[ns] Underwater Channel in basic NS2
baldo at dei.unipd.it
Thu May 8 16:04:22 PDT 2008
Dewald Nolte wrote:
> In ns-miracle the documentation claims that the underwater channel
> works and that some basic MACs are provided, but in one of the mails
> in the mailing list I read that some of the routing protocols are not
> yet supported?
Basically the underwater-miracle module provides only Channel, PHY and
MAC, and relies on nsmiracle for the rest of the protocol stack. The
current release of nsmiracle provides only static routing. The future
release will include support for routing protocols such as AODV.
However, the release date for this version of nsmiracle cannot be
predicted at this moment.
> Also if I go the basic ns way I have to fix the code
> myself. It has some errors at the moment. Doesnt seem too difficult to
> fix though.
> 1. In the underwater-phy.cc of the unsupported underwater code, lambda
> is defined as:
> lambda_ = SPEED_OF_LIGHT / freq_;
> Considering that its an underwater channel, should it not then be
> the speed of sound??
I guess this value was not used in practice. What I remember of the ns2
underwater module is that is basically used the underwater-phy as an
entry point for some other external code. Most of the code copied from
the ns2 wireless-phy is not actually used. However, you need to read the
code yourself to really understand it. I guess it could be very
difficult to contact the original developers of that module.
> I want to implement my own MAC for the underwater environment. I am
> looking to use the RTS, CTS, DATA, ACK handshake to implement MACAW.
> Some of this is already implemented in the 802.11 MAC. So I will try
> to port that to MACAW. So basically I want to try and use the
> framework supplied by the 802.11 code and just change what is
> necessarry to implement my MAC (MACAW). The problem is I dont have
> enough experience with ns to write my own MAC
> from scratch, so im doing it this way.
> 2. Now would it be easier to go with ns-miracle, or try to integrate
> the unsupported code for the
> basic ns and use that to keep the routing modules intact?
> 3. And lastly, can the 802.11 MAC run on the underwater physical layer
> as it is? Just for
> starters, I will try to port it eventually to the MACAW protocol...
What I can tell you (just my opinion of course) is that dealing with the
ns2 underwater module at the PHY and MAC layer is a real mess. This is
the main reason why we wrote the underwater-miracle module almost from
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