In this paper, we investigate the performance of a practical aggregated LiFi-WiFi system with the discrete constellation inputs from a practical view. We derive the achievable rate expressions of the aggregated LiFi-WiFi system for the first time. Then, we study the rate maximization problem via optimizing the constellation distribution and power allocation jointly. Specifically, a multilevel mercy-filling power allocation scheme is proposed by exploiting the relationship between the mutual information and minimum mean-squared error (MMSE) of discrete inputs. Meanwhile, an inexact gradient descent method is proposed for obtaining the optimal probability distributions. To strike a balance between the computational complexity and the transmission performance, we further develop a framework that maximizes the lower bound of the achievable rate where the optimal power allocation can be obtained in closed forms and the constellation distributions problem can be solved efficiently by Frank-Wolfe method. Extensive numerical results show that the optimized strategies are able to provide significant gains over the state-of-the-art schemes in terms of the achievable rate.
翻译:在本文中,我们用离散星座投入来调查一个实用的、综合的LiFi-WiFi系统的性能。我们第一次从一个实用的观点中得出综合的LiFi-WiFi系统的可实现速率表达方式。然后,我们通过优化星座分布和联合分配来研究率最大化问题。具体地说,通过利用相互信息和离散输入最小平均差错之间的关系,提出了多层次的施惠分配权力计划。与此同时,为了获得最佳概率分布,提出了一种不精确的梯度下降方法。为了在计算复杂性和传输性能之间取得平衡,我们进一步制定了一个框架,使可实现率的下限最大化,以便以封闭形式获得最佳的电力分配,而星座分配问题可以通过Frank-Wolfe方法有效解决。广泛的数字结果显示,优化战略能够在可实现率方面为最新计划带来重大收益。