In large-array millimeter-wave (mmWave) systems, hybrid pre-coding is one of the most attractive research topics. This paper first presents a flexible adaptive overlapped subarray (OSA) architecture for the analog precoder, whose architecture can be adjusted by a connection network. An objective function is formulated to maximize the energy efficiency (EE) in consideration of the insertion loss for the proposed adaptive OSA based hybrid precoder. The optimal scheme is intractable to achieve, so that we present a heuristic hybrid pre-coding scheme, where the digital precoder is designed based on the zero-forcing (ZF) rule and the analog precoder is designed based on simplified EE optimization in consideration of the insertion loss. We discuss the effect of non-ideal factors on the EE performance, such as quantized phases, imperfect channel state information (CSI), and faulty switches. Simulation results show that, when the initial transmit power is large, our proposed scheme offers a better EE performance than the fully digital pre-coding scheme and many other popular hybrid pre-coding schemes. Moreover, it is found that faulty switches make the double-edged effect on the EE performance when the numbers of activated phase shifters and combiners are pre-defined.

中文翻译：

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用于大阵列毫米波系统的具有自适应重叠子阵列的节能混合预编码器

在大阵列毫米波 (mmWave) 系统中，混合预编码是最具吸引力的研究课题之一。本文首先为模拟预编码器提出了一种灵活的自适应重叠子阵列 (OSA) 架构，其架构可以通过连接网络进行调整。考虑到所提出的基于自适应 OSA 的混合预编码器的插入损耗，制定了一个目标函数以最大化能量效率 (EE)。最优方案难以实现，因此我们提出了一种启发式混合预编码方案，其中数字预编码器基于迫零（ZF）规则设计，模拟预编码器基于简化的EE优化设计，考虑到插入损耗。我们讨论了非理想因素对 EE 性能的影响，例如量化相位、不完善的信道状态信息 (CSI) 和故障切换。仿真结果表明，当初始发射功率较大时，我们提出的方案比全数字预编码方案和许多其他流行的混合预编码方案提供更好的EE性能。此外，发现当激活的移相器和组合器的数量是预先定义的时，故障开关会对 EE 性能产生双重影响。