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 By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 15, 2009. Haerri, et al. Expires January 15, 2009 [Page 1] Internet-Draft Position Signaling: Problem Statement July 2008 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 Haerri, et al. Expires January 15, 2009 [Page 2] Internet-Draft Position Signaling: Problem Statement July 2008 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. Haerri, et al. Expires January 15, 2009 [Page 3] Internet-Draft Position Signaling: Problem Statement July 2008 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. Haerri, et al. Expires January 15, 2009 [Page 4] Internet-Draft Position Signaling: Problem Statement July 2008 VANET - Vehicular Ad Hoc Networks. A particular set of MANET where cars and road infrastructures are equiped with wireless devices. Haerri, et al. Expires January 15, 2009 [Page 5] Internet-Draft Position Signaling: Problem Statement July 2008 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. Haerri, et al. Expires January 15, 2009 [Page 6] Internet-Draft Position Signaling: Problem Statement July 2008 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. Haerri, et al. Expires January 15, 2009 [Page 7] Internet-Draft Position Signaling: Problem Statement July 2008 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] Haerri, et al. Expires January 15, 2009 [Page 8] Internet-Draft Position Signaling: Problem Statement July 2008 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. Haerri, et al. Expires January 15, 2009 [Page 9] Internet-Draft Position Signaling: Problem Statement July 2008 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. Haerri, et al. Expires January 15, 2009 [Page 10] Internet-Draft Position Signaling: Problem Statement July 2008 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 Haerri, et al. Expires January 15, 2009 [Page 11] Internet-Draft Position Signaling: Problem Statement July 2008 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] Haerri, et al. Expires January 15, 2009 [Page 12] Internet-Draft Position Signaling: Problem Statement July 2008 7. IANA considerations This document does not require any IANA action. Haerri, et al. Expires January 15, 2009 [Page 13] Internet-Draft Position Signaling: Problem Statement July 2008 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. Haerri, et al. Expires January 15, 2009 [Page 14] Internet-Draft Position Signaling: Problem Statement July 2008 9. References 9.1. Normative References [MetricTLV] Dean, J., "Representing metric values in MANETs", . [NemoROAuto] Baldessari, R., Ernst, T., Festag, A., and M. Lenardi, "Automotive Industry Requirements for NEMO Route Optimization", . [PacketBB] Clausen, T., Dearlove, C., Dean, J., and C. Adjih, "Generalized MANET Packet/Message Format", . [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", . [GPSR] Karp, B., "Greedy Perimeter Stateless Routing (GPSR)", . [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)", . Haerri, et al. Expires January 15, 2009 [Page 15] Internet-Draft Position Signaling: Problem Statement July 2008 [MEXT] Laganier, J. and M. Bagnulo, "Mobility EXTensions for IPv6 (MEXT) WG", . [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)", . [OSPF] Lindem, A. and A. Roy, "Open Shortest Path First IGP (OSPF) WG", . [ROLL] Vasseur, J. and D. Culler, "Routing Over Low power and Lossy networks (ROLL) WG", . [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. Haerri, et al. Expires January 15, 2009 [Page 16] Internet-Draft Position Signaling: Problem Statement July 2008 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 Haerri, et al. Expires January 15, 2009 [Page 17] Internet-Draft Position Signaling: Problem Statement July 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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