We experimentally demonstrate a software-defined 2x2 MIMO VLC system employing link adaptation of spatial multiplexing and diversity. The average error-free spectral efficiency of 12 b/s/Hz is achieved over 2 meters indoor transmission after an obstruction. OCIS codes: (060.2605) Free-space optical communication; (230.3670) Light-emitting diodes; (060.4230) Multiplexing. Worldwide growth in wireless data traffic has led to the development of the next generation mobile communication networks to address several critical challenges, such as broadband capacity, spectral efficiency, energy efficiency, mobility coverage, and quality-of-services. Visible light communications (VLC) based on lightemitting diodes (LEDs) merges lighting and data communications in applications for their high energy efficiency, spectral efficiency, security and reliability [1] . VLC applications as shown in Fig.1 (a) are relevant to 5G networks, Internet-of-Things, WPANs, aerospace, automotive, healthcare industries, and ad-hoc networks. The phosphorbased white-light LED has a limited modulation bandwidth [2] that can be improved by using a blue filter and equalization of the driving circuitry [3] . Techniques such as high spectrally efficient modulation [4], wavelength division multiplexing (WDM) [5] and optical multi-input multi-output (MIMO) [6] have enhanced capacity of VLC system. However, current MIMO VLC demonstrations feature the direct line of sight, fixed MIMO technique, offline signal processing and static ideal channel condition estimation. In practical indoor wireless mobile communications, any line of sight link may be blocked by an obstruction such as human shadowing, and the complex channel conditions are expected to be changed dramatically. Once any sub-channel condition becomes degraded due to lineof-sight blockage, MIMO VLC system using the fixed spatial multiplexing will suffer link interruption. MIMO VLC using spatial diversity can improve link reliability with tolerance to shadowing, but there's no gain in spectral efficiency even with good channel condition. Thus, we propose software defined adaptive MIMO VLC, that both modulation techniques and MIMO techniques are dynamically adapted to the changing channel conditions, for enhancing both link reliability and spectral efficiency. Software defined implantation can assist in enabling an adaptive and reconfigurable MIMO VLC system without hardware changes. In this paper, we experimentally demonstrate a real-time software-defined Single-Carrier M-QAM MIMO visible light communication system by using link adaptation of spatial multiplexing and spatial diversity. The average error-free spectral efficiency of adaptive 2x2 MIMO VLC achieved 12 b/s/Hz over 2 meters indoor dynamic transmission after an obstruction.
In REF authors demonstrated an SDR-based 2×2 MIMO VLC system employing spatial multiplexing and diversity.
Software defined adaptive MIMO visible light communications after an obstruction
2017 Optical Fiber Communications Conference and Exhibition (OFC)
2017 Optical Fiber Communications Conference and Exhibition (OFC)
Mathematics Engineering Computer Science