為了要能夠達到International Mobile Telecommunications Advanced (IMT-Advanced)的內容規範，在先進長程演進計畫(Long Term Evolution Advanced; LTE-Advanced)引進了載波聚合(Carrier Aggregation；CA)的技術。而3GPP在LTE Release-8也提倡通信業者能夠建置毫微微型基地台(Femtocell)，也稱為家庭基地台(HeNB)。但是由於HeNB不像大型基地台(Macrocell)是經過規劃後架設，因此容易造成不規則的佈建狀況，導致基地台間或基地台與使用者設備間的訊號干擾，使得整體的載波利用率及傳輸速度降低。
　　因此3GPP提出了載波自主重新分配選擇(Autonomous Component Carrier Selection； ACCS)的方法，每個基地台會依照鄰近基地台的干擾狀況選擇適合的載波使用，以避免HeNB不規則佈建所產生的載波干擾。但由於ACCS的分配方法並不完善，仍舊會造成的系統傳輸量不佳、載波使用率不佳、亦或是會造成能夠與基地台取得連線的使用者設備數量低落等問題。
　　故本論文將以提升使用者連線數為主要目標，在ACCS的基本載波分配方法架構下提出一個新的載波重新分配方法，自主載波分配選擇-備用載波調整機制(Backup Mechanism for ACCS； B-ACCS)。此調整機制在基地台遇到干擾而無法有效分配載波資源時，欲分配載波之基地台會詢問鄰近基地台是否有備用載波可以做調整，藉由調整鄰近基地台已分配的載波來達成更多的載波分配數量。模擬結果顯示，本論文研究提出的備用載波調整機制能提升主載波的資源分配數量以達成更多的使用者連線數，同時提升次載波的資源分配數量來滿足使用者設備的頻寬需求。

　　To attain the regulations of the international mobile telecommunications advanced (IMT-Advanced), this study induces the technology of carrier aggregation (CA) in the long-term evolution advanced project (LTE-Advanced). Besides, 3GPP in the LTE Release-8 also advocates that people in the communications industry establish femtocells also called HeNB. However, unlike macrocells which is established after elaborate planning, HeNB is much more easily leads to the irregular establishment. Thus, this condition will bring about signal interference between base stations and user equipment (UE), which makes the whole carrier utility and throughput speed lower.
　　Therefore, 3GPP proposes the approach of autonomous component carrier selection (ACCS), which makes every base station choose appropriate carrier according to the interference conditions near base stations to avoid the carrier interference caused by the irregular establishment of HeNB. However, the selection way of ACCS is imperfect and it will result in poor performance of system throughput and carrier utility and lower the connection of UE.
　　This study aims to enhance the users’ connection. We will propose a new CA reselection –backup mechanism for ACCS (B-ACCS) under the basic CA selection framework of ACCS. This backup mechanism will be interfered and unable to distribute carrier resources effectively. Once a base station distributes carrier, it will request near base stations if there is spare carrier to adjust by adjusting distributed carrier of near base stations to achieve more carrier distribution.Finally, simulation results show that B-ACCS proposed by this study can raise resource distribution of main carrier to attain more users’ connection and simultaneously elevate the resource distribution of sub-carrier to meet the demands of UE bandwidth.

[1]3GPP Tdoc R1-084321, Algorithms and results for autonomous component carrier selection for LTE-Advanced, Nokia Siemens Networks, Nokia
[2]3GPP Tdoc R1-090235, Use of Background Interference Matrix for Autonomous Component Carrier Selection for LTE-Advanced, Nokia Siemens Networks, Nokia
[3]G. Yuan, X. Zhing, W. Wang and Y. Yang, “Carrier Aggregation for LTE-Advanced Mobile Communication Systems,” IEEE Magazine, vol. 48, Feb. 2010, pp. 88-93.
[4]D. Erik, P. Stefan and S. Johan.(2011) “4G LTE/LTE-Advanced for Mobile Broadband”. Academic Pr
[5]“4G LTE Advanced For Communication,” Available:
http: // www. 2cm.com.tw/technologyshow_content.asp?sn=1211060003
[6]IEEE 802.16m系統下 Femto ABS 干擾消除技術 工研院資通所 / 林榮懋
[7]“Femtocell for LTE” Available: http://www.2cm.com.tw/technologyshow_content.asp?sn=120426000
[8]M. Iwamura, K. Etemad, Mo-Han Fong, R. Nory and R. Love, “Carrier aggregation framework in 3GPP LTE-advanced [WiMAX/LTE Update],” Communications Magazine, IEEE , vol.48, no.8, pp.60,67, August 2010
[9]“Specification for LTE-A System,” Available:
http://www.ncp.org.tw/vanilla/vj-attachment/2011/10/attach148.pdf
[10]3GPP Tdoc R2-103223, “DL/UL CC activation and deactivation,”NTT DOCOMO, INC.
