Subject: [coman] Merged terminology draft

From: Carsten Bormann <[email-masked]>
Date: Thu, 8 Nov 2012 14:43:18 -0500

As discussed in LWIG and COMAN today, Mehmet and I have extracted our
common, "essential" terminology out of the LWIG WG document and
Mehmet's COMAN draft, and merged it into one document.

The intention is to move this forward within LWIG independently, in an
expedited way, and reference it from the next version of
draft-ietf-lwig-guidance as well as further COMAN documents.

Since we got positive feedback in the LWIG meeting for this little
piece of surgery, I'm now asking the LWIG chairs to ask the question
on the mailing list for working group adoption of this draft.

Htmlized:        http://tools.ietf.org/html/draft-bormann-lwig-terms-00

Clearly, this isn't perfect yet, but further improving the document is
the point of the WG process.
Of course, comments that could lead to improvement are highly welcome.

Grüße, Carsten

---

From: peter van der Stok <[email-masked]>
Date: Fri, 09 Nov 2012 15:51:35 +0100

Dear all,

Next to the classification on memory, I should like to add a 
classification on power availability. In small nodes the largest power 
consumer is the transmitter. So I propose to classify the nodes 
according to their power-supply expressed as its transmission capacity. 
I propose three types of devices:

P0: battery-less devices. They have a capacitor which is charged by 
harvesting power delivered by a small movement or light. The stored 
energy  is just sufficient to send 1 or at most 2 packets per 
communication. For example, think of a light switch where the 
transmission power is delivered by pushing the button.

P1: battery-constrained devices. They have a battery with a limited 
charge. The device can continue sending packets over years by executing 
a cycle of relatively long off periods and short on periods in which a 
few packets can be sent and received. For example, think of a 
battery-powered temperature sensor with a life-time of 7-10 years.

P2: battery-unconstrained devices. They may have a battery which is 
usually rechargeable. The device can send and receive packets at any 
moment during its operational life. For example, think of a thermostat 
connected to an external power supply.

Hope this is helpful.

Peter van der Stok

Carsten Bormann schreef op 2012-11-08 20:43:
> Htmlized:        
> http://tools.ietf.org/html/draft-bormann-lwig-terms-00
>
> _______________________________________________
> coman mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/coman

---

From: Carsten Bormann <[email-masked]>
Date: Fri, 9 Nov 2012 10:17:08 -0500

Hi Peter,

in RFC6606, we are using the following terms (section 5):

   o  host nodes drawing their power from primary batteries or using
      energy harvesting (sometimes called "power-constrained nodes")

   o  mains-powered host nodes (an example of what we call "power-
      affluent nodes")

   o  power-affluent (but not necessarily mains-powered) high-
      performance gateway(s)

   ... (further distinctions not relevant here)

Clearly, it is a bit more complicated than just power-constrained vs. power-affluent.

Even for power-affluent nodes, we don't want to waste energy (green and all that).
One group of power-affluent nodes has a tens-of-kJ secondary battery that is regularly recharged (e.g., smartphones), so the energy supply is large, but with a defined limit per period (e.g, 24 hours for most smartphones); a typical amount of power continuously available (on average) is in the hundreds of mW.

The typical primary-battery powered node has an average power availability on the order of tens to hundreds of µW.  So there is a clear difference -- around three orders of magnitude.  That should nicely separate the classes.

Energy harvesting nodes are different enough to warrant their own group.  But there is a group of energy harvesting devices that find enough energy to almost be power-affluent.  So it might be useful to actually give an approximate boundary, e.g., in µW actually available averaged over a long time.  (That doesn't work very well for event-based harvesting, but you can just assume an event frequency and likely will arrive at a useful number.)

Grüße, Carsten

On Nov 9, 2012, at 09:51, peter van der Stok <[email-masked]> wrote:

> Dear all,
> 
> Next to the classification on memory, I should like to add a classification on power availability. In small nodes the largest power consumer is the transmitter. So I propose to classify the nodes according to their power-supply expressed as its transmission capacity. I propose three types of devices:
> 
> P0: battery-less devices. They have a capacitor which is charged by harvesting power delivered by a small movement or light. The stored energy  is just sufficient to send 1 or at most 2 packets per communication. For example, think of a light switch where the transmission power is delivered by pushing the button.
> 
> P1: battery-constrained devices. They have a battery with a limited charge. The device can continue sending packets over years by executing a cycle of relatively long off periods and short on periods in which a few packets can be sent and received. For example, think of a battery-powered temperature sensor with a life-time of 7-10 years.
> 
> P2: battery-unconstrained devices. They may have a battery which is usually rechargeable. The device can send and receive packets at any moment during its operational life. For example, think of a thermostat connected to an external power supply.
> 
> Hope this is helpful.
> 
> Peter van der Stok
> 
>

---

From: peter van der Stok <[email-masked]>
Date: Fri, 09 Nov 2012 16:29:09 +0100

Hi Carsten,

thanks for the pointer.
I did not want to go into in watss and watthours but wanted to classify 
according to network behavior.
I thought that was more relevant in the long term because technology 
advances on battery side, harvesting side, and transmitter side.
However, at the end of the day these devices are optimized to a wanted 
behavior on the network for a minimum cost.

