Context Awareness in Network Resource Management

1. Context Awareness in Network Resource Management Χρήστος Αναγνωστόπουλος Communications Network Laboratory Pervasive Computing Research Group Department Informatics and Telecommunications University of Athens - Greece bleu@di.uoa.gr,p-comp@di.uoa.gr

2. Θέματα: • Έννοια της Πληροφορίας Πλαισίου(Context) • Πόροι Δικτύου (Network Resources) • Διαχείριση Πόρων Δικτύου βασισμένη στην Πληροφορία Πλαισίου (Context-Aware Resource Management)

3. Θέμα Πρώτο Context…

4. Πληροφορία Πλαισίου - Context • Context: “Τhe information that can be used to characterize the situation of an entity, where an entity can be a person, place, physical or computational objects” [Rakotonirainy 2000] • Οτιδήποτε κρίνεται σημαντικό για να περιγράψει κάτι, την κατάστασή του, και τον τρόπο συμπεριφοράς του.

5. Πληροφορία Πλαισίου - Context • Κατηγοριοποίηση • Primary/Physical Context: Location, Identity, Time, Activity {where, when, what occurs} • User Context: User requirements, profile, charging and security policies, Position, QoS {who} • Device Context: H/S Characteristics, Location, Connectivity, OS/Application running, Manufacturer, Network Operator, Security policy, Owner {what can be used} • Application Context: Data format, Display, Voice, Connectivity, State {what can be obtained} • Network Context: Bandwidth, Storage, Protocols, Caches, Signaling • context information is not complete

6. Πληροφορία Πλαισίου - Context • Relation between contexts: • The location of a device, which belongs to a user, may be his/her location • A user’s activity depends on his/her location • My PDA is located in Room 1, your laptop is located in Room 2, and Rooms 1 and 2 are rooms of the 1st floor, then, my PDA is next to your laptop • In Room 22, the number of people is greater than 5 and a .ppt application is running and Chris’ location is this room, then, the activity in Room 22 is presentation and speech notes are downloaded to the PDA of each user located in this room, during that presentation. Physical Social Application User Activity Device Physical

7. Θέμα Δεύτερο Network Resources…as Network Context…

8. Network Resources • Basic Resources (physical entities/measurable quantities): • Bandwidth: The transferred capacity between nodes of the network. Also, Timeslots and Frequencies • Power: Overall Signal to Noise ratio (SNR) • Storage:The computing power of the network element • Implicit Resources • Cache: Replicating part of the information residing to a remote server in the local system or in systems geographically dispersed inside the network • Protocol: Efficient protocol implementation/configuration (e.g., TCP window size) (IP vs. mobile IP) • Signaling: Specific protocols for: connecting wirelessly, handing over,…[Signaling messages consume part of useful bandwidth]

9. Network Resources signaling processing cache storage protocol power Health Safety High Autonomy Operator perspective R User perspective Blocking Probability Capacity=#users served simultaneously Dropping Probability High Utilization Periods of Interruptions Load Balancing Stable QoS {Allocated bandwidth, BER, Delay}

10. Θέμα Τρίτο Context…Awareness

11. Setting up the Scene • Resource Management  Improvement of network performance • Resources are specific and can be reused • Mobility • No fixed point of connection • Dynamical resource allocation within mobile networks Task: Find specific characteristic that may assist us in the network resource management Velocity Direction Location Pattern…

12. Location Estimation • Tracking and Positioning • Cell Of Origin (COO): The differentiation of each cell • Time Of Arrival (TOA): The time window between sending and receiving signal • Angle Of Arrival (AOA): Measures the angle of the received signal, at least two directional antennas • Signal Strength Measurement (SSM): By the signal attenuation equation

13. Positioning Systems Outdoor Indoor Terrestrial-based Separate Positioning Infrastructure Wi-Fi-enabled Satellite-based GPS EGNOS GLONASS GALILEO GSM WLAN (Nibble, Ekahau) Positioning Systems Physical Location Symbolic Location Tree-based Spatial Ontologies Relative Absolute COO TOA AOA GPS accuracy Categorization of Positioning Systems Infrastructure Information

