Subject: Re: [manet] New drafts for DLEP layer1 metrics

From: Abdussalam Baryun <[email-masked]>
Date: Sun, 12 Sep 2021 23:10:57 +0200

Hi Henning,

On Wed, Aug 11, 2021 at 8:37 AM Rogge, Henning <
[email-masked]> wrote:

> Hi,
>
> I published an update to two of my DLEP drafts:
>
> https://datatracker.ietf.org/doc/html/draft-rogge-manet-dlep-channel-utilization-01.txt
>
> https://datatracker.ietf.org/doc/html/draft-rogge-manet-dlep-radio-quality-01.txt
>
> I suggest that second draft include the use cases or the importance of using
it,  the radio quality draft, how we can compare between it and the
use of RFC8175 section
13.18 and 13.19.

the third one is still in draft 02:
>
> https://datatracker.ietf.org/doc/html/draft-rogge-manet-dlep-radio-band-02.txt

by reading draft not sure of the use case of selected frequency and band,
however, I suggested in another message my opinion.

>
> I think the most work have to be done for the "BitError" TLV in the
> radio-quality draft... I am still not happy with the encoding but I am not
> quite sure what to do.
>

for the radi-quality-draft ....the error bit-rate not much value only if
router knows the data rate/speed, which is specified in rfc8175, so I
suggest  the draft needs to show the importance of this item related to
data item of speed.

Regards
AB

---

From: Henning Rogge <[email-masked]>
Date: Mon, 13 Sep 2021 09:11:40 +0200

On Sun, Sep 12, 2021 at 11:19 PM Abdussalam Baryun
<[email-masked]> wrote:
>> I think the most work have to be done for the "BitError" TLV in the radio-quality draft... I am still not happy with the encoding but I am not quite sure what to do.
>
>
> for the radi-quality-draft ....the error bit-rate not much value only if router knows the data rate/speed, which is specified in rfc8175, so I suggest  the draft needs to show the importance of this item related to data item of speed.

If you look up some technical specification of a digital radio, you
will (most likely) find tables for each modulation that show the
correlation between biterror-rate and (necessary) signal-to-noise
ratio. This means a radio measuring the biterror rate can give you an
estimate what error-rate you can expect at other modulations.

The biterror rate will also make it possible to estimate the different
frame-error-rates of small and large frames, which could give you a
more precise way to calculate the link metric for a routing protocol.

Henning Rogge

---

From: Abdussalam Baryun <[email-masked]>
Date: Fri, 24 Sep 2021 08:29:03 +0200

> estimate what error-rate you can expect at other modulations.

There are some-assumptions (e.g low mobility environment) in all tables. As
usually assumes fixed data-speed and channel-bandwidth, so any increase in
data rate increases bit error rate depending on physical-comm-channel.

> more precise way to calculate the link metric for a routing protocol.

That should be discussed I think in the draft. Is there a possibility of
error in getting the BER? however, the bit-error rate is not a rate of
time, just number of errors detected per received bits, also the modulated
signal is not in bits but demodulated is in bits. Each channel has a
maximum data rate, getting equal to that speed or less can increase or
reduce bit error rate while fixed modulation, channel, and noise.

For example, if the router finds increase/decrease in error rate without
knowing changes in data speed then it will expect either change in noise or
channel. Therefore, I suggested the knowledge of speed with BER and some
details on ways of estimating BER or frame-error-rate in draft.

Best Regards
AB