1. 3G (UMTS) HANDOVER ISSUES
Team Members: Cuong Pham & Thomas Truong

2. Handover in network

3. UMTS Handover Intra-system Handover: Intra-frequency HO
Inter-frequency HO
Inter-system HO
• Different radio access technologies (e.g.
UMTS and GSM/EDGE)
• Different radio access modes (e.g.
FDD/WCDMA and TDD/TD-CDMA)

4. Hard handover
Hard handover `break-before-make' is applied when the user’s equipment communicates with only just one Node B. Connection with the old Node B is broken before the new connection is established

5. Soft handover
UE is located in the coverage area of two or more different Node Bs. The UE simultaneously communicates with two or more Node Bs via two or more radio channels. A received signal in Node B is routed to the RNC (Radio Network Controller). The RNC compares the signal on the frame by- frame basis. The best frame is selected for the next processing; the others frames are discarded.

6. Softer handover
Softer handover is similar to soft handover. The main difference between these two handovers resides in fact that a UE is located in the coverage area of two sectors of one Node B

8. Handover Phases Handover detection Handover preparation
Handover execution

9. Handover Detection
One of the responsibilities of the handover entity is monitoring and triggering the handover.

10. Handover Preparation
In this phase, the handover entity requests for the other networks resource availability information.

11. Handover Execution
A handover execution message is responsible for triggering the handover to another network and is sent by the handover entity.

12. Handover Procedure HO access BTSold BSCnew measurement result BSCold
Link establishment
MSC MS
report
HO decision
HO required
BTSnew
HO request
resource allocation
ch. activation
ch. activation ack
HO request ack
HO command
HO complete
clear command
clear complete

13. Hard Handoff Procedure

14. 3G (UMTS)
Soft Handoff Procedure

15. UMTS Radio Access Network Architecture - Mobility and Handover Issues
RNC
Iub
RNS CN
Iur Iu
Node B UE
RNC: Radio Network Controller
RNS: Radio Network Subsystem
UTRAN comprises several RNSs
Node B can support FDD or TDD or both
RNC is responsible for handover decisions requiring signaling to the UE
Cell offers FDD or TDD

16. UMTS HO Algorithm
The algorithm samples the signal strength of the surrounding base stations every 1 sec.
3dB threshold for soft handover.
6dB threshold for hard handover.
The size of the Active Set is 3 signals

17. SHO Algorithm
Each UE is connected to its Primary_BS, and keeps an Active_ Set (2 “closest” cells)
Each UE measures the SIR received from the surrounding cells.
If (AS1_SIR – Pr_BS_SIR) >3dB OR (AS2_SIR – Pr_BS_SIR) > 3dB
- UE enters Soft Handover
- UE keeps a simultaneous connection to the Primary_BS and one or both of the Active_Set cells

18. HHO Algorithm
Neighboring cells replace the cells in the Active_Set if their SIR exceeds the Active_Set cells’ SIR by 6dB.
- If (AS1_SIR – Pr_BS_SIR) > 6dB for three measurements in a row: AS1 becomes the Primary_BS
- If (AS2_SIR – Pr_BS_SIR) > 6dB for three measurements in a row: AS2 becomes the Primary_BS

19. Hard & Soft HO in UMTS
Cell 6
Cell 7
Cell 11
Cell 10

21. Parameters - UE speed = 38 km/h and moving among 3 cells.
Soft handover Threshold = 3 dB
Traffic = 12.2 kbps
Path loss = Vehicular

22. Case 1

27. Case 2

29. Case 3

30. Case 3

31. Case 4

32. Case 4

33. Average UL Transmission Power

34. Path Loss

35. Algorithm of SHO

36. References
   1/ Sattari, N.; Pangalos, P.; Aghvami, H.; Seamless handover between WLAN and UMTS Vehicular Technology Conference, VTC 2004-Spring IEEE 59th Volume 5,  May 2004 Page(s): Vol.5 Digital Object Identifier /VETECS    2/ H. Buddendick , G. Wölfle, S. Burger, and P. Wertz Simulator for Performance Analysis in UMTS FDD Networks with HSDPA 15th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) 2004, Barcelona (Spain), Sept / P. Wertz, R. Hoppe, G. Wölfle, H. Buddendick, and F.M. Landstorfer Dynamic Simulator for the Analysis of the Performance of WCDMA Radio Networks 4thCOST 273 MCM-Meeting in Lisbon, Portugal, COST 273 TD(02)148, Sept / R. Hoppe, G. Wölfle, H. Buddendick, and F.M. Landstorfer Fast Planning of Efficient WCDMA Radio Networks 54th IEEE Vehicular Technology Conference (VTC) Fall, Atlantic City (New Jersey, USA), October / R. Hoppe, H. Buddendick, G. Wölfle, and F.M. Landstorfer Dynamic Simulator for Studying WCDMA Radio Network Performance 53rd Vehicular Technology Conference (VTC) Spring, Rhodos (Greece), May 2001

37. References
6/ Hung-Hui Juan; Ching-Yao Huang; Adaptive UMTS Handover Control Algorithm in Third Generation Wireless Systems Information, Communications and Signal Processing, 2005 Fifth International Conference on Dec Page(s):
7/ Danyan Chen; Xiaofeng Wang; Elhakeem, A.K.; Performance analysis of UMTS handover with the help of WLAN Quality of Service in Heterogeneous Wired/Wireless Networks, Second International Conference on Aug Page(s):8 pp. Digital Object Identifier /QSHINE
8/ Richardson, K.W.;
UMTS overview Electronics & Communication Engineering Journal Volume 12,  Issue 3,  June 2000 Page(s):