在無線網路日亦成長的時代,
基地台必須處理更多行動裝置, 因此基地台的負擔越來越重;
然而,使用有效的換手參數來減少換手失敗和多餘的換手次數,
可以很直接的減輕基地台的負擔, 尤其是在高速環境下;
然而,營運商不可能一一的手動調整和維護換手參數,
所以在3GPP Release 8中提出自我優化(Self-Optimization)機制,
它會根據基地台之間的測量報告去調整換手參數,
但目前的優化機制都是實作在基地台中, 無法切實解決UE個別的狀況;
本論文針對此點,
提出新的演算法USP (UserEquipment Specific Parameter)根據UE本身的狀況去調整並執行於UE上,
如此一來不但能找出適合的參數又能分攤基地台的工作。
最後,透過模擬結果顯示, USP改善整體的系統換手失敗率、Ping-Pong率和大部分的欲想換手的次數。

With the rapid growth of mobile communication, base stations need to handle more mobile devices, so the load will be much heavier in the base stations.
However, using the effective handover parameters can decrease handover failure and redundant handovers, and also alleviate base stations' load directly, especially in the high speed environment.
It's difficult to adjust and maintain the handover parameters by operator one by one, so the 3GPP LTE Release 8 introduces the self-optimization mechanism which can collect the information between neighboring nodes.
Although the self-optimization algorithm is executed by the base station mostly, it can't really solve the problems on UE.
In order to solve this problem, our thesis introduces the USP (UserEquipment Specific Parameter) algorithm which can auto-modify the handover parameters by collecting the UE's real condition.
This algorithm is executed by UE, so that USP not only can adjust the proper parameters but reduce the load from base stations.
Finally, according to our simulation results, USP decreases system's handover failure ratio, Ping-Pong ratio and most of the redundant handovers.

[1]
A. Skopljak-Ramovic, S. Pivac, and BH Mobile, Radio Network Planning, Core Network Planning, BH Telecom, Sarajevo, Bosnia-Herzegovin,
''The challenge of implementation of long term evolution / system architecture evolution (LTE/SAE),'' in
MELECON 2010 - 2010 15th IEEE Mediterranean Electrotechnical Conference. Apr 2010, pp. 1241-1246.

[2]
A. Larmo, M. Lindstrom, M. Meyer, G. Pelletier, J. Torsner, and Ericsson Res.,
''The LTE link-layer design,''
Communications Magazine, IEEE. vol. 47, no. 4, pp. 52-59, Apr. 2009.

[3]
J. Gazda, P. Drota, P. Galajda, and D. Kocur
''Comparative evaluation of OFDMA and SC-FDMA based transmission systems,'' in
Applied Machine Intelligence and Informatics (SAMI). Jan 2010, pp. 177-181.

[4]
H. Ekstrom, A. Furuskar, J. Karlsson, M. Meyer, S. Parkvall, J. Torsner, and M. Wahlqvist,
''Technical Solutions for the 3G Long-Term Evolution,''
IEEE Communications Magazine. vol. 44, no. 3, pp. 38-45, Mar. 2006.

[5]
A. Golaup, M. Mustapha, and P. Leo Boonchin,
''Femtocell Access Control Strategy in UMTS and LTE,''
IEEE Communications Magazine. vol. 47, no. 9, pp. 117-123, Sep. 2009.

[6]
A. Barbieri, A. Damnjanovic, T. Ji, J. Montojo, Y. Wei, D. Malladi, O. Song, G. Horn, and Corp. R&D, Qualcomm Inc.,
''LTE Femtocells: System Design and Performance Analysis,''
IEEE Journal on Selected Areas in Communications vol. 30, no. 3, pp. 586-594, 2012.

[7]
Y. Yuan, M. Wu, Z. Chen, and Broadband Commun. Network Lab., Beijing Univ,
''A study of algorithm for LTE intra-frequency handover,'' in
Computer Science and Service System (CSSS). Jun 2011, pp. 1986-1989.

[8]
3GPP, ``TR 36.902: Self-configuring and self-optimizing network (SON) use cases and solutions(Release 9),'' 2010.

[9]
Z. Wei,
''Mobility robustness optimization based on UE mobility for LTE system,'' in
Wireless Communications and Signal Processing (WCSP). Oct. 2010, pp. 1-5.

[10]
3GPP,
''TS 36.331 V9.1.0: Evolved Universal Terrestrial Radio Access (EUTRA)
Radio Resource Control (RRC) Protocol specification,'' 2010.

[11]
M. Li, X. She, L. Chen, H. Otsuka, and DOCOMO Beijing Commun. Labs. Co., Ltd., Beijing, China,
''A novel resource reservation scheme for fast and successful handover,'' in
2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications. Sep. 2009, pp. 556-560.

[12]
K. Dimou, M. Wang, Y. Yang, M. Kazmi, A. Larmo, J. Pettersson, W. Muller, Y. Timner, and Ericsson Res.,
''Handover within 3GPP LTE: Design Principles and Performance,'' in
Vehicular Technology Conference Fall (VTC 2009-Fall), 2009 IEEE 70th. Sep. 2009, pp. 1-5.

