and there is little experience in the world about antenna sharing).

217 In some cases the physical mast space might be technically available but the location has been reserved for future services. However, the Regulator should provide a site sharing regulatory framework and monitor any strategic blocking that may occur.

1. For infrastructure incompatibility:

a. If there is a lack of antenna space: reduce the number of antenna layers and at the same time increase the transmitter power so as to compensate for the reduced antenna gain²¹⁸. This option is becoming more and more (economically) feasible as transmitter prices continue to drop and the price differences between various power ranges are diminishing too. Conversely, a lack of floor space can be compensated by increasing antenna gain;

b. If there is a lack of transmitter space: place transmitters in prefabricated containers adjacent to the existing premises of the transmitter tower. However, this may be limited by the maximum length of the feeder cable. Prefabricated container production has got the added benefit and convenience of enabling construction off-site (e.g. at the manufacturers premises) and therefore increasing production output;

c. If there is a lack of both floor space and antenna space: reduce both the transmitter power and the antenna gain and consequently lower the ERP. In order to compensate for this reduced ERP, the planner can either:

i. Increase the robustness of the signal. At the cost of having less services but having the same reception mode/system variant (in-door or roof-top reception) and associated coverage, or;

ii. Change the reception mode/system variant. At the cost of requiring a more sensitive receiver installation, possibly only achievable with a roof-top antenna, but having the same coverage and number of services;

iii. Reduce coverage. At the cost of having less viewers, but having the same number of channels and reception mode.

d. Lack of antenna space and capacity: split analogue antenna in two for respectively the analogue and digital services at the cost of accepting a reduced analogue service and having a larger digital transmitter²¹⁹. In this way the analogue service can be gradually degraded (by further reducing power), providing an incentive to viewers to switch to digital. In the ultimate case, a temporary site should be considered. The cost of having a temporary site can be minimized by reusing these temporary sites by moving them from region to region after each regional switch-off, which will need careful planning.

2. For spectrum incompatibility:

a. Make a service trade off between the number of affected analogue viewers and new digital viewers. This rationale could help the network planner in balancing service levels of both television services. This may be a complicated and delicate exercise when both services are not operated by the same service provider/operator. In some cases, this might be even a cross-border exercise when analogue services abroad are affected;

b. Assess the incompatibility problems first in the group of gap-fillers or small relay transmitters because:

i. The problems will be the largest in this group of transmitters (because there are so many of them), and;

218 The gain of the antenna is directly related to number of layers of the antenna, hence the physical length of the antenna and perhaps more importantly the wind load.

219 Assuming the analogue antenna is made redundant by having a ‘switch-able’ top- and bottom-half.

ii. In this group of transmitters, the largest degree of ‘engineering’/planning freedom as they are small and very often in shielded areas. Also these frequencies can be moved around the country to free-up spectrum elsewhere;

c. Assess site by site the possibilities for balancing the service levels of the digital and analogue service. The network planner can:

i. Improve the digital service by lowering the ERP of the analogue transmitter, increasing the robustness of the digital signal or reducing coverage of digital services;

ii. Allow more digital interference on analogue services. Check the level of interference which can be tolerated by the viewers. Planners should consider reducing analogue service levels, in order to provide an incentive for viewers to switch to digital.