A High-Diversity Transceiver Design for K-User MISO Broadcast Channels
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In this paper, a new transceiver architecture is proposed for K-user multiple-input single-output (MISO) broadcast channels (BCs) to overcome the drawback of the conventional linear zero-forcing (ZF) downlink beamforming. The proposed transceiver architecture is based on channel-adaptive user grouping and mixture of linear and nonlinear reception: it groups users with closely-aligned channels and applies superposition coding and successive interference cancellation (SIC) decoding to each group composed of users with closely-aligned channels, while applying ZF beamforming across roughly-orthogonal user groups. The outage probability and diversity order of the proposed transceiver architecture are analyzed based on newly derived closed-form lower bounds on the achievable rates of a general multi-user (MU) MISO BC with superposition coding and SIC decoding and the property of the proposed user grouping algorithm. It is shown that the proposed transceiver architecture can achieve the diversity order of the single-user maximum ratio transmit (MRT) beamforming. Hence, the proposed transceiver architecture can provide much higher diversity order and more reliable communication compared to the conventional ZF downlink beamforming under channel fading environments. Numerical results validate our analysis and show the superiority of the proposed scheme over the conventional ZF downlink beamforming in outage performance.
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