Harmonic Suppression in Frequency Shifted Backscatter Communications
Harmonic Suppression in Frequency Shifted Backscatter Communications
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DOI：
10.1109/ojcoms.2020.3011520
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发表时间：
2020-07
影响因子：
7.9
通讯作者：
Yuan Ding;Romwald Lihakanga;R. Correia;G. Goussetis;N. Carvalho
中科院分区：
文献类型：
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作者：
Yuan Ding;Romwald Lihakanga;R. Correia;G. Goussetis;N. Carvalho
本文对频移后向散射通信系统产生的谐波进行了全面的研究。不同谐波的抑制和可操纵性对于避免当多个反向散射节点（以及可能还有其他活动无线用户）在网络中同时操作时的有害用户间干扰是重要的。本文首先介绍了一种广泛采用的开-短反向散射标签结构所产生的谐波。然后讨论了不产生谐波的理想后向散射系统，由此引出了各种谐波抑制策略。特别地，应用反向散射标签硬件能力的实际约束，例如，可以合成的离散反射系数的数量以及反射系数的维数（实值或复值）。此外，发现基于双晶体管的IQ反向散射调制器可用于抑制所有镜像谐波和任何指定的高阶谐波。这些建议的谐波抑制方法的适用性证明了由多个节点同时执行二进制频移键控（2FSK）调制的反向散射通信组成的示范反向散射网络。
This paper provides a comprehensive study of the harmonics generated by a frequency shifted backscatter communication system. The suppression and the manipulability of different harmonics are of importance to avoid detrimental inter-user interference when a number of backscattering nodes (and perhaps also other active wireless users) operate simultaneously in a network. In this paper the harmonics generated by a widely adopted open-short backscatter tag architecture is firstly presented. Then the ideal backscatter system which generates no unwanted harmonics is discussed, which inspires various harmonic suppression strategies. In particular, practical constraints of the backscatter tag hardware capabilities are applied, e.g., the number of discrete reflection coefficients that can be synthesized, and the dimension of the reflection coefficients (real-valued or complex-valued). Furthermore, the dual-transistor based IQ backscatter modulator is found useful to suppress all mirror harmonics and any specified higher order harmonics. The applicability of these proposed harmonic suppression approaches are demonstrated by an exemplar backscatter network consisting of multiple nodes performing binary frequency shifted keying (2FSK) modulated backscatter communications simultaneously.