Subject: [manet] QoS on ad-hoc networks

From: Carlos García <[email-masked]>
Date: Thu, 23 Jan 2003 16:35:19 +0100

Hi everybody,

I am very interesting in the support of QoS on adhoc networks.

I will be very pleased if someone could help me finding papers or proyects
related to this subject.

Thank you very much,
 Carlos García

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From: John Tapsell <[email-masked]>
Date: Thu, 23 Jan 2003 17:28:45 +0000

Disclaimer:  I know nothing.  My knowledge is incomplete and ba and you 
shouldn't trust it at all.

I had a look at this, and had a quite few problems trying to set up such a 
network.  Basically what I managed to learn was:
  * The idea has been around longer than I've been alive.
  * Hardly anyone seems to be working on it.
  * RSVP was played about with a lot, but died on adhoc's because it is
trying to enforce stateful connections on a stateless network.
  * You need to have a very clear idea of what properties your network has.  
How much everything moves about, whether there are groupings, whether there 
are fixed points, etc.
  * If things are going to be moving about, then the QoS is basically doomed 
:)   So switch your focus on looking whether best-effort is good enough.  
  * Implementations of various QoS systems for linux are in a bad state.  An 
implementation of dRSVP that I tried to set up had bugs that the author was 
still trying to fix.  ( I found that out _after_ spending ages trying to find 
out what was wrong).  I did manage to get another implementation of dRSVP 
working tho.  Although this was through a lot of sweat and blood - mostly due 
to my ignorance in this area.  I still don't really get the whole class based 
queueing system.
  * If you want to study QoS, make sure you study and understand routing on 
adhocs first.
  * It seems to me, in my very humble opinion, that there isn't likely to be a 
'wonder' protocol that works on any network, but rather you need to evaluate 
the network closely and see what fits best.

Take what I've said with a pinch of salt, but I hope I can help in some small 
way.

JohnFlux

---

From: "Andrew T. Campbell" <[email-masked]>
Date: Thu, 23 Jan 2003 13:08:49 -0500

Hello John and Carlos:

We looked at both stateful and
(INSIGNIA http://comet.columbia.edu/insignia/
stateless (SWAN http://comet.columbia.edu/swan/)
approaches to MANET-QOS. There are papers
and code there.

There are various tradeoffs to consider
but I now feel that the solution space
is more likely to be dominated by
stateless solutions (SWAN is one) because
they are less complex to implement and better suited
to cope with mobility.

I'm sure there are a number of interesting
solutions that lie between these stateful and stateless
approaches. I do not think RSVP in a MANET is a
good idea BTW.

IDs for our work:

INSIGNIA:

http://www.comet.columbia.edu/insignia/draft-ietf-manet-insignia-01.txt

SWAN:

http://comet.columbia.edu/swan/draft-ahn-swan-manet-00.txt

QOS has never really been on the radar screen for the WG
but maybe a good scope item for the new IRTF MANET initiative.

Its still early days for this topic I suspect.

---
Andrew
http://comet.columbia.edu/~campbell

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On Behalf Of
> John Tapsell
> Sent: Thursday, January 23, 2003 12:29 PM
> To: Carlos García
> Cc: [email-masked]
> Subject: Re: [manet] QoS on ad-hoc networks
>
>

---

From: Pablo Serrano Yáñez-Mingot <[email-masked]>
Date: Thu, 23 Jan 2003 20:20:43 +0100 (CET)

Hi all,

I fully agree with 'SWAN philosophy', in the sense that
only a practical approach is feasible in ad hoc networks
(via a simple service differentiation).

However, for me there is still an unanswered question,
of "certain importance": When is needed QoS in ad hoc
networks? I think ad hoc networks are created towards
one concrete purpose, therefore all traffic might be
considered of the same importance.

I don't think ad hoc networks are going to be used as
"multipurpose networks", where service differentiation
is a must, at least during X months/years.

Does anybody have an actual application where there is
a true need for QoS?

"Its still early days for this topic I suspect", 
Andrew stated. I also agree here.

Cheers,

Pbl

---

From: Bin Lu <[email-masked]>
Date: Thu, 23 Jan 2003 17:36:53 -0600 (CST)

I know "security" problem is not a consideration when designing a QoS
model, but probably because my interest is security, I can't help thinking
about it when looking at QoS architectures. 

