Hi Pat,
Thanks! I see your concerns.
Let us hope we will have advanced IoT controllers, similar to WLAN controllers,
which manage and provide a deterministic and efficient 6tisch network!
Anand
On Tue, 9 Jun 2015, Pat Kinney wrote:
Anand;
You raise valid points and in a professionally installed system, the installers
would have made sure that the transmit power levels were appropriate. My
concerns are for non-professionally installed systems and/or systems with low
duty cycle mobile end nodes. Normally, in professional installations we ensure
a 20 dB signal margin for end nodes, and populate routers to minimize ?choke?
points and maximize spectrum reuse. However, in non-professional installs, we
cannot assume these nodes will be properly set up. Also, I am concerned that
the IEEE 802.15.4 standard for the O-QPSK PHY in the 2450 MHz band does not
require transmit power leveling nor multiple power set points, so any use of
transmit power control would depend upon proprietary capabilities. Finally,
although phyTxPower is not marked as a read-only attribute, it is not described
as an attribute that actively controls transmit power, hence its use as such
would be proprietary.
Pat
Pat Kinney
Kinney Consulting LLC
IEEE 802.15 WG vice chair, TG chair
ISA100.11a WG chair
O: +1.847.960.3715
[email protected] <mailto:[email protected]>
On 9, Jun2015, at 2:50, S.V.R.Anand <[email protected]> wrote:
Hi Pat,
Thanks a lot for the insightful comments!
The main theme of my mail is to use transmit power control is to enable better
spatial re-use of the channels, managed by an external controller. The focus is
not much on the power savings. With respect to the effect of power control on
CSMA behaviour for the shared timeslots, one comes across literature that talks
about optimal power control that trades-off between hidden node and exposed
node problems. The latter is for better spatial re-use. As Michel pointed out
in his mail, the nodes can use different output power levels. Left to them,
this could lead to unpredictable the contention regions, and all the associated
unfairness issues as well.
A well provisioned power levels managed by a centralized controller can also
help support more "deterministic" tracks that use dedicated TX timeslots. For
reasons I cited in my earlier mail, don't you think a handle to transmit power
control helps in managing the network better, at least in the case of non-CSMA
timeslots ?
Anand
On Monday 08 June 2015 10:49 PM, Pat Kinney wrote:
Reducing transmit power may
seem like a great idea but it creates havoc in many systems due to
the hidden node problem. A reduction in transmit power will
often degrade the effectiveness of the CSMA mechanism which is
used in shared timeslots. The reduced effectiveness frequently
appears as lost packets, requiring retransmissions, requiring more
energy than that saved by reduction of transmit power. However,
since the CSMA is not required for TX only timeslots, changing TX
power in these timeslots may be done with fewer ill effects.
>
> Pat
> Pat Kinney
> Kinney Consulting LLC
> IEEE 802.15 WG vice chair, TG chair
> ISA100.11a WG chair
> O: +1.847.960.3715
> [email protected]
<mailto:[email protected]>
>
>
>
>
>
>
> On 8, Jun2015, at 10:33, Michel Veillette
<[email protected]>
<mailto:[email protected]> wrote:
>
> Hi Anand and Qin
>
>
>
> Ill like to introduce the idea of supporting the option of
adding the phyTXPower value in an IE within BEACON frames.
>
> Provisioning the phyTXPower can be an issue when targeting
multiple markets with different output power limits.
>
> Including the phyTXPower within BEACON frames will enable
joining nodes to adjust dynamically their output power based on a
value managed at the PAN coordinator.
>
>
>
> <image001.jpg>
>
>
> Michel Veillette
> System Architecture Director
>
> Trilliant Inc.
> Tel: 450-375-0556 ext. 237
> [email protected]
<mailto:[email protected]>
>
> www.trilliantinc.com <http://www.trilliantinc.com/>
>
>
>
>
>
> From: 6tisch [mailto:[email protected]
<mailto:[email protected]>] On Behalf Of
Qin Wang
> Sent: 8 juin 2015 11:08
> To: [email protected] <mailto:[email protected]>; Kris Pister
> Cc: [email protected] <mailto:[email protected]>
> Subject: Re: [6tisch] 6top and transmit power control
>
>
>
> Hi Anand,
>
>
>
> Regarding to power management, there is a parameter in the
IEEE802.15.4 PIB, i.e. phyTXPower. You can control the
transmitting power by changing its value. Is that what you want?
If so, I think 6tisch MIB will provide the interface to access
phyTXPower, which will be defined in the 6tisch-interface draft.
>
>
>
> Thanks
>
> Qin
>
>
>
>
>
>
>
> On Saturday, June 6, 2015 2:50 PM, "[email protected]"
<mailto:[email protected]>
<[email protected]> <mailto:[email protected]> wrote:
>
>
>
> Hi Kris,
>
> Thanks!
>
> I was not sure if and how such a parameter can be
accommodated in the
> current scheme of things, although it could be a useful
control parameter
> from the operator's perspective.
>
> Anand
>
>
>
> > seems like a good idea.
> >
> > ksjp
> >
> > On 6/4/2015 4:15 AM, SVR Anand wrote:
> >> Dear All,
> >>
> >> A slight digression from the ongoing ML discussions.
Hope the timing
> >> is OK!
> >>
> >> As we all know, transmit power control is one of the
powerful knobs
> >> that can be
> >> used to minimize the interference and thereby
improve the wireless
> >> network
> >> performance and also provide deterministic network.
Cell breathing
> >> technique
> >> used in WLANs comes to our mind. When it comes to
6tisch, one might
> >> argue that
> >> with 16 channels at our disposal, the interference
can be avoided
> >> through smart
> >> 6top cell management interface without worrying much
about transmit
> >> power
> >> control. However, there can be scenarios where
transmit power control
> >> might be
> >> required, for instance, (i) large scale dense
deployments with heavy
> >> traffic
> >> demands (ii) Co-existing WiFi reducing available
non-overlapping
> >> channels for
> >> 15.4 (iii) prevent wireless leaks beyond the
periphery of the
> >> deployement
> >> region and (iv) OTF scheduling where nodes make
local decisions for
> >> managing
> >> cells, may be more.
> >>
> >> One possibility is to leave the power management to
the nodes. We are
> >> then
> >> leaving this to implementors to device their own
algorithms to handle
> >> interference. Alternatively, a centralised
controller (NME) knowing the
> >> information about conflicting links can adaptively
and optimally
> >> adjust the
> >> operating transmit power of the nodes to avoid the
interference and
> >> maximize
> >> the wireless network performance.
> >>
> >> If we treat transmit power as one of the
controllable parameters along
> >> with the
> >> cell management parameters, wondering if 6tisch 6top
interface MIB is
> >> the place
> >> to define this. Or this parameter is beyond the
scope of 6tisch.
> >>
> >> Any suggestions ?
> >>
> >> Anand
> >>
> >
> >
> > --
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