LoRa 流体天线多址接入
LoRa Fluid Antenna Multiple Access
- Beijing University of Posts and Telecommunications（北京邮电大学）
- Peng Cheng Laboratory（鹏城实验室）
- Shenzhen University（深圳大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出 lora-FAMA 框架，利用单个流体天线在相同资源上实现 LoRa 多用户并发传输，无需多个射频链，可同时服务超过 10 个终端设备。
AI中文摘要：
在相同的时间、频率和扩频因子（SF）资源上进行的并发远距离（LoRa）传输通常会导致数据包冲突，因为网关无法区分来自不同终端设备（ED）的重叠信号。本文提出了一种新的用于 LoRa 的流体天线多址接入（FAMA）框架，称为 lora-FAMA，为 LoRa 多用户通信提供空间机会。在 lora-FAMA 中，网关采用一个仅连接到一个射频（RF）链的流体天线，其辐射元件在每个符号间隔内通过依次访问所有候选位置（即流体天线“端口”）来遍历天线孔径。沿轨迹收集的信号段使用目标 ED 的信道状态信息进行补偿。因此，期望信号被相干累积，而来自其他 ED 的信号经历不匹配的信道变化，因此无法相干组合。对每个活动 ED 分别应用补偿可实现同时多用户传输。我们分析了 lora-FAMA 在异步传输和空间相关衰落下的统计性能，以及具有独立同分布衰落的大孔径极限情况。数值结果显示解析结果与蒙特卡洛结果非常吻合。结果表明，在归一化孔径为 4×4 且 SF=9 的情况下，网关可以在相同频率和 SF 资源上同时服务超过 10 个 ED，同时保持符号错误率低于 10^-4。这些结果展示了流体天线在无需多个 RF 链的情况下实现 LoRa 多址接入的潜力。
英文摘要：
Concurrent long-range (LoRa) transmissions over the same time-frequency and spreading factor (SF) resources generally result in packet collisions, as the gateway cannot distinguish the overlapping signals from different end devices (EDs). This paper advocates a new fluid antenna multiple access (FAMA) framework for LoRa, referred to as {\it lora}-FAMA, to provide spatial opportunities for LoRa multiuser communications. In {\it lora}-FAMA, a gateway employs a single fluid antenna connected to only one radio-frequency (RF) chain, whose radiating element traverses the antenna aperture by sequentially visiting all candidate positions, i.e., fluid antenna `ports', within each symbol interval. The signal segments collected along the trajectory are compensated using the channel state information for the target ED. As a result, the desired signal is coherently accumulated, whereas the signals from other EDs experience unmatched channel variations and thus cannot be coherently combined. Applying the compensation separately to each active ED enables simultaneous multiuser transmission. We analyze the statistical performance of {\it lora}-FAMA under asynchronous transmissions and spatially correlated fading, as well as the large-aperture limiting case with independent and identically distributed fading. Numerical results show close agreement between the analytical and Monte Carlo results. It is revealed that, with a normalized aperture of $4\times4$ and $\mathrm{SF}=9$, a gateway can simultaneously serve more than $10$ EDs over the same frequency and SF resources while maintaining a symbol error rate below $10^{-4}$. These results demonstrate the potential of fluid antennas to enable LoRa multiple access without multiple RF chains.
