蜂窝系统多用户MIMO信道传输反馈方法研究
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摘要
为了更好地满足无线蜂窝环境下用户对多媒体等数据业务的需求,能获取高效频谱效率的多天线技术成为了未来无线通信系统的重要技术。尤其在多用户系统中,多天线技术的引入,即使用户配置单根接收天线,仍可以使系统获得相当于发送天线数的空分复用增益,并可以获得相比于用户数目对数增加的多用户分集。传统的蜂窝通信系统中,边缘用户服务质量受小区间干扰的制约,而多天线技术的引入使得小区间干扰更为复杂。协作多小区技术,通过多基站天线间的协作,形成一个虚拟多天线系统,降低邻小区干扰信号幅度或将其转变为有用信号,极大降低了小区间干扰,获取了小区边缘吞吐率的提升。
本文聚焦于不完善信道信息下,多天线技术应用于蜂窝通信系统面临的两大挑战——用户间、小区间干扰,对基于信道反馈的多天线广播信道、协作多天线多小区信道的传输反馈方法进行了深入的研究。
本文首先考虑存在信道估计误差和反馈差错的多用户多天线广播信道,指出其仍能保持与拥有准确信道信息的系统一样的多用户分集和空分复用增益。进一步提出在用户数较大的情况下,基于信道阈值判决的部分用户反馈策略,在降低上行信道反馈开销的同时,仍获得了和全部用户反馈相比拟的多用户分集和空分复用。本文进一步考虑多小区信道,分析了基于有限反馈的两小区局部联合传输模式的性能。基于此,提出当激活用户任意分布于小区边缘不同位置时,协作传输模式的切换策略。本文最后针对下行多用户多天线传输,提出了基于码本阈值的预编码索引增强反馈方案,通过用户反馈矢量空间距离阈值,以提供基站多用户调度时可选配对用户的波束子集,该子集由与当前用户预编码小于反馈阈值并使得当前用户仍保持较优的信干燥比的码字构成,相比现有LTE系统多用户传输模式,提升了系统吞吐率。
With the demand of high-rate data transmission such as multimedia service in wireless cellular systems, multi-antenna technology which timely improves the frequency spectrum efficiency becomes a key technology in future wireless communication systems. The multi-antenna technologies in multiuser systems can exploit spatial multiplexing gain proportional to the number of transmit antennas and multiuser diversity even with single-antenna mobiles. In conventional cellular networks, cell edge throughput is degraded by interference from neighboring Base Stations (BS), deploying multi-antenna technology in commercial cellular systems makes this effect more significant. Multiple BSs collaborate with each other to form a virtual multi-antenna system, which mitigate other-cell interference or even transform to helpful signals, thus offer significant cell edge throughput improvement.
This thesis focuses on the cellular multi-antenna technology with imperfect CSI, and considers tow main interference: residual same-cell inter-user interference and other-cell interference. Based on these effects, we further propose some efficient transmission and CSI acquirement methods.
This thesis first points out that with the impact of channel estimation and feedback errors, the multi-antenna multiuser systems can still obtain full multiplexing gain and multiuser diversity as with perfect CSI. When the user number becomes larger, a channel norm threshold-based partial user feedback scheme is proposed. With reduced uplink feedback overhead, it is still capable of achieving the same throughput scaling law as compared to full user feedback. This thesis additionally offers the performance analysis of 2-cell cooperation with imperfect CSI. Based on this effect, we offer a adaptive multi-mode coordinated multi-cell transmission scheme which switches transmission mode according to the location of active cell edge users. This thesis also considers the performance limits on codebook-based precoding of LTE in multiuser downlink transmission. We propose a enhanced Precoding Matrix Indexes (PMI) feedback methods. With the help of feedbacking threshold on codeword spatial distance, this scheme offers a large paring user group, which is consisted of users causing reasonable inter-user interference and the spatial distance with both PMIs is guaranteed by feedback thresholds. This method enhances the multiuser transmission in LTE and improves the average cell throughput. Our research provides very good references for the design of the future cellular MIMO wireless communication downlink system.
