Distributed Multi-Cell Zero-Forcing Beamforming in Cellular Downlink Channels

Abstract— For a multiple-input single-output (MISO) downlink channel with ¢ transmit antennas, it has been recently proved that zero-forcing beamforming (ZFBF) to a subset of (at most) ¢ “semi-orthogonal” users is optimal in terms of the sum-rate, asymptotically with the number of users. However, determining the subset of users for transmission is a complex optimization problem. Adopting the ZFBF scheme in a cooperative multi-cell scenario renders the selection process even more difficult since more users are involved. In this paper, we consider a multi-cell cooperative ZFBF scheme combined with a simple sub-optimal users selection procedure for the Wyner downlink channel setup. According to this sub-optimal procedure, the user with the “best” local channel is selected for transmission in each cell. It is shown that under an overall power constraint, a distributed multi-cell ZFBF to this sub-optimal subset of users achieves the same sum-rate growth rate as an optimal schem...

• Type: Conference
• Year: 2006
• Where: GLOBECOM
• Authors: Oren Somekh, Osvaldo Simeone, Yeheskel Bar-Ness, Alexander M. Haimovich
• Keywords: Cooperative Multi-cell Scenario, Downlink Channel, GLOBECOM 2006, Overall Power Constraint, Telecommunications