[Cu-wireless] 802.11 & multihop networks

David Young dyoung at pobox.com
Thu Apr 17 17:37:02 CDT 2003

On Wed, Apr 16, 2003 at 09:34:09AM -0500, Zachary C. Miller wrote:
> I'm guessing changing this would mean hacking the firmware on all the
> radios in the network. Not really something that is going to happen
> outside the domain of theory...

  Right. And it won't be much longer that there are even firmwares;
  makers are putting the 802.11 MAC into silicon. This actually makes the
  radios more versatile, provided that the 802.11 MAC is satisfactory.
  If not, well....

> so I'd think we'd just have to live
> with it and keep our pods small as we already knew we had to. (Or we
> could change to a heirarchical design with directional antennas... :)

  Nothing stops us from using a single directional antenna at each
  station, and I would like for us to do that at houses on Green Street
  and on Race Street which are too near their nexthop to grow the
  network. Those will be well-served by a $30 patch antenna.

  Hierarchical routing is fine provided that it is ad hoc.  I am convinced
  that we have come this far only because when we have turned on two
  nodes, they have ordinarily found each other and "just worked." If we
  have to start designing the network, we are going to get stuck.

  A design with directional antennas is fine, too, provided that it
  is ad hoc.  Since radios have gotten so cheap ($35 for a decent PCI
  radio with SMA connector), I am entertaining this notion that we could
  put two, four, or more small patches on a single mast, "bond" their
  interfaces together with a software bridge device, and then run OSPF
  on the bridge device precisely as we do now. But here we are talking
  about more connectors and more cable, and it is likely that antennas on
  the same mast will interfere with each other unless they are very nice
  (read: very expensive) antennas.


David Young             OJC Technologies
dyoung at ojctech.com      Urbana, IL * (217) 278-3933

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