policy based autonomic decision making for wireless networks n.
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Policy Based Autonomic Decision Making for Wireless Networks
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  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.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.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

  12. 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

  13. 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

  14. 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 Example Rule

  15. 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))

  16. RWNO-GPRS RWNO-WiFi UoA-WiFi 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

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

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

  19. 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)

  20. 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()

  21. 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

  22. 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

  23. Thank You Questions?