摘要
异构网络技术被普遍认为是第三代伙伴计划(3GPP)制定增强型长期演进(LTE-Advanced)标准的关键候选技术之一。异构网络技术融合了多种不同类型的基站,包括宏蜂窝基站、微蜂窝基站、微微蜂窝基站、毫微微蜂窝基站、中继基站和射频单元节点。异构网络技术在传统宏蜂窝基站的覆盖区域中部署了多种类型的低功率基站,用于消除传统宏蜂窝基站的覆盖“盲区”和“忙区”,并大幅提升蜂窝网络的总容量。相比于传统的宏蜂窝基站,低功率基站(如微微蜂窝基站、家庭基站和中继基站)是一种更经济的方式来提高网络的容量。但是,在异构网络中同时部署多种类型基站,不可避免的出现不同基站覆盖区域重叠的现象。因此,异构网络需要解决复杂的小区间干扰。
本文重点研究了异构网络小区间干扰协调算法、基于功率消耗和干扰抑制的资源优化算法。异构网络小区间干扰协调算法可以有效降低小区间干扰,提高小区边缘用户的信道质量,进一步提高网络的容量和用户的性能。资源优化算法可以在满足用户需求的前提下,降低异构网络的总功率损耗,并抑制网络总干扰功率。主要研究工作和贡献如下:
提出了一种异构网络小区间干扰协调算法。根据服务用户和相邻基站的干扰关系,建立由基站节点和干扰关系连线组成的干扰图。研究了一种基于图节点染色算法的正交频带分配算法,为干扰图中相邻基站节点分配互不重叠的频带资源,在分配的正交频带完全消除了来自相邻小区的强干扰。正交频带分配方案是根据边缘用户需要满足的信噪比要求分配频带资源,可以有效控制频带内的干扰并保证边缘用户的信道质量。
为了进一步提高频谱利用率,在正交频带分配算法的基础上,提出了一种基于用户信道差异的自适应频带分配算法。自适应频带分配算法是根据本基站用户和相邻基站用户的信道质量信息与信噪比门限的比较结果,采用“申请-反馈-判决”三个连续步骤,每个基站利用相邻基站反馈的共用信息独立判断频带是否可以共用。自适应频带分配算法只需要基站间交换一定数量的频带申请、反馈信息,就可以实现资源的快速分配,提高了频谱利用率。
提出一种基于功率优化的资源分配算法。该算法在保证用户最小传输速率的限制条件下,优化异构网络中基站的功率资源和频率资源的分配。基于功率优化的资源分配算法包括集中式算法和分布式算法。区别于传统的优化算法,集中式算法综合考虑了基站负载因子、用户满意度、基站调度优先级和基站发射功率等因素,利用效用函数矩阵确定基站和用户使用频率资源的顺序,并根据已分配资源的用户的受限矩阵限制存在较强干扰的相邻基站使用相同的资源。最后,联合计算相同频带上所有基站的发射功率。集中式算法可以协调分配所有基站的频率和功率资源,并降低异构网络内所有基站消耗的总功率。而分布式算法是根据用户类型把基站使用的频带划分为正交频带和非正交频带。小区边缘用户优先使用正交频带资源可以消除来自相邻小区的干扰,而小区中心用户在所有频带内都满足信噪比门限要求。结合功率控制算法和用户频带扩展可以进一步降低基站下行链路需要的发射功率。分布式算法只需要相邻基站之间的信道信息和干扰信息就可以优化分配基站的频率资源和功率资源。
最后一部分提出了一种基于干扰抑制的分布式资源分配算法。由于自适应调制与编码技术的应用,基站根据用户的信道条件指定用户的调制与编码方式(MCS)。但是,用户的调制与编码方式也会影响基站的功率消耗、网络内总干扰功率。首先,分布式算法根据每个基站服务用户可能采用的调制与编码方式组成所有用户的调制与编码方式搜索空间。随后,分布式算法按照搜索空间中用户的调制与编码方式的组合,根据网络总干扰功率增量最小准则,确定频率资源和功率资源的分配结果。最后,根据异构网络总干扰功率最小的原则,确定用户的调制与编码方式、频率资源和功率资源的最优分配结果。
Heterogeneous networks (HetNets) technique has been widely considered to be accepted by3rd Generation Partnership Project (3GPP) as one of the key candidate technologies of LTE-Advanced standards. HetNets consist of several types of base stations, such as macrocell, microcell, picocell, femtocell, relay and remote radio head (RRH). HetNets deploy multi-type of low power base stations in the coverage area of traditional cellular system, in order to eliminate the areas of both blind-zone and hot-zone, which will tremendously increase the network capacity. Compared with traditional macro cellular base stations, low power base stations, such as picocell, femtocell and relay, are a more economical approach to enhance the network capacity. However, a phenomenon cannot be avoided that the coverage areas of different base stations deployed in the same area simultaneously would be overlapping. Therefore, the complicated inter-cell interference is required to be tackled.
