Hello Alex,
Please excuse my delay in answering -- your email got buried in a mass
flood of other emails. Follow-up below...
On 5/18/2016 4:37 AM, Alexandre Petrescu wrote:
Hello,
I would like to give a few comments on this draft.
Thanks much for your review!
It says:
For the purposes of this document, a multi-hop ad hoc wireless
network will be considered to be a collection of devices that each
have a radio transceiver (i.e., wireless network interface), and that
are moreover configured to self-organize and provide store-and-
forward functionality as needed to enable communications.
1. when it says 'multi-hop', it actually means multiple-layer2-hops,
not multiple-IP-hops in particular, right?
Actually, we did have in mind multiple IP hops, but the IP hops could
naturally be considered to be single physical-layer links. For
situations in which the IP hop is composed of multiple layer-2 hops,
then the nature of the layer-2 (?bridge?mesh-under?) protocol makes all
the difference about whether or not the effects described in our draft
are relevant. For instance, layer 2 could counteract effects of time
variations.
2. each node has a wireless network interface: yes, not two.
We do not place this constraint. I will clarify that.
These deployments use routers running IP protocols e.g., OLSR
(Optimized Link State Routing [RFC3626]) on top of IEEE 802.11 in ad
hoc mode with the same ESSID (Extended Service Set Identification) at
the link layer.
3. Please note there is no RFC that specifies how to run IP on top of
802.11. One can say OLSR runs on top of 802.11, but at the same
time there is no RFC that tells how _IP_ runs on it, as "IPv6 over
foo". I think this is worth mentioning in the draft.
And yet people run IP over 802.11 without significant difficulty, so
perhaps the consensus has been that such a specification is not urgently
needed.
Wireless communications are subject to limitations to the distance
across which they may be established.
4. This distance limitation in itself is not enough to distinguish
wireless communications from wired communications. In
wired communications limits on the distance apply as well. In that
sense, it should say "Wireless communications - like all other
communication media - are subject to limitations [...]"
Yes, but the limitations are much more pronounced with wireless media.
What would you think of the following:
Wireless communications are particularly subject to limitations to
the distance across which they may be established.
The range-limitation factor creates specific problems on multi-hop ad
hoc wireless networks. In this context, the radio ranges of several
devices often partially overlap.
5. The overlapping is indeed particular to wireless communications
(not seen in wires). However, overlapping is due to the lack of
isolation between the guides, not because of a distance range: whereas
each wire is always isolated by a plastic shield leaving only two ends
open (two wires wouldn't overlap), in wireless 802.11 the 'channeled'
transmission can have many open ends at different distance from one
another (some would overlap).
How about:
.... Due to the lack of isolation between the transmitters,
the radio ranges of several devices often partially overlap, ...
Moreover, the range may vary from one device to another, depending
on location and environmental factors.
6. This is true, but 'from one device to another' sounds ambiguous:
distance from A to B? Or 'range of reach by emission from A, is
different than the reach of reach by emission from B, depending on
environmental factors like solid obstacles, rain, and more'.
How about the following:
....... Moreover, the range of each
device may
depend on location and environmental factors.
Thanks for your comments. I will submit a revision today that
incorporates the above text in an attempt to resolve the issues you have
raised. Please take a look.
Regards,
Charlie P.
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