Context-aware Adaptive Routing for Delay Tolerant Networking Mirco Musolesi Joint work with Cecilia Mascolo Department of Computer Science University College London Delay Tolerant Networks Research Group Meeting 65th IETF Meeting - Dallas, 23 March 2006

Outline of this Talk Overview of the Context-aware Adaptive Routing (CAR) protocol Extension to hybrid networks Integration with the DTN reference implementation Current research directions

Context-aware Adaptive Routing (CAR) Routing protocol for delay tolerant networks initially designed for delay tolerant mobile ad hoc networks Extension to hybrid networks, where some nodes are fixed or act as gateways for interconnecting different regions Context-aware routing designed for scenarios where: Deterministic routing information is not available No geographical information (like GPS coordinates) are available Definition of context Adaptive Routing for Intermittently Connected Mobile Ad Hoc Networks Mirco Musolesi, Stephen Hailes and Cecilia Mascolo In Proceedings of 6th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM'05). Taormina, Italy. June 2005.

Overview of the Protocol Based on host(s) acting as carrier(s) for asynchronous delivery of messages to hosts that can be: Final recipient of the message/bundle Gateways between regions (fixed or mobile, such as mobile sinks) Choice of the best carrier(s) based on the evaluation of the context information Host colocation Host mobility Battery level …

The Novelty of Our Approach Novelty of our approach: store-and-forward decisions based on the prediction of the evolution of the DTN scenario In particular, we use Time Series Analysis based on State Space Models (Kalman Filter) to keep history into account and to predict the evolution of DTN scenarios

Asynchronous Delivery: An Example B P C A M R D E N F L I Q H O

Calculation of the Host Utility Host utility calculated using multi-criteria decision theory A utility is associated to each context attribute (i.e., a utility associated to host colocation Utilities are then composed using a weighted functions

Calculation of the Host Utility We tested the algorithm considering two attributes Colocation with a certain host (that may be the final recipient of the message or a gateway) Change degree of connectivity

Kalman Filter Prediction Very lightweight Only information about the current state must be maintained Suitable for resource-constrained devices No “learning” phase is necessary Fast convergence of the filter Different prediction models (considering trends and seasonal/periodic behavior)

Context-aware Adaptive Routing Protocol Host utilities are calculated by each host and are sent to the others together with the routing tables (in our implementation DSDV) Based on local calculations Adaptive refresh interval based on the context variability If the carrier of the message gets in reach with a host that can guarantee a better delivery probability, the message is transferred to that host Local decisionsless traffic DSDV

Predictability of Context Information Key issue for CAR: predictability of context information Forecasting model cannot provide accurate predictions due to the inherent characteristics of the time series (for example randomness) Design of an autonomic component that is able at runtime to analyze the predictability of the time series of the context information If context information is not predictable, alternative routing strategies can be adopted: Intelligent epidemic routing … Evaluating Context Information Predictability for Autonomic Communication Mirco Musolesi and Cecilia Mascolo In Proceedings of 2nd IEEE Workshop on Autonomic Communications and Computing (ACC'06). Niagara Falls, NY. June 2006. To appear.

Integration of CAR in the DTN Reference Implementation Implementation in the DTN2 reference implementation in process (testing phase) Porting to resource-constrained devices Integration of DTN reference implementation in a hybrid environment DTN reference implementation for gateways? Integration with other DTN systems for constrained devices (Bluetooth equipped mobile phones, sensor networks).

CAR Implementation in DTN2

CAR for Multi-Regions DTNs Based on deterministic and probabilistic mechanisms For example a server connected to the Internet has delivery probability equal to 1 for the smtp domain. Message ferries will have a delivery probability equal to 1 to hosts that are on their pre-defined paths Host utilities used to measure The probability of delivering message to the recipients of the message for intra-region communication the probability of delivering messages to gateways (or sinks in sensor networks) for inter-regions communication Deployed on heterogeneous devices: mobile phones and WiFi APs (in progress), sensor networks (planned)

Our Current Research Directions Implementation of a system based on CAR for inter-regions communications CAR for sensor networks with mobile sinks Porting of DTN for Contiki (SICS, Sweden) Content based routing based on CAR Design of realistic mobility models based on social networks theory validated using real traces SCAR: Context-aware Adaptive Routing in Delay Tolerant Mobile Sensor Networks Cecilia Mascolo and Mirco Musolesi CS-UCL Research Note. January 2006.Submitted for Publication.

Questions? Mirco Musolesi Adaptive Routing for Intermittently Connected Mobile Ad Hoc Networks Mirco Musolesi, Stephen Hailes and Cecilia Mascolo In Proceedings of 6th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM'05). Taormina, Italy. June 2005 Evaluating Context Information Predictability for Autonomic Communication Mirco Musolesi and Cecilia Mascolo In Proceedings of 2nd IEEE Workshop on Autonomic Communications and Computing (ACC'06). Niagara Falls, NY. June 2006. To appear. SCAR: Context-aware Adaptive Routing in Delay Tolerant Mobile Sensor Networks Cecilia Mascolo and Mirco Musolesi CS-UCL Research Note. January 2006.Submitted for Publication. Mirco Musolesi Department of Computer Science University College London m.musolesi@cs.ucl.ac.uk http://www.cs.ucl.ac.uk/staff/m.musolesi