Internet DRAFT - draft-haerri-manet-position-problem-statement
draft-haerri-manet-position-problem-statement
Mobile Ad hoc Networking (MANET) J. Haerri
Internet-Draft Karlsruhe Institute of Technology
Intended status: Experimental (KIT), Germany
Expires: January 15, 2009 C. Bonnet
F. Filali
Institut Eurecom, France
July 14, 2008
MANET Position and Mobility Signaling: Problem Statement
draft-haerri-manet-position-problem-statement-01
Status of this Memo
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Abstract
This document states the problem of optimizing the structures created
by mobile network or MANET protocols to a mobile network topology.
It also justifies the use and the transmission of position
information to mitigate this problem.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Vehicular Ad Hoc Networks . . . . . . . . . . . . . . . . 6
3.2. Wireless Sensor Networks . . . . . . . . . . . . . . . . . 6
3.3. Mobile Wireless Networks . . . . . . . . . . . . . . . . . 7
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 9
5.1. Geographic Routing Protocols . . . . . . . . . . . . . . . 9
5.2. Routes and Links Instability . . . . . . . . . . . . . . . 10
6. Approach Rationals . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Geographical Routing Protocols . . . . . . . . . . . . . . 11
6.2. Routes and Links Instability . . . . . . . . . . . . . . . 11
6.3. Route Optimizations for NEMO and MIPv6 . . . . . . . . . . 11
7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Security considerations . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . . . 18
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1. Introduction
The current effort in mobile wireless network protocols is to make
them perform better at a lower maintenance overhead. For that
matter, a joint effort has been conducted in order to better adapt
the structures created by the protocols to the dynamic topology
created by nodes mobility, yet still limiting te requirement to a
ressource demanding maintenance process.
Unfortunately, the current mobile network protocols haven not been
created to understand and benefit from nodes mobility but have
instead only been designed to react blindly to the effects of
mobility on the network topology. They are notably unable to benefit
from the knowledge of nodes mobility in order to optimize the
structure with respect to the instantaneous or an expectedd future
network topology.
The knowledge of position information is one of the solutions to
improve mobile network protocols and optimize their maintenance in
order to make them more reactive with respect to the constraints
created by nodes mobility on the network topology. The community
working in this field became aware of the potential benefits from
using position information in order to improve links stability,
periodic maintenance, power consumption or even security.
In challenging vehicular environments for example, various consortia
(VII, C2C-CC, ISO CALM) even assume the native availability of
position information and are currently standardizing the content and
format of the information that should be transmitted between
vehicles.
The aim of this document is to describe possible new orientations in
protocol design that would benefit from position information and to
provide some approach rationals in that domain. This document is
also the problem description and justification for the proposal of an
extension to the metricTLV document [MEXT] that is able to exchange
mobility information for MANET protocols.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
in this document are to be interpreted as described in [RFC2119].
Additionally, this document introduces the following terminology
GPS - Global Positioning System. A geolocalization system
developped and operated by the US Department of Defense that is
able to provide accurate worldwide coordinates of devices equiped
with GPS receivers. A similar European system is currently under
developpement under the name of Galileo. The GPS system does not
work without a clear access to at least 3 satellites, thus is
inoperable for indoor positioning.
GPS-free Positioning - A set of techniques that has been developped
in order to provide a mean of localization in situation when a
clear access to satellites is not possible. Most of the methods
use multilateration techniques and require either a formal
training, or an anchor node that knows its accurate position.
Time - The universal GPS time expressed in seconds.
Longitude - The longitude describes the location of a place on Earth
east or west of a north-south line called the Prime Meridian
located in Greenwich, UK. Longitude is given as an angular
measurement ranging from 0 degree at the Prime Meridian to +180
degree eastward and -180 degree westward.
Latitude - The latitude gives the location of a place on Earth north
or south of the equator. Latitude is an angular measurement
ranging from 0 degree at the Equator to 90 degree at the poles.
Elevation - The elevation is the altitude of an object from a known
level or datum. Common datums are mean sea level and the surface
of the WGS-84 geoid, used by GPS.
Azimuth - Azimuth is the horizontal component of a direction,
measured around the horizon, from the north toward the east in the
northern hemisphere, and from the south toward the west in the
southern hemisphere.
Mobility - mobility information related to a specific address, which
MAY consist of a longitude, latitude and elevation, a velocity, an
azimuth, or the time this mobility information has been sampled.
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VANET - Vehicular Ad Hoc Networks. A particular set of MANET where
cars and road infrastructures are equiped with wireless devices.