The inter-cell interference coordination algorithm, the resource optimization algorithms to minimize the total power consumption and the network interference power level, are researched in the thesis. The inter-cell interference coordination algorithm could effectively decrease the inter-cell interference power level and improve the channel qualities of cell-edge users, which would further enhance the network capacity and users'performance. Resource optimization algorithms reduce the power consumption and suppress the total interference power level of the network, while satisfy the users demands. The main research work and contributions are summarized as follows:
A novel algorithm to coordinate the inter-cell interference in HetNets is firstly proposed. On the basis of the interference relationship of users being served and neighbor base stations, an interference graph is constructed by the nodes and edges, which represent the base stations and the interference relationships respectively. An orthogonal spectrum allocation algorithm is studied, which is based on the coloring algorithm according to the vertex degree to assign the adjacent base stations in the graph with non-overlapping frequency bandwidth. The algorithm eliminates the strong interference from adjacent base stations is eliminated. The orthogonal frequency bandwidth is assigned to the base stations, which effectively controls the interference power level in the bandwidth and satisfies the signal to interference plus noise ratio (SINR) requirements of cell-edge users.
To further improve the spectrum utilization ratio than the study above, an adaptive frequency resource allocation algorithm is proposed to explore the variations of the users'channel qualities. Based on the comparison results of the SINR threshold and the channel quality information from both the users being served and nearby users of the adjacent base stations, the adaptive frequency allocation algorithm is consisted of three consecutive steps as'request-reply-decision', in which each base station independently determines whether the spectrum could be shared according to the feedback spectrum sharing information. The adaptive frequency resource allocation algorithm only needs to exchange limited information including the bandwidth request and feedback spectrum sharing information, and quickly assigns the frequency resource to improve the spectrum utilization ratio.
The resource allocation algorithms are well researched in the thesis, which optimize the power allocation in HetNets scenario and guarantee the users' minimum transmission rate. The power optimization algorithms consist of the centralized algorithm and the distributed algorithm. Different from other optimization methods, several factors including the load of base stations, users' dissatisfactory ratio, scheduling priority and the downlink transmission power, are jointly considered to design the centralized algorithm. The scheduling priorities of base stations and users are determined according to the utility values in the centralized algorithm. But the base stations in the restricted matrix are forbidden to share the same bandwidth to eliminate the strong co-channel interference received by the users of the adjacent base stations. The transmission power levels of all base stations, which are selected as the values of the utility matrix in ascending order, within the same bandwidth are jointly calculated. The power and frequency resource allocation of all the base stations are coordinated to minimize the total power consumption of all the base station in the centralized algorithm. However, the total bandwidth is classified into the orthogonal bandwidth and non-orthogonal bandwidth according to users' types in the distributed algorithm. The cell-edge users are permitted to occupy the orthogonal bandwidth with higher priority to eliminate the interference from neighboring base stations, while the cell-center users could satisfy the SINR threshold requirements in the whole bandwidth. With the power control algorithm and user bandwidth extension, the downlink transmission power consumption of each base station is further reduced to a lower level. The channel quality and interference information, which is used to perform the deployment optimization of both the frequency resource and power allocation, is just required to exchange among the adjacent base stations in the distributed algorithm.
A distributed resource allocation algorithm is proposed in the last section, which is designed to suppress the interference power level. With the application of adaptive modulation and coding (AMC) technique, the modulation and coding scheme (MCS) of the users are determined by the serving base stations according to the channel qualities. However, the MCS levels of users have great influence on the power consumption of base stations and the total interference power level of the network. The distributed algorithm firstly constructs the MCS search space according to all the possible combinations of the MCS levels of all users. Then, the distributed algorithm determines the frequency and power resource allocation results depending on the selected MCS combination of users, which is in accordance with the rule of the minimum increment of total network interference power. Finally, the optimal assignment results of the MCS levels of all users, frequency resource and power level are determined according to the criterion of minimizing interference power level of the HetNets.
