DUMBO II: a V-2-I emergency network
Authors: Kanchana Kanchanasut, Thirapon Wongsaardsakul, Manutsiri Chansutthirangkool, Anis Laouiti, Hajime Tazaki, Khandakar Rashedul Arefin
Venue: Proceedings of the 4th Asian Conference on Internet Engineering (2008)

Project DUMBO (Digital Ubiquitous Mobile Broadband OLSR) deploys Mobile Ad Hoc Network (MANET) for post- disaster situations where fixed network infrastructure is unavailable; an emergency network has to be put in place urgently. DUMBO allows streaming video, VoIP and short messages to be simultaneously transmitted from a number of mobile laptops or PDA's to/from the central command center, or to the other recovery workers within the same or different disaster sites. We assume that our proposed emergency network must be easy to set up with standard Wi-Fi, laptops and/or PDA's, which are readily available commercially. Besides, we set up a series of experiments realizing emergency networks with locally available vehicles such as elephants, long tailed boats, local utilities (Tuk-Tuks), bicycles and motorcycles forming vehicle-to-vehicle as well as vehicle-to-infrastructure network. In 2006, a pure OLSR DUMBO I experiment [1] was successfully carried out involving two simulated disaster sites in forest environment with elephants carrying supplies and communication nodes linked up among the two sites and a simulated headquarter in Bangkok using IPStar VSAT satellite. In DUMBO II, it is assumed that traditional communication infrastructure has been partially restored, thus limited access to the Internet can be made available. MANETs are thus used as emergency networks extending the network connectivity to areas which are still out of reach of the fixed infrastructure. In this second phase of the project, we deployed an emergency wireless network for post-disaster rescue operation with an emphasis on connecting the emergency wireless networks the fixed infrastructure. We explored the conditions where disaster areas are on the beach front with local long tailed boats in use for the post-disaster rescue operation on the sea, and other local vehicles commuting on the nearby roads with a simulated headquarter inside the 2008 international conference on Intelligent Transport System Telecommunications main conference room. Two different approaches were experimented with a common objective of providing session mobility for the mobile users; one with pure OLSR [2] attached to the Internet via access gateways and another is using MANEMO (MANET for Network Mobility (NEMO)) at Karon beach in Phuket on October 23, 2008. Real-time visualization with GPS integrated with the Google map is provided at the headquarter to track the positions and movements of the network nodes at the disaster areas. When a victim is found at the disaster area, the rescue worker informs the headquarter and shows the condition of the victim using streaming VDO. Observing the condition and position of the victim, headquarter can instruct the rescue worker to move to a specified location where the ambulance will pick up the victim to the hospital within the shortest possible time. OLSR network in the DUMBO II context is different from DUMBO I. In DUMBO I mobility is considered as slow. In fact the network was set up on back of walking elephants through the jungle, implying slow topology changes. Default values of Hello and TC period transmission proposed by the OLSR RFC were well adapted to the DUMBO I mobility scenario. In DUMBO II scenario, the use of different kind of vehicles (Tuk-Tuk, long tail boats, motorcycle) induced higher mobility and frequent topology changes. In order to offer connectivity to all the participant elements within the DUMBO II network, OLSR parameters were tuned such a way that the nodes get more frequent updates of neighborhood and topology information. DUMBO I network is a flat topology, where all OLSR nodes are connected in an isolated MANET, while DUMBO II presents Internet connected MANET. One machine is setup as an OLSR gateway with two interfaces, which are wireless and LAN. Its wireless interface operates in Ad Hoc mode joining OLSR network, and LAN interface is connected to the Internet enabling the communication with the headquarter machine. In addition, Host and Network Association (HNA) message is used to dynamically propagated default route information to OLSR networks. To provide multimedia communications on above MANET, an application called EasyDC (Easy Disaster Communication) was used. EasyDC is a novel SIP overlay network on Optimized Link State Routing (OLSR) by using a Structured Mesh Overlay Network (SMON) [3], allowing VoIP applications to operate on MANET without deploying any centralized servers. We use a Distributed Hash Table (DHT) to distribute the SIP object identifications over the mesh overlay network to provide SIP service lookups on the MANET dynamically and efficiently. SMON is a cross-layer design, which exploits routing information locally, resulting in achieving high performance with fast SIP call setup time. On the second approach, we conducted an experiment using MANEMO or MANET with NEMO functionality to provide global reachability for a mobile access network with session connectivity and Tree Discovery(TD). Routing information is provided by the Network In Node Advertisement (NINA) which exploits the loop-less cluster established by Tree Discovery protocol [4]. By using NINA on top of the TD established tree, MANEMO reproduce the NEMO behavior for a whole subtree by reducing to a single host footprint and enables it to move within the network as a single host [5]. We deployed the nested NEMO topology to extend the network coverage by using Mobile Router (MR). MR has one ingress interface which acts as an Access Points and one egress interface which acts as a MANET interface. All the mobile nodes and the lower level MRs are attached to the ingress interface and the MR itself is connected to the upper level MR with its egress interface. The information exchange optimally between local mobile networks uses MANET protocol. Each MR acts as MANET node and exchanges route information with other MRs. With this characteristics of MANEMO, the problem of NEMO such as multiple encapsulation in nested case, redundant path inside nested MRs, and the isolated network without Home Agent can be solved. With NEMO functionality, every end node does not have to use any routing protocol in order to access any external nodes. To provide video communication in the post-disaster recovery network, we can use classical WiFi devices, which have only Infrastructure mode 802.11 interfaces, and we can also use normal multimedia application like a SIP phone, which we are always using. In our scenario we provided multimedia communication using Linphone [6] which is a SIP based P2P multimedia communication tool. Generally it uses point to point communication. We customized it to support point to multipoint communication. DUMBO II provides a proof of concept on stretching connectivity of the Internet to disaster affected areas with the use of wireless mobile ad hoc networks; both schemes worked well, and in particular, the OLSR survived the condition of the long tailed boats in a slightly rough sea. In this presentation, both approaches and experiments will be described together with our preliminary analysis of DUMBO II performances.