[Studies in Computational Intelligence 481] Artur Babiarz, Robert Bieda, Karol Jędrasiak, Aleksander Nawrat (auth.), Aleksander Nawrat, Zygmunt Kuś (eds.) - Vision Based Systemsfor UAV Applications (2013, Sprin
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278 A. <strong>Nawrat</strong> et al.<br />
particular channel some subcarriers are dampened or distorted, e.g. as a result of<br />
<strong>in</strong>terference or selective fad<strong>in</strong>g. This <strong>in</strong>creases transmission reliability but at the<br />
same time makes it impossible to achieve high spe<strong>eds</strong>, which <strong>in</strong> case of HAN does<br />
not pose a problem. Contrary to HomePlug AV, the GP version does not provide<br />
TDMA access. A novelty <strong>in</strong> HomePlug GP, though, is an additional work mode<br />
with a limitation on power consumption as well as a so-called DBC (Distributed<br />
Bandwidth Control) mechanism <strong>in</strong>troduced so as to prevent possible transmission<br />
<strong>in</strong>terferences <strong>in</strong> HomePlug AV com<strong>in</strong>g from devices support<strong>in</strong>g HomePlug AV<br />
standard. HomePlug GP is also compatible with ZigBee wireless technology, more<br />
precisely – with ZigBee Smart Energy 2.0 profile.<br />
Although HomePlug GP currently holds the lead<strong>in</strong>g position <strong>in</strong> the competition<br />
for dom<strong>in</strong>ation over HAN market when it comes to the PLC communication standards,<br />
this does not mean the technology is free from challengers. Recently, <strong>in</strong><br />
particular <strong>in</strong> Europe, two specifications have been ga<strong>in</strong><strong>in</strong>g popularity: PRIME<br />
(Powerl<strong>in</strong>e Related Intelligent Meter<strong>in</strong>g Evolution) and G3. PRIME standard was<br />
written from a scratch as a specification <strong>in</strong>tended to support communication <strong>in</strong><br />
<strong>in</strong>telligent energy systems, especially <strong>in</strong> HAN networks. It takes advantage of<br />
OFDM modulation and 9-95 kHz frequency. Transmission speed <strong>in</strong> PRIME standard<br />
ranges from 16 to 130 kb/s. G3 networks, on the other hand, work <strong>in</strong> band<br />
from 10 to 490 kHz. This standard also uses OFDM modulation. Maximum<br />
transmission speed for G3 is 250 kb/s, and transferred data can be encrypted us<strong>in</strong>g<br />
AES-128 algorithm. This standard enables transmission <strong>in</strong> both low-power and<br />
middle-power networks. Therefore G3 is named as one of the candidates for connect<strong>in</strong>g<br />
HAN to the public power grid. By means of this connection, a meter with<br />
a two-way communication capability will send to the energy supplier the data<br />
about the energy consumption and at the same time receive from them various<br />
commands, control signals and also e.g. <strong>in</strong>formation about the scale of prices<br />
which will be sent further with<strong>in</strong> HAN network.<br />
Another competitor of PLC is the G.hn standard. Work on its development has<br />
been conducted by HomeGrid Forum for some time now under the patronage of<br />
ITU-T. Orig<strong>in</strong>ally G.hn is expected to be used to transmit multimedia data, mostly<br />
HD video signals, by means of wires used <strong>in</strong> households (coaxial, electric and<br />
phone cables). So far three types of the standard have been developed: broadband<br />
version which provides transmission at a speed of up to 200 Mb/s, profile for<br />
smart grid application, especially as a HAN connection with public power grid -<br />
therefore the maximum speed is expected to reach 25 Mb/s and a narrowband<br />
version, so-called G.hnem, optimized for HAN application. G.hnem is a simplified<br />
version of the basic specification, which enables transmission at spe<strong>eds</strong> below<br />
500 kb/s.<br />
It must be remembered that measurement data transmission <strong>in</strong> data acquisition<br />
systems which smart grid networks undoubtedly are requires that selected measurement<br />
data transmission network’s <strong>in</strong>fluence on the measurement results is<br />
exam<strong>in</strong>ed. It is crucial to determ<strong>in</strong>e parameters of teletransmission network which<br />
affect the f<strong>in</strong>al measurement result and which of them may be view as not exert<strong>in</strong>g<br />
any <strong>in</strong>fluence. Among them one can <strong>in</strong>clude e.g. various delays which transmission<br />
l<strong>in</strong>es <strong>in</strong>troduce and which must be identified and first of all measured [12]. In