In stateless models, once the packets are differentiated by the classifier
residing at border hosts, the intermediate nodes don't keep per-flow
information and therefore don't have any control over the admission. 
The intermediate nodes roughly just forward it according to the service
levels marked by the border hosts. But the problem is, what if a selfish,
greedy or malicious node who cooperates with the classifier node steals
the services? Or the classifier mismarks the packets? It is easy
because in some models (such as FQMM) the source node even classify the
packets by itself. The intermediate nodes can't do flow admissions and
therefore won't be able to detect any intrusions.

It is different in stateful QoS models. Since the intermediate nodes still
keep the per-flow information, they can check or perform admission
control.

Is there any solution for this problem in stateless models, or is there
any existing technique that can help solve the problem?

Any hint will help. Thanks in advance!

Bin

---

From: Rex Buddenberg <[email-masked]>
Date: 23 Jan 2003 15:46:38 -0800

Pablo,

The military scenarios for MANET are ones where some QoS control is
needed.  There is lots of traffic -- expect it to exceed the capacity
available forever.  And some traffic is more urgent than other.  So some
means of priority queueing and probably some admittance control is going
to be required. 

But ....

We have empirical evidence even in the wired Internet that most QoS
control scheme cures are worse than the disease.  The stateful
orientation of RSVP is an obvious one, but even diff-serv showed up a
lot of warts.  But the IETF diff-serv exercise has to be leavened with
at least two comments:
	- MANET is expressly designed to handle topology volatility.  That
volatility is guaranteed to make any QoS control scheme harder than in a
comparatively stable wired internet.  
	- the military MANET scenario is one where the standard ISP trick of
overprovisioning isn't readily available.  

If you don't care for the military scenario -- an army division on the
move -- then an emergency services one might fit just as well.  Consider
the emergency response and comms needs for a large fire (e.g. forest
fire) or a chem/bio attack on a civilian population and the
applicability of MANET capability as a need pops right out.

---

From: Pablo Serrano Yáñez-Mingot <[email-masked]>
Date: Sat, 25 Jan 2003 16:31:30 +0100 (CET)

Hi Rex,

First, thanks for your reply, but I have some brand
new comments!

I don't care for the military scenario (I mean: not from
a technical point of view :)

But I don't think 'emergency services' fit into a 
'QoS provisioning scenario', because it should be
considered an 'overlay network', and not a true
mobile ad hoc network.

I mean: in emergency situation, a new ad hoc network
should be deployed (I think). You won't have a previously
installed services, because there won't be what I called
'multipurpose ad hoc networks'. All traffic on the
network will be the same (from my point of view) in 
terms of priorities.

Also, in emergency situation you will need a reliable
authentication system, so as to only authorized nodes
are given a 'premium services' (this is why I envision
an overlay network, and not a network with QoS support)

And that's all, by the way. Cheers,

Pbl

On 23 Jan 2003, Rex Buddenberg wrote:

> On Thu, 2003-01-23 at 11:20, Pablo Serrano YÃ¡Ã±ez-Mingot wrote:
> > Hi all,
> >

---

From: David Young <[email-masked]>
Date: Thu, 23 Jan 2003 15:44:26 -0600

> Does anybody have an actual application where there is

Yes.

Let's posit a "neighborhood area network" (NAN) connecting homes in a
25 city block region with a multihop radio network. It is desirable for
it to be built on a grassroots basis. Moreover, it is *possible* for it
to be built on a grassroots basis if certain technical conditions are
met. I can think of two technical conditions off the top of my head: 1)
Nodes on the network can be installed as or more easily than television
aerials, and 2) the network is self-organizing.

Cleary a self-organizing multihop network such as a NAN needs an ad hoc
routing protocol. What are its uses that it requires QoS, though?

Media activists would like for a NAN to carry radio and video streams
containing local programming. Consumers will benefit from IP telephony
on the NAN: there will be no per-call or per-minute fees, and all
the "extras" the local telco sells them (voicemail, call-waiting,
call-forwarding) can be provided by their home PC.  Both of these
applications benefit from QoS.