本文聚焦于不完善信道信息下,多天线技术应用于蜂窝通信系统面临的两大挑战——用户间、小区间干扰,对基于信道反馈的多天线广播信道、协作多天线多小区信道的传输反馈方法进行了深入的研究。
本文首先考虑存在信道估计误差和反馈差错的多用户多天线广播信道,指出其仍能保持与拥有准确信道信息的系统一样的多用户分集和空分复用增益。进一步提出在用户数较大的情况下,基于信道阈值判决的部分用户反馈策略,在降低上行信道反馈开销的同时,仍获得了和全部用户反馈相比拟的多用户分集和空分复用。本文进一步考虑多小区信道,分析了基于有限反馈的两小区局部联合传输模式的性能。基于此,提出当激活用户任意分布于小区边缘不同位置时,协作传输模式的切换策略。本文最后针对下行多用户多天线传输,提出了基于码本阈值的预编码索引增强反馈方案,通过用户反馈矢量空间距离阈值,以提供基站多用户调度时可选配对用户的波束子集,该子集由与当前用户预编码小于反馈阈值并使得当前用户仍保持较优的信干燥比的码字构成,相比现有LTE系统多用户传输模式,提升了系统吞吐率。
With the demand of high-rate data transmission such as multimedia service in wireless cellular systems, multi-antenna technology which timely improves the frequency spectrum efficiency becomes a key technology in future wireless communication systems. The multi-antenna technologies in multiuser systems can exploit spatial multiplexing gain proportional to the number of transmit antennas and multiuser diversity even with single-antenna mobiles. In conventional cellular networks, cell edge throughput is degraded by interference from neighboring Base Stations (BS), deploying multi-antenna technology in commercial cellular systems makes this effect more significant. Multiple BSs collaborate with each other to form a virtual multi-antenna system, which mitigate other-cell interference or even transform to helpful signals, thus offer significant cell edge throughput improvement.
This thesis focuses on the cellular multi-antenna technology with imperfect CSI, and considers tow main interference: residual same-cell inter-user interference and other-cell interference. Based on these effects, we further propose some efficient transmission and CSI acquirement methods.
This thesis first points out that with the impact of channel estimation and feedback errors, the multi-antenna multiuser systems can still obtain full multiplexing gain and multiuser diversity as with perfect CSI. When the user number becomes larger, a channel norm threshold-based partial user feedback scheme is proposed. With reduced uplink feedback overhead, it is still capable of achieving the same throughput scaling law as compared to full user feedback. This thesis additionally offers the performance analysis of 2-cell cooperation with imperfect CSI. Based on this effect, we offer a adaptive multi-mode coordinated multi-cell transmission scheme which switches transmission mode according to the location of active cell edge users. This thesis also considers the performance limits on codebook-based precoding of LTE in multiuser downlink transmission. We propose a enhanced Precoding Matrix Indexes (PMI) feedback methods. With the help of feedbacking threshold on codeword spatial distance, this scheme offers a large paring user group, which is consisted of users causing reasonable inter-user interference and the spatial distance with both PMIs is guaranteed by feedback thresholds. This method enhances the multiuser transmission in LTE and improves the average cell throughput. Our research provides very good references for the design of the future cellular MIMO wireless communication downlink system.
引文
[1] G. Caire and S. Shamai, "On the achievable throughput of a multiantenna Gaussian broadcast channel," Information Theory, IEEE Transactions on, vol. 49, pp. 1691-1706, 2003.
[2] T. Cover, "Broadcast channels," Information Theory, IEEE Transactions on, vol. 18, pp. 2-14, 1972.
[3] U. Erez and S. ten Brink, "Approaching the dirty paper limit for canceling known interference," Proc. Allerton Conf. Commun., Control, Comput, pp. 799–808, 2003.
[4] G. J. Foschini and M. J. Gans, "On limits of wireless communications in a fading environment when using multiple antennas," Wireless Personal Communications, vol. 6, pp. 311-335, 1998.
[5] N. Jindal, W. Rhee, S. Vishwanath, S. A. Jafar, and A. Goldsmith, "Sum power iterative water-filling for multi-antenna Gaussian broadcast channels," Information Theory, IEEE Transactions on, vol. 51, pp. 1570-1580, 2005.
