How mobile tv works

Probably, many people remember a small mobile TV from the Soviet Union, which could be seen in cars and over which tourists were pinned wildly. Small portable TVs almost guaranteed a fuzzy image and interference even with slow motion, but they were a success. Since then, a lot has changed - and now there are three options for receiving television data on the phone:

Analog receiver

• Standard technology since the USSR. A limited set of phones with a retractable antenna and an analog TV tuner is available.
• Consuming battery life is quite significant.
• Strong noise and distortion, deteriorating during movement.

DVB-H

• Special network for TV broadcasting on mobile devices: in our country (by country), this would have to be built and operated. The choice of phone models with technology support is extremely limited.
• Battery life is consumed most economically.
• Reception is good when driving at speeds up to 150 kilometers per hour.
• Requires the allocation of natural frequencies for broadcasting.

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Streaming tv

• Uses standard operator network. Coverage matches network. Easy to implement, supported by many phones, available in operation in Russia.
• The battery life is very much consumed: constant reception and complex post-processing.
• Mobility is very limited: the faster the movement, the worse the speed (network feature).

Analog receivers

Since the time of the USSR, many things have been miniaturized, and telephones with built-in TV tuners have appeared. Stretching a small antenna you can get a picture with constant noise, fuzzy geometry and unimaginable colors. And even though Samsung even has a model with a built-in analog TV tuner, key mobile device manufacturers do not implement this feature in large quantities.

Mobile devices have their own standard for digital broadcasting - DVB-T. If you need a clear image in motion, you need not only to work with another signal, but also to have special software handlers on board the device.

DVB-H - a digital broadcasting standard for mobile devices

Under the mobile was created several special standards for digital broadcasting. This diversity is due to the fact that by the time work began on mobile TV in various regions of the world, certain frequencies were already occupied, and most of the standards were developed as independent systems that required building their own network and were tied to specific frequency spectra. In Russia, as in Europe, DVB-H (digital video broadcasting - Handheld) format is chosen, in the USA and North America MediaFLO, in South America and Japan 1seg (ISDB) is used, and China and Korea with numerous neighbors made a choice in favor T-DMB.



As a result, many phones with support for digital mobile TV understand only national standards. All this is reflected both in the cost of the chips and in the desire of the phone manufacturers to promote the new technology everywhere.
Formats have a lot in common - they are adapted for mobile devices. DVB-H is a logical continuation of DVB-T (Digital Video Broadcasting - Terrestrial) standard with support for additional features, adapted for self-powered portable mobile devices.

DVB-H uses time slicing time slicing technology, through which IP datagrams are transmitted in small sets of packets in time slots. Each of such sets can reach up to 2 Mbit of data, including the correction code, in which for every 191 bits of the payload there are 64 bits of the correction code protected by the Reed-Solomon code. The receiving mobile device is switched on only during those time intervals in which the data sets corresponding to the channel selected by the user are transmitted. During this short interval, data transmitted at high speed can be placed in the buffer of the receiving device, which can contain both downloaded data and streaming video being played. This can significantly reduce power consumption and prolongs the duration of the mobile operation of the device. Depending on the operating conditions, this battery saving can be up to 90%.

Since December 2009, Moscow residents were able to receive the DVB-H signal from two broadcasters at once. Then these projects did not become commercial and did not extend beyond the capital. Perhaps this is due to the fact that the Russian telecom giants saw another opportunity to bring a television picture to the subscriber’s phone.

Streaming video over 3G

Unlike the diversity of mobile digital broadcasting standards, mobile operators around the world agreed that it is possible to organize mobile TV based on existing deployed 2G / 3G networks, because in this case, there is no need to use special equipment; most phones support streaming audio and video over packet networks.

Streaming TV, using video streaming technologies, launched the majority of telecom operators in Russia and hundreds of operators around the world. The service is in demand mainly only in large cities. “The demand for television services via a mobile phone in Russia is still hampered by the need to buy expensive mobile equipment supporting this service,” PWC analysts say. However, individual solutions allow us to provide the service on devices costing less than 3,000 rubles, as well as on the Nokia 40s and 60s series phones that have become “classic”. Geographically, the largest number of Streaming TV users is concentrated in the Central Federal District, Volga Federal District and North-West Federal District. According to expert estimates, by the beginning of 2012, the number of service users in Russia reached approximately 2 million people.

