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New Mercurial repository

I've just converted netsukuku's SVN repository to Mercurial and published it at 



This is initially intended to be used by me, but if anyone else wants to use it, feel free to.

There's also a wiki and an issue tracker there.

Regards,

--
Elifarley Cruz

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" Do not believe anything because it is said by an authority, or if it  is said to come from angels, or from Gods, or from an inspired source.   Believe it only if you have explored it in your own heart and mind and body and found it to be true.  Work out your own path, through diligence."
- Gautama Buddha
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Korvin | 12 Apr 22:21 2010

Suggestions on AP range and power management

Hello again.

Could someone tell me, whether is it possible to tune AP transmit power/range 
individually for each node? I know that modern wlan cards support this 
feature. 

My idea is to tune node's range in order to optimize Netsukuku covering.

In normal conditions, redundancy is good, but when amount of APs grows, they 
begin interfering with each other, causing degradation of overall speed. If 
we'll try to manage the tx power, things would be better.

So, each node knows amount of other devices in range. If there are no devices 
around, or it's count is small, node transmits signal at full power, 
maximizing the covering. 

When amount of in-range devices grows, node may slightly decrease it's range 
and try to detect actual range to other devices. By knowing alternate routes 
to peers we may detect whether peer is fully dependant on our node, or it has 
another links to the world.

Then we may decide, whether to decrease the range forcing remote peer to use 
other links, or to leave the things untouched. 

In case of overpopulated area, there is high possibility that node may have 
many routes to the world, so this would not be a problem. 

So:

1) if reducing of signal strengh would increase the overall quality of service 
(because of reduced interference) and out-of-range devices may switch to other 
nodes, then it is a good idea. 

2) If reducing of signal strengh leads to loss of connectivity with large 
amount of nodes or even netsplit is occured, then it is a bad idea, so this 
node is important to network and actually needed to be fully powered.

Actual algorithm is need to be discussed, but I think it may be some kind of 
minimax. Of course this operation need to be tied to actual network topology 
and range detection should be done using 'non invasive' method.

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Roberto Previdi | 13 Apr 10:55 2010
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Re: Suggestions on AP range and power management

Il 12/04/2010 22:21, Korvin ha scritto:
> Hello again.
> 
> Could someone tell me, whether is it possible to tune AP transmit power/range 
> individually for each node? I know that modern wlan cards support this 
> feature. 
> [...]

If this management is possible it could be a good thing to consider
lowering the AP power to save some energy when there is no need to go at
full power. Suppose that an AP is serving connection to just 1 device,
it just need to use the power sufficient to reach that device, with a
tolerance of some meters. It surely don't need to go 50 meters far from it.
Maybe if there is the need to scan for other devices in the area that
could be done one time each 30 seconds or so at full power, going back
to low power to serve the normal connection if there are no more devices..
This would even contribute to keep low the amount and intensity of
electromagnetic waves, which is always a good thing.

roby

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ZioPRoTo (Saverio Proto | 13 Apr 14:01 2010
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Re: Suggestions on AP range and power management

In real life, if you don't boost to the maximum power your access
point, you will have no connection at all in ad-hoc mesh networks at
2.4Ghz.

Moreover, the other interfering nodes will not run the proposed
algorithmn (because are not from your network), so if you lower the
txpower you will isolate that node.

Again, this proposal is cross-layer. You are binding the routing
protocol to a specific radio equipment. Is this what you want ? We
want to get rid of ISO/OSI so quickly ?

Please before starting to propose new ideas, everybody should have a
look to the state of the art, like OLSR, BABEL, BATMAN, the Freifunk
network in Berlin etc etc .... we don't need to start from 0 again :)

