Context Awareness in Network Resource

Management

Χρήστος Αναγνωστόπουλος

Communications Network LaboratoryPervasive Computing Research GroupDepartment Informatics and TelecommunicationsUniversity of Athens - Greece

bleu@di.uoa.gr,p-comp@di.uoa.gr

Θέματα:

Έννοια της Πληροφορίας Πλαισίου (Context)

Πόροι Δικτύου (Network Resources)

Διαχείριση Πόρων Δικτύου βασισμένη στην Πληροφορία Πλαισίου (Context-Aware Resource Management)

Θέμα Πρώτο

Context…

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.

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

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.

Social

Application Use

r

Activity

Device

Physical

Physical

Θέμα Δεύτερο

Network Resources…as Network Context…

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]

RUserperspective

Operatorperspective

Periods of Interruptions

Dropping Probability

Blocking Probability

High Utilization

Capacity=#users served simultaneously

Stable QoS {Allocated bandwidth, BER, Delay}

High Autonomy

Health Safety

Load Balancing

power

processing

signaling

cach

e

protocol stor

age

Network Resources

Θέμα Τρίτο

Context…Awareness

Setting up the SceneResource Management Improvement of network performanceResources 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 networkresource management

Location

Velocity

DirectionPattern…

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

Categorization of Positioning Systems

Positioning Systems

Indoor Outdoor

Separate Positioning

Infrastructure

Wi-Fi-enabled Satellite-based Terrestrial-based

GPSEGNOSGLONASSGALILEO

GSMWLAN(Nibble,Ekahau)

Positioning Systems

Symbolic Location Physical Location

Tree-based Spatial Ontologies Relative Absolute

Infrastructure

Information

accuracy

COO TOA AOA GPS

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., 1. Bhattacharya and Das (1999) Theory of Entropy (LeZi)2. Maguire and Liu (1996) Regularity-pattern detection (Kalman

Filters)3. Hadjiefthymiades and Merakos (1999) Learning Automaton

(Reward/Penalty)

?

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)

time

synchronous

SnapshotSort Term Management

time

asynchronous

SnapshotLong Term Management

recording

proactive

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}

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)

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

}

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

}

More advancedWireless Resource Management

No advance reservation in candidate cells

[No HO provision]

Less advanced

Advance reservation in

all cells[Crude HO provision]

Advance reservation in

most likely cells[Direction Sensitive

HO provision]

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)

Location User profile {Charging options, Preferences, Personalized

services}

Device profile {Capabilities}

Service profile {LBS, software}

…

From Mobile Computing toContext-Aware Computing toUbiquitous and Pervasive Computing

http://p-comp.di.uoa.gr

More context…