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Increasing communication availability with signal-based mobile controlled handoffs

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 handoffs

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  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

  2. Increasing communication availability with signal-based mobile controlled handoffsPresentation overview • 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? 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

  3. Increasing communication availability with signal-based mobile controlled handoffsIntroduction • 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. Mobile Node Mobile Node Mobile Node Increasing communication availability with signal-based mobile controlled handoffsHierarchical Mobile IP Home Network CN HA Internet HFA1 Foreign Network SFA FA1 FA1 FA2 WLAN FA3 FA3 FA4 FA4 FA4 FA5 FA6

  11. 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

  12. 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)

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

  14. Increasing communication availability with signal-based mobile controlled handoffsConfigurable 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

  15. Increasing communication availability with signal-based mobile controlled handoffsLost packets/ location update Data stream: 100kB/s, 1kB packets CN HA HFA FA11 FA12 Data stream CN --> MN FA13 FA3 FA3 FA3 FA29 FA14 FA15 FA31 FA32 Data stream MN --> CN

  16. Increasing communication availability with signal-based mobile controlled handoffsData throughput

  17. Increasing communication availability with signal-based mobile controlled handoffsConclusions • 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

  18. Increasing communication availability with signal-based mobile controlled handoffsConclusions • 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

  19. 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.

  20. 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}@cs.hut.fi WWW http://www.cs.hut.fi/Research/Dynamics/

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