[6] A. Paulraj, R. Nabar, and D. Gore, Introduction to Space-Time Wireless Communications: Cambridge University Press, 2003.
[7] C. E. Shannon, "A mathematical theory of communication," Bell System Technical Journal, vol. 27, pp. 379-423, 623-656, 1948.
[8] M. Sharif and B. Hassibi, "A Comparison of Time-Sharing, DPC, and Beamforming for MIMO Broadcast Channels With Many Users," Communications, IEEE Transactions on, vol. 55, pp. 11-15, 2007.
[9] M. Sharif and B. Hassibi, "On the capacity of MIMO broadcast channels with partial side information," Information Theory, IEEE Transactions on, vol. 51, pp. 506-522, 2005.
[10] E. Telatar, "Capacity of multi-antenna Gaussian channels," European Transactions on Telecommunications, vol. 10, pp. 585-595, 1999.
[11] S. Vishwanath, N. Jindal, and A. Goldsmith, "Duality, achievable rates, and sum-rate capacity of Gaussian MIMO broadcast channels," Information Theory, IEEE Transactions on, vol. 49, pp. 2658-2668, 2003.
[12] H. Viswanathan, S. Venkatesan, and H. Huang, "Downlink capacity evaluation of cellular networks with known-interference cancellation," Selected Areas in Communications, IEEE Journal on, vol. 21, pp. 802-811, 2003.
[13] T. Yoo and A. Goldsmith, "On the optimality of multiantenna broadcast scheduling using zero-forcing beamforming," Selected Areas in Communications, IEEE Journal on, vol. 24, pp. 528-541, 2006.
[14] T. Yoo and A. Goldsmith, "Optimality of zero-forcing beamforming with multiuser diversity,", 2005 IEEE International Conference on Communications, vol. 1, 2005.
[15] T. Yoo and A. Goldsmith, "Sum-rate optimal multi-antenna downlink beamforming strategy based on clique search," IEEE Global Telecommunications Conference vol. 3, pp. 1510-1514, 2005.
[16] T. Yoo, N. Jindal, and A. Goldsmith, "Multi-Antenna Downlink Channels with Limited Feedback and User Selection," Selected Areas in Communications, IEEE Journal on, vol. 25, pp. 1478-1491, 2007.
[17] W. Yu and J. M. Cioffi, "Sum capacity of Gaussian vector broadcast channels," Information Theory, IEEE Transactions on, vol. 50, pp. 1875-1892, 2004.
[18] W. Yu, W. Rhee, S. Boyd, and J. M. Cioffi, "Iterative water-filling for Gaussian vector multiple-access channels," Information Theory, IEEE Transactions on, vol. 50, pp. 145-152, 2004.
[19] W. Yu, D. P. Varodayan, and J. M. Cioffi, "Trellis and convolutional precoding for transmitter-based interference presubtraction," Communications, IEEE Transactions on, vol. 53, pp. 1220-1230, 2005.
[20] S. Zhou, Z. Wang, and G. Giannakis, "Quantifying the power loss when transmit beamforming relies on finite-rate feedback," Wireless Communications, IEEE Transactions on, vol. 4, pp. 1948-1957, 2005.
[21] M. Sharif and B. Hassibi, 2007.“Scaling Laws of Sum Rate Using Time-sharing, DPC, and Beamforming for MIMO Broadcast Channels.”IEEE Transaction on Communications, 55(1):11-15.
[22] N. Jindal,“MIMO Broadcast Channels with Finite Rate Feedback”. IEEE Global Telecommunications Conference, 3:1520–1524. 2005.
[23] KK Mukkavilli, A Sabharwal and E Erkip, et al.“On Beamforming with Finite Rate Feedback in Multiple-Antenna Systems”. IEEE Transactions on Information Theory, 49(10):2562– 2579. 2003
[24] C. Au-Yeung and D. J. Love,“On the Performance of Random Vector Quantization Limited Feedback Beamforming in a MISO System”. IEEE Transaction Wireless Communication, 6(2): 458-462. 2007.
[25] D. J. Love, R. W. Heath Jr., and T. Strohmer,“Grassmannian beamforming for multiple-input multiple-output wireless systems”. IEEE Transactions on Information Theory, 49(10): 2735–47. 2003.