The main protocol used for Streaming TV is RTSP. It is supported by the embedded media players of most phones, incl. smartphones with Symbian and Android. RTSP is an application protocol designed for use in systems that work with multimedia data and allows the client to remotely control the flow of data from the server, providing the ability to execute commands, such as Start, Stop, and access time on network storage. The average bit rate in the 3G network is about 170kbps, which allows you to watch programs in high quality. And in the EDGE network, the bitrate reaches an average of 80kbps, which allows watching news channels with satisfactory quality (for example, without a sharp change of pictures). Many Streaming TV platforms adapt the bit rate for the data transfer rate available at the time the service is accessed.

For users of iOS devices, HLS (HTTP Live Streaming) is used, and more recently Smooth Streaming Technology is supported for devices with the latest Microsoft operating systems. Smooth Streaming uses a simple but powerful concept of delivering small pieces of content (usually within two seconds) and checking that each one has the proper time and is played at the expected level of quality. If a fragment does not meet these requirements, the next fragment will be delivered at a lower quality level. Conversely, when conditions permit, the quality of subsequent fragments will be at a higher level. This encoding mode allows you to broadcast several video bitrates at once, which allows the client to get an optimized video stream in real time up to HD-1080p quality based on its connection speed, processor power and screen resolution.

DVB-H vs. Streaming TV

The main problem of the DVB-H technology is that the deployment of broadcasting throughout Russia would require huge investments. And for Streaming TV, the coverage boundary coincides with the zone of 3G / 2G networks. Of course, watching videos in EDGE is not always comfortable on the big screen, but on a small one, it is quite possible.

Another enemy of DVB-H is the fact that you have to choose among 3 phones. Enough expensive, but not prestigious. Of course, in the case of ubiquitous DVB-H devices would be more, but now manufacturers have no incentive to incur costs for unsupported massively phone functions.

Mobility DVB-H, which showed a steady reception at speeds up to 150 km / h in Moscow. With the mobility of Streaming TV services based on 3G networks, things are different. In practice, the transmission / reception rate depends on many factors and often turns out to be very far from theoretical limits. Two main factors are the quality of the area covered by the 3G signal and the speed of the subscriber. Theoretically, in 3G, in places separately allocated by the operator, speeds of up to 2 Mbit / s should be available. Moreover, 2 Mbit / s are intended only for slow-moving users, the speed of which is less than 3 km / h. The speed of the subscriber always reduces the speed of information transfer, often several times.

This is due to limitations in the very principle of operation of the access system in 3G. For mobile objects, transmission speeds are provided in UMTS networks - up to 144 kbit / s (12-120 km / h) and up to 384 kbit / s (3-12 km / h), but in practice it turns out only about 20 kbit / s. Trains, subways, public transport, car - while a luxury for Streaming TV, although for 2-3 minutes viewing downloaded data may be enough.

DVB-H is a truly mobile technology that provides the best quality service. But only if subscribers are ready to buy a special phone for her, and telecommunication operators to invest millions of dollars in infrastructure. And those and others were not ready for such decisive steps. As a result, the share of broadcast mobile TV around the world is declining, and streaming - is increasing (according to forecasts, from 40% in 2011 to 53% in 2013).

Perspectives

In the segment, analysts regularly predict an annual steady increase in the subscriber base, which by 2016 should reach almost 6 million people - or 4% of cellular subscribers. Such forecasts are based primarily on the demand for mobile broadcast of sports events and the experience of the development of the market in Western Europe.

Now Russian subscribers watch “mobile TV” on average three to five times a month for a few minutes, however, on the days of significant sports competitions and national holidays, there are significant surges in consumption. Practice shows that the TV on the phone is viewed either on the road or at home, for example in bed, when the big screen is not available, or if the person really does not want to miss a specific program, but does not have access to the TV. Therefore, you can forgive the service on the basis of 3G its voracity with respect to the battery charge. The possibilities of “Television for Mobile” as a classic advertising platform will also remain insignificant, since use of the service has been and will remain short-term. As a result, the likelihood that the subscriber will see the commercial is already low, and if you consider that it is very easy for the subscriber to switch to another channel, then it tends to zero.

It is still a bit early to talk about this, but it is assumed that in the future it will be possible to partially abandon the broadcasting network characteristic of analogue times. It will be important for urgent news and sports events, and the rest of the content will be provided to the user of choice.