Limitations[edit]

IPTV is sensitive to packet loss and delays if the streamed data is unreliable. IPTV has strict minimum speed requirements in order to facilitate the right number of frames per second to deliver moving pictures. This means that the limited connection speed and bandwidth available for a large IPTV customer base can reduce the service quality delivered.

Although a few countries have very high-speed broadband-enabled populations, such as South Korea with 6 million homes benefiting from a minimum connection speed of 100 Mbit/s, in other countries (such as the UK) legacy networks struggle to provide 3–5 Mbit/s^{[59][needs update]} and so simultaneous provision to the home of TV channels, VOIP and Internet access may not be viable. The last-mile delivery for IPTV usually has a bandwidth restriction that only allows a small number of simultaneous TV channel streams – typically from one to three – to be delivered.^[60]

Streaming IPTV across wireless links within the home has proved troublesome; not due to bandwidth limitations as many^[who?] assume, but due to issues with multipath and reflections of the RF signal carrying the IP data packets. An IPTV stream is sensitive to packets arriving at the right time and in the right order. Improvements in wireless technology are now^[when?] starting to provide equipment to solve the problem.^[61]

Due to the limitations of wireless, most IPTV service providers today use wired home networking technologies instead of wireless technologies like IEEE 802.11. Service providers such as AT&T (which makes extensive use of wireline home networking as part of its AT&T U-verse IPTV service) have expressed support for the work done in this direction by ITU-T, which has adopted Recommendation G.hn (also known as G.9960), which is a next-generation home networking standard that specifies a common PHY/MAC that can operate over any home wiring (power lines, phone lines or coaxial cables).^[62][63]

Latency[edit]

The latency inherent in the use of satellite Internet is often held up as reason why satellites cannot be successfully used for IPTV. In practice, however, latency is not an important factor for IPTV, since it is a service that does not require real-time transmission, as is the case with telephony or videoconferencing services.

It is the latency of response to requests to change channel, display an EPG, etc. that most affects customers’ perceived quality of service, and these problems affect satellite IPTV no more than terrestrial IPTV. Command latency problems, faced by terrestrial IPTV networks with insufficient bandwidth as their customer base grows, may be solved by the high capacity of satellite distribution.

Satellite distribution does suffer from latency – the time for the signal to travel up from the hub to the satellite and back down to the user is around 0.25 seconds, and cannot be reduced. However, the effects of this delay are mitigated in real-life systems using data compression, TCP-acceleration, and HTTP pre-fetching.^[64]

Satellite latency can be detrimental to especially time-sensitive applications such as on-line gaming (although it only seriously affects the likes of first-person shooters while many MMOGs can operate well over satellite Internet^[65]), but IPTV is typically a simplex operation (one-way transmission) and latency is not a critical factor for video transmission.

Existing video transmission systems of both analogue and digital formats already introduce known quantifiable delays. Existing DVB TV channels that simulcast by both terrestrial and satellite transmissions experience the same 0.25-second delay difference between the two services with no detrimental effect, and it goes unnoticed by viewers.

Bandwidth requirements[edit]

Digital video is a combination of sequence of digital images, and they are made up of pixels or picture elements. Each pixel has two values, which are luminance and chrominance. Luminance is representing intensity of the pixel; chrominance represents the colour of the pixel. Three bytes would be used to represent the colour of the high quality image for a true colour technique. A sequence of images is creating the digital video, in that case, images are called as frames.

Bandwidth capacity for simultaneously two HDTV streams, two SD streams, additional to HSD and voice

Movies use 24 frames per second; however, the rate of the frames can change according to territories' electrical systems so that there are different kinds of frame rates, for instance, North America is using approximately 30 frames per second where the Europe television frame rate is 25 frames per second. Each digital video has dimensions width and height; when referred to analogue television, the dimension for SDTV is 720×480 pixels, on the other hand, numerous HDTV requires 1920×1080 pixels. Moreover, whilst for SDTV, two bytes (16 bits) is enough to create the colour depth, HDTV requires three bytes (24 bits) to create the colour depth.^{[citation needed]}

Thereby, with a rate of 30 frames/second, the uncompressed data rate for SDTV becomes 30×720×480×16,^[vague] in other words, 147,456,000 bits per second. Moreover, for HDTV, at the same frame rate, uncompressed date rate becomes 30×1920×1080×24 or 1,492,992,000 bits per second. Using that simple calculation, a service provider's service delivery to the subscribers is limited unless a lossy compression method is used.

There is no absolute answer for the bandwidth requirement for the IPTV service because the bandwidth requirement is increasing due to the devices inside the household. Thus, currently compressed HDTV content can be delivered at a data rate between 8 and 10 Mbit/s, but if the home of the consumer equipped with several HDTV outputs, this rate will be multiplied respectively.

The high-speed data transfer will increase the needed bandwidth for the viewer, at least 2 Mbit/s is needed to use web-based applications on the computer. Additionally to that, 64 kbit/s is required to use landline telephone for the property. In minimal usage, to receive an IPTV triple-play service requires 13 Mbit/s to process in a household.