Low-power long-range (LoRa) modulation has been used to satisfy the low power and large coverage requirements of Internet of Things (IoT) networks. In this paper, we investigate performance improvements of LoRa modulation when a gateway is equipped with multiple antennas. We derive the optimal decision rules for both coherent and non-coherent detections when combining signals received from multiple antennas. We present expressions of the symbol/bit error probabilities of both the coherent and non-coherent detections in AWGN and Rayleigh fading channels, respectively. Moreover, we also propose an iterative semi-coherent detection that does not require any overhead to estimate the channel-state-information (CSI) while its performance can approach that of the coherent detection. Simulation and analytical results show very large power gains provided by the use of multiple antennas for all the detection schemes considered.

中文翻译：

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信号组合对LoRa调制的性能改进

低功率远程（LoRa）调制已用于满足物联网（IoT）网络的低功率和大覆盖范围的要求。在本文中，我们研究了网关配备多个天线时LoRa调制的性能改进。当组合从多个天线接收的信号时，我们针对相干和非相干检测得出最佳决策规则。我们分别给出了在AWGN和瑞利衰落信道中相干和非相干检测的符号/误码率表示。此外，我们还提出了一种迭代半相干检测，该迭代半相干检测不需要任何开销即可估计信道状态信息（CSI），而其性能可以达到相干检测的性能。