To analyze the achievable performance of antenna selection (AS) in practical multi-antenna systems, this paper studies the receive antenna selection (RAS) in single-input multiple-output (AS-SIMO) systems under discrete inputs. We first propose an approximate expression to evaluate the instantaneous mutual information (MI) of $M$ -ary quadrature amplitude modulation ( $M$ -QAM) signaling over additive white Gaussian noise (AWGN) channels. Then, by exploiting this approximate formula, we develop a closed-form formula for the ergodic MI in AS-SIMO systems with $M$ -QAM signaling. Additionally, we also analyze the asymptotic MI for a large number of receive antennas $N_{\mathrm{r}}$ . This asymptotic analysis suggests that the scaling rate of the MI with $N_{\mathrm{r}}$ becomes zero rate in contrast to the double logarithmic rate under Gaussian inputs. Besides, our result is also extended to discuss the mutual information of multiple-input multiple-output (MIMO) systems having discrete inputs with receive antenna selection, and an upper bound for the MI is derived. Finally, the derived result is applied to analyze several performance measures of the discrete inputs driven AS-SIMO systems. Specifically, it is first used to discuss the relationship between the ergodic MI and the number of active antennas. Our investigation shows that this relationship follows Pareto principle, i.e., 80% of the MI of full-antenna selection can be achieved via 20% of the total antennas. Then, our proposed approximation is employed to analytically study the effective MI which takes channel estimation (CE) into consideration, indicating that CE is a main limit of large-scale systems. Moreover, the energy efficiency (EE) is explored on the basis of our results, and we find there exists an optimal number of active antennas to maximize the energy efficiency. In addition to theoretical derivations, all the analytical results are validated by numerical simulations.

中文翻译：

---

离散输入下的接收天线选择：近似和应用

为了分析实际多天线系统中天线选择 (AS) 的可实现性能，本文研究了离散输入下单输入多输出 (AS-SIMO) 系统中的接收天线选择 (RAS)。我们首先提出了一个近似表达式来评估瞬时互信息（MI） 百万美元 -ary 正交调幅 ( 百万美元 -QAM) 信号通过加性高斯白噪声 (AWGN) 信道。然后，通过利用这个近似公式，我们为 AS-SIMO 系统中的遍历 MI 开发了一个封闭形式的公式 百万美元 -QAM 信令。此外，我们还分析了大量接收天线的渐近 MI $N_{\mathrm{r}}$ . 这种渐近分析表明 MI 的缩放率与 $N_{\mathrm{r}}$ 与高斯输入下的双对数率相比，变为零率。此外，我们的结果还扩展到讨论具有离散输入和接收天线选择的多输入多输出 (MIMO) 系统的互信息，并推导出 MI 的上限。最后，导出的结果用于分析离散输入驱动的 AS-SIMO 系统的几种性能度量。具体来说，首先用来讨论遍历MI与有源天线数的关系。我们的调查表明，这种关系遵循帕累托原则，即全天线选择的 MI 的 80% 可以通过总天线的 20% 来实现。然后，我们提出的近似值用于分析研究考虑信道估计 (CE) 的有效 MI，表明 CE 是大规模系统的主要限制。此外，在我们的结果的基础上探索了能源效率 (EE)，我们发现存在最佳数量的有源天线来最大化能源效率。除理论推导外，所有分析结果均通过数值模拟进行验证。