1. 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

2. 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

3. 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

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

5. 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

6. 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

7. Scanning Period

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

9. 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

10. Radio Handover Execution

11. 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

12. 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

13. Analysis of Slow Network Handover

14. Packet Loss during Slow Network Handover

15. 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

16. Fast Network Handover Procedure

17. Analysis of Fast Network Handover

18. 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

19. 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)