Context Awareness in Network Resource Management

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Context Awareness in Network Resource Management

• ???st?? ??a???st?p?????
• Communications Network Laboratory
• Pervasive Computing Research Group
• Department Informatics and Telecommunications
• University of Athens - Greece
• bleu_at_di.uoa.gr,p-comp_at_di.uoa.gr

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T?µata

• ?????a t?? ?????f???a? ??a?s??? (Context)
• ????? ???t??? (Network Resources)
• ??a?e???s? ????? ???t??? ßas?sµ??? st??
  ?????f???a ??a?s??? (Context-Aware Resource
  Management)

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T?µa ???t?

• Context

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?????f???a ??a?s??? - Context

• Context ?he 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
• ?t?d?p?te ????eta? s?µa?t??? ??a ?a pe??????e?
  ??t?, t?? ?at?stas? t??, ?a? t?? t??p?
  s?µpe??f???? t??.

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?????f???a ??a?s??? - Context

• ?at??????p???s?
• 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

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?????f???a ??a?s??? - Context

• Relation between contexts
• The location of a device, which belongs to a
  user, may be his/her location
• A users 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
Physical
Application
User
Activity
Device
Physical
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T?µa ?e?te??

• Network Resourcesas Network Context

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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)
• StorageThe 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/config
  uration (e.g., TCP window size) (IP vs. mobile
  IP)
• Signaling Specific protocols for connecting
  wirelessly, handing over,Signaling messages
  consume part of useful bandwidth

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Network Resources
signaling
processing
cache
storage
protocol
power
Health Safety
High Autonomy
Operator perspective
R
User perspective
Blocking Probability
Capacityusers served simultaneously
Dropping Probability
High Utilization
Periods of Interruptions
Load Balancing
Stable QoS Allocated bandwidth, BER, Delay
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T?µa ???t?

• ContextAwareness

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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
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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

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Categorization of Positioning Systems
Infrastructure
Information
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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)

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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
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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

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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)
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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

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Long Term Resource Management (LRM)

• Fine-grained pre-reservation of resources
• GoalOvercoming 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
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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)
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More context

• Location
• User profile Charging options, Preferences,
  Personalized services
• Device profile Capabilities
• Service profile LBS, software
• From Mobile Computing to
• Context-Aware Computing to
• Ubiquitous and Pervasive Computing
• http//p-comp.di.uoa.gr