Dave

-- 
David Young             OJC Technologies
[email-masked]      Engineering from the Right Brain
                        Urbana, IL * (217) 278-3933
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From: Rex Buddenberg <[email-masked]>
Date: 27 Jan 2003 09:35:11 -0800

> considered an 'overlay network', and not a true

Any real world scenario of any scale will be a mixture of infrastructure
and MANET.  I can't imagine a practical standalone MANET of any size. 
So yes, there will be a fixed infrastructure -- that the fire
departments use on a daily basis and for both operational and
non-operational traffic.
	In the event of a catastrophe (the large forest fire example) a couple
things happen:
		- some fixed infrastructure is damaged
		- the existing fire department resources may need to extend
connectivity into unplanned places so you have ad hoc buildout.
		- the local fire department is augmented with assets that surge into
the area.  A lot more ad hot (freudian sic... hoc) buildout.
		- as the fire progresses and assets move, the topology of the ad hoc
part of the network will surely change.  Similarly, the places where the
ad hoc portions of the network connect to the fixed portions can be
expected to change too.  

> should be deployed (I think). 

If you have any experience with either military or emergency services,
you should have develope antibodies that say: 'the last thing you should
do in the face of a crisis is reorganize'.  The order of battle should
be the same as the order of sailing (Nelson). 

You won't have a previously
> 'multipurpose ad hoc networks'.

All emergency services outfits I've ever dealt with have previously
installed services that they use daily -- this is a Good Thing since the
crew knows how the stuff works.  

 All traffic on the
> network will be the same (from my point of view) in 

Don't agree, but easy to go overboard.  There will be urgent traffic and
there will be not so urgent traffic.  
	But sorting this into more than about 4 bins represents such a
departure from KISS that you get in real trouble.  One outfit I'm
working with (government, of course) is looking at 64 levels of priority
since they have 6 bits to work with ... aaack.  
	These comments are to substantive traffic (I need the next water drop
over here).  They are not directed at the network convergence traffic,
which may indeed be single priority.  

> an overlay network, and not a network with QoS support)

Take a look at the IETF diff-serv exercise that ended last year.  The
hard lessons learned there:
	- the QoS control cures may be worse than the disease
	- departure from KISS has severe consequences.
Note that the need for authentication assumes the need for QoS control.
	- attempts to diddle with the DS byte open DoS attack vectors.

Second, take a look at the IEPREP working group in IETF.  Lotsa cruft in
the archive, but the basics are 1) overprovision the fixed network and
pre-empt the QoS control problem there.  2) Yes, if you're going to
provide _any_ kind of premium service, you're going to need an
authentication system to prevent abuse (by both insiders and
outsiders).

---

From: David Young <[email-masked]>
Date: Thu, 23 Jan 2003 15:44:26 -0600

Yes.

Dave

---

From: "Ankur Jain" <[email-masked]>
Date: Wed, 29 Jan 2003 00:57:25 +0530

Hello everybody,

I have some doubt about QoS after doing experiments on the testbed for ad
hoc networks.

In our experiments, we placed the nodes strategically so that they are on
the periphery of the radio range of each other. Then we started the packets
transfer and asked the nodes to move about their position. Our results show
that the wireless link is so unstable that sometimes 50% of packets get
lost.  Fifty percent is such a high figure for packet loss. I repeated the
experiments many times but the loss percantage varied from 5% to upto 70%.
We conducted the expts. in the office environment so there was some
interference with the office's wireless LAN and other RF expts running
nearby.

I wanted to ask that if we can't even ensure connectivity in such a small
region, how will we guarantee QoS over any infrastructure-less network. If
there is some fixed infrastructure then we can give some assurance of QoS
over some no. of hops. But I don't think that we can fully guarantee to
provide specified bandwidth in real ad hoc networks - be it a militray
application or in emergency situations and the network containing hundreds
of nodes. And in case of fairs/sports events, I think the network won't even
work with 802.11b due to hidden node / exposed node problem where many nodes
are in the radio range of each other.

