Hello!
Am 02.06.2010 00:13, schrieb Krzysztof Urbas:
So my questions are:
- Do you have any suggestions how to build multi-hop testbed in
laboratory environment (in one room)?
A multi-hop testbed in a single room will probably only work if you use attenuators between your device and the antenna. This setup was used in the following paper: http://wirelessafrica.meraka.org.za/wiki/images/9/98/Batman_ifip.pdf
If your testbed should be more realistic, you really need to distribute your devices over a larger area, but with only 4 nodes, interesting multi-hop connections will be rather hard to achieve. If there's only one possible path for the signal, a routing protocol cannot show how reliably it choses a stable path.
- How to make testing proces more automatic (some kind of central
server to run tests and collect data)?
Use Ethernet to connect your devices so you can manage your experiments out of band. With pssh or cssh, the same command can be run on multiple nodes at the same time (if you need that). With pssh, you can even push/retrieve data to/from multiple nodes.
* http://code.google.com/p/parallel-ssh/ * http://sourceforge.net/apps/mediawiki/clusterssh/index.php?title=Main_Page
- Do you have any other
suggestions/observations/conclusions/example_data from your tests?
TCP over lossy (wireless!) networks is a big problem since TCP's congestion control algorithm interprets packet loss as congestion, which is great for wired networks but in most cases wrong for wireless. This can seriously impair throughput.
A second factor for low througput: A station that forwards data communicates with all of its neighbors on the same channel which means that while sending, it cannot receive data at the same time. This can impact performance quite seriously.
There's literature (try Google Scholar) on both problems.
Regards, Daniel