Due to extremely low power consumption, backscatter has become the transmission mechanism of choice for battery-free devices that operate on harvested energy. However, a limitation of recent backscatter systems is that the communication range scales with the strength of the ambient carrier signal(ACS). This means that to achieve a long range, a backscatter tag needs to reflect a strong ACS, which in practice means that it needs to be close to an ACS emitter. We present TunnelScatter, a mechanism that overcomes this limitation. TunnelScatter uses a tunnel diode-based radio frequency oscillator to enable transmissions when there is no ACS, and the same oscillator as a reflection amplifier to support backscatter transmissions when the ACS is weak. Our results show that even without an ACS, TunnelScatter is able to transmit through several walls covering a distance of 18 meter while consuming a peak biasing power of 57 microwatts. Based on TunnelScatter, we design battery-free sensor tags, called TunnelTags, that can sense physical phenomena and transmit them using the TunnelScatter mechanism.

中文翻译：

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TunnelScatter：使用隧道二极管的传感器标签低功耗通信

由于功耗极低，反向散射已成为依靠收集能量运行的无电池设备的首选传输机制。然而，最近的反向散射系统的一个限制是通信范围随环境载波信号 (ACS) 的强度而变化。这意味着要实现远距离，反向散射标签需要反射强 ACS，这实际上意味着它需要靠近 ACS 发射器。我们提出了 TunnelScatter，这是一种克服此限制的机制。TunnelScatter 使用基于隧道二极管的射频振荡器在没有 ACS 时启用传输，并使用与反射放大器相同的振荡器在 ACS 较弱时支持反向散射传输。我们的结果表明，即使没有 ACS，TunnelScatter 能够通过覆盖 18 米距离的几堵墙进行传输，同时消耗 57 微瓦的峰值偏置功率。基于 TunnelScatter，我们设计了无电池传感器标签，称为 TunnelTags，可以感知物理现象并使用 TunnelScatter 机制传输它们。