臺灣博碩士論文加值系統

增強型細胞間干擾消除(Enhanced inter-cell interference coordination, eICIC)為一種有效降低細胞間干擾的重要方法相同頻帶。由於在異質性網路中，佈建低功率小基地台可以提升原有細胞的覆蓋範圍以及提升總體吞吐量，因此使用者原有大基地台的範圍下積極佈建，但卻導致小基地台使用者遭受來自大基地台的嚴重訊號干擾。在本論文中，我們針對增強型細胞間干擾消除的時間維度的方法來有效降低細胞間的干擾，並且在細胞範圍延伸(Cell Range Expansion, CRE)保護小細胞的範圍，以及空白子片段(Almost Blank Subframe, ABS)的技術使用下，提出一個以干擾為基礎之適應性空白子片段配置(Interference-aware adaptive ABS allocation)來最大化每個子片段的吞吐量總和，並且提升細胞邊緣使用者的吞吐量。模擬結果顯示可以提升細胞邊緣使用者的吞吐量達50%，本論文所提出的方法可用來有效提升細胞邊緣干擾減低的重要參考方法。

In this thesis, we present an interference-aware slot allocation technique for improve the system performance of the low-power pico-cells and overlaying macro-cells. In the 3rd Generation Partnership Project (3GPP) Long-Term Evolution- Advanced (LTE-A), this kind of interference between pico-cells and its overlaying macro-cell is called the interference in heterogeneous network (HetNet), which will decrease the coverage area of pico-cells and overall system throughput. In the 3GPP LTE-A cellular system, enhanced inter-cell interference coordination (eICIC) technique adopts Almost
Blank Subframes (ABS) to control the inter-cell interference between pico-cells and macro-cells. However, because of the fixed ratio ABS design, the current eICIC techniques will degrade the macrocellular performance severely and the improvement of throughput of pico-cells is also limited in a dynamic traffic environment. Thus, we propose an interference-aware slot allocation technique to adjust the ratio of ABS dynamically based on the estimated interference between macro-cells and pico-cells. Furthermore, the proposed interference-aware slot allocation technique distributively designate the blank slots. Our results show that the proposed interference-aware slot allocation technique can improve the throughput for both macro-cells and pico-cells simultaneously. In the considered case, the throughput of pico-cells and macro-cell cell edge users are improved by at least 13% and 7% respectively, compared to the current fixed ratio ABS design approach.

1 Introduction 1
1.1 Problem and Solution 2
1.2 Thesis Outline 3
2 Background 4
2.1 Overview on Heterogeneous Network 4
2.2 Introduction to Enhanced Inter-Cell Interference Coordination (eICIC) 5
2.3 Literature Survey 8
3 System Models and Problem Formulation 11
3.1 eICIC Baseline Techniques 11
3.1.1 Almost Blank Subframe(ABS) 11
3.1.2 Centralized and Distributed ABS Allocation Methods 15
3.1.3 Cell Range Expansion(CRE) 15
3.2 X2 Interface Enhancements for Time-Domain ICIC 15
3.2.1 UE side enhancement 18
3.3 Doppler Effect 21
3.4 Performance Metrics 23
3.4.1 System Sum Rate 23
3.4.2 Fairness Index 23
3.5 Problem Formulation 23
4 Interference-aware Adaptive Almost Blank Subframe Allocation in
eICIC System 26
4.1 Maximize Throughput of Each Single Subframe 26
4.2 Almost Blank Subframe Design 28
5 Numerical Results and Discussions 31
5.1 Simulation Assumptions 31
5.2 Interference-aware Adaptive ABS Allocation Method 34
5.3 Fairness of Our Method and Related Work 39
5.4 Prediction of Throughput 40
5.5 Uplink Side Transmission 40
6 Conclusion 44
6.1 Conclusions 44
Bibliography 45
Vita 47