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3. Use Cases
3.1. Vehicular Ad Hoc Networks
A vehicular ad hoc network (VANET) is a specific case of mobile ad
hoc networks, where vehicules and road infrastructures are equiped
with wireless devices. Accordingly, vehicles are able to communicate
with each others as well as interacting with the road infrastructure.
One straightforward application of VANETs is safety, where
communications are exchanged in order to improve the driver's
responsiveness and safety in case of road incidents.
A Vehicular ad hoc network is set up between cars and between cars
and road infrastructures. Due to the increased mobility, basic MANET
routing protocols are inefficient. Novel approaches have been
suggested such as state-less geographical routing, where packets are
routed without any specific route setup in the direction of the
maximum progress toward the destination node. This class of routing
protocols require the knowedge of, at least, the destination and the
forwarding node positions. Most of them use GPS-provided
coordinates.
In order to obtain a routing decision, nodes MUST exchange position
data by means of level 3 messages between cars, road infrastructures,
and location servers.
3.2. Wireless Sensor Networks
A Wireless Sensor Network (WSN) is an extreme form of a MANET in
terms of the amount of devices and of their highly limited
capabilities. Sensors can be low cost, mass produced devices
operating for years on a pair of AAA batteries. A sensor dust can be
spread over a monitored location, and from that moment on, the
sensors are fixed and operate for the lifetime of their batteries,
which are their most critical resource.
Around a Sensor Network, sinks are deployed in order to collect the
measurements from the sensors and relay the commands from the
controllers. Thus, sensors automatically form a structure to forward
unicast packets from the sensors to the sinks, and to propagate
broadcast packets across the network from the sinks.
In order to establish a routing infrastructure and scale to a large
geographic area, sensors can be deployed to form a tree, a mesh or
any kind of distributed graph that aims at optimizing communication
and energy consumption. Due to the challenging routing environment,
position information could be used to improve the routing structure.
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The IETF Roll WG [ROLL] currently reviews the available routing
protocols developped by the MANET and OSPF WGs for routing in low
power and lossy environments. If these protocols are not
satisfactory, new approaches might be envisionned, possibly
containing position information.
As sensor may only be aware of their own location, in order to
improve the creation of a routing topology, position information MAY
be exchanged between sensors and sinks. Moreover, as a mean of
improving the detection and localization of a device moving in a
monitored area, sensors MAY also have to exchanged location or
mobility information between each others.
3.3. Mobile Wireless Networks
A Mobile Wireless Network is a network where at least a group of
nodes are mobile. A Mobile Wireless Network includes infrastructure
and ad-hoc networks, VANETs, WSN, or Mesh Networks.
The mobility of routers or clients involved in a Mobile Wireless
Network is a major source of burden in standard routing protocols,
including handovers, route errors, and reduced capacity. In order to
improve this effort, mobility COULD be estimated in order improve
mobility and ressource management techniques or Quality of Service.
With the current activity of the IETF Mext WG [MEXT], it is
envisioned to allow NEMO Route Optimizations (RO) when a mobile
device leaves the area covered by an Access Router and makes a NEMO
tunnel to its Home Agent suboptimal. Such decision COULD be made
based on position information.
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4. Requirements
MANET Position and Mobility Signaling has the following requirements
R1: All nodes requirering position information SHOULD be equipped
with GPS devices. That will allow the network to have a
synchronized time as well as position information.
R2: Location signaling MUST be compatible with non-location
signaling format, more specifically, the generalized packet/
message format [PacketBB] and the Metric TLV format [MetricTLV]
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5. Problem Statement
When designing routing protocols for mobile networks, it is crutial
to make them adapted to the dynamic topology created by nodes
mobility. The more a protocol knows about the current topology or
the estimated future changes of such topology, the better is its
routing structure. To reach this objective, one method is to
increase the rate of the maintenance procedure at the consequence of
an increased maintenance overhead. On another hand, the transmission
of position information could be a mean to provide hints to the
routing protocol of the evolution of the mobile topology without
increasing the maintenance overhead.
All protocols standardized or currently in the process of being
standardized neither make any assumption on a positioning system nor
on protocols to exchange position information, which could provide a
mean of knowing neighboring nodes' coordinates and mobility. A node
ID is the major (sometimes the only) source of information about
other nodes.
Whereas those protocols have been designed to work without this kind
of strong assumption, a growing popularity appeared in the community
for location-enhanced protocols, the objective being to reduce the
maintenance process and improve the reliability of the created
structure.
