Technologies for all IP Cable Networks

Last month we read about the opportunities for Cable Operators to leverage the IP technology. In the second part of this article we provide different technologies that operators can choose to deliver the context in most efficient way.

This article is based on a white paper by  Farncombe 

sponsored by NAGRA.

Ideally, cable operators want to be able to offer just as much content choice at any time, on just as many devices, and to just as many locations, as their new OTT-based challengers  and to offer it securely. But how to deliver this?

Linear viewing over the managed QAM network continues to deliver value  but is increasingly shared with unmanaged devices

In practice, a logical way to achieve this is to target the devices falling into that category which has the highest penetration in the households passed by the cable network (although, given the potential for marketing multiscreen services off-net, consideration should also be given to the nature of devices further afield).

How OTT technologies can benefit cable

Leveraging new technologies and frameworks

When cable operators originally began offering high-speed Internet access alongside TV and telephony, it was not in the expectation that their subscribers would use that service opportunistically for video delivery.

However, as Figure 1 in our opening section demonstrates, that type of usage has rapidly emerged as a popular activity. Not unreasonably, cable operators are taking the view that if they are providing an infrastructure which others are taking advantage of, why should they not take advantage of it themselves?

Accordingly, many of them are already putting technological foundations in place which are  deliberately or otherwise  adapting their system for a transition to a full, multi-device, multiscreen, open Internet environment.

Cable operator takeaway: New Internet/mobile-based technologies and standards mean that it is becoming steadily easier for cable operators to extend their operations into the OTT space. Adaptive Bit Rate (ABR) and interoperable multiple DRM solutions are particularly useful.

For example, some are already creating new technical units within their organizations that include a content-preparation chain able to target iOS and Android clients.

In many cases, they are also using various flavours of ABR to support IP-based ondemand and catch-up services (either their own or other broadcasters')  providing access to such services through a clickable app or widget accessed through a browser (for instance, one using HTML-5).

Using this type of approach for new services can be described as 

Step 1 on the journey towards the creation of a full multiscreen environment. However, it is the next three steps that provide the biggest opportunity for cable operators:

Step 2 is to move existing QAM-based VOD services to IP-based ABR

Step 3 is to move niche linear QAM-based services (i.e. channels with less than one viewer per node on average) to this unicast model

Step 4 is to move all traditional QAM-based linear services to IP/ABR unicast Steps 2 and 3 constitute a challenging transition, clearly, since for most cable operators there exists an installed base of QAM legacy cable set-top boxes that may not support IP-based ABR and would therefore be disenfranchised by these moves.

Step 4 represents the biggest hurdle, however, as it requires the cable DOCSIS network to be scaled to support a significant sustained peak usage. But it is also the one that completes the migration to a full, all-IP video environment, since it results

in the creation of a single back-end system that delivers everything.

Comparison with Telecoms Operators

It may come as a surprise to some cable operators that we are not advocating the deployment of an IP Multicast approach for the switch to an all-IP multiscreen environment. Is this not, after all, what IPTV operators are choosing to do?

It has certainly been an assumption for some time by many of them that deployment of IP Multicast all the way to the end-user will enable them to be more competitive with their TV offers, since they believe it will allow them to deliver broadcast channels more cheaply.

Across the globe major telecoms operators in all geographies are using IP Multicast delivery for their TV services.

This model is at first sight tempting for cable operators, since the core of their HFC network is already using IP Multicast for distribution of broadcast channels to edge- QAM modulators.

However, it is an approach which is increasingly being questioned for Greenfield IPTV deployments, not least because the ability to deliver a managed multicast network requires expensive network upgrades in both the core and access network.

An example of this trend is represented by the Spanish telco Jazztel, which closed its multicast IPTV service in 2010. Jazztel re-launched both live and on-demand video services using IP-based ABR in December 2011, scrapping its previous IP Multicast

approach  in both the core and access parts of its network. Jazztel used a commercial CDN service speed up their launch, but have since migrated to their own CDN.

What is interesting about the case is that Jazztel is not looking to become an OTT service provider, and only offers video services on its own network. It is in fact easier to make the argument for such a strategy in an IPTV environment, because although the use of IP Multicast is more efficient in the core network, the benefits it brings to IPTV operator's access networks is questionable: these are star networks (unlike cable operators' tree-and-branch structure), so the access network capacity is not shared between homes.

Jazztel are not alone in this shift from multicast to ABR. A number of major national European telecoms operators, with successful multicast based IPTV offerings, are working on extending the reach of their services to parts of their network that are

not multicast enabled with ABR based services.

In this context, switching to an IP-based ABR approach does not seem such a radical move, and is in fact relatively straightforward from a capacity planning point of view, with the access network being provisioned by a conventional CDN (as in the Jazztel example) or some other type of managed network.

Paradoxically, then, IPTV operators may actually emerge in the vanguard of the switch towards a full all-IP ABRbased model.

Cable operators, as we have suggested, face greater practical challenges, and should initially pursue a hybrid model involving the use of DVB-C for broadcast channels alongside an IP/ABR approach.

Cable operator takeaway: The switch to IP-based ABR is easier for telcos. Cable operators will still need to deploy ABR alongside DVB-C as an interim step.

Impact of OTT technologies on QoE

In describing our multi-phased approach to an all-IP, multiscreen future, we have so far neglected the issue of what's in it for cable subscribers.

Is it not the case that an ABR approach will inevitably degrade subscribers' Quality of Experience (QoE) because it provides lower picture-quality? In fact, the opposite may be true, but it does depend on the viewer.

In a QAM-based VOD set-up, the operator makes a calculation about the number of QAM channels to be allocated to VOD, a decision which in turn determines how many simultaneous VOD sessions can be supported. As long as the system is operating within that figure, the quality received by the viewer will be high.