[26] S. Shamai (Shitz) and B. M. Zaidel,“Enhancing the cellular downlink capacity via co-processing at the transmitting end,”in Proc. IEEE Veh. Technol. Conf., Rhodes, Greece, May 2001, pp. 1745–1749.
[27] S. A. Jafar, G. Foschini, and A. J. Goldsmith,“Phantomnet: Exploring optimal multicellular multiple antenna systems,”EURASIP Journal on Appl. Signal Processing, Special issue on MIMO Comm. and Signal Processing, pp. 591–605, May 2004.
[28] J. G. Andrews, W. Choi, and R. W. Heath, Jr., "Overcoming interference in spatial multiplexing MIMO cellular networks," IEEE Wireless Communications Magazine, vol. 14, no. 6, pp. 95-104, Dec. 2007.
[29] O. Somekh, O. Simeone, Y. Bar-Ness, and A. M. Haimovich,“Distributed multi-cell zero-forcing beamforming in cellular downlink channels,”in Proc. IEEE Globecom, San Francisco, Nov. 2006, pp. 1–6.
[30] H. Dahrouj and W. Yu,“Coordinated beamforming for the multi-cell multi-antenna wireless system,”in Conference on Information Sciences and Systems (CISS), Princeton, NJ, Mar. 2008.
[31] B. O. Lee, H. W. Je, I. Sohn, O.-S. Shin, and K. B. Lee,“Interferenceaware decentralized precoding for multicell MIMO TDD systems,”in Proc. IEEE GLOBECOM’08, 2008.
[32] J. Zhang, R. Chen, J. G. Andrews, A. Ghosh, and R. W. Heath Jr.,“Networked MIMO with clustered linear precoding,”IEEE Trans. Wireless Commun., vol. 8, no. 4, pp. 1910–1921, Apr. 2009.
[33] Y. Hadisusanto, L. Thiele, and V. Jungnickel,“Distributed base station cooperation via block-diagonalization and dual-decomposition,”in Proceedings of the IEEE Global Telecommunications Conference, pp. 3539–3543, New Orleans, La, USA, November-December 2008.
[34] W. Yu and T. Lan,“Transmitter optimization for the multi-antenna downlink with per-antenna power constraints,”IEEE Trans. Signal Processing, vol. 55, no. 6, pp. 2646–2660, Jun. 2007.
[35] Motorola,“CoMP Support in Rel-10: Performance with intra-eNB CoBF and Cell-edge Improvements”. 3GPP TSG RAN WG1 Meeting #60, R1-101130. 2010.
[36] Naijin Liu, Ling Qiu, Jinkang Zhu,”A proactive interference suppression scheme for cellular MIMO systems”in Proceedings of GMC 2007, Shanghai, China, October 2007
[37] R. Bhagavatula and R. W. Heath, Jr., ``Adaptive Limited Feedback for Sum-Rate Maximizing Beamforming in Cooperative Multicell Systems" IEEE Trans. on Signal Processing, December 2009.
[38] R. Bhagavatula, R. W. Heath, Jr., and B. Rao ``Limited Feedback with Joint CSI Quantization for Multicell Cooperative Generalized Eigenvector Beamforming,'' to appear in Proc. of the IEEE Int. Conf. on Acoustics, Speech, and Signal Proc., Dallas, TX, March 14-19, 2010.
[39] Caire G, Jindal N, Kobayashi M, Ravindran N.“Quantized vs. analog feedback for the MIMO broadcast channel: a comparison between zero-forcing based achievable rates”. ISIT2007, IEEE, Nice, France, June, 2007: 2046-2050.
[40] Marzetta T L, Hochwald B M.“Fast transfer of channel state information in wireless systems”. IEEE Trans. on Signal Processing, 2006, 54(4):1268–1278.
[41] Huawei, TP for 3GPP TR36.814 on CoMP[C], 3GPP TSG RAN WG1 Meeting #60, R1-101679. 2010,
[42] S. Shamai (Shitz), O. Somekh, and B. M. Zaidel,“Multi-cell communications: An information theoretic perspective,”in Joint Workshop on Communications and Coding (JWCC), Florence, Italy, Oct. 2004.
