Improved Iterative Coordinated Beamforming Based on Singular Value Decomposition for Multiuser Mimo Systems With Limited Feedforward

 

L. Soriano–Equigua*¹, J. Sánchez–García², C.–B. Chae³, R. W. Heath Jr.⁴

 

^1,2 Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada–Tijuana No. 3918, Zona Playitas, Ensenada, B. C. México. C.P. 22860. *E–mail: lsoriano@cicese.mx

³ School of Integrated Technology, College of Engineering, Yonsei University, 162–1 Songdo–dong, Yeonsu–gu, Incheon, 406–840, Korea

⁴ Wireless Networking and Communications Group (WNCG), Department of Electrical and Computer Engineering, The University of Texas at Austin, 1 University Station C0803, Austin, TX, USA 78712.

 

ABSTRACT

Coordinated beamforming based on singular value decomposition is an iterative method to jointly optimize the transmit beamformers and receive combiners, to achieve high levels of sum rates in the downlink of multiuser systems, by exploiting the multi–dimensional wireless channel created by multiple transmit and receive antennas. The optimization is done at the base station and the quantized beamformers are sent to the users through a low rate link. In this work, we propose to optimize this algorithm by reducing the number of iterations and improving its uncoded bit error rate performance. Simulation results show that our proposal achieves a better bit error rate with a lower number of iterations than the original algorithm.

Keywords: Coordinated beamforming, multiuser MIMO, iterative, convergence, bit error rate.

 

RESUMEN

El beamforming coordinado basado en descomposición de matrices en valores singulares, es un método iterativo que nos permite calcular conjuntamente los vectores de peso de las antenas transmisoras en la estación base y las antenas receptoras en los móviles, para alcanzar altos niveles de tasas de bits en el canal de bajada de sistemas MIMO multiusuario. La optimización se realiza en la estación base y los vectores de peso cuantizados del transmisor se envían a cada usuario a través de un enlace de baja velocidad. En este trabajo, nosotros proponemos optimizar este algoritmo para reducir el número de iteraciones necesarias para que el algoritmo converja y mejorar la tasa de bit errónea. Los resultados de las simulaciones realizadas muestran que nuestra propuesta alcanza una mejor tasa de bit errónea con un menor número de iteraciones.

 

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Acknowledgements

The work of C.–B. Chae was in part supported by the Ministry of Knowledge Economy under the "IT Consilience Creative Program" (NIPA–2010–C1515–1001–0001).

 

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