H ELSINKI U NIVERSITY OF T ECHNOLOGY 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

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Presentation 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 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?

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Introduction 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 –Dynamics - HUT Mobile IP this presentation assumes that you are familiar with basic mobile IP

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Motivation 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 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

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Criteria 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

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

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Signal 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

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Policies 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

H ELSINKI U NIVERSITY OF T ECHNOLOGY 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 Increasing communication availability with signal-based mobile controlled handoffs Policies and configurability

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Hierarchical Mobile IP CNHA Internet Home Network WLAN FA5 FA2 HFA1 FA1 FA3FA6 Mobile Node FA4 SFA FA4FA3 FA1 Foreign Network FA4

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Two 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 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 Iphase II

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Tests 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)

H ELSINKI U NIVERSITY OF T ECHNOLOGY HACN HFA FA2 FA3 FA13 FA29 FA14 FA32 FA15 FA1 Location update latencies for some transitions FA11FA12 FA13 FA31 Increasing communication availability with signal-based mobile controlled handoffs Handoff times in hierarchy

H ELSINKI U NIVERSITY OF T ECHNOLOGY 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

H ELSINKI U NIVERSITY OF T ECHNOLOGY HACN HFA FA12 FA3 FA31 FA29FA14 FA32 FA15 FA11 FA3 FA13 Data stream CN --> MN Data stream MN --> CN Increasing communication availability with signal-based mobile controlled handoffs Lost packets/ location update Data stream: 100kB/s, 1kB packets

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Data throughput

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Conclusions the mobile user can change the policy and handoff parameters dynamically without disturbing the communication sessions the solution is not dependent on the handoff management below the network layer with soft handoffs neither buffering nor multicasting is required to achieve seamless handoffs the prioritiy-based FA comparison is feasible because it is not bound to the signal quality values and, thus, not only to the WLANs

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Conclusions 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 protocol signal quality awareness is a simple way to improve the communication availability without extending mobility protocols

H ELSINKI U NIVERSITY OF T ECHNOLOGY Increasing communication availability with signal-based mobile controlled handoffs Future 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.

H ELSINKI U NIVERSITY OF T ECHNOLOGY D. Forsberg, J.T. Malinen, J.K. Malinen, H.H. Kari {dforsber, jtm, jkmaline, WWW Increasing communication availability with signal-based mobile controlled handoffs Questions?