14. Location Prediction ?     • Knowledge of the future location enables the network to avert undesirable situations (e.g., dropping a call/unavailability of resources) • Required knowledge: • Velocity and Direction • History of Movements/Handover behavior • Time in the cell of residence • Handoff estimation / predictive-adaptive bandwidth reservation e.g., • Bhattacharya and Das (1999) Theory of Entropy (LeZi) • Maguire and Liu (1996) Regularity-pattern detection (Kalman Filters) • Hadjiefthymiades and Merakos (1999) Learning Automaton (Reward/Penalty)

15. Location-Aware Resource Management • Exploitation of the terminal instantaneous position information toward the management of network resources (Synchronous Management) • Continuous recording of terminal position + historical movements patterns + velocity/acceleration/direction implies proactive management of network resources (Asynchronous Management) synchronous asynchronous proactive time time recording Snapshot Sort Term Management Snapshot Long Term Management

16.  Short Term Resource Management (SRM) • Admission Control: • Context = {Users position, Idle/Active sessions, Roaming in the current cell} • Event = {User on the boundary of two or more cells} • Action= {Refuse the call initiation. This can be handled by an adjacent base station}

17.        Short Term Resource Management (SRM) • Network Reconfiguration: • Context = {Users position, Idle/Active sessions, Roaming in a cluster of cells} • Enhanced Context = {Calculation of the load in each cell, e.g., session initiation/termination probabilities} • Event = {Some cells are congested} • Action= {Re-organization/reconfiguration of resources. • (i) Frequencies are temporarily borrowed by adjacent cells to cater for increased load • (ii) Inside a cell with low user density, common channels (e.g., RACH-GSM), is reconfigured to use less timeslots per time unit • (iii) Rearrangement of user population in order to optimally distribute the load and maximize utilization • The user is provided with specific proposals on how to reach other cells where traffic load is less and better QoS can be attained } Case Study: MITOS (Alyfantis, Hadjiefthymiades, Merakos 2005)

18.  Short Term Resource Management (SRM) • Handover: • Context = {Users position, Idle/Active sessions, Roaming in the current cells} • Event = {User on the boundary of the cell, The load in the adjacent cell is lighter} • Action= { • (i)The terminal is instructed to switch communication i.e., perform a forced handover to the indicated base station. • (ii) Forced handover could be the support of specific QoS requirements of the user (user profile, policy,terminal capability).No physical relocation is required }

19. Long Term Resource Management (LRM) • Fine-grained pre-reservation of resources: • Goal={Overcoming HO-induced problems. The user does not experience service discontinuations or low service quality. Reduction of HO blocking probability} • Context = {User in the current cell} • Action= {Find the most likely neighbor cell(s) of the current cell and reserve resources in those cells} • Result={ • (i) Too early reservation leads to undesired waste of resources and low network utilization. • (ii) Delayed pre-reservation may en-up with few resources than required, forcing the termination of sessions and low experienced QoS } No advance reservation in candidate cells [No HO provision] Advance reservation in all cells [Crude HO provision] Advance reservation in most likely cells [Direction Sensitive HO provision] More advanced Less advanced Wireless Resource Management

20.  Long Term Resource Management (LRM) • Protocol Management: • Context = {Different networks (GSM/WLAN), where the user can have access, User position, Spatial information about the network resources, like protocol stack/components/modules (4G infrastructures), Dual protocol stacks is not feasible} • Event = {Switch from one network to other (TCP variant GSM to plain-vanilla TCP/WLAN)} • Action= { • (i) Advance protocol reconfiguration (downloading) to cater for another network, Push components, which will be requested by the terminal, to its nearest nodes/access points/base stations • (ii) Tune protocol parameters w.r.t. current location and network status } Case Study: Museum Wearable (Sparacino 2002)

21. More context… • Location • User profile {Charging options, Preferences, Personalized services} • Device profile {Capabilities} • Service profile {LBS, software} • … FromMobile Computingto Context-Aware Computing to Ubiquitous and Pervasive Computing http://p-comp.di.uoa.gr