The benefits of transmitting position information is possibility
related to the following working groups:
o Existing Routing Protocols ([MANET], [OSPF])
o Mobility EXTensions for IPv6 (Mext) [MEXT]
o Ad-Hoc Network Autoconfiguration (AUTOCONF) [AUTOCONF]
o Routing Over Low power and Lossy networks (ROLL) [ROLL]
5.1. Geographic Routing Protocols
The Manet working group within the IETF standardized two well known
protocols, AODV and OLSR. AODV is a reactive protocol, which opens a
route on the specific request from a source node. On the other hand,
OLSR is a proactive, also called table-driven protocol, which
computes all possible routes from and to any reachable destination.
In that perspective, the IETF is providing the community with two
sets of protocols for different applications, possiblity working
together in hybrid configurations.
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However, in recent years, a new class of routing protocol appeared.
Geographical Routing Protocols, also called Stateless Routing as no
formal routing techniques are considered, choose the forwarder based
on the "best" progress towards a destination node. The "best"
progress is not only the maximum progress, but includes a set of
heuristics that chooses the optimal forwarder based on positions,
directions, local density, or even interference level. The common
point in all these techniques is that they guarantee packet correct
delivery and rely on the knowledge of the destination and the
potential forwarder's locations.
In particularly challenging environment, where a statefull approach
may not be considered, geographic routing MAY be a promizing solution
that could also be standardized by the IETF.
5.2. Routes and Links Instability
In the Mobile Ad Hoc Network community, a major source of instability
in the provided protocols comes from nodes mobility. OLSR uses
periodic topology maintenance, and AODV developped local route
breaches repairing techniques. Yet, any kind of optimization based
on a static topology (even related to a large set of nodes) needs to
be run again after a couple of seconds when nodes are moving.
However, although those techniques may be appropriate for low mobile
networks, they reach their limits when local mobility is sudden or
lacks any correlation with the neighboring nodes. That is indeed not
a surprise if geographic routing protocols became popular in VANET,
where maintaining even a single open route (not mentionning a set of
routing tables) is often impossible.
In order to solve this issue, a growing popularity came from
mobility-aware or mobility prediction techniques used as means to not
only choose the best "actual" forwarder, but the best forwarder over
time or the best actual AND future forwarders that would reduce the
maintenance burden. Similarly to Geographical Forwarding Protocols,
the common points in all mobility predictions techniques is a node's
access to its own location and a method to spread it to neighoring
nodes. Mobility Predictions has been widely successfully studied in
the last three years, from reactive to proactive approaches even to
geographical routing protocols.
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6. Approach Rationals
MANET Position and Mobility Signaling aims at extending a node metric
TLV as defined in [MetricTLV] to define a standardized stucture to
exchange position and mobility information and to improve the
stability of MANET routing protocols. This section covers the
rationale behind this approach.
6.1. Geographical Routing Protocols
There is a large source of litterature on Geographic Routing
Protocols [Survey]. The most widely known is the Greedy Perimeter
Stateless Routing [GPSR] protocol. The major source of burden in
geographical forwarding techniques is to avoid falling into local
maxima, which is when a node cannot find any neighbor providing a
better progress than itself to the destination. In that case, one
has to define backoff techniques, which guarantee to leave the local
maximum at a cost of local detours. This is not the purpose of this
document to be exhaustive on all geographical routing protocols
developped so far. The German project Networks on Wheels (NoW) [NoW]
has been studying and improving this approach on Vehicular Ad Hoc
Networks for the last 3 years and could be a good starting point.
6.2. Routes and Links Instability
It has been shown that a simple single order mobility prediction
model was able to deliver superior routing performances than DSR or
AODV [AGAR]. A similar study has been extended to location services
[KUMAR]. The conclusions were quite similar, by noticing that the
diffusion of predicted future locations of nodes in the network could
improve the performances of location services.
On the other side of the routing techniques, different groups
developped mobility prediction techniques in order to improve
proactive protocols. It has been shown that the choice by OLSR of
nodes moving in similar direction could improve its performance
[MOLSR]. Moreover, an appropriate choice of Multipoint Relays based
on actual and the predicted future topology configuration could
significantly improve the MPR protocol, and accordingly, OLSR [KMPR].
6.3. Route Optimizations for NEMO and MIPv6
To the objective of providing internet connectivity to VANETs, a
general structure has been proposed by the various consortia related
to vehicular communication and the IETF in which a vehicle is
virtually connected to a Home Agent (HA) using NEMO and IPv6-in-IPv6
tunnels. The precise wireless multi-hop route employed between the
vehicle and an access router located in a road-side unite is
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currently not specified. A sub-IP routing mechanism has yet the
favor of the various consortia, where geographic routing, as a more
efficient mechanism in highly mobile environment than statefull
routing, is currently perferred.