[11]3GPP Tdoc R2-103061, “Enhancements related to inter-eNB handover during CA,”NTT DOCOMO
[12]Y. Lee, J. Zhao and H. Qu, "A combined handover scheme for LTE-advanced system," Advanced Communication Technology (ICACT), 2012 14th International Conference on , pp.154,157, 19-22 Feb. 2012
[13]M. Li, L. Liu, X. She and L. Chen, "Handover Methods Considering Channel Conditions of Multiple Aggregated Carriers," Vehicular Technology Conference (VTC Spring), 2012 IEEE 75th , pp.1,5, 6-9 May 2012
[14]X. Cao, D. Xiao and C. Xiu, "Handover performance of relaxing SCell measurement period in LTE-A with carrier aggregation," Electric Information and Control Engineering (ICEICE), 2011 International Conference on , pp.438,441, 15-17 April 2011
[15]3GPP Tdoc R2-100531, “Carrier aggregation deployment scenarios,” NTT DOCOMO.
[16]3GPP Tdoc R2-102490, “CA deployment scenarios,”NTT DOCOMO.
[17]H. Wang; C. Rosa and K. Pedersen,“Performance Analysis of Downlink Inter-Band Carrier Aggregation in LTE-Advanced,” Vehicular Technology Conference (VTC Fall), 2011 IEEE , pp.1,5, 5-8 Sept. 2011
[18]Y. Yan, A. Li, X. Gao and H. Kayama, “A New Autonomous Component Carrier Selection Scheme for Home eNB in LTE-A System,” in IEEE Vehicular Technology Conference, May 2011.
[19]L.G.U. Garcia, K.I. Pedersen and P.E. Mogensen, “Autonomous Component Carrier Selection: Interference Management in Local Area Environments for LTE-Advanced,” IEEE Communication Magazine, pp. 110–116, Sept. 2009.
[20]L.G.U. Garcia, K.I. Pedersen and P.E. Mogensen, “Autonomous Component Carrier Selection for Local Area Uncoordinated Deployment of LTE-Advanced,” Vehicular Technology Conference Fall (VTC 2009-Fall), 2009 IEEE 70th , pp.1,5, 20-23 Sept. 2009
[21]L. Liu, M. Li, J. Zhou, X. She, L. Chen, Y. Sagae, M. Iwamura,“Component Carrier Management for Carrier Aggregation in LTE-Advanced System,” Vehicular Technology Conference (VTC Spring), 2011 IEEE 73rd , pp.1,6, 15-18 May 2011
[22]Y. Wang, K.I. Pedersen, T.B. Sorensen, P.E. Mogensen,“Carrier load balancing and packet scheduling for multi-carrier systems,” Wireless Communications, IEEE Transactions on , vol.9, no.5, pp.1780,1789, May 2010
[23]X. Duan, H. Zhang, W. Li, Y. Liu and L. Zhang, “Load balancing performance of dynamic SCell measurement period relaxing in LTE-A,” Consumer Communications and Networking Conference (CCNC), 2013 IEEE , pp.773,777, 11-14 Jan. 2013
[24]C. Li, B. Wang, W. Wang, Y. Zhang and X. Chang, “Component carrier selection for LTE-A systems in diverse coverage carrier aggregation scenario,” Personal Indoor and Mobile Radio Communications (PIMRC), 2012 IEEE 23rd International Symposium on , pp.1004,1008, 9-12 Sept. 2012
[25]S. Wang, J. Wang, J. Xu, Y. Teng and K. Horneman,“Cooperative component carrier (Re-)selection for LTE-advanced femtocells,” Wireless Communications and Networking Conference (WCNC), 2011 IEEE , pp.629,634, 28-31 March 2011
[26]W.C. Hong and Z. Tsai,“Improving the autonomous component carrier selection for home eNodeBs in LTE-Advanced,” Consumer Communications and Networking Conference (CCNC), 2011 IEEE , pp.627,631, 9-12 Jan. 2011
[27]S. Uygungelen, Z. Bharucha and G. Auer,“Decentralized interference coordination via autonomous component carrier assignment,” GLOBECOM Workshops (GC Wkshps), 2011 IEEE , pp.219,224, 5-9 Dec. 2011
[28]T. M. WANG, “Enhance the Autonomous Component Carrier Selection for HeNB in LTE-A,” NTUST,TPE.