引文
[1]吴伟陵,牛凯,移动通信原理,电子工业出版社
[2]3GPP, TR36.913 v1.0.0, Requirements for Further Advancements for E-UTRA, May,2008
[3]王映民,孙韶辉等,TD-LTE技术原理与系统设计, 人民邮电出版社.
[4]沈嘉,索十强,全海洋等,3GPP长期演进(LTE)技术原理与系统设计,人民邮电出版社
[5]Astely, D.; Dahlman, E.; Furuskar, A.; Jading, Y.; Lindstrom, M.; Parkvall, S., "LTE:the evolution of mobile broadband," Communications Magazine, IEEE, vol.47, no.4, pp.44-51, April 2009 doi:10.1109/MCOM.2009.4907406
[6]Zukang Shen; Papasakellariou, A.; Montojo, J.; Gerstenberger, D.; Fangli Xu, "Overview of 3GPP LTE-advanced carrier aggregation for 4G wireless communications," Communications Magazine, IEEE, vol.50, no.2, pp.122-130, February 2012
[7]Irmer, R.; Droste, H.; Marsch, P.; Grieger, M.; Fettweis, G.; Brueck, S.; Mayer, H.-P.; Thiele, L.; Jungnickel, V., "Coordinated multipoint:Concepts, performance, and field trial results," Communications Magazine, IEEE, vol.49, no.2, pp.102-111, February 2011
[8]Damnjanovic, A.; Montojo, J.; Yongbin Wei; Tingfang Ji; Tao Luo; Vajapeyam, M.; Taesang Yoo; Osok Song; Malladi, D., "A survey on 3GPP heterogeneous networks," Wireless Communications, IEEE, vol.18, no.3, pp.10-21, June 2011
[9]Khandekar, A.; Bhushan, N.; Ji Tingfang; Vanghi, V., "LTE-Advanced:Heterogeneous networks," Wireless Conference (EW),2010 European, vol., no., pp.978-982,12-15 April 2010.
[10]Lopez-Perez, D.; Guvenc, I.; de la Roche, G.; Kountouris, M.; Quek, T.Q.S.; Jie Zhang, "Enhanced intercell interference coordination challenges in heterogeneous networks," Wireless Communications, IEEE, vol.18, no.3, pp.22-30, June 2011
[11]Chandrasekhar, V.; Andrews, J.; Gatherer, A., "Femtocell networks:a survey," Communications Magazine, IEEE, vol.46, no.9, pp.59-67, September 2008
[12]de la Roche, G.; Valcarce, A.; Lopez-Perez, D.; Jie Zhang, "Access control mechanisms for femtocells," Communications Magazine, IEEE, vol.48, no.1, pp.33-39, January 2010
[13]3GPP Std, R1-103561, Improving control reliability in severe interference conditions. Qualcomm Incorporated,2010.
[14]3GPP R1-104661, Comparison of Time-domain eICIC Solutions. LG Electronics.,2010.
[15]3GPP R1-103561, Improving control reliability in severe interference conditions, Qualcomm Incorporated,2010.
[16]3GPP R1-103494, Analysis of Time-Partitioning Solution for Control Channel, CATT,2010.
[17]3GPP R1-101122, Downlink Control Protection in LTE, Motorola,2010.
[18]3GPP R1-104049, Discussion on Enhanced ICIC Schemes for Control Channel in HetNet, Fujitsu,2010.
[19]3GPP R1-104659, Evaluation of control channel coordination in co-channel CSG deployment, LG Electronics,2010.
[20]孟德香,吴晓岩,党梅梅等,IEEE 802.16e-2005采用部分频率重用技术的频率复用方式研究,中国通信标准化协会TC5 WG3,2007年10月
[21]3GPP R1-060135, Interference Mitigation by Partial Frequency Reuse, Siemens,2006.
[22]3GPP R1-050507, Soft Frequency Reuse Scheme for UTRAN LTE, Huawei,2005.
[23]3GPP R1-050764, Inter-cell Interference Handling for E-UTRA, Ericsson,2005.
