User Pairing Scheme Research Articles

Robust user pairing algorithm under channel estimation errors for uplink virtual multiple-input multiple-output systems

Employing user pairing schemes in uplink virtual multiple-input multiple-output (V-MIMO) systems can significantly improve system capacity owing to multi-user diversity. Most of the existing user pairing algorithms were developed under the assumption that a scheduler always possesses the perfect channel state information (CSI). In this paper, taking into account the effects of channel estimation error (CEE), the authors propose a robust user pairing algorithm based on a closed-form average sum rate under CEE. In addition, the authors further propose an adaptive user selection scheme as an effort to maximise the sum rates owing to the rate constraint under CEE. The gain of the proposed method is shown in simulation results.

Joint User Pairing and Precoding in MU-MIMO Broadcast Channel with Limited Feedback

In this paper, we propose a joint user pairing and precoding scheme in MU-MIMO broadcast channel with limited feedback. In the proposed scheme, each user feeds back its preferable precoding vector index and two scalars denoting quantization error and the largest singular value of channel matrix, respectively. Base station (BS) selects the first user who has highest estimated SINR, and generates a unitary precoding matrix based on the first user's preferred precoding vector. Then, BS selects users one by one. In each step, BS calculates the estimated SINR for each un-selected user, using the generated precoding vector, and then chooses the user with largest estimated SINR. Numerical results verify its effectiveness.