Opportunistic eigenbeamforming: Exploiting multiuser diversity and channel correlations

Multiuser diversity is an inherent form of diversity present in any time-varying system with several users. An opportunistic scheduler has to be used in order to exploit this type of diversity. A scheme that increases the effective dynamic range of the channel by deploying multiple antennas at the transmitter is called opportunistic beamforming. Opportunistic beamforming increases the degree of multiuser diversity in several scenarios, including correlated channels. Nevertheless, multiuser diversity can also be combined with other transmit schemes that have proven to be effective in correlated channels, such as eigenbeamforming. Eigenbeamforming is a point-to-point link transmit technique that could easily be combined with an opportunistic scheduler to extract multiuser diversity. We refer to the joint use of eigenbeamforming with an opportunistic scheduler as opportunistic eigenbeamforming. In this work, we show that the available multiuser diversity with opportunistic eigenbeamforming is larger than the one achieved when opportunistic beamforming is employed using the proportional fair scheduler under different degrees of correlation in the channel. In the present work we have considered a single-cell scenario.