[24]3GPP R1-104968. Summary of the description of candidate eICIC solutions, CMCC,2010.
[25]3GPP TR 36.814 (V9.0.0), Evolved Universal Terrestrial Radio Access (E-UTRA) Further advancements for E-UTRA physical layer aspects (Release 9),2010
[1]Guoqing Li; Hui Liu, "Downlink Radio Resource Allocation for Multi-Cell OFDMA System," Wireless Communications, IEEE Transactions on, vol.5, no.12, pp.3451-3459, December 2006.
[2]V.H. MacDonald, "The cellular concept", Bell System Technical Journal, vol.58, pp.15-41, January 1979.
[3]Begain, K.; Rozsa, G.I.; Pfening, A.; Telek, M., "Performance analysis of GSM networks with intelligent underlay-overlay," Computers and Communications,2002. Proceedings. ISCC 2002. Seventh International Symposium on, vol., no., pp.135-141,2002.
[4]3GPP R1-050507, "Soft Frequency Reuse Scheme for UTRAN LTE ", Huawei, May 2005.
[5]3GPP R1-060291, "OFDMA Downlink Inter-Cell Interference Mitigation",Nokia, February 2006.
[6]Rahman, M.; Yanikomeroglu, H.; Wong, W., "Interference Avoidance with Dynamic Inter-Cell Coordination for Downlink LTE System," Wireless Communications and Networking Conference,2009. WCNC 2009. IEEE, vol., no., pp.1-6,5-8 April 2009.
[7]Rahman, M.; Yanikomeroglu, H., "Enhancing cell-edge performance:a downlink dynamic interference avoidance scheme with inter-cell coordination," Wireless Communications, IEEE Transactions on, vol.9, no.4, pp.1414-1425, April 2010.
[8]Rahman, M.; Yanikomeroglu, H., "Inter-Cell Interference Coordination in OFDMA Networks: A Novel Approach Based on Integer Programming," Vehicular Technology Conference (VTC 2010-Spring),2010 IEEE 71st, vol., no., pp.1-5,16-19 May 2010.
[9]Stolyar, A.L.; Viswanathan, H., "Self-Organizing Dynamic Fractional Frequency Reuse in OFDMA Systems," INFOCOM 2008. The 27th Conference on Computer Communications. IEEE, vol., no., pp.691-699,13-18 April 2008.
[10]Weiwei Wu; Sakurai, T., "Capacity of reuse partitioning schemes for OFDMA wireless data networks," Personal, Indoor and Mobile Radio Communications,2009 IEEE 20th International Symposium on, vol., no., pp.2240-2244,13-16 Sept.2009.
[11]Shukry, S.M.; Elsayed, K.; Elmoghazy, A.; Nassar, A., "Adaptive Fractional Frequency Reuse (AFFR) scheme for multi-cell IEEE 802.16e systems," High-Capacity Optical Networks and Enabling Technologies (HONET),2009 6th International Symposium on, vol., no., pp.96-102, 28-30 Dec.2009.
[12]Li Li; Dong Liang; Wenbo Wang, "A Novel Semi-Dynamic Inter-Cell Interference Coordination Scheme Based on User Grouping," Vehicular Technology Conference Fall (VTC 2009-Fall),2009 IEEE 70th, vol., no., pp.1-5,20-23 Sept.2009.
[13]Lopez-Perez, D.; Juttner, A.; Jie Zhang, "Dynamic Frequency Planning Versus Frequency Reuse Schemes in OFDMA Networks," Vehicular Technology Conference,2009. VTC Spring 2009. IEEE 69th, vol., no., pp.1-5,26-29 April 2009.
[14]Ali, S.H.; Leung, V.C.M., "Dynamic frequency allocation in fractional frequency reused OFDMA networks," Wireless Communications, IEEE Transactions on, vol.8, no.8, pp.4286-4295, August 2009.
[15]Yong Bai; Juejia Zhou; Lan Chen, "Hybrid spectrum sharing for coexistence of macrocell and femtocell," Communications Technology and Applications,2009. ICCTA '09. IEEE International Conference on, vol., no., pp.162-166,16-18 Oct.2009.
[16]Weitzen, J.; Grosch, T., "Comparing coverage quality for femtocell and macrocell broadband data services," Communications Magazine, IEEE, vol.48, no.1, pp.40-44, January 2010.
