[ns] Bandwidth of wireless channel
mahrenho at ivs.cs.uni-magdeburg.de
Thu Apr 13 06:00:35 PDT 2006
> Actually, my problem involves calculating the effective bandwidth of a
> wireless node (more specifically in a MANET). I guess the bandwidth_
> variable of MAC or Phy layers dont give this value.
> I am using the default parameters given in the AODV implementation.
> To put it more clearly, suppose node 'S' wants to send a pkt to 'R'.
> This pkt can either be forwarded through 'A' or 'B' (A & B are one hop
> neighbors of S) depending on the bandwidth. So, I am planning to
> calculate the effective bandwidths of A and B and choose the node
> based on it.
> Can you (or anyone) suggest a way for this. I would be thankful
If nodes A and B are direct neighbors of S it is most likely that A and
B have to share the medium either because they are in direct
communication range or through the physical carrier sense. If I
understand you right, you try to compute the bandwidth that one node
(e.g. S) can use to transmit a packet. A node has to share the medium
with all nodes within interference range. So if S wants to transmit a
packet via nodes A, D, and F to R and A,D are within interference range
of S then the available bandwidth of S will reduce three times by the
bandwidth required to transmit the packet. This is because the packet
utilizes the medium (from S's point of view) when S transmits it, and
when A and D forward it. Beyond this point S will not be influenced by
the further forwarding of the packet because it is out of interference
In your case you have to take all possible routes and calculate the
changes in the channel utilization for every node along the route or at
least within your own interference range to know what effect the route
decision will have on your available end-to-end bandwidth.
Hope this clarifies more than it confuses,
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