[43] O. Somekh, B. M. Zaidel, and S. Shamai (Shitz),“Sum rate characterization of joint multiple cell-site processing,”IEEE Trans.Inform. Theory, vol. 53, no. 12, pp. 4473–4497, Dec. 2007.
[44] E. Bjornson, R. Zakhour, D. Gesbert, B. Ottersten,“Distributed multicell and multiantenna precoding: characterization and performance evaluation”, in Proc. of IEEE Globecom Conference, Hawai, 2009.
[45] Dana A F, Sharif M, Hassibi B.“On the capacity region of multi-antenna Gaussian broadcast channels with estimation error”. ISIT2006, IEEE, Seattle, Washington, USA, July, 2006: 1851-1855.
[46] Liu Y, Qiu L.“Impact of channel estimation error on the sum-rate in MIMO broadcast channels with user selection”. IEICE Transactions on Communication, 2008, E91-B(3): 955-958.
[47] Caire G, Jindal N, Kobayashi M, Ravindran N.“Multiuser MIMO downlink made practical: achievable rates with simple channel state estimation and feedback schemes.”Submitted to IEEE Trans. on Information Theory, 2007.
[48] Huang K, Heath Jr R W, Andrews J G.“Space division multiple access with a sum feedback rate constraint”. IEEE Trans. on Signal Processing, 2007, 55(7): 3879-3891.
[49] J. Zhang and J. G. Andrews.“Adaptive spatial intercell interference cancellation in multicell wireless networks”. Submitted to IEEE J. Select. Areas Commun., Sept. 2009.
[50] D. Gesbert, A. Hjorungnes, and H. Skjevling,“Cooperative spatial multiplexing with hybrid channel knowledge,”in IEEE International Zurich Seminar on Communications, 2006.
[51] Alcatel-Lucent,2009,““Best Companion”reporting for improved single-cell MU-MIMO pairing,”, 3GPP TSG RAN WG1 Meeting #57bis,R1-092546
[52] Ericsson, ST-Ericsson, 2010,“PMI-based Multi-Granular Feedback for SU/MU-MIMO Operation”, 3GPP TSG RAN WG1 Meeting #60, R1-100852
[53] Huawei, 2010,“Extensions to Rel-8 type CQI/PMI/RI feedback using double codebook structure”, 3GPP TSG RAN WG1 Meeting #59bis, R1-100251
[54] 3GPP TR 36.212:“Evolved Universal Terrestrial Radio Access (E-UTRA);Physical Channels and Modulation”
[55] Motorola, 2009,”DL Codebook Design for 8 TX Antennas for LTE-A”, 3GPP TSG RAN WG1 Meeting#57, R1-092175
[56] Huawei,“DL Codebook Design for 8 Tx MIMO in LTE-A”, 3GPP TSG RAN WG1 Meeting#57, R1-091819
[57] Fujitsu,"Performance Evaluation of Coherent SU and MU CoMP for LTE-A",3GPP TSG RAN1 WG1 Meeting#57,R1-091955
[58] H. Huang and R. A. Valenzuela,“Fundamental simulated performance of downlink fixed wireless cellular networks with multiple antennas,”in Proc. of the IEEE Int. Symp. on Personal Indoor and Mobile Radio Comm., Berlin, Germany, Sept. 2005, pp.161–165.
[2] T. Cover, "Broadcast channels," Information Theory, IEEE Transactions on, vol. 18, pp. 2-14, 1972.
[3] U. Erez and S. ten Brink, "Approaching the dirty paper limit for canceling known interference," Proc. Allerton Conf. Commun., Control, Comput, pp. 799–808, 2003.
[4] G. J. Foschini and M. J. Gans, "On limits of wireless communications in a fading environment when using multiple antennas," Wireless Personal Communications, vol. 6, pp. 311-335, 1998.
[5] N. Jindal, W. Rhee, S. Vishwanath, S. A. Jafar, and A. Goldsmith, "Sum power iterative water-filling for multi-antenna Gaussian broadcast channels," Information Theory, IEEE Transactions on, vol. 51, pp. 1570-1580, 2005.
