Digital Signal Processing Reference
In-Depth Information
Figure 13-8.
PSNR values as a function of the number of relay nodes, when two TCP traffic
sources are considered and the playout buffer is equal to 1 s. The results are plotted for different
values of the error probability over the wireless channel.
network simulations. Various scenarios have been tested, with different levels of
background interfering traffic and with different network configurations. Results
give a clear indication on how to select the system parameters. In particular,
we have observed that a video packet size as small as 300 bytes should be used
when channel conditions are not favorable. A maximum number of transmission
attempts at the MAC layer equal to 3 enables us to obtain a high PSNR for most
channel conditions. Moreover, in case of interactive video services, the number
of TCP sources that can be admitted in the network should be limited and the
number of hops must be kept very small, i.e., smaller than 4, in order to meet
the QoS requirements.
References
[1]
(1999). Wireless LAN Medium Access Control (MAC) and Physical Layer
(PHY) Specifications.
ISO/IEC 8802-11, ANSI/IEEE Std 802.11.
[2]
Freytes, M., Rodriguez, C.E., and Marques, C.A. (2001). Real-Time
H.263+ Video Transmission on 802.11 Wireless LANs. In
Int. Conf. on
Information Technology: Coding and Computing
, Las Vegas, NV.