Peter

Carsten Bormann schreef op 2012-11-09 16:17:
> One group of power-affluent nodes has a tens-of-kJ secondary battery
> that is regularly recharged (e.g., smartphones), so the energy supply
> is large, but with a defined limit per period (e.g, 24 hours for most
> smartphones); a typical amount of power continuously available (on
> average) is in the hundreds of mW.
>
> The typical primary-battery powered node has an average power
> availability on the order of tens to hundreds of µW.  So there is a
> clear difference -- around three orders of magnitude.  That should
> nicely separate the classes.
>
> Energy harvesting nodes are different enough to warrant their own
> group.  But there is a group of energy harvesting devices that find
> enough energy to almost be power-affluent.  So it might be useful to
> actually give an approximate boundary, e.g., in µW actually available
> averaged over a long time.  (That doesn't work very well for
> event-based harvesting, but you can just assume an event frequency 
> and
> likely will arrive at a useful number.)
>
> Grüße, Carsten
>
>
>> according to their power-supply expressed as its transmission 
>> capacity. I propose three types of devices:
>>
>> charge. The device can continue sending packets over years by 
>> executing a cycle of relatively long off periods and short on periods 
>> in which a few packets can be sent and received. For example, think of 
>> a battery-powered temperature sensor with a life-time of 7-10 years.
>>

---

From: peter van der Stok <[email-masked]>
Date: Mon, 12 Nov 2012 13:36:28 +0100

Hi Michael,

Completely agree, much better,

Peter

Michael Richardson schreef op 2012-11-11 22:05:
>>>>>> "peter" == peter van der Stok <[email-masked]> writes:
>     peter> Next to the classification on memory, I should like to add 
> a
>     peter> classification on power availability. In small nodes the
>     peter> largest power consumer is the transmitter. So I propose to
>     peter> classify the nodes according to their power-supply 
> expressed
>     peter> as its transmission capacity. I propose three types of
>     peter> devices:
>
>     peter> P0: battery-less devices. They have a capacitor which is
>     peter> charged by harvesting power delivered by a small movement 
> or
>     peter> light. The stored energy is just sufficient to send 1 or 
> at
>
> Is it important to realize that P0 devices are not limited by the 
> number
> of packets they can send, just limited as to the rate?
>
>     peter> P1: battery-constrained devices. They have a battery with 
> a
>
> Whereas, P1 devices are limited by the total number of packets they 
> can
> send.  Every packet they send today is a packet they can not send
> tomorrow.

---

From: Pierpaolo Giacomin <[email-masked]>
Date: Wed, 14 Nov 2012 20:08:10 +0200

Dear all,

Sorry for cross posting, but I think the subject is really relevant for
both mls.
Peter van der stok in the coman ml proposed the following classification:

>>     peter> Next to the classification on memory, I should like to add a
>>     peter> classify the nodes according to their power-supply expressed
>>     peter> charged by harvesting power delivered by a small movement or
>>     peter> light. The stored energy is just sufficient to send 1 or at
>>
>> Is it important to realize that P0 devices are not limited by the number
>>     peter> P1: battery-constrained devices. They have a battery with a
>>
>> Whereas, P1 devices are limited by the total number of packets they can

I totally second Peter's classification with regard to power.
As far as I know draft-cao-lwig-syn-layer-00 was the first draft in lwig
dealing with the subject or reducing power consumption and, while a big
amount of the work can be achieved with the radio duty cycle I think
such kind of work should be heavily encouraged.
Moreover, it seems to me it would be reasonable to split in different
constrain classes data memory and code memory. While that's true than in
current devices the two follows more or less the classes presented in
draft-bormann-lwig-terms-00, implementing "low complexity code" often
clash with "reducing data memory usage". Refusing to use a managed
memory allocator (as presented in draft-kovatsch-lwig-class1-coap and as
I personally do) is a very good example of that, even if that's true
that is a practice used mainly in order to achieve predictability.
Regarding data memory it seems also reasonable to me to consider also
stateless devices.
Finally, to complete the classification I'd consider also "computing
power" because clock, register bit length, hw crypto support (think aes)
and  instruction set can really make the difference both wrt complexity
and feasibility.
I think for both coman and lwig this 4-axis classification could be useful.
Any feedback?

Best regards,
Pierpaolo