Saverio

2010/4/12 Korvin <korvin@...>:
> Hello again.
>
> Could someone tell me, whether is it possible to tune AP transmit power/range
> individually for each node? I know that modern wlan cards support this
> feature.
>
> My idea is to tune node's range in order to optimize Netsukuku covering.
>
> In normal conditions, redundancy is good, but when amount of APs grows, they
> begin interfering with each other, causing degradation of overall speed. If
> we'll try to manage the tx power, things would be better.
>
> So, each node knows amount of other devices in range. If there are no devices
> around, or it's count is small, node transmits signal at full power,
> maximizing the covering.
>
> When amount of in-range devices grows, node may slightly decrease it's range
> and try to detect actual range to other devices. By knowing alternate routes
> to peers we may detect whether peer is fully dependant on our node, or it has
> another links to the world.
>
> Then we may decide, whether to decrease the range forcing remote peer to use
> other links, or to leave the things untouched.
>
> In case of overpopulated area, there is high possibility that node may have
> many routes to the world, so this would not be a problem.
>
> So:
>
> 1) if reducing of signal strengh would increase the overall quality of service
> (because of reduced interference) and out-of-range devices may switch to other
> nodes, then it is a good idea.
>
> 2) If reducing of signal strengh leads to loss of connectivity with large
> amount of nodes or even netsplit is occured, then it is a bad idea, so this
> node is important to network and actually needed to be fully powered.
>
> Actual algorithm is need to be discussed, but I think it may be some kind of
> minimax. Of course this operation need to be tied to actual network topology
> and range detection should be done using 'non invasive' method.
>
> _______________________________________________
> Netsukuku mailing list
> Netsukuku@...
> http://lists.dyne.org/mailman/listinfo/netsukuku
>
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Michael Blizek | 13 Apr 19:28 2010

Re: Suggestions on AP range and power management

Hi!

On 02:21 Tue 13 Apr     , Korvin wrote:
> Hello again.
> 
> Could someone tell me, whether is it possible to tune AP transmit power/range 
> individually for each node? I know that modern wlan cards support this 
> feature. 

I am not sure whether modifying tranmit power is a good idea at all and one
global transmit power setting per node is very likely way too course. Reasons:

1) Some nodes with poor connectivity will loose their connection.

2) Reducing transmit power reduces throughput. This means more time spend
   sending which may reduce the positive effect of reduced transmit power.

3) A node which does not reduce the transmit power may get more bandwidth
   than it should, while possibly slowing down others.

How to do it right? My proposal:

1) The mac layer should provide the cost metric itself and upper layers should
   read and honor it. This way, the mac layer will not have to transmit many
   packets between nodes with poor connectivity. Whether you see them or not
   becomes irrelevant (at least as long as the overhead for finding routes is
   small).

2) If the connectivity is good, packet sizes and/or frame aggregating should
   increase to reduce congestion avoidance overhead. The upper layer should
   try to send packets as big as possible and avoid lots small packets, except
   when sensing and reacting to poor connectivity.

3) The upper layer should try to be latency and loss tolerant and leave
   congestion avoidance to the MAC layer. If your protocol operates as a
   (linux) kernel layer 3 one, you can distinguish between drops by "radio
   noise" and drops by "sending queue full". The "radio noise" should not
   cause the slowdown of sending. Otherwise the available bandwidth will not
   be fully used and frame aggregating will not be as efficient as possible.

4) Transmit power should be *entirely* independent of the number of visible
   nodes. It may be reduced if done on the granularity of a "connection
   between 2 neighbors" and only the mac layer itself without other layers
   interfering. It may help when the connectivity is very good and packets are
   too small for congestion avoidance to do its work well.

5) In case congestion is still too high, the MAC layer should enable RTS/CTS
   and increase frame aggregating further without any command from upper
   layers.

	-Michi
--

-- 
programing a layer 3+4 network protocol for mesh networks
see http://michaelblizek.twilightparadox.com

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Luca Dionisi | 13 Apr 19:42 2010
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Re: Suggestions on AP range and power management

On Tue, Apr 13, 2010 at 2:01 PM, ZioPRoTo (Saverio Proto)
<zioproto@...> wrote:
> Again, this proposal is cross-layer. You are binding the routing
> protocol to a specific radio equipment. Is this what you want ? We
> want to get rid of ISO/OSI so quickly ?

This is important, IMHO.
Netsukuku is a routing protocol, we should discuss about issues at that level.
That is, level 3 of OSI.

> Please before starting to propose new ideas, everybody should have a
> look to the state of the art, like OLSR, BABEL, BATMAN, the Freifunk
> network in Berlin etc etc .... we don't need to start from 0 again :)

Right, again.
If you feel you have an interesting idea about wireless
communications, then maybe you should propose it to the proper
audience. (after having read and understood the state of the art, of
course)
Frankly, I don't think netsukuku is the right place.

--Luca
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Korvin | 13 Apr 20:37 2010

APs, frequencies, channels and related mesh network problem

Hi guys. Actually, I've sent this mail before, but I was experiensing some 
problems with maillist. So this is resend.

...

Some time ago I wrote an article at some of russian IT community sites 
(habrahabr.ru), which caused a lot of response.