[1] 3GPP, TR 36.814 (v9.0.0), “3rd generation partnership project: Technical specification group radio access network; evolved universal terrestrial radio access (E-UTRA); further advancements for e-UTRA physical layer aspects,” Mar. 2010.
[2] K. Okino and C. Yamazaki, “Pico cell range expansion with interference mitigation toward LTE-Advanced heterogeneous networks,” IEEE International Conference on Communications (ICC Workshops ’11), 2011.
[3] M. Vajapeyam, “Downlink FTP performance of heterogeneous networks for LTE-Advanced,” IEEE International Conference on Communications (ICC Workshops ’11), Jun. 2011.
[4] K. Balachandran, “Cell selection with downlink resource partitioning in heterogeneous networks,” IEEE International Conference on Communications (ICC Workshops ’11), Jun. 2011.
[5] R. Madan and T. Ji, “Cell association and interference coordination in heterogeneous LTE-A cellular networks,” IEEE Journal on Selected Areas in Communications, vol. 28, no. 9, pp. 1479–1489, Dec. 2010.
[6] T. Hu and P. Godin, “Chapter 31: Additional features of LTE release 10,” in LTE- The UMTS Long Term Evolution: From Theory to Practice, 2011, pp. 701–714.
[7] A. Damnjanovic and J. Montojo, “A survey on 3GPP heterogeneous networks,” IEEE Wireless Communications Magazine, pp. 10–21, Jun. 2011.
[8] J. T. Aamod Khandekar, Naga Bhushan and V. Vanghi, “LTE advanced: Heterogeneous networks,” European Wireless Conference (EW ’10), Qualcomm Inc., vol. 18, Feb. 2010.
[9] G. J. S. L. Stefan Parkvall, Erik Dahlman and L. Lindbom, “Heterogeneous network deployments in LTE,” Erricsson, Feb. 2011.
[10] J. D. N. Volker Pauli and E. Seidel, “Heterogeneous LTE networks and inter-cell interference coordination,” Nomor Research, Dec. 2010.
[11] 3GPP, R1-100061, “On technical aspects on heterogeneous networks,” Jan. 2010.
[12] 3GPP, R1-101505, “Extending Rel-8/9 ICIC into Rel-10,” Feb. 2010.
[13] 3GPP, R1-101504, “Enhanced interference management for co-channel support of HetNet deployments,” Feb. 2010.
[14] 3GPP TSG RAN WG1, “Comparison of time-domain eICIC solutions,” Aug. 2010.
[15] 3GPP, R1-103713, “Views on PDCCH interference mitigation for Het-Nets,” Jun. 2010.
[16] A. Barbieri and F. Xue, “Coordinated downlink multi-point communications in heterogeneous cellular networks,” Information Theory and Applications Workshop (ITA), 2012.
[17] G. Li and H. Liu, “Downlink radio resource allocation for multi-cell OFDMA system,” IEEE Transactions on Wireless Communications, vol. 5, no. 12, pp. 3451 –3459, Nov. 2006.
[18] C. Koutsimanis and G. Fodor, “A dynamic resource allocation scheme for guaranteed bit rate services in OFDMA networks,” IEEE International Conference on Communications (ICC Workshops ’08), pp. 2524–2530, 2008.
[19] A. Abrardo, “Centralized radio resource allocation for OFDMA cellular systems,” IEEE International Conference on Communications (ICC ’07), pp. 5738–5742, 2007.
[20] S. Roth and D. Danev, “Subframe allocation for relay networks in the LTE-Advanced standard,” IEEE 21st International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), 2010.
[21] A. R. Gabor Fodor, C. Koutsimains, “Intercell interference coordination in OFDMA networks and in the 3gpp long term evolution system,” IEEE Wireless Communications Magazine, vol. 4, no. 7, pp. 445 –453, Aug. 2009.
[22] V. Pauli and E. Seidel, “Inter-cell interference coordination for LTE-A,” Sep. 2011.
[23] I. Gvenc and M.-R. Jeong, “Range expansion and inter-cell interference coordination (ICIC) for picocell networks,” IEEE Vehicular Technology Conference (VTC Fall), pp. 1 –6, Fall 2011.