ZyXEL Communications PLA-470 V2 - V3.0.5 Instalační příručka stáhnout pdf (Strana 196)

Table 8.10 shows the results obtained for various technologies with this test bed.

Table 8.11 summarizes the necessary data rates for certain usual Internet appli-

cations (data, voice, or video applications).

Data Rate Variation

In a PLC network, the constraints related to the electrical interface can result in a

variation of the data rate provided by the network. As previously explained, inter-

ference originating from the electrical devices and the multiplication of PLC devices

on the electrical network are some examples that can cause data rate variations.

The PLC data rate varies automatically as soon as interference occurs in the

environment. This is a user-transparent mechanism. So, the HomePlug 1.0 data rate

changes from 14.1 Mbit/s to 12.83, 10.16, 8.36, 6.35, 4.04, 2.67, and even to 0.9

Mbit/s when the environment is highly degraded.

A different data rate can be given to any of the network’s stations with the auto-

matic data rate variation scheme.

Figure 8.21 illustrates the variation of the theoretical data rate and of the useful

throughput following measurements performed during tests with the Iperf tool.

When the network is comprised of several stations, we have seen that the data

rate for each station corresponds to the maximum useful throughput divided by the

number of stations. However, we have considered that the waiting time is equal to

the transmission time for a given station considering that the transmission speed is

equal for all stations.

Network Data Rates 177

Table 8.10 Maximum Actual Data Rates of PLC Technologies

STANDARD OR

TECHNOLOGY

USEFUL

THROUGHPUT

(Mbit/s)

MAX. ACTUAL

DATA RATE

(Mbit/s)

HomePlug 1.0 (14 Mbit/s) 5.1 4.35 Mbit/s

HomePlug Turbo (85 Mbit/s) 40 11.5 Mbit/s

HomePlug AV (200 Mbit/s) 150 60.5 Mbit/s

DS2 (200 Mbit/s) 150 61.2 Mbit/s

Table 8.11 Necessary Data Rates for

Typical Internet Applications

APPLICATION

NECESSARY

BIT RATE

Surf over Internet

and e-mail:

–down

–up

50 Kbit/s

5 Kbit/s

Voice over IP 80 Kbit/s

Streaming audio:

–down

–up

80 Kbit/s

14 Kbit/s

SDTV video channel 1.5 Mbit/s

HDTV video channel 8 Mbit/s

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