[17]Yuanye Wang; Marchetti, N.; Kovacs, I.Z.; Mogensen, P.E.; Pedersen, K.I.; Sorensen, T.B., "An Interference Aware Dynamic Spectrum Sharing Algorithm for Local Area LTE-Advanced Networks," Vehicular Technology Conference Fall (VTC 2009-Fall),2009 IEEE 70th, vol., no., pp.1-5,20-23 Sept.2009.
[18]Xiaoli Chu; Yuhua Wu; Benmesbah, L.; Wing-Kuen Ling, "Resource Allocation in Hybrid Macro/Femto Networks," Wireless Communications and Networking Conference Workshops (WCNCW),2010 IEEE, vol., no., pp.1-5,18-18 April 2010.
[19]Mostafa Zaman Chowdhury; Yeong Min Jang; Haas, Zygmunt J., "Interference mitigation using dynamic frequency re-use for dense femtocell network architectures," Ubiquitous and Future Networks (ICUFN),2010 Second International Conference on, vol., no., pp.256-261, 16-18 June 2010.
[20]Rong-Terng Juang; Pangan Ting; Hsin-Piao Lin; Ding-Bing Lin, "Interference management of femtocell in macro-cellular networks," Wireless Telecommunications Symposium (WTS), 2010, vol., no., pp.1-4,21-23 April 2010.
[21]Yuanye Wang; Kumar, S.; Garcia, L.; Pedersen, K.I.; Kovacs, I.Z.; Frattasi, S.; Marchetti, N.; Mogensen, P.E., "Fixed Frequency Reuse for LTE-Advanced Systems in Local Area Scenarios," Vehicular Technology Conference,2009. VTC Spring 2009. IEEE 69th, vol., no., pp.1-5,26-29 April 2009.
[22]Xuehong Mao; Maaref, A.; Koon Hoo Teo, "Adaptive Soft Frequency Reuse for Inter-Cell Interference Coordination in SC-FDMA Based 3GPP LTE Uplinks," Global Telecommunications Conference,2008. IEEE GLOBECOM 2008. IEEE, vol., no., pp.1-6, Nov.30 2008-Dec.4 2008.
[23]Hongjia Li; Xiaodong Xu; Dan Hu; Xiqiang Qu; Xiaofeng Tao; Ping Zhang, "Graph Method Based Clustering Strategy for Femtocell Interference Management and Spectrum Efficiency Improvement," Wireless Communications Networking and Mobile Computing (WiCOM), 2010 6th International Conference on, vol., no., pp.1-5,23-25 Sept.2010.
[24]Necker, M.C., "A Graph-Based Scheme for Distributed Interference Coordination in Cellular OFDMA Networks," Vehicular Technology Conference,2008. VTC Spring 2008. IEEE, vol., no.,pp.713-718,11-14 May 2008.
[25]Chandrasekhar, V.; Andrews, J., "Spectrum allocation in tiered cellular networks," Communications, IEEE Transactions on, vol.57, no.10, pp.3059-3068, October 2009.
[26]Bharucha, Z.; Haas, H.; Auer, G.; Cosovic, I., "Femto-Cell Resource Partitioning," GLOBECOM Workshops,2009 IEEE, vol., no., pp.1-6, Nov.30 2009-Dec.4 2009.
[27]Barbieri, A.; Damnjanovic, A.; Tingfang Ji; Montojo, J.; Yongbin Wei; Malladi, D.; Osok Song; Horn, G., "LTE Femtocells:System Design and Performance Analysis," Selected Areas in Communications, IEEE Journal on, vol.30, no.3, pp.586-594, April 2012.
[28]Necker, M., "Interference Coordination in Cellular OFDMA Networks," Network, IEEE, vol.22, no.6, pp.12-19, November-December 2008.
[29]3GPP TR 36.814 (V9.0.0), Evolved Universal Terrestrial Radio Access (E-UTRA) Further advancements for E-UTRA physical layer aspects (Release 9),2010.
[30]李慧霸,王凤芹,图论简明教程,清华大学出版社,2004年。
[1]Lopez-Perez, D.; Guvenc, I.; de la Roche, G.; Kountouris, M.; Quek, T.Q.S.; Jie Zhang, "Enhanced intercell interference coordination challenges in heterogeneous networks," Wireless Communications, IEEE, vol.18, no.3, pp.22-30, June 2011.