But the operator knows that, on occasion there will be peaks where the maximum number of concurrent VOD streams will be exceeded. In that case the viewer requesting an on-demand asset will receive a message to the effect that the VOD service, or the movie requested, is temporarily unavailable.

In a service using ABR, such a catastrophic loss of service is unlikely to happen: a sudden surge of on-demand requests will squeeze bandwidth, causing the viewer's video quality to suffer when the client drops to the lower-bit-rate stream, but this will not prevent any customers gaining access to the service  and indeed, the drop in video quality may only be transient (if noticeable at all) in many scenarios.

In both cases, the viewer receives a high QoE when the service is operating under capacity  but the QoE when the service is at or over-capacity is moot.

To take the QAM-based VOD example, some users might well prefer, when ordering an HD movie, to be guaranteed that their VOD experience was going to be high (if permitted), but prefer not to view the movie at all if it were to be delivered at a lower resolution.

For others, not getting the movie at all is perceived by them as imposing a lower QoE than, for instance, being able to access an SD version rather than an HD one.

While it might seem preferable for all customers connected to the service to receive a momentarily lower quality of service than for some customers not to be able to watch what they wanted to at all, the flip side is that if a customer should complain about the quality  noting, of course, that it is likely only to be momentary  then in an extremely poor QoE situation, operators may need to consider refunding the cost of the VOD session.

For catch-up content, which is becoming the most popular form of VOD, convenience is likely to be even more important to consumers than guaranteed video quality.

In each situation, users' perceived QoE therefore depends, at least in part, on whether they have been made aware of these alternatives in advance, and have 'opted in' to them  rather than on what the rival technology solutions impose.

Thus it is not true to say that ABR can necessarily be associated with lower QoE  it depends to a large extent on how the cable operator is managing customer expectations.

If network capacity is not so well planned in an IP network, and the operator becomes aware of a shortfall in QoE, this can be addressed by re-planning the network, for example, by moving a node so that it serves fewer households.

Finally, there is a QoE benefit to be derived from the fact that cable operators run managed networks. On the open Internet, the bit-rates of the ABR streams may be set quite low to cope with random congestion peaks  whereas by leveraging its managed network, the cable operator may be able to competitively differentiate its OTT offer by offering higher bit-rate streams.

Cable operator takeaway: Operators can use their managed networks to offer a premium quality assured ABR service  something which over the open public Internet is difficult or impossible

OTT as an off-net solution

A cable operator's business is traditionally limited by the number of households its network 'passes', or the proportion of those homes that can be economically marketed.

Since cable TV is a mature industry in the West, penetration of its coverage areas in these countries is generally already saturated or close to it. The only way the operator is able to increase revenues is by increasing ARPU, which is challenging. However, if operators were able to offer all or a subset of their current offerings outside their service areas, this would clearly provide further growth potential.

The beauty of migrating their networks to multiscreen  understood as the OTT-centric model we have described  is that it offers precisely this opportunity:

once an operator is equipped to offer its services OTT using ABR, it can in principle offer them anywhere it wants outside its cable service area  that is, off-net.

At a local level, it is possible for cable operators to deliver a reasonable QoE for OTT services delivered to un-managed iOS and Android devices off-net if using ABR, since the delivery range maybe small enough to minimize latency and throughput issues.

However, the use of CDNs will be advantageous to help guarantee the best QoE for its services over a greater geographical area.

There are a number of advantages to this scenario:

1) Existing subscribers can continue to receive operator services when on-themove, using a handheld or portable device

2) Potential customers previously out of reach outside the coverage area can be converted to paying ones with the promise of access to a superior content offering on their tablets, smartphones and TVs through OTT set-top boxes.

It should not be forgotten that the very fact of offering a managed OTT service which may offer superior QoE to that available through other rival platforms is in itself an incentive for non-cable customers within the operator's coverage area to sign up.

Summary

There are two risks facing cable operators: the first is that if they do nothing, OTT video distribution may disintermediate them.

The second is - if they decide to act  they could waste money on the wrong strategic and technical migration-path. On the other hand, the opportunities are considerable: if properly executed, an OTT-friendly model can open up new revenue streams through the launch of new services, and potentially attract a new customer base through the provision of an off-net presence.

An OTT-friendly model can open up new revenue streams through the launch of new services, and potentially attract a new customer base through the provision of an offnet presence.

 

In these circumstances, given that multiscreen (if not multi-platform) video delivery is rapidly becoming a 'must-have' feature, one must surely assume that it is in the interests of all cable companies to become 'OTT-friendly'  or at least to head off in that direction.

While the ultimate goal of cable operators should be all-IP delivery, this will be difficult to achieve and take a long time to accomplish given the network upgrades and set-top box replacement required.

There are many steps that cable operators can take towards this but we foresee a long period where some higher viewership broadcast service continue to be delivered to the home via DVB-C alongside a broad range of linear and on-demand IP services.

Gateway devices could play an important part in this transition, enabling IPonly devices within the home to access services that remain as DVB-C broadcasts.

The four-step model we have outlined in this paper will, of course, need to be modified depending on the individual cable operator's situation.

For instance, the proportion of the installed base of STBs that is capable of downloading an OTT stack will vary  as will the capacity of the network and how much of it is already allocated to on-demand services.

Other variables include take-up of second-screen devices (laptops, smartphones and tablets) among the subscriber base, and the nature of the cable offer in the territory concerned ('utility' model versus US-style 'big basic', etc.)

Source: http://cablequest.org/articles/cable-tv/item/2568-technologies-for-all-ip-cable-networks.html
Source: http://cablequest.org/articles/cable-tv/item/2568-technologies-for-all-ip-cable-networks.html