Digital Signal Processing Reference
In-Depth Information
Figure 13-2.
PSNR values as a function of the maximum number of transmission per MPDU at
the MAC level. The results are plotted for various channel conditions.
that the average length of an error burst is equal to 1.1. The value of varies so
as to represent a range of channel conditions with different values of the average
error probability.
We present two sets of simulation scenarios in a multi-service network which
provides video transmission and data transfer. The first set of simulations ana-
lyzes the video transmission quality in a simple two-hop scenario (i.e., with one
relay node only) under different network scenarios in which the error probability
over the radio channel and the number of background data traffic sources vary.
In the second set of simulations, we fix the number of background data sources
and we investigate the impact of the number of relay nodes on the video quality.
4.2 Two-hop scenario
We first analyze the behavior of the transmission system when no background
traffic is present in the network.
Figure 13-2 shows the impact of the maximum number of transmissions per
MPDU on the perceptual video quality, measured by the peak SNR (PSNR), for
four different channels. Almost optimal video quality can be achieved by setting
the maximum number of transmission attempts per MPDU,
to 3. If no re-
transmissions are present
the quality rapidly decreases, showing that
