Mobility Support in Wireless LAN CHEN Zhiming 52479H Department of Electrical and Communications Engineering 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Acknowledgement Supervisor : Professor Sven-Gustav Häggman Instructor : Lic.Tech Michael Hall Communications Laboratory,HUT 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Agenda Thesis Introduction IEEE802.11 WLAN overview Base Mobile IP (v4/v6) review Enhancements to the base Mobile IP A new proposed protocol Summary 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Thesis Introduction 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Thesis Introduction The work of the thesis is mainly based on literature study Standarized specifications Drafted specifications Research publications Discussion with the professor and the instructor 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Thesis Introduction Main goal: Investigate how mobility is supported in WLAN, especially in the network layer. 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Thesis Introduction Major contributions: An in-depth study in Mobile IP and its enhancements for ’seamless’ handover Categorization of these enhancements A new protocol proposal 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT IEEE802.11 WLAN overview 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT IEEE802.11 WLAN overview An Extended Service Set (ESS) 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT IEEE802.11 WLAN overview IEEE802.11 defines three categories of mobility in a WLAN: No-transition: a MN is either static or moving within a BSS. BSS-transition: a MN moves from one BSS to another within the same ESS. ESS-transition: a MN moves from a BSS in one ESS to a BSS in a different ESS. 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT IEEE802.11 WLAN overview No-transition: supported by the association service BSS-transition: supported by the association and reassociation service. IAPP (Inter Access Point Protocol ) provides a secure handover mechanism between APs in the same ESS. (Layer-2 solution). 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT IEEE802.11 WLAN overview ESS-transition: Involves different IP subnets Is not supported by the IEEE802.11 specifications Mobile IP provides a solution in the network layer (L3) 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT IEEE802.11 WLAN overview Session Initiation Protocol (SIP) Mobility support in the application layer The basic SIP supports only personal mobility Minor chnages must be added to support terminal mobility 3.5.2019 S-72 Communications Laboratory, HUT

Base Mobile IP (v4/v6) review 3.5.2019 S-72 Communications Laboratory, HUT

Base Mobile IP (v4/v6) review Mobile IP allows a Mobile Node (MN) to use two IP addresses: Static home address Dynamic care-of address (CoA) 3.5.2019 S-72 Communications Laboratory, HUT

Base Mobile IP (v4/v6) review Mobile IPv4 operations Discovering the CoA CoA assigned by a foreign agent (FA),or CoA assigned by the Dynamic Host Configuration Protocol (DHCP) Registering the CoA The MN registers the acquired CoA with the HA Tunneling to the CoA Route optimization 3.5.2019 S-72 Communications Laboratory, HUT

Base Mobile IP (v4/v6) review Follows the basic design of Mobile IPv4 Works without a FA. A MN can configure its CoA by using Stateless Address Autoconfiguration and Neighbor Discovery Route Optimization is a part of the standard Ingress filtering problem can be solved by using the home address destination option 3.5.2019 S-72 Communications Laboratory, HUT

Base Mobile IP (v4/v6) review Example of WLAN with Mobile IPv4 3.5.2019 S-72 Communications Laboratory, HUT

Base Mobile IP (v4/v6) review Research results: Mobile IPv4 can be successfully implemented in the WLAN platform However, handover delay and data loss are too significant for real-time services like VoIP. 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to the base Mobile IP 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP Enhancement methods can be divided into four categories: Hierarchical FA structure or Regional Registration Fast IP address Acquisition Buffering or Smooth Handover L2 triggers 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP Hierarchical FA structure or Regional Registration CN HA RCoA MAP Mobility Anchor Point AR1 AR2 LCoA2 LCoA1 MN movement 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP Hierarchical FA structure or Regional Registration Goal: to reduce the Binding Update or Registration with the HA and CNs. How: limiting the Registration within the foreign network as long as the MN roams within the foreign network. 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP 2. Fast IP address Acquisition WLAN Frames Current fields in the association-related frames New proposed fields Association Request Capability, listen interval, SSID, supported rates Mobile IP bit, current IP address (128 bit to support IPv6) Association Response Capability, Status Code, Association ID (AID), supported rates IP address (128 bits to support IPv6) Reassociation Request Capability, listen interval, SSID, supported rates, current AP address Reassociation Response Capability, Status Code, AID, supported rates 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP Fast IP address Acquisition MN inserts its current IP address into a new field of 32 bits (128 bits for IPv6) and a Mobile IP bit in the Association and Reassociation messages. In the Response to the Association and Reassociation messages, there will be an IP address field of 32 bits (128 bit for IPv6). MN can start the Registration right after. Router Advertisement and Movement Detection are not needed. 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP Buffering or Smooth Handover Basic idea: Make routers or APs buffer incoming traffic for the MNs. By buffering, the packets in flight during a handover will not be lost. 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP L2 triggers In a normal handover process, usually the L3 handover will not take place until the MN finishes the L2 handover and then connects to a new link. By using L2 triggers, L3 handover can start earlier before a L2 handover is completed. 3.5.2019 S-72 Communications Laboratory, HUT

Enhancements to base Mobile IP L2 triggers The old FA continues to provide services (e.g. advertisement from the neighboring new FAs ) to the MN even after the MN has moved into a new FA (the new link is not fully established yet) L2 events trigger the set-up of communications between the old and new FAs. 3.5.2019 S-72 Communications Laboratory, HUT

A new proposed protocol 3.5.2019 S-72 Communications Laboratory, HUT

A new proposed protocol Follows the design scheme of category #2 ” Fast IP address Acquisition” Speeds up L3 handover without the need of Agent Advertisement, Movement Detection and Agent Solicitation. 3.5.2019 S-72 Communications Laboratory, HUT

A new proposed protocol Improvements: No need to modify the existing association and reassociation request frames. Instead,utilizes the SSID information contained in the existing association and reassociation requests frames. Thus, it appears more practical than the method used in category #2. 3.5.2019 S-72 Communications Laboratory, HUT

A new proposed protocol Basic idea: The APs and FAs have been pre-configured so that they have knowledge of their IP domains. The new FA will respond to the assocaition/ reassociation request with a CoA if the MN has moved into a new IP subnet (from the SSID). The MN can start registration right after. 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Summary 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Summary IEEE802.11 WLAN mobility support can be realized: In layer 2 – IAPP In layer 5 – SIP (with minor changes to the base protocol) In layer 3 – Mobile IP Problems: handover delay and data loss Solutions: enhancements to the base Mobile IP 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Summary Categorization of the enhanvement methods: Hierarchical FA structure or Regional Registration Fast IP address Acquisition Buffering or Smooth Handover L2 triggers 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Summary The proposed protocol: Speeds up the Mobile IP handover without modifying the existing association and reassociation request frames. 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Thnak you! 3.5.2019 S-72 Communications Laboratory, HUT

S-72 Communications Laboratory, HUT Questions?? 3.5.2019 S-72 Communications Laboratory, HUT