Increasing communication availability with signal-based mobile controlled handoffs

1
Increasing communication availability with
signal-based mobile controlled handoffs

• D. Forsberg, J.T. Malinen, J.K. Malinen, H.H.
  Kari
• TSE-Institute
• Telecommunications and Software Engineering
• Laboratory of Information Processing Science
• Helsinki University of Technology
• Finland

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Increasing communication availability with
signal-based mobile controlled handoffsPresentati
on overview

• Introduction
• Wireless Mediapoli
• Dynamics - HUT Mobile IP
• Motivation
• Criteria
• Improving communication availability with Mobile
  IP
• Policy based mobility agent selection and
  detection with prioritization
• Signal quality awareness
• Two phase handoff
• Signal quality awareness
• 802.11 link layer modes
• Policies and configurability

Two phase, forward and mobile controlled soft
handoff Enables glitchless handoffs Transparent
to the mobile user Tests Handoff times Packet
loss per location update Configurable monitor
testing Data throughput Conclusions Future
work Dynamic and automatic policy
configurations Dynamic advertising of access
network services and capabilities Questions?
3
Increasing communication availability with
signal-based mobile controlled handoffsIntroducti
on

• communication availability problem
• CA is readiness for usage
• we solved the problem under signal quality based
  handoff management with Mobile IP in WLAN
• developed system is currently in use and evolving
  
• Wireless Mediapoli
• http//www.mediapoli.com/wireless
• Dynamics - HUT Mobile IP
• http//www.cs.hut.fi/Research/Dynamics/
• this presentation assumes that you are familiar
  with basic mobile IP

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Increasing communication availability with
signal-based mobile controlled handoffsMotivation

• clients require mobility in the Internet
• wireless mobile computers and portable digital
  assisstants (PDA) are becoming more common
• increased use of multimedia content with mobile
  computers (mp3 streams, real video and audio
  etc.)
• Mobile computers are powerful enough and WLANs
  have enough bandwidth to deliver the content
• mobile users want to roam between different link
  layer technologies
• Our environment is built on top of 802.11 and
  Ethernet
• user wants to control the communication
  parameters
• The user may want to use different service
  providers based on his needs and current resources

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Increasing communication availability with
signal-based mobile controlled handoffsCriteria

• mobility should not affect the data transmission
• tolerance for congestion
• efficiency
• the mobile node should use the mobility agent
  that offers the best communication availability
• the word best may not mean the same between two
  different mobile users (cost, bandwidth, services
  etc.)
• independence of the underlying radio technology
• roaming between different wireless networks

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Increasing communication availability with
signal-based mobile controlled handoffsImproving
communication availability with Mobile IP
signal quality awareness - every available MA
gets its own priority based on the signal quality
(SNR) value
two phase, soft handoff
policy based mobility agent selection and
detection with prioritization - MN can hear
possibly many MAs - priority modification
techniques
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Increasing communication availability with
signal-based mobile controlled handoffsSignal
quality awareness

• comparisons and selections are based on dynamic
  node priorities
• the signal quality can be seen as a meaningful
  distance for the mobile node between the access
  point and mobile node
• Meaningful in the sense that the communication
  availability is highly dependant on the signal
  strength in the communication path
• priorities are based on signal quality values
  received from the mobility agents
• In our system the mobility agent is running in an
  access point and thus the advertisements have
  different signal quality source

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Increasing communication availability with
signal-based mobile controlled handoffsPolicies
and configurability

• policy is a set of rules that affect the node
  selection process in the mobile node
• four different policies implemented
• default-policy uses signal quality history and
  threshold when selecting or comparing the current
  mobility agent
• newest-FA the mobile node selects the most
  recently detected mobility agent
• eager-switching neither signal quality history
  nor threshold is used during mobility agent
  selection
• early-expire the mobile node expires the
  mobility agent from the list of available
  mobility agents more eagerly

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Increasing communication availability with
signal-based mobile controlled handoffsPolicies
and configurability

