Phaseforming: a suitable representation of array gain in broadband multicarrier transmissions

Standard beamforming designs are typically based on narrowband transmissions and narrow angle spread scenarios. In this situation, pointing a narrow beam towards the main reflector is a suitable strategy for transmit beamforming in order to minimize interuser interference while a wider beam should be introduced in receiving applications in order to increase signal to noise ratio (SNR). In both cases, design is based on beamformer concepts where distribution of array gain for different angles is a good description. However, in multicarrier (MC) transmissions through wide angle spread channels, phase shift between different antennas for all the carriers provide a more suitable description for the array gain concept. In this paper we will describe this procedure for MC-CDMA as a candidate for B3G (beyond 3G) mobile application analysing different alternatives if channel state information (CSI) is assumed or partial CSI has to be considered.