Equal Gain MIMO Beamforming in the RF Domain for OFDM-WLAN Systems

Date Added: Jun 2010
Format: PDF

Equal Gain Beam-forming (EGB) schemes are typically applied in the baseband domain and hence require complex RF transceivers. In order to simplify the circuitry and energy consumption of the MIMO transceiver, in this paper the authors consider an EGB scheme that operates in the RF domain by means of analog phase shifters. Under OFDM transmissions, the design of the optimal phases is a complicated non-convex problem with no closed-form solution. Building upon a previously proposed solution for flat-fading MIMO channels, this paper describes an alternating minimization algorithm to find an approximate (sub-optimal) solution for the OFDM case. Monte-Carlo simulations are performed in order to demonstrate the effectiveness of this new analog beam-forming scheme under coded and un-coded WLAN 802.11a transmissions.