标题： 共生散射通信：对散射设备调制方案的设计视角 显示英文标题

标题： Symbiotic Backscatter Communication: A Design Perspective on the Modulation Scheme of Backscatter Devices

摘要： 共生散射通信（SBC）已成为一种频谱高效且低功耗的通信技术，其中散射设备（BDs）调制并反射来自主发射机（PTs）的入射射频（RF）信号。 尽管之前的研究假设了BD信号服从圆对称复高斯（CSCG）分布，但这一假设可能不切实际，因为生成CSCG信号的高复杂度无法由低成本的BD支持。 在本文中，我们通过研究两种低复杂度调制方案的SBC来弥补这一差距，即$M$进制幅度键控（MASK）和$M$进制相位键控（MPSK），其中BD的信号本质上偏离了CSCG分布。 我们的目标是推导在MASK/MPSK下PT和BD的可实现速率，并设计MASK/MPSK调制方案以最大化PT的速率。 为此，我们首先推导了PT速率和BD速率的表达式。 理论结果表明，BD是否能提高PT的速率取决于MASK/MPSK调制的相位，而BD的速率与该相位无关。 随后，我们分别在MASK和MPSK调制方案下，通过调整相位来最大化PT的速率，提出了两个优化问题，并以闭合形式推导出每种调制方案的最佳相位。 仿真结果表明，MASK/MPSK的最佳相位可以确保PT速率的提升，并表明在改善PT速率方面，低阶ASK调制比低阶PSK更优，尤其是在SBC中直射链路并不明显弱于散射链路的情况下。 显示英文摘要

摘要： Symbiotic Backscatter Communication (SBC) has emerged as a spectrum-efficient and low-power communication technology, where backscatter devices (BDs) modulate and reflect incident radio frequency (RF) signals from primary transmitters (PTs). While previous studies have assumed a circularly symmetric complex Gaussian (CSCG) distribution for the BD's signal, this assumption may not be practical because the high complexity of generating CSCG signals is not supported by the low-cost BD. In this paper, we address this gap by investigating SBC for two low-complexity modulation schemes, i.e., $M$-ary amplitude-shift keying (MASK) and $M$-ary phase-shift keying (MPSK), where BD's signals inherently deviate from CSCG distribution. Our goal is to derive the achievable rate of the PT and BD under the MASK/MPSK and to design MASK/MPSK modulation scheme for maximizing the PT's rate. Towards this end, we first derive the expressions of both the PT's rate and BD's rate. Theoretical results reveal that whether or not the BD improves the PT's rate depends on the phase of MASK/MPSK modulation, while the BD's rate is independent of this phase. We then formulate two optimization problems to maximize the PT's rate by adjusting the phase under the MASK and MPSK modulation schemes, respectively, and derive the optimal phases for each modulation scheme in closed forms. Simulation results demonstrate that the optimal phase of MASK/MPSK can ensure an improvement in the PT's rate, and reveal that a low-order ASK modulation is better than a low-order PSK for the BD in terms of improving PT's rate, especially when the direct link is not significantly weaker than the backscatter link in SBC.