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A Message Ferrying Approach for Data Delivery in Sparse Mobile Ad Hoc Networks. Wenrui Zhao, Mostafa Ammar and Ellen Zegura. Presentation by: Carlos Castillo. Message Ferrying. Routing in ad hoc networks Sparse networks General approach: Store-Carry-Forward
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A Message Ferrying Approach for Data Delivery in Sparse Mobile Ad Hoc Networks Wenrui Zhao, Mostafa Ammar and Ellen Zegura Presentation by: Carlos Castillo
Message Ferrying • Routing in ad hoc networks • Sparse networks • General approach: Store-Carry-Forward • Reactive Approaches: Epidemic Routing • Proactive Approaches: MF
Approaches to MF • The paper studies two approaches to MF • Node-initiated MF • Ferry-initiated MF
Message Ferrying Applications • Crisis-driven: battlefield and disaster applications • Geography-driven: for example ZebraNet • Cost-driven: for example DakNet • Service-driven: to provide privacy or anonymity
Node-Initiated MF • The ferry moves according to a specific route • Nodes make proactive movement to meet up with ferry • There are two types of drops: buffer overflow or message time out
Node Trajectory Control • Balance between meeting with ferry and performing tasks. • The paper describes a policy which allows a node to move to the ferry only when: where Di(td) = Din(td)+Dif(td)
Node Trajectory Control • Message drop rate:
Mode transition diagram for NIMF nodes: State Transitions
Ferry-Initiated MF • In this scheme the ferry takes proactive movement to meet up with nodes. • Long range radios in nodes are used to transmit control messages. • Message forwarding, device discovery and message drop computation are the same in both schemes.
Ferry-Initiated MF Operations • A node can be in two states DISSASOCIATED and ASSOCIATED. • The ferry can be in two states: IDLE and WORKING.
Node Notification Control • The goal of notification control is to minimize message drops while considering energy constraints. • The paper describes a criteria when to actually send notification control messages. • Nodes send notification messages to request communication service from the ferry. Notification messages can be: • Service_Request • Location_Update
Ferry Trajectory Control • The expected message drops for a route P is: • The ferry route problem can be stated as finding the route that minimizes Dp • When Din(t)+Dif(t)=1 for all i and t, this problem becomes a Minimum Latency Problem (MLP).
Heuristics for Ferry Control • To overcome the intractability of the initial formulation, the authors study two heuristics: • Nearest neighbor (NN) • Traffic aware (TA)
Performance Evaluation • The performance evaluation was done through simulations in the ns simulator. • Metrics: message delivery rate, message delay, delivered messages per unit of energy.
Impact of Node Mobility • Random waypoint, limited random waypoint and area based:
Closing Remarks • The paper studies the problem of data delivery in sparse ad hoc networks • The work is limited to one ferry • Contention and resources