A BEAMFORMER FOR 120-DEGREE SECTORIZATION IN LTE SYSTEMS
Keywords:
Beamforming network, inter-cell nterference, LTE, mobile networks, switched-beam antennas, sectorizationAbstract
Long term evolution (LTE) technology is the most likely candidate for the next generation of mobile wireless communications. One drawback of LTE is interference from neighboring cells, so called inter-cell interference. Fractional frequency reuse (FFR) has been proposed to handle the problem. Also lately, a soft FFR technique has been introduced for better utilization of the frequency spectrum. In addition, the beamforming technique is considered to be the solution to improve the performance of wireless communication systems. Therefore, this paper proposes a new beamforming matrix suitable for LTE systems in which the coverage area is divided into 3 120°-sectors. The appropriate number of antenna elements and beam patterns is discussed. The computer simulation in terms of beam patterns confirms the proposed concept. Also, a prototype of the new beamformer is fabricated and tested to reveal the real performance in terms of the signal-to-interference ratio and channel capacity. The obtained results how that the soft FFR technique including beamforming is the best choice for LTE systems.
References
Alexiou, A. and Haardt, M. (2004). Smart antenna technologies for future wireless systems: trends and challenges. IEEE Commun. Mag., 42(9): 90-97.
Balanis, C.A. and Ioannides, P. (2007). Introduction to Smart Antennas. Morgan & Claypool Publishers, San Rafael, CA, USA, 162p.
Bona, M., Manholm, L., Starski, J.P., and Svensson, B. (2002). Low-loss compact Butler matrix for a microstrip antenna. IEEE T. Microw. Theory, 50(9):2069-2075.
Chu, S., Lin, H., and Lin, D. (2005). Performance enhancement by using switch-beam smart an¬tenna in 802.11a WLAN system. Proceedings of the IEEE/ACES International Conference on Wireless Communications and Applied Com¬putational Electromagnetics; April 3-7, 2005; Hoholulu, HI, USA, p. 1001-1005.
Collin, R.E. (2001). Foundations for Microwave Engineering. John Wiley & Sons, Inc., Hoboken, NJ, USA, 944p.
Das, A. and Das, S.K. (2002). Microwave Engineering. McGraw-Hill Education, New York, NY, USA, 516p.
The 3rd Generation Partnership Project. (2006). Requirements for Evolved Universal Terrestrial Radio Access (UTRA) and Universal Terrestrial Radio Access Network (UTRAN). TR 25.913 v7.3.0. 3GPP, Sophia Antipolis, Valbonne, France.
Ho, M., Stüber, G.L., and Austin, M.D. (1998). Performance of switched beam smart antennas for cellular radio systems. IEEE T. Veh. Technol., 47(1):1-19.
Ibrahim, J. (2002). 4G Features. Bechtel Telecommuni¬cations Technical Journal, 1(1):11-14.
Khan, F. (2009). LTE for 4G Mobile Broadband. Air Interface Technologies and Performance. Cambridge University Press, Cambridge, UK, 492p.
Liberti, J.C. and Rappaport, T.S. (1999). Smart Antennas for Wireless Communications:IS-95 and Third Generation CDMA Applications. Prentice Hall PTR, Upper Saddle River, NJ, USA, 528p.
Liu, G,, Zhang, J., Jiang, D., Lei, L., Wang, Q., and Qin, F. (2009). Downlink interference coordination and mitigation for future LTE-Advanced system. Proceedings of the 15th IEEE Asia-Pacific Conference on Communications; October 8-10, 2009; Shanghai, China, p. 225-229.
Lott, M. (2006). Adaptive random access with beamforming in 4G mobile networks. Proceedings of the 63rd IEEE Vehicular Technology Conference; May 7-10, 2006; Melbourne, Vic, Australia, p. 435-439.
Moody, H. (1964). The systemmatic design of the Butler matrix. IEEE T. Antenn. Propag., 12(6):786-788.
Pozar, D.M. (1998). Microwave Engineering. 2nd ed. John Wiley & Sons, Inc., Hoboken, NJ, USA, 736p.
Santhi, K.R., Srivastava, V.K., Kumaran, G.S., and Butare, A. (2003). Goals of true broad band’s wireless next wve (4G-5G). Proceedings of the 58th IEEE Vehicular Technology Conference; October 6-9, 2003; Orlando, FL, USA, p. 2317- 2321.