One of commentars was quite sceptic about actual possibility of widespread 
mesh newtork. He provided two interesting links as a proof:

1) 
http://www.strixsystems.com/products/datasheets/StrixWhitepaper_Multihop.pdf
2) http://www.belairnetworks.com/resources/pdfs/Mesh_Capacity_BDMC00040-
C02.pdf

These papers are analyzing current wireless technologies in terms of mesh 
networking. Authors are saying, that modern single channel AP's are almost 
unusable in large scale networks, as latency/bandwidth degradation gets more 
and more valuable. They said that even 5 hops may kill the idea (huh?) even on 
almost noise-clean environment.

Their main argument is half duplex nature of modern WiFi and need of backhaul 
traffic forwarding along with the user one. Authors conclude that mesh networks 
may exist only with respect to separation of user/backhaul traffic 
frequencies/channels.

Could you please give a feedback/comment about it? 

-----

Anyway, whether this is true or not, I may suggest some ideas which probably 
may be taken in mind:

Overpopulated regions with many WiFi hotspots may experience problems with the 
lack of free channels. Overinterference may cause major slowdown of the whole 
thing. 

If we'll try to consciously distribute the channels on our network things may 
change. My suggestion is to use some kind of map colouring algorithm. 

Look at the picture on the page 
http://en.wikipedia.org/wiki/Four_color_theorem Suppose that different colors 
are representing different channels of WiFi, and different shapes reflecting 
radiowave interference on the urban relief. 

Because we know the placement and interconnection of our own spots, we may 
select the frequencies in a way to minimize interference with other networks, 
yet achieving good connectivity of our own. Of course this is almost opposite 
poles and improvement of one will lead to other's degradation. 

The key may be in multi channel spanning of the network, which needed to be 
handled by Netsukuku protocols.

Suppose we have two nodes: 
   ((( A )))   [[[ B ]]]
A operates on channel 6 and B on channel 10. In the current design different 
channels are treated as completely different networks which may not be aware of 
each other. Netsukuku daemons running on both nodes could not see each other, 
thus could not take this into account.

Now we adding two more WiFi spots: A2 and B2 linked to their companion by 
ethernet cable. Operating channels are reversed:
   [(  (A)<-->[A2]  )]   <~~link~~>  [(  [B] <--> (B2)  )]

Now all four nodes may be interconnected into one subnet. Of course, this may 
be done without any protocol updates. But if nodes will be aware of channels, 
they may intentionally select the operating channel to increase overall 
span/quality. On a heavy loaded environment we may intentionally create 
several layers of Netsukuku using the colouring method described above. 

By analyzing current state and channel utilization, nodes may vote and decide 
to migrate to another channel if it will improve the overall quality. On the 
other hand, such migration may lead to a network split if there are no border 
nodes linked to a previous channel and fallback internet tunnels are also 
unavailable.

P.S. I was told that recent Linksys APs have two or even three independent 
transcievers builtin. Such APs may operate on many channels at once and thus 
may be used as such ‘supernode’. (actually I don't know whether such devices 
are really exist. maybe this is not true)

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Luca Dionisi | 13 Apr 20:47 2010
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Re: APs, frequencies, channels and related mesh network problem

I will try just a shoot at it...

Wherever you are planning to deploy an AP, deploy instead a bunch of
devices, say 3, connected via a wire. Each device has a radio
transceiver on a different channel. Its mode is ad-hoc. Obviously,
each device runs Netsukuku.

You're done.

--Luca
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Korvin | 13 Apr 21:57 2010

Re: APs, frequencies, channels and related mesh network problem


> Wherever you are planning to deploy an AP, deploy instead a bunch of
> devices, say 3, connected via a wire. Each device has a radio
> transceiver on a different channel. Its mode is ad-hoc. Obviously,
> each device runs Netsukuku.
> 
> You're done.

This is true, of course. But not every man would like to buy three of them 
instead of one :)
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crash | 13 Apr 22:45 2010

Re: APs, frequencies, channels and related mesh network problem

Korvin writes:

> This is true, of course. But not every man would like to buy three of them 
> instead of one :)

Not every but some,
the vision behind presupposes, differently from actual internet, 
that if you want to act as "backbone" you can simply do it. 

If nobody care about network resilence and sustainability 
there is no network to do.

Here by now, freedom, is the only innovation you should trust.

-crash 

(0x)06BA60BC
crash(at)freaknet.org
hinezumi.org/~crash
88 de IT9VRG

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Gmane