[2]Chandrasekhar, V.; Andrews, J.G.; Muharemovic, T.; Zukang Shen; Gatherer, A., "Power control in two-tier femtocell networks," Wireless Communications, IEEE Transactions on, vol.8, no.8, pp.4316-4328, August 2009.
[3]Han-Shin Jo; Jong-Gwan Yook; Cheol Mun; Moon, J., "A self-organized uplink power control for cross-tier interference management in femtocell networks," Military Communications Conference,2008. MILCOM 2008. IEEE, vol., no., pp.1-6,16-19 Nov.2008.
[4]Xiangfang Li; Lijun Qian; Kataria, D., "Downlink power control in co-channel macrocell femtocell overlay," Information Sciences and Systems,2009. CISS 2009.43rd Annual Conference on, vol., no., pp.383-388,18-20 March 2009.
[5]Liqun Fu; Soung Chang Liew; Jianwei Huang, "Fast algorithms for joint power control and scheduling in wireless networks," Wireless Communications, IEEE Transactions on, vol.9, no.3, pp.1186-1197, March 2010.
[6]Bernardo, F.; Agusti, R.; Cordero, J.; Crespo, C., "Self-Optimization of Spectrum Assignment and Transmission Power in OFDMA Femtocells," Telecommunications (AICT),2010 Sixth Advanced International Conference on, vol., no., pp.404-409,9-15 May 2010.
[7]Wei Yu; Wonjong Rhee; Boyd, S.; Cioffi, J.M., "Iterative water-filling for Gaussian vector multiple-access channels," Information Theory, IEEE Transactions on, vol.50, no.1, pp.145-152, Jan.2004.
[8]Wei Yu, "Multiuser Water-filling in the Presence of Crosstalk," Information Theory and Applications Workshop,2007, vol., no., pp.414-420, Jan.29 2007-Feb.2 2007.
[9]Wunder, G.; Michel, T., "Optimal Resource Allocation for Parallel Gaussian Broadcast Channels:Minimum Rate Constraints and Sum Power Minimization," Information Theory, IEEE Transactions on, vol.53, no.12, pp.4817-4822, Dec.2007.
[10]Yu, D.D.; Cioffi, J.M., "SPC10-2:Iterative Water-filling for Optimal Resource Allocation in OFDM Multiple-Access and Broadcast Channels," Global Telecommunications Conference, 2006. GLOBECOM '06. IEEE, vol., no., pp.1-5, Nov.27 2006-Dec.1 2006.
[11]Gerhard Wunder and Thomas Michel,"Optimal Resource Allocation for Parallel Gaussian Broadcast Channels:Minimum Rate Constraints and Sum Power Minimization," IEEE Transaction on Information Theory, Vol.53, No.12, pp.4817-4822,2007.
[12]Kibeom Seong; Mohseni, M.; Cioffi, J.M., "Optimal Resource Allocation for OFDMA Downlink Systems," Information Theory,2006 IEEE International Symposium on, vol., no., pp.1394-1398,9-14 July 2006.
[13]Abrardo, A.; Alessio, A.; Detti, P.; Moretti, M., "Centralized Radio Resource Allocation for OFDMA Cellular Systems," Communications,2007. ICC '07. IEEE International Conference on, vol., no., pp.5738-5743,24-28 June 2007.
[14]Haichao Zhang; Qinghai Yang; Feifei Gao; Kyung Sup Kwak, "Distributed Adaptive Subchannel and Power Allocation for Downlink OFDMA with Inter-Cell Interference Coordination," Global Telecommunications Conference (GLOBECOM 2010),2010 IEEE, vol., no., pp.1-5,6-10 Dec.2010.
[15]Fraimis, I.G.; Papoutsis, V.D.; Kotsopoulos, S.A., "A Decentralized Subchannel Allocation Scheme with Inter-Cell Interference Coordination (ICIC) for Multi-Cell OFDMA Systems," Global Telecommunications Conference (GLOBECOM 2010),2010 IEEE, vol., no., pp.1-5, 6-10 Dec.2010.
