EU Project BRAIN Handover in the IP-based Radio Access Network Arndt Kadelka Aachen University of Technology, ComNets, Germany Mobility Concept investigated in European BRAIN Project Serving Global and Local IP Mobility Performance of HiperLAN/2 Handover Procedures Integration of HiperLAN/2 Mobility and Local IP Mobility

BRAIN System Concept using HiperLAN/2-based Access BRAIN Radio Cells Horizontal Handover RNC UTRAN Node B Roaming Vertical SGSN Other Networks IP Backbone IP WAN Supports: - QoS for realtime services - Multicast - Handover

Serving Local and Global Mobility Hierarchical Mobility Mobility across Wireless Access Networks served by rather slow Mobile IP Mobility within Wireless Access Network served by fast protocols, e.g., Cellular IP, HAWAII

Local Handover within Access Network – Cellular IP Route update by Uplink IP packets sent hop-by-hop to Gateway Router

HiperLAN/2-based Radio Access Operates in the license exempt spectrum in 5-6 GHz band Radio cells up to 200 m 25 Mbit/s typical data rate Radio access can be adapted to various networks BRAIN: IP Conv. Layer

Actions to Perform a handover In H/2 fast handover decision and execution is performed by the MTs: Scanning for alternative channel, i.e., served by different APT MT indicates absence to serving AP, AP stops data transmission MT performs measurements on alternative channel(s) MT may return to serving AP or perform a handover Handover decision MT decides to perform a handover based on RSSI and PER measurements Hysteresis to avoid ping-pong-effects Handover execution MT may indicate handover intention to serving AP MT initiates handover by Handover_Request to target APT, i.e, forward handover Re-establishment of link layer communication

Scanning Period

Packet Transmission Delay owing to Scanning Downlink Transmission Uplink Transmission Amount of data effected by scanning:

Handover within H/2 Radio Access Network Radio HO performed within DLC IP layer not involved Inter-Subnet Network Handover involves also IP layer Route update of IP routing tables

Radio Handover Execution

Serving Local Mobility with H/2 Changing point of attachment to the network Re-establishment of link layer communication via the air interface Re-registration to the IP network Authentication Maintaining on-going DLC connections Integration with IP mobility via IP CL

Slow Network Handover Procedure Interworking with Cellular IP IP CL triggers route update packet Loss of IP packets received at APold before route update execution

Analysis of Slow Network Handover

Packet Loss during Slow Network Handover

Fast Network Handover with Backbone Signaling Information about on-going DLC connections retrieved via backbone Packets routed to APold are tunneled to APnew DLC address of APold is indicated during HO_Association AP has to maintain address mapping table APold DLC  IP address

Fast Network Handover Procedure

Analysis of Fast Network Handover

Making use of Slow and Fast Network Handover To make best use of Fast Network Handover procedure IP address of old AP must be known Mapping table may be set up manually, by operation and maintenance procedures administration effort not flexible dynamically, by following procedure AP selects handover procedure to be executed, i.e., Slow or Fast Network Handover MT performing 1st Handover from APold to Apnew carries out Slow Network Handover and provides DLC address (during HO_Association) and IP address of Apold (via Info_Transfer) Stores DLC/IP-address mapping Subsequent handovers from this APold are performed according Fast Handover procedure

Conclusion H/2 defines handover procedures to serve local mobility For H/2 mobility integration with IP local mobility interworking functions are investigated and defined for the new IP CL To perform network handover involving the IP network almost as fast as radio handover address mapping table has to be maintained in IPCL Procedure defined to set up the mapping table dynamically Work will be continued in follow-up project MIND Specification of IPCL and contribution to ETSI/BRAN Mobility integration with UMTS (Vertical Handover)