When vehicles are moving, they change from access router along their
trip. Keeping the tunnel binding from a vehicle to its home agent
through a specific access router may be seen as suboptimal, notably
when the physical distance between the vehicle and the destination is
considerably smaller than to its home agent. It is currently
envisioned at the Mext WG [MEXT] to propose a Route Optimization (RO)
mechanism to update the IPv6-in-IPv6 tunnel with the closest access
router to the vehicle. In order to provide sufficient information
for a correct and possibly anticipated handover decision, the
position of the vehicle and that of the AR would be necessary. More
information related to NEMO requirements for RO for automotive
environment may be found in [NemoROAuto]
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7. IANA considerations
This document does not require any IANA action.
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8. Security considerations
This document is a problem statement and does not create any security
threat. It discusses the concepts of the use of Position and
Mobility information in Mobile Ad Hoc Networks.
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9. References
9.1. Normative References
[MetricTLV]
Dean, J., "Representing metric values in MANETs",
<tools.ietf.org/id/draft-dean-manet-metriclv-01.txt>.
[NemoROAuto]
Baldessari, R., Ernst, T., Festag, A., and M. Lenardi,
"Automotive Industry Requirements for NEMO Route
Optimization", <www.ietf.org/internet-drafts/
draft-ietf-mext-nemo-ro-automotive-req-00.txt>.
[PacketBB]
Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
"Generalized MANET Packet/Message Format",
<tools.ietf.org/id/draft-ietf-manet-packetbb-13.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References
[AGAR] Agarwal, A. and S. Das, "Dead Reckoning in Mobile Ad-Hoc
Networks", IEEE WCNC 2003, the 2003 IEEE Wireless
Communications and Networking Conference, March 2003.
[AUTOCONF]
Singh, S. and T. Clausen, "Ad-Hoc Network
Autoconfiguration (AUTOCONF) WG", <www.ietf.org/
html.charters/autoconf-charter.html>.
[GPSR] Karp, B., "Greedy Perimeter Stateless Routing (GPSR)",
<http://www.icir.org/bkarp/gpsr/gpsr.html>.
[KMPR] Harri, J., Filali, F., and C. Bonnet, "On the application
of mobility predictions to multipoint relaying in MANETs:
kinetic multipoint relays", AINTEC 2005, Asian Internet
Engineering Conference, December 2005.
[KUMAR] Kumar, V. and S. Das, "Performance of Dead Reckoning-Based
Location Service for Mobile Ad Hoc Networks", IEEE
Wireless Communications and Mobile Computing Journal,
March 2004.
[MANET] Macker, J. and I. Chakeres, "Mobile Ad-hoc Networks
(MANET)", <www.ietf.org/html.charters/manet-charter.html>.
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[MEXT] Laganier, J. and M. Bagnulo, "Mobility EXTensions for IPv6
(MEXT) WG", <www.ietf.org/html.charters/
mext-charter.html>.
[MOLSR] Menouar, H., Leonardi, M., and F. Filali, "A movement
prediction-based routing protocol for vehicle-to-vehicle
communications", V2VCOM 2005, 1st International Vehicle-
to-Vehicle Communications Workshop, July 2005.
[NoW] "Networks On Wheels (NoW)",
<http://www.network-on-wheels.de/documents.html>.
[OSPF] Lindem, A. and A. Roy, "Open Shortest Path First IGP
(OSPF) WG", <www.ietf.org/html.charters/
ospf-charter.html>.
[ROLL] Vasseur, J. and D. Culler, "Routing Over Low power and
Lossy networks (ROLL) WG", <www.ietf.org/html.charters/
roll-charter.html>.
[Survey] Mauve, M., Widmer, J., and H. Hartenstein, "A Survey on
Position-Based Routing in Mobile Ad-Hoc Networks", IEEE
Network Magazine, 15(6):30--39, November 2001.
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Authors' Addresses
Jerome Haerri
Karlsruhe Institute of Technology (KIT), Germany
Phone: +49 721 608-6407
Email: jerome.haerri@kit.edu
Christian Bonnet
Institut Eurecom, France
Phone: +33 4 93 00 8108
Email: bonnet@eurecom.fr
Fethi Filali
Institut Eurecom, France
Phone: +33 4 93 00 8134
Email: filali@eurecom.fr
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