1. Policy Based Autonomic Decision Making for Wireless Networks Niki Gazoni, Fontas Fafoutis {ngazoni,fontas}@csd.uoc.gr Department of Informatics and Telecommunications University of Athens, 2007

2. E2RII End-To-End Reconfigurability Phase II –http://e2r2.motlabs.comhttp://e2r2.motlabs.com Intelligent Wireless Communication System –Main Characteristics RAT Interoperability Context Aware Autonomic Reconfigurable

3. RAT Interoperability Multiple Radio Access Technologies –WLAN, WiFi, WiMAX –GSM/GPRS, UMTS, HSDPA –Bluetooth, Infrared

4. Context Aware Aware of their environment –Location –Device Capabilities Static (Hardware, OS, Java VM) Dynamic (Memory, Battery, CPU, Signal Strength) –User Preferences Tariff Class, Network Preferences –Network Characteristics Static (Capacity, Coverage) Dynamic (Congestion, Delay, Available Bandwidth) –Service Requirements Resources –etc

5. Autonomic Minimize human interference –Self – Management –Self – Configuration –Self – Awareness –Self – Healing –Self - *

6. Reconfigurable Dynamic Adaptation based on Contextual Information –Protocol Adaptation (Transport Layer) A protocol reconfigures its congestion control algorithm to a more suitable according to the monitored traffic –Service Adaptation (Application Layer) Video conference application “downgrades” to phone conference when network cannot support video requirements due to heavy load Seamless –Transparent to the User

7. Basic Architecture Service Provisioning Self-Configuration / Self-Management Autonomic Decision Making Context Management

8. Autonomic Decision Making Wireless Communication World –Modeled in OWL Policies define the behavior of the System –Expressed in SWRL rules Decision Making Process –Contextual Information is imported into the Ontology –Reasoner infers knowledge based on rules and context –Decision is parsed from the output of the reasoner

9. Protégé Developed by Stanford University –http://protege.stanford.eduhttp://protege.stanford.edu Graphical Ontology Designer –Developed in Java –Open Source –Supports OWL / RDF Ontologies –Supports SWRL Rules bound to the Ontology –Supports Plug-ins (Reasoners) –Provides Java Library: protégé.jar –Differences between Protégé OWL implementation and standard OWL Unique Name Assumption (UNA) –Survey (2007) suggests that 70% of academic researchers use Protégé as ontology editor

10. Ontology - OWL Classes Device –Cell phone, Laptop, PDA Network –Instance that has specific operator and uses specific RAT Service –Classified based on requirements –SMS, Phone Call, File Transfer, Web, Video Streaming Area –User Location, Coverage CostProfile –Free, Economic, Advanced RAT –GPRS, UMTS, WiFi

11. Ontology – OWL Properties Values –Provided by the Context Management module –Produced by the Reasoner Example Properties –hasCost (Network → CostProfile) –hasService (Network → Service) –PrefersOperator (User → Operator) –hasLowBudget (User → boolean) –isCustomer (User → Operator

13. Expressing policies in SWRL rules Policy continuum Different stakeholders, different views –Business view, system view, administrator view, device view... Goals –Choosing the most appropriate network –Ability for handovers –Automated procedures (e.g mass updates) Restrictions while using SWRL

14. Choosing the most appropriate network isAccessible –Set of networks that are available in the area and the user can connect to isProposed –Subset of available networks that support the desired service isPrefered-Cost –Subset of previous networks that comply with user’s budget profile isPrefered –Subset of previous networks that comply with user’s preferred provider profile

15. Example Rule a.PayedNetworks isInArea(?d, ?a) ^ availableAt(?n, ?a) ^ hasType(?n, ?r) ^ supportsRAT(?d, ?r) ^ operatedBy(?n, ?o) ^ usesDevice(?u, ?d) ^ isCustomer(?u, ?o) → isAccessible(?d, ?n) Device needs to be in network’s coverage Device must support network’s RAT User must be customer of network’s operator Device can connect to the network

