There is interest in the industry in delivering 3DTV services to mobile phones. It is perceived that simple lenticular screens can work well in this context and that the bandwidth (even though always at a premium in mobile applications) would not be too onerous overall; even assuming a model with two independent streams being delivered, it would double the bandwidth to 2 × 384 kbps or 2 × 512 kbps and the use of spatial compression (which should not be such a “big” compromise here) would be handled at the traditional data rate, 384 kbps or 512 kbps.
DVB-H, as noted in Table 4.2, is a DVB specification that deals with approaches and technologies to deliver commercial-grade medium-quality real-time linear and on-demand video content to handheld, battery-powered devices such as mobile telephones and PDAs (Personal Digital Assistants). IP Multicast is typically employed to support DVB-H.
DVB-H2 addresses the requirements for reliable, high-speed, high–data rate reception for a number of mobile applications including real-time video to handheld devices. DVB-H systems typically make use of IP Multicast. DVB-H is generating significant interest in the broadcast and telecommunications worlds, and DVB-H services are expected to start at this time. The DVB-H standards have been standardized through ETSI.
ETSI EN 302 304 “Digital Video Broadcasting (DVB); Transmission System for Handheld Terminals (DVB-H)” is an extension of the DVB-T standard. Additional features have been added to support handheld and mobile reception. Lower
power consumption for mobile terminals and secured reception in the mobility environments are key features of the standard. It is meant for IP-based wireless services. DVB-H can share the DVB-T MUX with MPEG-2/MPEG-4 services,
so it can be part of the IPTV infrastructure described in the previous chapter, except that lower bitrates are used for transmission (typically in the 384-kbps range). DVB-H was published as ETSI Standard in 2004 as an umbrella standard
defining how to combine the existing (now updated) ETSI standards to form the DVB-H system (Fig. 4.11).
DVB-H is based on DVB-T, a standard for digital transmission of terrestrial over-the-air TV signals. When DVB-T was first published in 1997, it was not designed to target mobile receivers. However, DVB-T mobile services have been launched in a number of countries. Indeed, with the advent of diversity antenna receivers, services that target fixed reception can now largely be received on the move as well. DVB-T is deployed in more than 50 countries. Yet, a new standard was sought, namely, DVB-H.
Despite the success of mobile DVB-T reception, the major concern with any handheld device is that of battery life. The current and projected power consumption of DVB-T front-ends is too high to support handheld receivers that are
expected to last from one to several days on a single charge. The other major requirements for DVB-H were an ability to receive 15 Mbps in an 8-MHz channel and in a wide area Single Frequency Network (SFN) at high speed. These requirements were drawn up after much debate and with an eye on emerging convergence devices providing video services and other broadcast data services to 2.5G and 3G handheld devices. Furthermore, all this should be possible while
maintaining maximum compatibility with existing DVB-T networks and systems. Figure 4.12 depicts a block-level view of a DVB-H network.
In order to meet these requirements, the newly developed DVB-H specification includes the capabilities discussed next.
- Time-Slicing: Rather than continuous data transmission as in DVB-T, DVBH employs a mechanism where bursts of data are received at a time—a so-called IP datacast carousel. This means that the receiver is inactive for much of the time, and can thus, by means of clever control signaling, be “switched off.” The result is a power saving of about 90% and more in some cases.
- “4-K Mode”: With the addition of a 4-K mode with 3409 active carriers, DVB-H benefits from the compromise between the high-speed small-area SFN capability of 2-K DVB-T and the lower speed but larger area SFN of 8-K DVB-T. In addition, with the aid of enhanced in-depth interleavers in the 2-K and 4-K modes, DVB-H has even better immunity to ignition interference.
- Multiprotocol Encapsulation–Forward Error Correction (MPE-FEC): The addition of an optional, multiplexer level, FEC scheme means that DVB-H transmissions can be even more robust. This is advantageous when considering
the hostile environments and poor (but fashionable) antenna designs typical of handheld receivers.
Like DVB-T, DVB-H can be used in 6-, 7-, and 8-MHz channel environments. However, a 5-MHz option is also specified for use in non-broadcast environments. A key initial requirement, and a significant feature of DVB-H, is that it can coexist
with DVB-T in the same multiplex. Thus, an operator can choose to have two DVB-T services and one DVB-H service in the same overall DVB-T multiplex.
Broadcasting is an efficient way of reaching many users with a single (configurable) service. DVB-H combines broadcasting with a set of measures to ensure that the target receivers can operate from a battery and on the move, and is thus an ideal companion to 3G telecommunications, offering symmetrical and asymmetrical bidirectional multimedia services.
DVB-H trials have been conducted in recent years in Germany, Finland, and the United States. Such trials help frequency planning and improve understanding of the complex issue of interoperability with telecommunications networks and
services. However, to date at least in the United States, there has been limited interest (and success) in the use of DVB-H to deliver video to hand-held devices. Providers have tended to use proprietary protocols.
Proponents have suggested the use of DVB-H for delivery of 3DTV to mobile devices. Some make the claim that wireless 3DTV may be introduced at an early point because of the tendency of wireless operators to feature new applications
earlier than traditional carriers. While this may be true in some parts of the world—perhaps mostly driven by the regulatory environment favoring wireless in some countries, by the inertia of the wireline operators, and by the relative
ease with which “towers are put up”—we remain of the opinion that the spectrum limitations and the limited QoE of a cellular 3D interaction do not make cellular 3D such a financially compelling business case for the wireless operators to
induce them to introduce the service “over night.”