[6] A. Paulraj, R. Nabar, and D. Gore, Introduction to Space-Time Wireless Communications: Cambridge University Press, 2003.
[7] C. E. Shannon, "A mathematical theory of communication," Bell System Technical Journal, vol. 27, pp. 379-423, 623-656, 1948.
[8] M. Sharif and B. Hassibi, "A Comparison of Time-Sharing, DPC, and Beamforming for MIMO Broadcast Channels With Many Users," Communications, IEEE Transactions on, vol. 55, pp. 11-15, 2007.
[9] M. Sharif and B. Hassibi, "On the capacity of MIMO broadcast channels with partial side information," Information Theory, IEEE Transactions on, vol. 51, pp. 506-522, 2005.
[10] E. Telatar, "Capacity of multi-antenna Gaussian channels," European Transactions on Telecommunications, vol. 10, pp. 585-595, 1999.
[11] S. Vishwanath, N. Jindal, and A. Goldsmith, "Duality, achievable rates, and sum-rate capacity of Gaussian MIMO broadcast channels," Information Theory, IEEE Transactions on, vol. 49, pp. 2658-2668, 2003.
[12] H. Viswanathan, S. Venkatesan, and H. Huang, "Downlink capacity evaluation of cellular networks with known-interference cancellation," Selected Areas in Communications, IEEE Journal on, vol. 21, pp. 802-811, 2003.
[13] T. Yoo and A. Goldsmith, "On the optimality of multiantenna broadcast scheduling using zero-forcing beamforming," Selected Areas in Communications, IEEE Journal on, vol. 24, pp. 528-541, 2006.
[14] T. Yoo and A. Goldsmith, "Optimality of zero-forcing beamforming with multiuser diversity,", 2005 IEEE International Conference on Communications, vol. 1, 2005.
[15] T. Yoo and A. Goldsmith, "Sum-rate optimal multi-antenna downlink beamforming strategy based on clique search," IEEE Global Telecommunications Conference vol. 3, pp. 1510-1514, 2005.
[16] T. Yoo, N. Jindal, and A. Goldsmith, "Multi-Antenna Downlink Channels with Limited Feedback and User Selection," Selected Areas in Communications, IEEE Journal on, vol. 25, pp. 1478-1491, 2007.
[17] W. Yu and J. M. Cioffi, "Sum capacity of Gaussian vector broadcast channels," Information Theory, IEEE Transactions on, vol. 50, pp. 1875-1892, 2004.
[18] W. Yu, W. Rhee, S. Boyd, and J. M. Cioffi, "Iterative water-filling for Gaussian vector multiple-access channels," Information Theory, IEEE Transactions on, vol. 50, pp. 145-152, 2004.
[19] W. Yu, D. P. Varodayan, and J. M. Cioffi, "Trellis and convolutional precoding for transmitter-based interference presubtraction," Communications, IEEE Transactions on, vol. 53, pp. 1220-1230, 2005.
[20] S. Zhou, Z. Wang, and G. Giannakis, "Quantifying the power loss when transmit beamforming relies on finite-rate feedback," Wireless Communications, IEEE Transactions on, vol. 4, pp. 1948-1957, 2005.
[21] M. Sharif and B. Hassibi, 2007.“Scaling Laws of Sum Rate Using Time-sharing, DPC, and Beamforming for MIMO Broadcast Channels.”IEEE Transaction on Communications, 55(1):11-15.
[22] N. Jindal,“MIMO Broadcast Channels with Finite Rate Feedback”. IEEE Global Telecommunications Conference, 3:1520–1524. 2005.
[23] KK Mukkavilli, A Sabharwal and E Erkip, et al.“On Beamforming with Finite Rate Feedback in Multiple-Antenna Systems”. IEEE Transactions on Information Theory, 49(10):2562– 2579. 2003
[24] C. Au-Yeung and D. J. Love,“On the Performance of Random Vector Quantization Limited Feedback Beamforming in a MISO System”. IEEE Transaction Wireless Communication, 6(2): 458-462. 2007.
[25] D. J. Love, R. W. Heath Jr., and T. Strohmer,“Grassmannian beamforming for multiple-input multiple-output wireless systems”. IEEE Transactions on Information Theory, 49(10): 2735–47. 2003.
