If you believe everything you read in the press then digital terrestrial television transmission is a dying technology. The march of IP-based distribution is unstoppable and within a relatively short period of time TV and radio transmitters will be a thing of the past. But just hang on – let’s look behind the headlines at some of the facts about terrestrial transmission networks.
Without doubt, there are new distribution technologies being developed and many of these are IP-based. But still, the majority of people worldwide receive their television signals via terrestrial broadcasts. Within the metropolitan centres there exists very good cable and IP networks, but outside of the cities and major towns not – and indeed there are still some entire countries that are totally dependent on terrestrial broadcasts.
In these countries and regions terrestrial broadcasts are an essential means of providing the population with their TV and radio broadcasts. The simple fact is that there is no alternative communications network for TV distribution and this situation will not change within the next five to ten-year period.
Also, the most efficient means of communicating the same content to very large audiences is via broadcasts. As a distribution technology cable is increasingly being replaced by IP, so it is just terrestrial and satellite that offers a way of broadcasting a channel to these very large audiences. However, satellite technology does not offer any options for portable/mobile TV, which is a big market driver. Satellite is a static reception platform requiring a fixed satellite dish, even at high bandwidth.
Mobile TV – is this the future?
At Rohde & Schwarz, we can see strong similarities between mobile terrestrial television networks and mobile telecommunication networks in the way that they support data communication.
For many years now there have been trials, such as DVB-H, which combine television broadcasts with mobile devices. Several technology companies, such as Qualcomm, have gone so far as to build infrastructures with network operations centres, chipsets to install in receiving devices and even content to distribute over their networks. But within the 3G era the experiment did not work – largely because the chipset was only available in relatively few smartphone models.
However, there is good reason for optimism in this area. Multicast-broadcast single-frequency network (MBSFN) is a communication channel defined in the fourth-generation cellular networking standard called Long Term Evolution (LTE). The transmission mode is intended as an improvement of the broadcast capabilities of the enhanced Multimedia Broadcast Multicast Service (eMBMS) service – now called FeMBMS , which can deliver services such as mobile TV using the LTE technology.
In particular, LTE’s Release 14 (summer 2017) includes three major improvements that have been made to FeMBMS. These are that it facilitates pure LTE Broadcast (downlink only) cells. Also, it offers Cycle Prefixes of up to 200µs, which enables the operation of large- scale FeMBMS cells, similar to terrestrial networks. And thirdly, it provides SIM-card less communication/devices.
LTE Broadcast offers simple access to standard smartphones with Mobile TV content – no need for consumers to purchase specific mobile devices, which are expensive since relatively few units are sold and therefore no economies of scale exist.
The FeMBMS service is based on the principles of Interactive Multicast, where TV content only is transmitted where there currently are viewers. The FeMBMS service provides better system spectral efficiency than video-on-demand over traditional cellular unicasting services, since in FeMBMS, each TV program is only transmitted once in each cell, even if there are several viewers of that program in the same cell. FeMBMS cells are much larger than LTE unicast cells – otherwise the probability of there being multiple viewers of the same content in the same small cell is low.
MBMS and mobile TV was a failure in 3G systems, and was offered by very few mobile operators, partly because of its limited peak bit rates and capacity, not allowing standard TV video quality. This is something that LTE with eMBMS does not suffer from and especially with FeMBMS expanded to network concepts of terrestrial broadcast networks.
Collaboration required between broadcasters and mobile network operators
This technological advance provides significant opportunities for many parties. For traditional broadcasters it provides a massive new market of potential viewers. And for the mobile network operators it offers the potential to provide high quality TV channels to a high number of subscribers without exceeding their installed LTE network capacity and with that blocking other data services.
At Rohde & Schwarz, we have a vision of the future that is based around this development. Major new viewing audiences and all the associated commercial advertising opportunities are created in ways that can be shared by both the TV broadcaster and the mobile network operator. It can provide completely new ways that people can view major sporting and cultural events where, when and how they wish.
The high power, high tower digital transmission network is an efficient resource to provide data coverage in a particular area. By combining cellular networks with larger transmission networks it is possible to create network division multiplexes – using whichever network is most appropriate to a given application at a given time. This combination of traditional terrestrial broadcast and cellular technologies offers a very powerful commercial proposition.
The challenge in realising this vision is to breakdown the barriers between the terrestrial broadcast and cellular networks which have co-existed without being integrated in any way until now. This needs broadcasters and mobile network operators to work together to achieve this. Also, I believe that a technology company such as Rohde & Schwarz has an important role to play.
Already, Rohde & Schwarz is working with most of the mobile network operators. Alongside our transmitter business, we are known as a pioneer in test & measurement: our T&M technology is used by most of the mobile network operators to support their infrastructure, monitor network throughput and assure quality of service and also quality of consumer experience throughout the distribution chain.
Rohde & Schwarz is in an ideal position to bring these various companies together. We are happy to work in this supporting role, and indeed we are already talking to several organizations in this way. So, my suggestion to those that say that terrestrial transmission is yesterday’s technology is to look again.
At Rohde & Schwarz, we have a large a vibrant customer base of transmission customers. Our commitment to them is that we will be there to support them through the interesting journey that the next 10 years presents. For sure, IP-based distribution is on the rise, but those that think that terrestrial transmission offers no business model for the future need to think again. 2018 will see some fascinating new transmitter product introductions from Rohde & Schwarz and our long-term commitment is undiminished.