In ambient backscatter communication (AmBC), strong direct interference from the ambient source poses a major challenge to reliable symbol detection. Although previous studies have shown that employing a low-noise amplifier (LNA) in conventional point-to-point communication improves symbol detection performance at low-to-moderate transmission power, it remains unclear whether this improvement also holds for AmBC. To respond it, in this work, we investigate the symbol detection performance of an AmBC receiver that is equipped with an LNA and adopts the energy detection (ED) to recover tag's information. Particularly, we first propose a new AmBC symbol detection framework that incorporates LNA parameters. On this basis, we derive the bit error rate (BER) of the ED and employ the deflection coefficient (DC) to demonstrate that the detection performance can be enhanced by the LNA at low-to-moderate ambient source transmission power. Then, we derive the near-optimal detection threshold to minimize the BER and propose a method to estimate the required parameters for this threshold by leveraging the tag's pilot symbols.

翻译：在环境反向散射通信（AmBC）中，来自环境源的强直接干扰对可靠符号检测构成主要挑战。尽管先前研究表明，在传统点对点通信中采用低噪声放大器（LNA）可在中低发射功率下改善符号检测性能，但该改进是否同样适用于AmBC尚不明确。为此，本研究探究了配备LNA并采用能量检测（ED）恢复标签信息的AmBC接收机的符号检测性能。具体而言，我们首先提出了一种融合LNA参数的新型AmBC符号检测框架。在此基础上，推导出ED的误码率（BER），并利用偏移系数（DC）证明在中低环境源发射功率下，LNA可提升检测性能。随后，推导出最小化BER的近似最优检测阈值，并提出一种利用标签导频符号估计该阈值所需参数的方法。