To support multiple users in an indoor multiple-input multiple-output visible light communication (MIMO-VLC) system adopting spatial multiplexing, orthogonal frequency division multiple access (OFDMA) is usually adopted, where the overall modulation bandwidth is shared by all the users. In this paper, by fully exploiting the spatial distributions of light-emitting diode (LED) transmitters in the ceiling and end users around the receiving plane, we propose a space division multiple access (SDMA) technique for indoor spatial multiplexing-based MIMO-VLC systems. When applying SDMA, users within the MIMO-VLC system are divided into different user groups (UGs) based on their spatial locations with respect to different LED transmitters. Specifically, each UG can use the overall modulation bandwidth of the system. For efficient implementation of SDMA, two distributed user grouping (DUG) approaches are proposed, including basic DUG and transmit diversity-enhanced DUG (TD-DUG), and a two-step resource allocation algorithm is further designed. The achievable rates of the MIMO-VLC system employing SDMA with both basic DUG and TD-DUG are derived accordingly. To verify the superiority of SDMA over conventional OFDMA, detailed analytical and simulation results are presented. Moreover, a proof-of-concept experiment is conducted to demonstrate the advantage of SDMA in a practical spatial multiplexing-based MIMO-VLC system.

中文翻译：

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适用于多用户MIMO-VLC系统的带分布式用户分组的空分多址

为了在采用空间复用的室内多输入多输出可见光通信（MIMO-VLC）系统中支持多个用户，通常采用正交频分多址（OFDMA），其中总调制带宽由所有用户共享。在本文中，通过充分利用天花板和终端用户周围接收平面周围的发光二极管（LED）发射器的空间分布，我们针对基于室内空间复用的MIMO-VLC提出了一种空分多址（SDMA）技术系统。当应用SDMA时，基于MIMO-VLC系统中的用户相对于不同LED发射器的空间位置，它们被分为不同的用户组（UG）。具体而言，每个UG都可以使用系统的整体调制带宽。为了有效实施SDMA，提出了两种分布式用户分组（DUG）方法，包括基本的DUG和传输分集增强型DUG（TD-DUG），并进一步设计了两步资源分配算法。相应地得出了采用同时具有基本DUG和TD-DUG的SDMA的MIMO-VLC系统的可达到速率。为了验证SDMA相对于传统OFDMA的优越性，给出了详细的分析和仿真结果。此外，进行了概念验证实验，以证明SDMA在实际的基于空间复用的MIMO-VLC系统中的优势。相应地得出了采用同时具有基本DUG和TD-DUG的SDMA的MIMO-VLC系统的可达到速率。为了验证SDMA相对于传统OFDMA的优越性，给出了详细的分析和仿真结果。此外，进行了概念验证实验，以证明SDMA在实际的基于空间复用的MIMO-VLC系统中的优势。相应地得出了采用同时具有基本DUG和TD-DUG的SDMA的MIMO-VLC系统的可达到速率。为了验证SDMA相对于传统OFDMA的优越性，给出了详细的分析和仿真结果。此外，进行了概念验证实验，以证明SDMA在实际的基于空间复用的MIMO-VLC系统中的优势。