[26] S. Shamai (Shitz) and B. M. Zaidel,“Enhancing the cellular downlink capacity via co-processing at the transmitting end,”in Proc. IEEE Veh. Technol. Conf., Rhodes, Greece, May 2001, pp. 1745–1749.
[27] S. A. Jafar, G. Foschini, and A. J. Goldsmith,“Phantomnet: Exploring optimal multicellular multiple antenna systems,”EURASIP Journal on Appl. Signal Processing, Special issue on MIMO Comm. and Signal Processing, pp. 591–605, May 2004.
[28] J. G. Andrews, W. Choi, and R. W. Heath, Jr., "Overcoming interference in spatial multiplexing MIMO cellular networks," IEEE Wireless Communications Magazine, vol. 14, no. 6, pp. 95-104, Dec. 2007.
[29] O. Somekh, O. Simeone, Y. Bar-Ness, and A. M. Haimovich,“Distributed multi-cell zero-forcing beamforming in cellular downlink channels,”in Proc. IEEE Globecom, San Francisco, Nov. 2006, pp. 1–6.
[30] H. Dahrouj and W. Yu,“Coordinated beamforming for the multi-cell multi-antenna wireless system,”in Conference on Information Sciences and Systems (CISS), Princeton, NJ, Mar. 2008.
[31] B. O. Lee, H. W. Je, I. Sohn, O.-S. Shin, and K. B. Lee,“Interferenceaware decentralized precoding for multicell MIMO TDD systems,”in Proc. IEEE GLOBECOM’08, 2008.
[32] J. Zhang, R. Chen, J. G. Andrews, A. Ghosh, and R. W. Heath Jr.,“Networked MIMO with clustered linear precoding,”IEEE Trans. Wireless Commun., vol. 8, no. 4, pp. 1910–1921, Apr. 2009.
[33] Y. Hadisusanto, L. Thiele, and V. Jungnickel,“Distributed base station cooperation via block-diagonalization and dual-decomposition,”in Proceedings of the IEEE Global Telecommunications Conference, pp. 3539–3543, New Orleans, La, USA, November-December 2008.
[34] W. Yu and T. Lan,“Transmitter optimization for the multi-antenna downlink with per-antenna power constraints,”IEEE Trans. Signal Processing, vol. 55, no. 6, pp. 2646–2660, Jun. 2007.
[35] Motorola,“CoMP Support in Rel-10: Performance with intra-eNB CoBF and Cell-edge Improvements”. 3GPP TSG RAN WG1 Meeting #60, R1-101130. 2010.
[36] Naijin Liu, Ling Qiu, Jinkang Zhu,”A proactive interference suppression scheme for cellular MIMO systems”in Proceedings of GMC 2007, Shanghai, China, October 2007
[37] R. Bhagavatula and R. W. Heath, Jr., ``Adaptive Limited Feedback for Sum-Rate Maximizing Beamforming in Cooperative Multicell Systems" IEEE Trans. on Signal Processing, December 2009.
[38] R. Bhagavatula, R. W. Heath, Jr., and B. Rao ``Limited Feedback with Joint CSI Quantization for Multicell Cooperative Generalized Eigenvector Beamforming,'' to appear in Proc. of the IEEE Int. Conf. on Acoustics, Speech, and Signal Proc., Dallas, TX, March 14-19, 2010.
[39] Caire G, Jindal N, Kobayashi M, Ravindran N.“Quantized vs. analog feedback for the MIMO broadcast channel: a comparison between zero-forcing based achievable rates”. ISIT2007, IEEE, Nice, France, June, 2007: 2046-2050.
[40] Marzetta T L, Hochwald B M.“Fast transfer of channel state information in wireless systems”. IEEE Trans. on Signal Processing, 2006, 54(4):1268–1278.
[41] Huawei, TP for 3GPP TR36.814 on CoMP[C], 3GPP TSG RAN WG1 Meeting #60, R1-101679. 2010,
[42] S. Shamai (Shitz), O. Somekh, and B. M. Zaidel,“Multi-cell communications: An information theoretic perspective,”in Joint Workshop on Communications and Coding (JWCC), Florence, Italy, Oct. 2004.
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