[13]
3GPP, ''TS 36.211 V9.1.0: E-UTRA Physical Channels and Modulation,'' 2010.

[14]
J. Puttonen, J. Kurjenniemi, O. Alanen, and Magister Solutions Ltd., Jyvaskyla, Finland,
''Radio problem detection assisted rescue handover for LTE,'' in
Personal Indoor and Mobile Radio Communications (PIMRC). Sep. 2010, pp. 1752-1757.

[15]
D. Aziz, R. Sigle, and Radio Access Domain Alcatel-Lucent Bell Labs.,
''Improvement of LTE Handover Performance through Interference Coordination,'' in
Vehicular Technology Conference, 2009. VTC Spring 2009. IEEE 69th. Apr. 2009, pp. 1-5.

[16]
M. Carvalho, P. Vieira, and Inst. de Telecomun. (IT), Lisbon, Portugal.
''An enhanced handover oscillation control algorithm in LTE Self-Optimizing networks,'' in
Wireless Personal Multimedia Communications (WPMC). Apr. 2011, pp. 1-5.

[17]
H. Hu, J. Zhang, X. Zheng, Y. Yang, P. Wu, and Chinese Acad. of Sci., Beijing, China,
''Self-configuration and self-optimization for LTE networks,''
Communications Magazine, IEEE. vol. 48, no. 2, pp. 94-100 , Feb. 2010.

[18]
S. Feng, and E. Seidel,
''Self-Organizing Networks (SON) in 3GPP Long Term Evolution,'' in
NOMOR whitepaper. May. 2010.

[19]
H. Zhang, and Nokia Siemens Networks, Beijing, China,
''Peer to peer technologies in future LTE self-organizing networks,'' in
Computing, Communications and Applications Conference (ComComAp), 2012. Jan. 2012, pp. 127-132.

[20]
A. Schroder, H. Lundqvist, and G. Nunzi,
''Distributed Self-Optimization of Handover for the Long Term Evolution,''
Proceedings of the 3rd international Workshop on Self-Organizing Systems. 2008, pp. 281-286.

[21]
T. Jansen, I. Balan, J. Turk, I. Moerman, T. Kurner, and Tech. Univ. Braunschweig,
''Handover parameter optimization in LTE self-organizing networks,'' in
Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd. Sep. 2010, pp. 1-5.

[22]
J. Alonso-Rubio, and Ericsson Res.,
''Self-Optimization for Handover Oscillation Control in LTE,'' in
Network Operations and Management Symposium (NOMS), 2010 IEEE. Apr. 2010, pp. 950-953.

[23]
W. Li, X. Duan, S. Jia, L. Zhang, Y. Liu, and J. Lin,
''A Dynamic Hysteresis-Adjusting Algorithm in LTE Self-Organization Networks,'' in
Vehicular Technology Conference (VTC Spring), 2012 IEEE 75th. May 2012, pp. 1-5.

[24]
A. Lobinger, S. Stefanski, T. Jansen, I. Balan, and Nokia Siemens Networks,
''Load Balancing in Downlink LTE Self-Optimizing Networks,'' in
Vehicular Technology Conference (VTC 2010-Spring), 2010 IEEE 71st. May 2010, pp. 1-5.

[25]
T. Komine, T. Yamamoto, S. Konishi, and KDDI R&D Laboratories Inc., 2-1-15 Ohara, Fujimino-shi, Saitama, 356-8502 Japan.
''A proposal of cell selection algorithm for LTE handover optimization,'' in
Computers and Communications (ISCC). Jul. 2012, pp. 000037-000042.

[26]
L. Ewe, H. Bakker, and Bell Labs., Alcatel-Lucent, Stuttgart, Germany,
''Base station distributed handover optimization in LTE self-organizing networks,'' in
Personal Indoor and Mobile Radio Communications (PIMRC). Sep. 2011, pp. 243-247 .

[27]
I. Balan, T. Jansen, B. Sas, I. Moerman, T. Kurner, and Interdiscipl. Inst. for Broadband Technol., Ghent,
''Enhanced weighted performance based handover optimization in LTE,'' in
Future Network & Mobile Summit (FutureNetw). 2011. Jun. 2011, pp. 1-8.

[28]
T. Jansen, I. Balan, S. Stefanski, I. Moerman, T. Kurner, and Tech. Univ. Braunschweig, Braunschweig, Germany,
''Weighted performance based handover parameter optimization in LTE,'' in
Vehicular Technology Conference (VTC Spring). May. 2011, pp. 1-5.

[29]
G. Piro, L.A Grieco, G. Boggia, F. Capozzi, P. Camarda, and Dipt. di Elettrotec. ed Elettron., Politec. di Bari, Bari, Italy,
''Simulating LTE Cellular Systems: An Open-Source Framework,''
IEEE Transactions on Vehicular Technology. vol. 60, no. 2, pp. 498-513 , Feb. 2011.

[30]
P. Legg, G. Hui, J. Johansson, and Huawei Technol.,
''A simulation study of LTE intra-frequency handover performance,'' in
2010 IEEE Vehicular Technology Conference Fall (VTC 2010-Fall). Sep. 2010, pp. 1-5.