Ambient backscatter communication (AmBC) leverages the existing ambient radio frequency (RF) environment to implement communication with battery-free devices. The key challenge in the development of AmBC is the very weak RF signals backscattered by the AmBC Tag. To overcome this challenge, we propose the use of orthogonal space-time block codes (OSTBC) by incorporating multiple antennas at the Tag as well as at the Reader. Our approach considers both coherent and non-coherent OSTBC so that systems with and without channel state information can be considered. To allow the application of OSTBC, we develop an approximate linearized and normalized multiple-input multiple-output (MIMO) channel model for the AmBC system. This MIMO channel model is shown to be accurate for a wide range of useful operating conditions. Two coherent detectors and a non-coherent detector are also provided based on the proposed AmBC channel model. Simulation results show that enhanced bit error rate performance can be achieved, demonstrating the benefit of using multiple antennas at the Tag as well as the Reader.

中文翻译：

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利用相干和非相干时空码增强环境反向散射通信


环境反向散射通信（AmBC）利用现有的环境射频（RF）环境来实现与无电池设备的通信。 AmBC 开发的主要挑战是 AmBC 标签反向散射的射频信号非常微弱。为了克服这一挑战，我们建议通过在标签和阅读器处合并多个天线来使用正交空时分组码（OSTBC）。我们的方法考虑了相干和非相干 OSTBC，以便可以考虑具有和不具有信道状态信息的系统。为了允许 OSTBC 的应用，我们为 AmBC 系统开发了近似线性化和归一化的多输入多输出 (MIMO) 信道模型。事实证明，该 MIMO 信道模型对于各种有用的操作条件都是准确的。基于所提出的 AmBC 信道模型，还提供了两个相干检测器和一个非相干检测器。仿真结果表明，可以实现增强的误码率性能，证明了在标签和阅读器上使用多个天线的好处。