[16]Zheng, K.; Wang, Y.; Lin, C.; Shen, X.; Wang, J., "Graph-based interference coordination scheme in orthogonal frequency-division multiplexing access femtocell networks," Communications, IET, vol.5, no.17, pp.2533-2541, November 25 2011。
[17]Juyeop Kim; Dong-Ho Cho, "A Joint Power and Subchannel Allocation Scheme Maximizing System Capacity in Indoor Dense Mobile Communication Systems," Vehicular Technology, IEEE Transactions on, vol.59, no.9, pp.4340-4353, Nov.2010.
[18]Aggarwal, R.; Assaad, M.; Koksal, C.E.; Schniter, P., "Joint Scheduling and Resource Allocation in the OFDMA Downlink:Utility Maximization Under Imperfect Channel-State Information," Signal Processing, IEEE Transactions on, vol.59, no.11, pp.5589-5604, Nov. 2011.
[19]Wang Chi Cheung; Quek, T.Q.S.; Kountouris, M., "Throughput Optimization, Spectrum Allocation, and Access Control in Two-Tier Femtocell Networks," Selected Areas in Communications, IEEE Journal on, vol.30, no.3, pp.561-574, April 2012.
[20]3GPP TR 36.814 (V9.0.0), "Evolved Universal Terrestrial Radio Access (E-UTRA) Further advancements for E-UTRA physical layer aspects (Release 9), "2010.
[21]3GPP TR 36.942(V10.2.0), "Evolved Universal Terrestrial Radio Access (E-UTRA) Radio Frequency (RF) system scenarios(Release 10), " 2010.
[1]Damnjanovic, A.; Montojo, J.; Yongbin Wei; Tingfang Ji; Tao Luo; Vajapeyam, M.; Taesang Yoo; Osok Song; Malladi, D., "A survey on 3GPP heterogeneous networks," Wireless Communications, IEEE, vol.18, no.3, pp.10-21, June 2011.
[2]Lopez-Perez, D.; Guvenc, I.; de la Roche, G.; Kountouris, M.; Quek, T.Q.S.; Jie Zhang, "Enhanced intercell interference coordination challenges in heterogeneous networks," Wireless Communications, IEEE, vol.18, no.3, pp.22-30, June 2011.
[3]Kibeom Seong; Mohseni, M.; Cioffi, J.M., "Optimal Resource Allocation for OFDMA Downlink Systems," Information Theory,2006 IEEE International Symposium on, vol., no., pp.1394-1398,9-14 July 2006.
[4]Haichao Zhang; Qinghai Yang; Feifei Gao; Kyung Sup Kwak, "Distributed Adaptive Subchannel and Power Allocation for Downlink OFDMA with Inter-Cell Interference Coordination," Global Telecommunications Conference (GLOBECOM 2010),2010 IEEE, vol., no., pp.1-5,6-10 Dec.2010.
[5]I. G. Fraimis,V. D. Papoutsis and S. A. Kotsopoulos, "A Decentralized Subchannel Allocation Scheme with Inter-cell Interference Coordination (ICIC) for Multi-Cell OFDMA Systems," IEEE Globecom 2010, pp.1-6,2008.
[6]Ki-Song Lee, Dong-Ho Cho, "Cooperation based resource allocation for improving inter-cell fairness in femtocell systems," Personal Indoor and Mobile Radio Communications (PIMRC), 2010 IEEE 21st International Symposium on, vol., no., pp.1168-1172,26-30 Sept.2010.
[7]Bennis, M.; Giupponi, L.; Diaz, E.M.; Lalam, M.; Maqbool, M.; Strinati, E.C.; De Domenico, A.; Latva-aho, M., "Interference management in self-organized femtocell networks:The BeFEMTO approach," Wireless Communication, Vehicular Technology, Information Theory and Aerospace & Electronic Systems Technology (Wireless VITAE),2011 2nd International Conference on, vol., no., pp.1-6, Feb.28 2011-March 3 2011.
[8]Lopez-Perez, D.; Ladanyi, A.; Juttner, A.; Rivano, H.; Jie Zhang, "Optimization method for the joint allocation of modulation schemes, coding rates, resource blocks and power in self-organizing LTE networks," INFOCOM,2011 Proceedings IEEE, vol., no., pp.111-115, 10-15 April 2011.
