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A Comparison of Wireless Mobile IP Movement Detection Methods for Complex Movement Patterns

A Comparison of Wireless Mobile IP Movement Detection Methods for Complex Movement Patterns. N. A. Fikouras and C. Görg Department of Communication Networks University of Bremen. Contents. Introduction to Mobile IP Mobile IP Hand-offs Movement Detection Methods Agent Selection

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A Comparison of Wireless Mobile IP Movement Detection Methods for Complex Movement Patterns

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  1. A Comparison of Wireless Mobile IP Movement Detection Methods for Complex Movement Patterns N. A. Fikouras and C. Görg Department of Communication Networks University of Bremen Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  2. Contents • Introduction to Mobile IP • Mobile IP Hand-offs • Movement Detection Methods • Agent Selection • Agent Advertisements • Regional Registrations • Complex Movement Patterns • Straight Line • Back & Forth • Simulation Setup • Simulation Results Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  3. Mobile IP • MIP is an extension to IP • Equivalent to the post office forwarding service • Enables IP Roaming • Introduces IP Layer Hand-offs • During Hand-offs the Mobile: • Detects Movement • Neighbouring Agent Discovery • Agent Selection • Registers • Hand-offs cause Packet Loss Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  4. Movement Detection • Advertisement Based • Requires Periodic Broadcast Agent Advertisements • Agent Discovery = Movement Detection • Hint Based • Requires Link-Layer Hand-off Information • LL Hand-off Hint = Movement Detection • Agents are solicited for Unicast Ads • Periodic Advertising is not needed • Solicited Ads = Agent Discovery Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  5. Optimal Movement Detection requires high advertisement rates High rates affect link throughput Advertisements require the presence of Agents Bibliography considers 100ms as optimal period Agent Advertisements Throughput of an 914MHz Lucent WaveLAN DSSS radio interface with respect to MIP agent advertisement size and period Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  6. Movement Detection Methods • Advertisement Based • Lazy Cell Switching (LCS) • Wait for Serving Agent to expire • Agent lifetime is 3 * Advertisement Period (on average: 2,5*period) • Eager Cell Switching (ECS) • Hand-off upon Agent Discovery (on average: 0.5*period) • Hint Based • Hinted Cell Switching (HCS) • Solicit when „hinted“ • Hand-off upon Agent Discovery (Mobile Node – Agent Round Trip Time) Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  7. Network Simulator: a discrete event simulator from UCB/LBNL/VINT supports Mobile IP extended to support: LCS, ECS and HCS Agent Selection as per Sun Labs MIP Regional Registrations Simulation Software Screenshot from the Simulation Visualisation with the Network Animator (NAM) Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  8. FA-MN link is wirelined No Wireless Loss Hand-offs managed through manipulation of links Controlled Cell Cross time Simulations terminated at 5% relative error rate Simulation Traffic RTP stream Emulates VAT traffic PCM encoding 78 kbps 200 octets/packet 20 ms inter-packet delay Simulation Setup Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  9. Complex Movement Patterns • Simulation Scenarios • 29 Location update frequency (locupd) rates (0.1 locupd/sec – 20 locupd/sec) • Mobile roams with a given rate on a per sec basis • Variable time between location updates - uniform(0,2/rate) • Represents variable cell size with constant size OR • Constant cell size with variable speed • Straight Line Movement (SLM) • Simulated topology: 50 FAs in a circle • With every completed circle all Agents are reinitialised • Straight line movement without patterns • Back & Forth Movement (BnFM) • Simulated topology: 2 FAs Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  10. During MIP Hand-offs a Mobile may not exchange traffic (Service Disruption) Unsuccessful Agent Selection leads to extended Service Disruption ECS/HCS outperform LCS/fLCS ECS/HCS Hands-off upon Agent Discovery HCS outperforms ECS due to faster Agent Discovery ECS waits for the next periodic broadcast HCS is “hinted” movement through LL hints HCS may solicit for Unicast Ads. SLM – Service Disruption Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  11. SLM – Service Disruption (cont.) Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  12. Agent Selection is based on the LocalMaTable (Sun Labs MIP v1.2) Selection Criteria: LCS (supported by Sun MIP): Always the Serving Agent when active OR Agent with longest lifetime ECS/HCS: Most Recently Discovered Agent OR Agent with longest lifetime fast extension (fHCS, fLCS) Ignore the LocalMaTable Make Agent Discovery based on Solicitation/Unicast Ads. Agent Selection Agent Selection in Sun Labs MIP v1.2 Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  13. BnFM – Service Disruption • In BnFM Service Disruption may be completed without a prior MIP hand-off • HCS faster Agent Discovery is not useful in BnFM. There are no agents to be discovered. • Agent Selection based on the LocalMaTable reacts only in the case of Agent Expiration • In HCS and with high lockupds expiration does not occur due to hinted solicitation • fHCS outperforms HCS due to more successful Agent Selection • The fast extension is not based on the LocalMaTable Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  14. BnFM – Service Disruption (cont.) Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  15. Conclusions (SLM) • MIP hand-offs depend on Movement Detection • MIP Movement Detection involves • Agent Discovery • Agent Selection • LCS/fLCS, ECS are based on Agent Ads. • Slow or unsuccessful Agent Discovery • LCS, ECS are based on the LocalMaTable • Unsuccessful Agent Selection • HCS/fHCS are based on LL hand-off „hints“ • Faster Agent Discovery • In Straight Line Movement HCS outperforms fLCS/LCS, ECS Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

  16. Conclusions (BnFM) • In Back & Forth Movement Agent Discovery performance is not as important • There are no new agents to be discovered • Agent Selection is more critical • LocalMaTable based methods depend on Agent Expiration • HCS does not expire agents due to solicitations • fHCS is based on the fast extension • Ignores LocalMaTable • Adapts to local Agent (Known or newly Discovered) • Performs more successful Agent Selection • Packet loss is directly dependent on service disruption • HCS/fHCS demonstrates constant best performance in both Straight Line and Back & Forth Movement Patterns Workshop: IP in Telekommunikationsnetzen Bremen, 25.1.01

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