Carvajal Henry, Orozco Nathaly, Cacuango Stalin, Salazar Paola, Rosero Edgar, Almeida Fernando
Faculty of Engineering and Applied Sciences (FICA), Telecommunications Engineering, Universidad de Las Américas (UDLA), Quito 170124, Ecuador.
School of Electrical and Computer Engineering, University of Campinas (UNICAMP), Campinas 13083-970, Brazil.
Sensors (Basel). 2022 Jul 19;22(14):5369. doi: 10.3390/s22145369.
For the receiver of multiple-input multiple-output (MIMO) systems, linear detectors are an interesting option due to their good performance and low complexity. Nevertheless, MIMO systems lose diversity in exchange for eliminating interference when linear detectors are used. Aiming to maintain the system diversity while mitigating interference between users, this work proposes a scheduling scheme for the uplink of multiuser MIMO (MU-MIMO) systems that employ antennas and the zero-forcing (ZF) detector at the receiver in the base station (BS). The channel model includes Rician fading and additive white Gaussian noise (AWGN) in an imperfect channel estimation scenario. The proposed scheme selects users from a group of Ut users to transmit simultaneously, so that the signal-to-noise ratio (SNR) is maximized. For this, an exact expression to evaluate the SNR of the users is obtained. With this result, the scheduling strategy is proposed. Results show that as Ut increases, the outage probability (OP), and the bit error rate (BER) decrease as the system diversity increases, even when the system is completely loaded, i.e., when U=A. Moreover, it is shown that the scheduling scheme counteracts the imperfect channel estimation effects as Ut increases. Finally, the proposed scheme is tested in presence of an external eavesdropper trying to decode the information sent by the users. The results show that the presented proposal allows for a reduction of the secrecy-outage-probability (SOP) as Ut increases.
对于多输入多输出（MIMO）系统的接收端而言，线性检测器因其良好的性能和较低的复杂度而成为一个有趣的选择。然而，当使用线性检测器时，MIMO系统以牺牲分集来换取干扰消除。旨在保持系统分集的同时减轻用户间干扰，本文提出了一种针对多用户MIMO（MU-MIMO）系统上行链路的调度方案，该系统在基站（BS）的接收端采用天线和迫零（ZF）检测器。信道模型包括在不完美信道估计场景下的莱斯衰落和加性高斯白噪声（AWGN）。所提出的方案从一组Ut个用户中选择用户同时进行传输，以使信噪比（SNR）最大化。为此，得到了一个用于评估用户信噪比的精确表达式。基于此结果，提出了调度策略。结果表明，随着Ut的增加，即使系统完全负载，即当U = A时，随着系统分集增加，中断概率（OP）和误码率（BER）会降低。此外，结果表明随着Ut的增加，调度方案能够抵消不完美信道估计的影响。最后，在存在试图解码用户发送信息的外部窃听者的情况下对所提出的方案进行了测试。结果表明，随着Ut的增加，所提出的方案能够降低保密中断概率（SOP）。
