ZyXEL Communications PLA-470 V2 - V3.0.5 Przewodnik Instalacji Pobierz pdf (Strona 113)

The 917 frequency sub-bands at the physical layer are used by HomePlug AV.

Each band then uses OFDM symbols in order to encode the data in an orthogonal

manner in the frequency domain. Therefore, the bands are independent in terms of

frequency and do not interfere with each other.

In each frequency band, the data and its OFDM symbols are encoded using a

turbo convolutional code. The modulation is then carried out; it is potentially differ-

ent for each frequency band (see Figure 5.8).

This modulation can range from the BPSK type, which encodes 1 bit for each

symbol and frequency band, to the 1024-QAM type, which encodes 10 bits for

each symbol and frequency band.

Functional Blocks

Therefore, a PLC device consists of various signal processing electronic elements.

Each electronic element has a precise function in the signal processing chain that

conveys data from the interface connected to an Ethernet network or from the inter-

face connected to an electrical network.

Figure 5.9 illustrates the functional blocks used to send and receive HomePlug

1.0 frames between the various network PLC devices with adaptations relating to

the quality of the electrical transmission channel.

These adaptations must be made as efficiently as possible in order to achieve

optimized performance for the upper protocol layers and the various terminals con-

nected to the Ethernet interfaces of each PLC device.

94 Frames

Figure 5.8 Details on frequency band use in HomePlug AV

1 2 ... 108 109 110 111 112 113 114 115 116 117 118 ... 348 349

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ZyXEL Communications PLA-470 V2 - V3.0.5 Przewodnik Instalacji Strona 113