A Message Ferrying Approach for Data Delivery in Sparse Mobile Ad Hoc Networks Reporter: Yanlin Peng Wenrui Zhao, Mostafa Ammar, College of Computing, Georgia Institute of Technology

Overview Introduction Message Ferrying scheme Performance Evaluation

Introduction

Project Message Ferrying for Sparse and Disconnected Mobile NetworksMessage Ferrying for Sparse and Disconnected Mobile Networks

Publication Involved –"Controlling the Mobility of Multiple Data Transport Ferries in a Delay-Tolerant Network," IEEE INFOCOM 2005, –"A Message Ferrying Approach for Data Delivery in Sparse Mobile Ad Hoc Networks," Proceedings of ACM Mobihoc 2004, Tokyo Japan, May –"Message Ferrying: Proactive Routing in Highly- Partitioned Wireless Ad Hoc Networks," Proceedings of the IEEE Workshop on Futrure Trends in Distributed Computing Systems, Puerto Rico, May 2003

Scenarios Disconnected or partitioned network –Battlefield & natural and human-made disaster events –For applications which can tolerate significant transfer delay Solutions – message ferrying –New devices to store, carry and forward messages –Non-random movement of ferries –A proactive approach for routing in disconnected ad hoc networks

Potential applications Crisis-driven –battlefield and disaster applications, otherwise no connections Geography-driven –wide area sensing and surveillance applications. Cost-driven –DakNet project, providing low cost access for village Service-driven –by-passing the existing infrastructure to obtain a different service

Other solutions Reactive –Epidemic routing –Modified epidemic routing Proactive –mobile nodes actively modify their trajectories in order to transmit messages as soon as possible

Message Ferrying Scheme

Functions Message Ferries –A set of devices take responsibility for carrying messages between disconnected nodes –Move around the deployed area according to known routes and communicate with other nodes they meet Regular nodes (non-ferries) –With knowledge of the ferry routes, nodes can adapt their trajectories to meet the ferries and transmit or receive messages

Example The ferry moves on a know route. The sending node S actively approaches the ferry and forwards its messages to the ferry.

Example The ferry goes on moving on the know route. The receiving node R actively approaches the ferry and receives the messages. The messages are delivered from S to R.

MF system – ferries An MF system may have one or more ferries, which may operate completely independently of each other or their movements may be coordinated. While the ferry is always a mobile entity, the regular nodes can be stationary or mobile. Ferries can be either specially designated nodes or regular nodes temporarily elevated. –In the former case, a ferry’s resources (power, memory, disk storage) are not as limited as typical nodes. –For the latter case, there is, of course, the question of when and how to change node designation.

MF system – non-ferries The regular nodes may operate independently to deliver to and receive from the ferry, or coordinate with each other to form connected clusters. Within a cluster, one or more gateway nodes are in charge of communicating with the ferry. When the ferry is in range of multiple nodes, some policy is used to schedule the transmission and reception of nodes.

Ferry Mobility Task-oriented (non-messaging reasons) –Piggybacking a ferry on a metropolitan area bus. Messaging-oriented (specifically designed for improving the performance of messaging) –The ferry is implemented in a subset of robots dispersed in a disaster area, and the mobility of the ferry robots is specifically optimized for maximizing the efficiency of messaging among the other robots.

Node-Initiated MF (NIMF) scheme ferries move around the deployed area according to known routes and communicate with other nodes they meet. With knowledge of ferry routes, nodes periodically move close to a ferry and communicate with the ferry.

Node operations Status machine Trajectory Control –Tradeoff between data delivery and degradation in assigned tasks resulting from such proactive movement.

Ferry-Initiated MF (FIMF) scheme Ferries move proactively to meet nodes. When a node wants to send packets to other nodes or receive packets, it generates a service request and transmits it to a chosen ferry using a long range radio1. Upon reception of a service request, the ferry will adjust its trajectory to meet up with the node and exchange packets using short range radios.

Example Default route Node Status Ferry Status

Controls Node Notification Control –Factors: message drops, ferry location and energy consumption Ferry Trajectory Control –how the ferry controls its trajectory to meet nodes with the goal of minimizing message drops.

Performance Evaluation Metrics –data delivery message delivery rate message delay –energy delivered messages per unit energy

Impact of node buffer size

Impact of WTP threshold on NIMF performance

More Concerns Multiple Ferries –extended to the case with multiple ferries Contention. –transmission contention –buffering contention MAC protocol, transmission schedule algorithm Coordination among Regular Nodes Long Range Communication

Questions&Comments?