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This study focuses on robust Tomlinson-Harashima precoding transceiver design for multi-cell multiple-input- multiple-output interference channel with statistical channel state information error. The objective is formulated to minimise the maximum per-user mean square error (MSE) with per-transmitter power constraint. Since the problem is not jointly convex, an approximated method is proposed. The authors optimise the receiver matrix to be minimum MSE form as well as derive the optimisation problems of transmitter matrix and feedback matrix to be second-order cone programming, respectively. By use of the results, the three matrices are updated iteratively. The convergence of the proposed method is also proved. Simulation results show that the proposed scheme outperforms the robust linear transceiver in both MSE and bit error ratio. [ABSTRACT FROM AUTHOR]

In conventional schedule-based wireless transmission system, frequent interactions between devices and access networks lead to significant signalling overhead, and thus limit the development of low-latency applications. Contention-based data transmission (CBDT) is widely used as a promising solution to address the above issues. In this study, the authors propose a detection-based retransmission scheme for CBDT to further reduce the delay-outage probability which cannot be avoided due to collision. In this scheme, each device simultaneously monitors the occupied resource blocks during data transmission. When a collision event is detected, the retransmission for this packet is determined without waiting for the acknowledgment message from the receiver. The reliability performance is significantly improved for low-latency applications, since the possible retransmission times for each packet is increased within the limited transmission period. In addition, the impacts of imperfect detection on extra transmission load and packet loss are analysed in detail. The simulation and analytical results demonstrate that the detection-based scheme significantly improves the reliability of CBDT. [ABSTRACT FROM AUTHOR]