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.

翻译：低功率长程调制(LoRa)已经用于满足物联网网络的低功率和大覆盖范围要求。在本文件中,我们调查了装有多天线的网关时Lora调制的性能改进情况。我们在综合从多天线收到的信号时,为一致和非一致的检测制定了最佳决策规则。我们分别展示了在AWGN和Rayleigh 的逐渐消失的渠道中连贯和不连贯的检测的符号/比特差概率。此外,我们还建议采用不要求任何间接费用来估计频道状态信息(CSI)的性能,而其性能可以接近连贯检测的性能。模拟和分析结果表明,在所有考虑的检测计划中,使用多天线可以带来巨大的能量增益。