Cable Quest: Building Cost-Effective Digital Terrestrial Television (DTT)

Cable Quest: Building Cost-Effective Digital Terrestrial Television (DTT)

Newtec in the press Friday 23 March 2018

For every DTT deployment, the Total Cost of Ownership (TCO) of the primary distribution network (playout to towers) needs to be considered.

Newtec's broadcast market director Hans Massart brought more light into this topcis in the latest Cable Quest issue; and below. Enjoy the read!

Depending on whether there is a Universal Service Obligation (USO), where DTH often complements the DTT distribution, or whether the operation is mainly driven by pay TV (often solely DTT distribution), specific CapEx and OpEx savings are possible.

To optimize the TCO, bi-directional IP connectivity with all towers and other remote sites is important. The IP network centralizes network management, significantly reducing OpEx for the distribution and contribution parts of the operation.

Smart solutions converge the video distribution, contribution and IP networking components, bringing additional CapEx savings at remote sites.

Legal Constraints and their Impact

One of the main prerequisites for DTT deployments is the legal framework. Public broadcasters with a USO or pay TV networks have different KPIs. Any DTT bundle could also be a combination of both. These elements will determine the constellation and the OpEx and CapEx of the DTT towers’ distribution network.

Architecture of a Modern DTT Network

For many broadcasters, OpEx will be the top priority. When content is distributed over satellite to remote DTT towers, a solution ensuring efficient use of the satellite payload to minimize costs is essential.

For commercial operations, there is often a multitude of content available, filling a complete satellite transponder. At the same time, there may be no obligations to cover 100% of a geographical area or population (USO). Efficiency can be improved by making use of technologies such as DVB-S2 Multistream, DVB-S2X including DVB-S2X Channel Bonding and Equalink predistortion. The return on investment is quick, as the cost of upgrading the remote equipment is heavily outweighed by the OpEx savings on the satellite.

For deployments driven by state-owned broadcast companies, there may be a USO obligation. Often DTH distribution complements the DTT distribution to fill any gaps. To improve space segment efficiency, the DTT and DTH carriers are overlaid. The limited capabilities of standard DTH set-top boxes (STBs), e.g. 8PSK and a Roll-Off factor of 15% rather than 5%, may negatively impact efficiency. DTH STBs supporting DVB-S2X are available today and will significantly improve efficiency.

Full Network Monitoring and Control

An area where large OpEX savings can be made in DTT distribution networks is full network management and control.

A bi-directional IP pipe to each transmission tower makes this possible: as well as the transmission equipment itself, all devices, device parameters or functionality at the tower sites can be reached, including off-air probes, windspeed monitors, thermometers, oil level tanks of diesel generators, CCTV, etc.

The full-scale IP bi-directional network allows a single Network Operations Center (NOC) to correlate alarms or monitor trends. This means responses can be proactive instead of reactive, fixing problems before they occur or viewers start complaining. Significant OpEx savings come from not having to dispatch skilled personnel for each event. Travelling to remote towers in the mountains or in wintery conditions, or to islands by helicopter is a costly undertaking which can be avoided by full remote control. This IP pipe can be provided by a VSAT network such as Newtec Dialog®.

Newtec Dialog provides a unique feature which merges the VSAT Forward IP pipe into the video distribution stream. This again reduces space segment OpEx. At the same time, compatibility with the DTT/DTH overlay model is preserved. CapEx savings are also possible as the merged carrier can be received by a single VSAT modem which generates the video distribution carrier, such as the T2-MI for DVB-T2 distribution, and sets up the local IP network.

The IP pipe also enables other applications. Transmitted content can be stored locally at the tower and requested by the NOC when required. With Newtec Dialog, the satellite return technology can be switched from MF-TDMA, used under normal conditions, to Mx-DMA®, Newtec’s award-winning dynamic satellite return technology. Mx-DMA provides a temporary high throughput pipe, allowing even large files to be retrieved in a short time. The forward VSAT IP pipe can also be used to forward files for regional ad insertion from the central NOC to each tower.

Once a Newtec Dialog platform has been deployed, it can be used for other applications, such as video IP contribution. The cost-effective modems at the remote contribution site enable full monitoring and control beyond the contribution of the linear video itself.
The dynamicity of Mx-DMA, as opposed to using rigid SCPC slots, helps improve space segment efficiency.

Technology at Work

Newtec’s Mx-DMA improves the effective use of the space segment by providing the right amount of bandwidth to each contribution site on demand. For example, when file transfer on top of standard linear transmission is required.

DVB-S2 Multistream allows broadcasters to combine independent transport streams and/or IP streams into one satellite carrier. Multistream does not modify the original transport streams, which is key for SFN transmission. Enabling Multistream results in a single satellite carrier, which may fill up a complete transponder. Further efficiency improvements can also be deployed, such as the Equalink® 3 pre-distortion technology. Improvements of more than 10% are common.

Newtec has also developed unique features to support Multistream deployments. Unlike typical rate limiting, Newtec’s MCX7000 Multi-Carrier Satellite Gateway comes with a tight rate control per stream via a control loop. This not only safeguards other streams in a Multistream environment where one stream would suddenly rise to a very high bitrate, destroying the entire transmission, but also removes jitter and monitors any under- or overflow on a stream basis.

(click to enlarge)