• configuration of parameters fine tune the handoff
  procedures and policies
• average length number of signal quality values
  taken into the priority calculation. Average is
  calculated.
• threshold mobile node will not change the
  current mobility agent if the signal quality
  difference is below the threshold
• min-balance do not use threshold if the signal
  quality goes below this level
• expirepercent degrade the mobility agent
  priority with this percentage if the
  advertisement from the mobility agent is old
  enough
• policies and configuration variables together
  form a adjustable environment for mobile users

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Increasing communication availability with
signal-based mobile controlled handoffsHierarchic
al Mobile IP
Home Network
CN
HA
Internet
HFA1
Foreign Network
FA2
FA1
SFA
FA1
WLAN
FA5
FA3
FA6
FA4
FA4
FA3
FA4
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Increasing communication availability with
signal-based mobile controlled handoffsTwo
phase, forward and mobile controlled soft handoff

• enables glitchless handoffs
• transparent to the mobile user

MN sends location update request to the new FA
SFA changes the downstream route and sends the
location update request reply
MN receives the reply and changes the upstream
route to the new FA
1.
2.
3.
every FA between the LFA and the SFA prepares the
downstream route for the MN
every FA between the SFA and the LFA prepares the
upstream route for the MN
phase I
phase II
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Increasing communication availability with
signal-based mobile controlled handoffsTests

• tests
• handoff times
• packet loss per location update
• configurable monitor testing
• data throughput
• forced location updates
• handoff latency measured in the MN
• data throughput measured with netperf
• maximum TCP throughput and paced UDP streams
  (about 1.4 Mbps)

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Increasing communication availability with
signal-based mobile controlled handoffs Handoff
times in hierarchy
HA
CN
Location update latencies for some transitions
HFA
FA2
FA1
FA11
FA12
FA3
FA29
FA14
FA15
FA13
FA13
FA32
FA31
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Increasing communication availability with
signal-based mobile controlled handoffs
Configurable monitor testing

• lost packets and location updates measurement
  with different settings of the monitor
• testbed emulated with signal quality environment
  recorder/replayer
• packet dropping based on low signal quality levels

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Increasing communication availability with
signal-based mobile controlled handoffs Lost
packets/ location update

• Data stream
• 100kB/s, 1kB packets

HA
CN
HFA
FA12
FA11
Data stream CN --gt MN
FA3
FA29
FA14
FA15
FA3
FA3
FA13
FA31
FA32
Data stream MN --gt CN
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Increasing communication availability with
signal-based mobile controlled handoffs Data
throughput
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Increasing communication availability with
signal-based mobile controlled handoffsConclusion
s

• the mobile user can change the policy and handoff
  parameters dynamically without disturbing the
  communication sessions

• with soft handoffs neither buffering nor
  multicasting is required to achieve seamless
  handoffs

• the solution is not dependent on the handoff
  management below the network layer

• the prioritiy-based FA comparison is feasible
  because it is not bound to the signal quality
  values and, thus, not only to the WLANs

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Increasing communication availability with
signal-based mobile controlled handoffsConclusion
s

• signal quality awareness is a simple way to
  improve the communication availability without
  extending mobility protocol

• the tests showed that hierarchical Mobile IP with
  signa quality awareness and two-phase handoff
  supports micro mobility

• signal quality awareness is a simple way to
  improve the communication availability without
  extending mobility protocols

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Increasing communication availability with
signal-based mobile controlled handoffsFuture
work

• scalability with multiple mobile nodes under the
  same FA hierarchy and an HA should be analysed
• hard handoff management is required whenchannel
  switching occurs in an ad hoc mode WLAN. Its use
  with the presented system should be evaluated.
• dynamic parameters in tha FA and agent
  advertisements to support mobility agent
  selection in the MN should be studied.

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Increasing communication availability with
signal-based mobile controlled handoffsQuestions?

• D. Forsberg, J.T. Malinen, J.K. Malinen, H.H.
  Kari
• Email
• dforsber, jtm, jkmaline, hhk_at_cs.hut.fi
• WWW
• http//www.cs.hut.fi/Research/Dynamics/