Space Division Multiple Access With Distributed User Grouping for Multi-User MIMO-VLC Systems

Abstract

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. Index Terms-Distributed user grouping (DUG), multiple-input multiple-output (MIMO), space division multiple access (SDMA), visible light communication (VLC).

Distributed Multiuser MIMO for LiFi in Industrial Wireless Applications

“…In [58], random grouping of users and zero forcing precoding was shown to increase spectral efficiency and fairness. The authors of [59] investigated user grouping for SDMA in the multiuser MIMO downlink and confirmed that exploiting the spatial domain enables higher sum throughput for LiFi compared to orthogonal frequency division multiple access (OFDMA). However, typical distributed MIMO LiFi channels have a lower rank than comparable radio channels [23].…”

Lights and Shadows: A Comprehensive Survey on Cooperative and Precoding Schemes to Overcome LOS Blockage and Interference in Indoor VLC

“…Most of the state-of-the-art SDMA techniques for VLC involve the fabrication of a new transceiver capable of transmitting multiple beams, which increases the cost and complexity considerably [ 130 , 131 ]. However, authors of [ 132 ] recently proposed a novel SDMA technique for MIMO-VLC systems that do not need a new transceiver design, and they demonstrate the superiority of SDMA against traditional OFDMA. On the contrary, SDMA techniques are classified into the multi footprint category.…”

Distributed Multiuser MIMO for LiFi: Experiments in an Operating Room

“…spatial diversity, to prevent sudden blockages of the LOS links. Moreover, coordinated parallel transmissions to multiple mobile devices are possible by using the space and time domains [28], [29], [30].…”