
noise can affect some symbols. In the OFDM technique, symbol losses in a carrier do
not affect other carriers.
•
High bit rate allocation flexibility for each user or each carrier. Each carrier can be
encoded independently from the other ones according to the quality of the physical
links and to the best suited modulation techniques.
•
Improvement of the transmission channel preliminary estimate. Training frames
used to identify the transmission channel capacities in the frequency domain are
used by the OFDM techniques.
Figure 5.7 gives an overview of the OFDM symbols in each channel (frequency
sub-band).
The HomePlug 1.0 frame uses several modulation, frequency division, and
error correction techniques, which constitute a data processing set for each PLC
device between the physical analog interface and the Ethernet interface of the RJ-45
type.
Frequency Band Use for HomePlug AV Devices
Technical evolutions in the field of signal processing in media with high interference
led the developers of PLC solutions within the HomePlug industrial consortium to
make maximum use of the authorized 1-30 MHz frequency band in order to achieve
transmission speeds around 200 Mbit/s.
The OFDM Interface Frame 93
Figure 5.7 Distribution of OFDM symbols over frequency bands
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