Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola

7 Conclusion
During this project the different measurements have been the major problem, and
already during our first measurement we ran into trouble. No DVB-T signal was
detected when measurements with the spectrum analyzer was done. The reason
for this is that the walls and windows attenuate the signal. The windows at Perlos
laboratory have a thin metal layer on the glass.
This means that there is no indoor coverage in Perlos laboratory in Lund and
probably not in larger parts of Skåne. For the DVB-H system to be successful
coverage inside cars, busses, trains and buildings has to be achieved. The base
stations operating today only provide full indoor coverage in the near of the base
stations. If the DVB-H system is successful more base stations are planed and full
indoor coverage will be achieved.
As you all now by now the frequencies used for the DVB-H system are 470-862
MHz. This frequency range is good in aspect of getting good coverage with few
base stations. The only drawback with these low frequencies is that the antennas
become electrically very small, and thereby inefficient. If higher frequencies had
been used more base stations had been required since higher frequencies have a
higher propagation loss.
DVB-H system can use all existing DVB-T base stations and only a handful new
base stations have to be built in the future. This is a huge economical advantage
against competing systems. Another big advantage is that it is a broadcasting
system, which means that it is spectrum efficient. That it is a broadcasting system
means that an infinite number of users can watch the same show without
occupying more bandwidth. This could be compared to the technique used today
in the 3G network where smaller shows are streamed to each user separately.
One of the reasons why shows are streamed separately is that in this way the
operators can easily control how long time each user has watched and thereby be
charged. Another reason is that the operators have a lot of unused capacity in the
3G network and want to use this to stream TV shows in.
A big difference between DVB-H and DVB-T is time slicing. This has been added
in the DVB-H standard to decrease the power consumption to a level suitable for
handheld devices. This technique has a couple of drawbacks. The first one is that
when the user likes to change channel it might take up to five seconds before the
next burst are transmitted. This means that no picture can be shown until the burst
for the chosen channel has been received. The second one is if the terminal has
bad reception during the burst time, then the terminal will not have any video to
play until the next burst is received. When this technique is used live shows will
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