French broadcast player TDF and Italian broadcaster RAI have come up with a really interesting experiment using LTE broadcast in a novel fashion, which may have significant real world applications. It is a hybrid approach broadcasting normally, but with less power than you would need to reach phones. A second broadcast is used from the cellular network using LTE broadcast, which can lead to lower total transmit power, especially given that to reach phones TV transmitter networks would need to broadcast at dramatically higher EIRP.
The two have launched field trials of LTE-A+ Broadcast from transmitter sites in Paris France and Aosta in the Italian Alps. The joint project is based on the Tower Overlay concept developed by German university TU Braunschweig and supported by German research institute IRT and broadcast solution providers Expway (France) and GatesAir, previously part of Harris in the US.
Tower Overlay uses a relatively small number of transmission towers in just one SFN (Single Frequency Network) overlaid on top of the cellular infrastructure, which can be shared by all the cellular operators in a particular territory. However it would exploit carrier aggregation features in LTE Advanced to enable provisioning of point to multipoint services. East Germany is hoping to adopt it, because it has no broadcast mast infrastructure, unlike West Germany.
The aim of the trial is to show that LTE-Advanced networks can broadcast TV channels which usually travel over digital terrestrial networks. AS normal broadcast signal is simultaneously transmitted by the LTE-A network in exactly the same spectrum as the TV broadcast, so TV services can simply be viewed by ALL LTE-A enabled phones, without a special antenna. We have seen SFN ideas like this in the past and one in 3 base stations would probably have to have these carrier aggregation services to make this work, rather than all of them and if that was shared over 4 competing cellcos, that could mean one in 12 base stations each, then everyone could have TV on their phones.
Italy has only DTT and DTH TV services, and no cable, and there have only been unsuccessful attempts at IPTV, so this may end up as a special case just for Italy, but may go further afield. There were two DVB-H systems built in Italy, one by RAI, which were eventually complete flops, and the cellular operators there hope to reach phones with TV services, without the need for any special hardware. There was a French consortium around DVB-H, of which TDF was a prominent member.
In the trials, two data streams share the same UHF channel separated in a time-division duplex: one stream is conveying conventional digital HDTV channels to be viewed on domestic DVB-T2 TV sets while a second embedded stream is conveying a specific broadcast flow for 4G LTE-A+ smartphones, laptops and tablets.
In the Paris trial, the Eiffel Tower transmitter site is used, operating on a UHF frequency (channel 54, temporarily authorized by CSA). The stream intended for mobile devices is aggregating a large range of digital media content (live TV, video-on-demand, catch-up TV, live radio, podcasts, magazines, newspapers, software updates). All content is received on the mobile device and stored until the consumer wants to view it at any chosen moment.
The Aosta trial consists of two adjacent transmitters located in the Aosta Valley in the northern part of Italy operating on the same frequency (single frequency network on UHF channel 53). It will be extended in the coming months by two additional transmitters. The transmitted data stream is shared by 4 HDTV channels using the DVB-T2 standard and 4 high-quality mobile video streams using LTE-A+. HEVC video coding is used in both streams.