I think right now the definition of QoS over ad hoc network is not clear. Is
there any proposal of including QoS in IRTF. Doing QoS tests in simulators
won't give the actual scenario. Has anybody done QoS experiments with the
actual testbed (with wireless links) for ad hoc networks. I am really
anxious to know their results. Please give me some pointers if there are any
papers on this.

Best Regards
Ankur

---

From: Yang Xiao <[email-masked]>
Date: Tue, 28 Jan 2003 12:25:48 -0800 (PST)

Ankur

Your testbed may depend on some WLAN cards/AP from particular
companies.
Those WLAN cards/AP cannot support QoS well.

Conclusions from such experiments should be not used as judgments for
QoS enabled Ad hoc networks in a near future.

Regards

Yang

> > authentication system to prevent abuse (by both insiders and

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From: "Kaustubh Phanse" <[email-masked]>
Date: Tue, 28 Jan 2003 15:24:11 -0500

Ankur,

	We have conducted similar experiments (in an indoor environment) as a part of our research. I would like to point out two things here: (1) Yes, there is considerable amount of "unpredictability" in the performance of nodes especially at the periphery or fringe of the radio range. However, its not necessary that this will always be the case in all real-life scenarios. (2) Secondly, this unpredictability "typically" increases considerably in an indoor environment (with lots of walls, metal structures, microwave ovens, etc.) as compared to an outdoor environment.
	So, what you are looking at is kind of a worst-case scenario.

	Talking about QoS in ad hoc networks, I agree that one may not be able to "fully" provide any guarantees (bandwidth, delay, etc.). However, as they say: "excellent is the enemy of good." I think the same philosophy can be applied to QoS in ad hoc networks -- just because we cannot have hard guarantess does not make the situation completely hopeless!
	Our preliminary wireless experiements did include dynamic bandwidth management, and demonstrated its effect using the VIC (video) application. Our results, some other observations, and lessons learnt can be found in the following paper:
K. Phanse, L. DaSilva and S. Midkiff, "Extending Policy-Based Management to Ad Hoc Networks," submitted to IEEE Network Magazine, October 2002. Available at: http://www.ee.vt.edu/~kphanse/Adhoc_policy_mgmt.pdf

Hope this helps.
Best regards,
Kaustubh
----------------------------------------------------
 Kaustubh S. Phanse     [email-masked]
 PhD candidate          http://www.ee.vt.edu/~kphanse
 Electrical & Computer Engineering Department
 Virginia Polytechnic Institute & State University
-----------------------------------------------------

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Ankur Jain
Sent: Tuesday, January 28, 2003 2:27 PM
To: [email-masked]
Subject: [manet] my doubts about QoS in ad hoc networks

Hello everybody,

Best Regards
Ankur

---

From: John Tapsell <[email-masked]>
Date: Tue, 28 Jan 2003 20:55:52 +0000

Sir,
  I'm not surprised at your results.  See the recent slashdot article on
wireless.

  QoS is a funny thing.  When you say "guarantee QoS", what do you
mean exactly?  For example, do you
_need_ a certain latency/throughput/etc, or do you merely want to be
notified if it fails?

 The idea of a traditional QoS (read that as "rsvp") on a manet
is obviously flawed.  Surely diffserv solutions and things like
Swan are the only way to go?

JohnFlux

---

From: "Ankur Jain" <[email-masked]>
Date: Wed, 29 Jan 2003 12:03:38 +0530

Hello Everybody,

Thanks for giving your inputs about QoS over Manets. I think there is a
general agreement that ensuring QoS over a standalone ad hoc network is
difficult. This is due to the inherent problems of dynamic topology,
unpredictable radio links etc.

According to me, it will be better to do research on QoS in ad hoc networks
wrt integration between fixed (aka base station ) and infrastructure-less
(or Manets) than doing QoS experiments on a stand-alone ad hoc network. Has
anybody done QoS expts on the real testbed?

I would suggest to WG (or IRTF) to include QoS as one of the news areas for
further research.

