EURASIP Journal on Wireless Communications and Networking
Volume 2007 (2007), Article ID 93421, 9 pages
doi:10.1155/2007/93421
Research Article
Optimal Design of Nonuniform Linear Arrays in Cellular Systems by Out-of-Cell Interference Minimization
1Dipartimento di Elettronica e Informazione, Politecnico di Milano, Milano 20133, Italy
2Center for Wireless Communications and Signal Processing Research (CCSPR), New Jersey Institute of Technology, University Heights, Newark 07102-1982, NJ, USA
Received 13 October 2006; Accepted 11 July 2007
Academic Editor: Monica Navarro
Copyright © 2007 S. Savazzi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Optimal design of a linear antenna array with nonuniform interelement spacings is investigated for the uplink of a cellular system. The optimization criterion considered is based on the minimization of the average interference power at the output of a conventional beamformer (matched filter) and it is compared to the maximization of the ergodic capacity (throughput). Out-of-cell interference is modelled as spatially correlated Gaussian noise. The more analytically tractable problem of minimizing the interference power is considered first, and a closed-form expression for this criterion is derived as a function of the antenna spacings. This analysis allows to get insight into the structure of the optimal array for different propagation conditions and cellular layouts. The optimal array deployments obtained according to this criterion are then shown, via numerical optimization, to maximize the ergodic capacity for the scenarios considered here. More importantly, it is verified that substantial performance gain with respect to conventionally designed linear antenna arrays (i.e., uniform λ/2 interelement spacing) can be harnessed by a nonuniform optimized linear array.