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Unified Wireless Access in Hot-Spot Environment

2003/12/2 報告者：黃立維. Unified Wireless Access in Hot-Spot Environment. Theodore B. Zahariadis , Member, IEEE, and Nikos A. Nikolaou , Member, IEEE IEEE COMMUNICATIONS LETTERS, VOL. 6, NO. 6, JUNE 2002. Introduction.

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Unified Wireless Access in Hot-Spot Environment

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  1. 2003/12/2 報告者：黃立維 Unified Wireless Access in Hot-Spot Environment Theodore B. Zahariadis, Member, IEEE, and Nikos A. Nikolaou, Member, IEEE IEEE COMMUNICATIONS LETTERS, VOL. 6, NO. 6, JUNE 2002

  2. Introduction • Interoperability, and mobility are the major factors of differentiation in 3G/WLAN network. • Mobile Internet applications with minimum delay, investment and operational cost in “hot spots” is to utilize already available wireless technologies, in a complementary and interoperable manner.

  3. Introduction • A prime challenge toward “hot-spot” deployment is the provision of session-oriented connections,providing roaming between heterogeneous wireless technologies. • This letter addresses the Unified Wireless Access(UniWA) architecture that is capable of support seamless handoff, utilizing existing wireless network technologies.

  4. Unified Wireless Access Architecture • UniWA is a hierarchical approach[2] that primarily focuses on “hot-spots”. • [2] D.Forsberg et al.,”Distributing mobility agents hierarchically under frequent location update”presented at 6th IEEE Int. • UniWA servers are organized in groups of UniWA Local Server(ULS), which cover “hot-spot” location, and UniWA Regional Server(URS), which cover larger,regional locations.

  5. Unified Wireless Access Architecture • Roaming within the same “hot-spot” is considered as local mobility. • Horizontal handover vs Vertical handover • Horizontal handover to a neighboring “hot-spot” is considered as regional roaming and is provided by utilizing the Mobile IP. • HLR(Home Location Register) • VLR(Visiting Location Register)

  6. Unified Wireless Access Architecture

  7. UniWA Roaming Algorithm Wireless LAN覆蓋範圍限制 • results in “many vertical roaming request”, “many routing entries updates”, and “many VLR and HLR signaling messages”. • In order to minimize this overhead in UniWA, we postpone the HLR update and treat the roaming in local or regional layer.

  8. UniWA Roaming Algorithm • What is the drawbacks of the limited WLAN’s coverage ？ • When is the roaming algorithm applied ？ • In order to minimize this overhead in UniWA, the author postpone the HLR update and treat the roaming in local or regional layer.

  9. UniWA Roaming Algorithm • When a terminal roams to a new servicing area a route between the new and the old ULS is created. • This is repeated until the local path’s length reaches a predefined threshold(TL). • Then an optimal routing algorithm is invoked to check if the path has some cycles, and if not a regional path’s path is created between the URS. • This is repeated until the regional path’s length reaches a threshold(TR). • Then the HLR is informed and the complete path to the UniWA terminal is refreshed.

  10. UniWA Paging/Traffic Routing Algorithm • Due to UniWA roaming algorithm, the paging algorithm is also modified. • Additionally to the direct indexing from HLR to the mobile terminal via the VHL,we have to trace the regional and local paths if exist. • However, this penalty is not significant in a PCS network the longer the forward chain, the largest saving can be obtained.

  11. Performance Analysis • Adapt the analytical model “Portable movement modeling for PCS network” [4] • [4]Yuguang Fang, Senior Member, IEEE, and Yi-Bing Lin, Senior Member,IEEE • TL：local path’s length • TR：regional path’s length • “l”一個terminal平均calls數 • “1/m”`:terminal落在一個ULS的平均時間 • Call-Mobility Ratio：CMR=p=“l/m” • n：使用者在兩個calls之間，漫遊了幾個UniWA server？

  12. Performance Analysis

  13. Performance Analysis_CROAM • CR is the cost of an HLR update • CULS and CURS the cost of inserting/updating a routing entry (lengthen the path) to a ULS and a URS, respectively. • Pr(n) is the probability that different UniWA servers are crossed within two calls. • “Reducing Location Update Cost in a PCS Network” Yi-Bing Lin, Senior Member, IEEE

  14. Performance Analysis_Cpage • If CLL and CRL are the costs to follow an entry in the ULS or the URS routing table. • CP is the cost for a direct terminal paging

  15. Performance Analysis

  16. Performance Analysis

  17. Performance Analysis

  18. My Conclusion • UniWA address a new architecture, that focuses on “hot-spot” and provides seamless handoff between IEEE 802.11 and 2G. • UniWA can solve the more handoff when the CMR is small.

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