Thanks,

Best Regards
Ankur

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--------------------------------------------

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----- Original Message -----
From: Kaustubh Phanse <[email-masked]>
To: Ankur Jain <[email-masked]>; <[email-masked]>
Sent: Wednesday, January 29, 2003 1:54 AM
Subject: RE: [manet] my doubts about QoS in ad hoc networks

Ankur,

We have conducted similar experiments (in an indoor environment) as a part
of our research. I would like to point out two things here: (1) Yes, there
is considerable amount of "unpredictability" in the performance of nodes
especially at the periphery or fringe of the radio range. However, its not
necessary that this will always be the case in all real-life scenarios. (2)
Secondly, this unpredictability "typically" increases considerably in an
indoor environment (with lots of walls, metal structures, microwave ovens,
etc.) as compared to an outdoor environment.
So, what you are looking at is kind of a worst-case scenario.

Talking about QoS in ad hoc networks, I agree that one may not be able to
"fully" provide any guarantees (bandwidth, delay, etc.). However, as they
say: "excellent is the enemy of good." I think the same philosophy can be
applied to QoS in ad hoc networks -- just because we cannot have hard
guarantess does not make the situation completely hopeless!
Our preliminary wireless experiements did include dynamic bandwidth
management, and demonstrated its effect using the VIC (video) application.
Our results, some other observations, and lessons learnt can be found in the
following paper:
K. Phanse, L. DaSilva and S. Midkiff, "Extending Policy-Based Management to
Ad Hoc Networks," submitted to IEEE Network Magazine, October 2002.
Available at: http://www.ee.vt.edu/~kphanse/Adhoc_policy_mgmt.pdf

Hope this helps.
Best regards,
Kaustubh

-----Original Message-----

Hello everybody,

Best Regards
Ankur

---

From: "Pedro M. Ruiz" <[email-masked]>
Date: Wed, 29 Jan 2003 11:24:37 +0100

Dear Ankur, all,

As some people have already commented, offering strict QoS guarantees in a changing topology network is nearly unrealistic. However, applications can help in maintaining a good user-perceived QoS even when in some periods the guarantees are violated. We think that a coupled approach between applications and network-layer QoS mechanisms can certainly offer a good overall QoS.

We did such experiments using our extensions to a realtime multimedia application (audio + video) on top of our multicast routing protocol for ad hoc network extensions (MMARP) in a real indoor scenario. The results are in this paper to appear in ICOIN'2003. (http://ants.dif.um.es/staff/pedrom/ruiz-adapt.pdf)

We have more measurments which were not included due to the max paper length. So, please do not hesitate to contact us in case you need further information.

Best Wishes,

Pedro

> -----Mensaje original-----
> De: [email-masked] [mailto:[email-masked]]En nombre de Ankur
> Jain
> Enviado el: martes, 28 de enero de 2003 20:27
> Para: [email-masked]
> Asunto: [manet] my doubts about QoS in ad hoc networks
> 
> 
> Hello everybody,
>

---

From: "Xiaoning He" <[email-masked]>
Date: Wed, 29 Jan 2003 10:38:15 -0800

Here is my 2 cents. 

I think the answer to this question depends on what kind of scenario you are
talking out, what technology you are using and what goal you want to
achieve. 

For me, ad-hoc is only a term used to emphasize infrastructureless network.
It is independent of moving speed. To one extreme, if all nodes are fixed, I
didn't see why QoS can not be provided. 802 WLAN may not work, but
point-to-point wireless such as 802.16 may work very well. To another
extreme, if all nodes are moving as fast as they want, that requires further
study and I think that's the case implied in this mailing list and in your
question. Even in your scenario, how you place the nodes, what kind of
interference exists around you will definitely affect your result.
Furthermore, besides the military usage and emergence usage, there are still
many other scenarios which ad-hoc network can be used. Under those
scenarios, 802.11 WLAN is not the best choice. 

In short, I think QoS for ad-hoc network is something important in the
future. But it heavily depends on the assumptions and scenarios.

Xiaoning He, Ph.D
Research Engineer
 
NTT-DoCoMo USA Labs
181 Metro Drive, Suite 300
San Jose, CA 95110
 
Email: [email-masked]
Phone: +1 (408) 451-4737
Fax:   +1 (408) 573-1090
 
-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Ankur
Jain
Sent: Tuesday, January 28, 2003 11:27 AM
To: [email-masked]
Subject: [manet] my doubts about QoS in ad hoc networks

Hello everybody,

Best Regards
Ankur