We investigate and elaborate upon a folklore in wireless communication systems that, when the nonlinearity at a transmitter is sufficiently weak so that the resulting spectral leakage is at a sufficiently low level, the capacity of the channel (including the transmitter) should be sufficiently close to the ideal channel capacity without transmitter nonlinearity. The context for this study is that effective predistortion techniques have been widely applied to linearize the transmitter nonlinearity in modern wireless communication systems, so as to render the electromagnetic radiation pattern to satisfy stringent spectral regrowth requirements. Based on the quasi-memoryless/memory polynomial model for the transmitter nonlinearity, via an information-theoretic approach, our study affirmatively validates the folklore, and more importantly, characterizes a quantitative relationship between the spectral leakage level and the capacity loss. Specifically, we prove that as the adjacent channel power ratio (ACPR) asymptotically vanishes, the capacity loss is upper bounded by a term that is proportional to the ACPR. We also establish a converse result, and further extend our results to spatial beamforming.

中文翻译：

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弱非线性发射机频谱泄漏约束下的渐近容量损失


我们研究并详细阐述了无线通信系统中的一个民间传说，即当发射机的非线性足够弱以致所产生的频谱泄漏处于足够低的水平时，信道（包括发射机）的容量应足够接近没有发射机非线性的理想信道容量。本研究的背景是有效的预失真技术已广泛应用于现代无线通信系统中发射机非线性的线性化，从而使电磁辐射方向图满足严格的频谱再生要求。基于发射机非线性的准无记忆/记忆多项式模型，通过信息论方法，我们的研究肯定地验证了民间传说，更重要的是，表征了频谱泄漏水平与容量损失之间的定量关系。具体来说，我们证明，随着相邻信道功率比 (ACPR) 渐近消失，容量损失的上限受到与 ACPR 成比例的项的限制。我们还建立了相反的结果，并将我们的结果进一步扩展到空间波束形成。