16. Jess Rule Engine Reasoner –Developed in Java –Free for Educational Use http://herzberg.ca.sandia.gov/jess –Can be imported in Protégé –Implements Rete Algorithm Charles Forgy Ph.D. Thesis How it works –Translates ontology knowledge into Jess Facts –Reasons Jess Facts using Rete Algorithm –Translates new Jess Facts back into ontology knowledge Jess Facts –(assert (property_name domain_class range))

17. Example Scenario Context –Two Operators UoA RWNO –Three Networks UoA-Wifi (Free) RWNO-GPRS (Economic) RWNO-WiFi (Advanced) –A User UoA Student Low Budget Preferred Operator: UoA Scenario –User is roaming while consuming a low requirement service Objective –Decide on the network which best fits to the contextual information RWNO-GPRS RWNO-WiFi UoA-WiFi

18. Network Selection (assert (isAccessible MobilePhone RWNO-GPRS)) (assert (isProposed MobilePhone RWNO-GPRS)) (assert (isPrefered-Cost MobilePhone RWNO-GPRS)) RWNO-GPRS RWNO-WiFi UoA-WiFi (assert (isAccessible MobilePhone RWNO-GPRS)) (assert (isAccessible MobilePhone RWNO-WiFi)) (assert (isProposed MobilePhone RWNO-WiFi)) (assert (isProposed MobilePhone RWNO-GPRS)) (assert (isPrefered-Cost MobilePhone RWNO-GPRS)) (assert (isAccessible MobilePhone RWNO-GPRS)) (assert (isAccessible MobilePhone RWNO-WLAN)) (assert (isAccessible MobilePhone UoA-WiFi)) (assert (isProposed MobilePhone RWNO-WLAN)) (assert (isProposed MobilePhone RWNO-GPRS)) (assert (isProposed MobilePhone UoA-WiFi)) (assert (isPrefered-Cost MobilePhone RWNO-GPRS)) (assert (isPrefered-Cost MobilePhone UoA-WiFi)) (assert (isPrefered MobilePhone UoA-WiFi))

19. Implementation So far everything runs on Protégé Platform How to implement it into a Java application? –protege.jar –jess.jar –swrl-jess-bridge.jar

20. Protégé-OWL API Parse an ontology file into an OWLModel class –OWLModel Constructor ProtegeOWL.createJenaOWLModelFromURI(String uri) Update the OWLModel –OWLModel methods OWLNamedClass getOWLNamedClass(String name) OWLProperty getOWLProperty(String name) OWLIndividual getOWLIndividual(String name) void createOWLIndividual(String name) void addPropertyValue (OWLProperty prop, Object value)

21. SWRL-Jess-Bridge API Links an OWLModel object to a Rete object (jess.jar) –SWRLJessBridge Constructor SWRLJessBridge(OWLModel model, Rete rete) Using the bridge we can control the reasoner –SWRLJessBridge Methods void resetBridge() void ImportSWRLRulesAndOWLKnowledge() void ExportSWRLRulesAndOWLKnowledge() void RunRuleEngine() void WriteAssertedIndividualsAndProperties2OWL() String[] getAssertedProperties() int getNumberOfAssertedProperties()

22. ADM Module Initialization –Import the owl file containing the ontology, the policies and (relatively) static knowledge into an OWLModel –Create a Rete object and bridge it with the model Decision Making in 5 steps –Update the OWLModel with dynamic knowledge –Infer knowledge using the bridge –Clear the OWLModel from useless knowledge –Parse the asserted properties –Return the decision

23. Difficulties Measurements on a desktop computer show a slow decision making procedure –Caching –Re-code some modules in C++ Impossible to run it on cell phones –Libraries in use do not run in J2ME –Much slower decision making due to limited computing power

24. Thank You Questions?