[9]Jianmin Zhang; Zhaoyang Zhang; Kedi Wu; Aiping Huang, "Optimal Distributed Subchannel, Rate and Power Allocation Algorithm in OFDM-Based Two-Tier Femtocell Networks," Vehicular Technology Conference (VTC 2010-Spring),2010 IEEE 71st, vol., no., pp.1-5, 16-19 May 2010.
[10]Qinliang Su; Aiping Huango; Zhouyun Wu; Guanding Yu; Zhaoyang Zhang; Kai Xu; Jin Yang, "A distributed dynamic spectrum access and power allocation algorithm for Femtocell networks," Wireless Communications & Signal Processing,2009. WCSP 2009. International Conference on, vol., no., pp.1-5,13-15 Nov.2009.
[11]Fengming Cao; Zhong Fan, "Power Loading and Resource Allocation for Femtocells," Vehicular Technology Conference (VTC Spring),2011 IEEE 73rd, vol., no., pp.1-5,15-18 May 2011.
[12]Akbudak, T.; Czylwik, A., "Distributed power control and scheduling for decentralized OFDMA networks," Smart Antennas (WSA),2010 International ITG Workshop on, vol., no., pp.59-65,23-24 Feb.2010.
[13]Bernardo, F.; Agusti, R.; Cordero, J.; Crespo, C., "Self-Optimization of Spectrum Assignment and Transmission Power in OFDMA Femtocells," Telecommunications (AICT),2010 Sixth Advanced International Conference on, vol., no., pp.404-409,9-15 May 2010.
[14]Gesbert, D.; Kiani, S.G.; Gjendemsj, A.; ien, G.E., "Adaptation, Coordination, and Distributed Resource Allocation in Interference-Limited Wireless Networks," Proceedings of the IEEE, vol.95, no.12, pp.2393-2409, Dec.2007.
[15]Duy Trong Ngo; Long Bao Le; Le-Ngoc, T.; Hossain, E.; Dong In Kim, "Distributed Interference Management in Two-Tier CDMA Femtocell Networks," Wireless Communications, IEEE Transactions on, vol.11, issue.3, pp.979-989, March 2012.
[16]Madan, R.; Sampath, A.; Khandekar, A.; Borran, J.; Bhushan, N., "Distributed Interference Management and Scheduling in LTE-A Femto Networks," Global Telecommunications Conference (GLOBECOM 2010), pp.1-5,2010.
[17]Soomin Ko; Hanbyul Seo; Hojoong Kwon; Byeong Gi Lee, "Distributed Power Allocation for Efficient Inter-cell Interference Management in Multi-cell OFDMA Systems, Communications (APCC),2010 16th Asia-Pacific Conference on, pp.243-248,2010.
[18]Xin Kang; Rui Zhang; Motani, M., "Price-Based Resource Allocation for Spectrum-Sharing Femtocell Networks:A Stackelberg Game Approach, " Selected Areas in Communications, IEEE Journal on, vol.30, issue.3, pp.538-549,2012.
[19]Shuhui Liu; Yongyu Chang; Ruiming Yang; Dacheng Yang, "Efficient Distributed Dynamic Resource Allocation for LTE System," Vehicular Technology Conference (VTC Fall), pp. 1-5,2011.
[20]de la Roche, G.; Ladanyi, A.; Lopez-Perez, D.; Chia-Chin Chong; Jie Zhang, "Self-Organization for LTE Enterprise Femtocells," GLOBECOM Workshops (GC Wkshps), pp.674-678,2010.
[21]Lopez-Perez, D.; Ladanyi, A.; Juttner, A.; Jie Zhang, "OFDMA femtocells:A self-organizing approach for frequency assignment," Personal, Indoor and Mobile Radio Communications, 20th International Symposium on, pp.2202-2207,2009.
[22]Ji-Hoon Yun; Shin, K.G. "Adaptive Interference Management of OFDMA Femtocells for Co-Channel Deployment," Selected Areas in Communications, IEEE Journal on vol.29, issue. 6, pp.1225-1241,2011.
[23]3GPP TS 36.213 v 10.2.0, "Evolved Universal Terrestrial Radio Access (E-UTRA) Physical layer procedures," June 2011.
[24]3GPP TR 36.814 (V9.0.0), "Evolved Universal Terrestrial Radio Access (E-UTRA) Further advancements for E-UTRA physical layer aspects (Release 9), " 2010.