The development of next generation wireless communication systems focuses on the expansion of existing technologies, while ensuring an accord between various devices within a system. In this article, we target the aspect of precoder design for simultaneous wireless information and power transmission (SWIPT) in a multi-group (MG) multicasting (MC) framework capable of handling heterogeneous types of users, viz., information decoding (ID) specific, energy harvesting (EH) explicit, and/or both ID and EH operations concurrently. Precoding is a technique well-known for handling the inter-user interference in multi-user systems, however, the joint design with SWIPT is not yet fully exploited. Herein, we investigate the potential benefits of having a dedicated precoder for the set of users with EH demands, in addition to the MC precoding. We study the system performance of the aforementioned system from the perspectives of weighted sum of signal-to-interference-plus-noise-ratio (SINR) and fairness. In this regard, we formulate the precoder design problems for (i) maximizing the weighted sum of SINRs at the intended users and (ii) maximizing the minimum of SINRs at the intended users; both subject to the constraints on minimum (non-linear) harvested energy, an upper limit on the total transmit power and a minimum SINR required to close the link. We solve the above-mentioned problems using distinct iterative algorithms with the help of semi-definite relaxation (SDR) and slack-variable replacement (SVR) techniques, following suitable transformations pertaining the problem convexification. The main novelty of the proposed approach lies in the ability to jointly design the MC and EH precoders for serving the heterogeneously classified ID and EH users present in distinct groups, respectively. We illustrate the comparison between the proposed weighted sum-SINR and fairness models via simulation results, carried out under various parameter values and operating conditions.

中文翻译：

---

异构用户SWIPT-多组组播系统的加权和-SINR和公平性优化

下一代无线通信系统的开发着眼于现有技术的扩展，同时确保系统内各种设备之间的协调一致。在本文中，我们将目标放在预编码器设计的方面，以便在能够处理异构类型的用户（即信息解码（ID））的多组（MG）多播（MC）框架中同时进行无线信息和功率传输（SWIPT）。明确的能量收集（EH）和/或ID和EH操作同时进行。预编码是一种众所周知的处理多用户系统中用户间干扰的技术，但是与SWIPT的联合设计尚未得到充分利用。在本文中，我们调查了除了MC预编码之外，针对具有EH需求的一组用户使用专用预编码器的潜在好处。我们从信号与干扰加噪声比（SINR）和公平性的加权总和的角度研究上述系统的系统性能。在这方面，我们为（i）最大化预期用户的SINR加权总和和（ii）最大化预期用户的SINR的最小化制定了预编码器设计问题。两者都受到最小（非线性）采集能量，总发射功率的上限以及关闭链路所需的最小SINR的限制。在涉及问题凸化的适当转换之后，我们借助半定松弛（SDR）和松弛变量替换（SVR）技术，使用独特的迭代算法解决了上述问题。所提出的方法的主要新颖之处在于能够共同设计MC和EH预编码器的能力，以分别服务于不同组中存在的异构ID和EH用户。我们通过仿真结果说明了在各种参数值和操作条件下进行的加权和SINR与公平模型之间的比较。