Inter-sector beamforming with MMSE receiver in the downlink of TDD cellular systems

The use of beamforming is effective for users in limited power environments. However, when it is applied to the downlink of a cellular system with universal frequency reuse, users near the sector boundary may experience significant interference from more than one sector. The use of a minimum mean square error (MMSE)-type receiver may not sufficiently cancel out the interference unless a sufficient number of receive antennas are used. In this paper, we consider the use of inter-sector beamforming that cooperates with a neighboring sector in the same cell to mitigate this interference problem in time-division duplex (TDD) environments. The proposed scheme can avoid interference from an adjacent sector in the same cell, while enhancing the transmit array gain by using the TDD reciprocity. The performance of the proposed scheme is analyzed in terms of the output signal-to-interference-plus-noise power ratio (SINR) and the output capacity when applied to an MMSE-type receiver. The beamforming mode can be analytically switched between the inter-sector and the single-sector mode based on the long-term channel information. Finally, the effectiveness of the proposed scheme is verified by computer simulation.

[1]  Rohit U. Nabar,et al.  Introduction to Space-Time Wireless Communications , 2003 .

[2]  Armin Dammann,et al.  Analysis of Coded OFDMA in a Downlink Multi-Cell Scenario , 2004 .

[3]  Jack M. Winters,et al.  Optimum Combining in Digital Mobile Radio with Cochannel Interference , 1984, IEEE Journal on Selected Areas in Communications.

[4]  Ieee Microwave Theory,et al.  Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems — Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands , 2003 .

[5]  Shlomo Shamai,et al.  Enhancing the cellular downlink capacity via co-processing at the transmitting end , 2001, IEEE VTS 53rd Vehicular Technology Conference, Spring 2001. Proceedings (Cat. No.01CH37202).

[6]  Keith G. Balmain,et al.  Multipath performance of adaptive antennas with multiple interferers and correlated fadings , 1999 .

[7]  Tung-Sang Ng,et al.  Advances in 3G Mobile Enhanced Technologies for Wireless Communications , 2002 .

[8]  Andrea J. Goldsmith,et al.  PhantomNet: Exploring Optimal Multicellular Multiple Antenna Systems , 2004, EURASIP J. Adv. Signal Process..

[9]  Keith Q. T. Zhang,et al.  Outage probability for optimum combining of arbitrarily faded signals in the presence of correlated Rayleigh interferers , 2004, IEEE Transactions on Vehicular Technology.

[10]  Frederick W. Vook,et al.  Transmit diversity and transmit adaptive arrays for broadband mobile OFDM systems , 2003, 2003 IEEE Wireless Communications and Networking, 2003. WCNC 2003..

[11]  Audra E. Kosh,et al.  Linear Algebra and its Applications , 1992 .

[12]  Mamoru Sawahashi,et al.  Performance Comparison Between Fast Sector Selection and Simultaneous Transmission with Soft-Combining for Intra-Node B Macro Diversity in Downlink OFDM Radio Access , 2006, 2006 IEEE 63rd Vehicular Technology Conference.

[13]  Guocong Song,et al.  Linear Interference Cancellation for Downlink Map Reception in IEEE 802.16E , 2006, 2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications.

[14]  Alister G. Burr,et al.  Survey of Channel and Radio Propagation Models for Wireless MIMO Systems , 2007, EURASIP J. Wirel. Commun. Netw..

[15]  Gene H. Golub,et al.  Matrix computations , 1983 .

[16]  Yikang Xiang,et al.  Inter-cell Interference Mitigation through Flexible Resource Reuse in OFDMA based Communication Networks , 2007 .

[17]  David Tse,et al.  Fundamentals of Wireless Communication , 2005 .

[18]  Sumit Roy,et al.  Downlink multicell MIMO-OFDM: an architecture for next generation wireless networks , 2005, IEEE Wireless Communications and Networking Conference, 2005.

[19]  Jun Tan,et al.  Multicarrier delay diversity modulation for MIMO systems , 2004, IEEE Trans. Wirel. Commun..

[20]  Amitava Ghosh,et al.  WiMAX System Performance with Multiple Transmit and Multiple Receive Antennas , 2007, 2007 IEEE 65th Vehicular Technology Conference - VTC2007-Spring.

[21]  Ranjan K. Mallik,et al.  Bounds and approximations for optimum combining of signals in the presence of multiple cochannel interferers and thermal noise , 2003, IEEE Trans. Commun..