In this article, we propose and investigate hybrid active and passive antenna selection for backscatter-assisted multiple input and single output (MISO) systems. Specifically, each transmit antenna is allowed to work on either the active radio (AR) mode or the passive radio (PR) mode, which are respectively powered by the battery as in traditional communication and the external power source as in the backscatter communication (BackCom). The advantage is that the link reliability can be enhanced, and the power consumption can be opportunistically reduced by switching between the AR and the PR modes. Adaptive antenna selection is investigated and analyzed, where the antenna is selected over all combinations of antennas and their working modes. However, the antenna with the best channel quality will always be chosen. In order to circumvent this problem, two alternative schemes, referred to as reactive antenna selection and proactive antenna selection, are considered, where all antennas take turns to transmit/backscatter the signal. Specifically, in the reactive antenna selection scheme, the working mode for each antenna is determined by choosing the maximum value of the transmit power in the AR mode and the backscatter power in the PR mode. The working mode for the proactive antenna selection scheme is, however, chosen beforehand. Since the exact closed-form expression for the average symbol error rate (SER) is not attainable, approximations and their asymptotic performance are derived for proposed schemes. The power consumption is also analyzed. Simulation results demonstrate the correctness and the tightness of our analysis, and the effectiveness of proposed schemes.

中文翻译：

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反向散射辅助 MISO 系统的混合有源和无源天线选择

在本文中，我们提出并研究了反向散射辅助多输入单输出 (MISO) 系统的混合有源和无源天线选择。具体来说，每个发射天线可以工作在有源无线电（AR）模式或无源无线电（PR）模式，分别由传统通信中的电池供电和反向散射通信（BackCom）中的外部电源）。优点是可以增强链路可靠性，并可以通过在AR和PR模式之间的切换机会降低功耗。研究和分析了自适应天线选择，其中在天线及其工作模式的所有组合中选择天线。但是，将始终选择具有最佳信道质量的天线。为了规避这个问题，考虑了两种替代方案，称为反应天线选择和主动天线选择，其中所有天线轮流发射/反向散射信号。具体而言，在无功天线选择方案中，通过选择AR模式下的发射功率和PR模式下的反向散射功率的最大值来确定每个天线的工作模式。然而，主动天线选择方案的工作模式是预先选择的。由于无法获得平均符号错误率 (SER) 的精确闭式表达式，因此推导出所建议方案的近似值及其渐近性能。还分析了功耗。仿真结果证明了我们分析的正确性和严密性，