WDM-VLC Receiver Sensors: Large-Scale Filter-Array Detectors With Optimized Selection Combining Methods

Optical Filter-Less WDM for Visible Light Communications Using Defocused MIMO

“…profile (Figure 4c) shows that both the B and R beams are skewed to the right and left, respectively, whereas the G beam is centered to the normal. Skewing of the B and R can actually assist in the diversity of H matrix rows, given that CSI is also dependent on the irradiance and illuminance angles (φ, ψ) as described in (4). Figure 4d highlights the relative positions of the colored chips on the LED die.…”

“…However, the small B mod of off-the-shelf LEDs can be a bottleneck for the development of high throughput VLC systems [3][4][5][6]. To increase the data rate of WPLEDs, there are few technologies such as optical blue filtering, equalization, high spectral-efficiency multi-level, and multi-carrier modulations, wavelength division multiplexing (WDM), and spatial multiplexing, i.e., multi-input multi-output (MIMO) [1,7,8].…”

“…RGB LEDs naturally render themselves to the parallel transmission of data, aggregating the data throughput or facilitating multiple access schemes [9]. WDM in VLC has been reported [3,4] with the data rates of >16 Gb/s [3]. MIMO VLC systems, using the multiple LEDs located on the ceiling for illumination, have been reported to increase data rates and to mitigate inter-channel crosstalk-induced interference in WDM systems using signal processing techniques to improve the link performance [5,6,[10][11][12].…”

“…The received WDM signal consists of superposed symbols, which comprise the sum of Kindependent on-off keying non-return to zero (OOK-NRZ) signals, which occupy the same frequency space, where K is the number of LED chips/wavelengths used for transmission. Signal demultiplexing is achieved using the ZF algorithm on the H matrix channel state information (CSI), which is simple to implement with low computational complexity at the cost of amplified noise [4]. The diversity required by H is achieved through the electrooptical (E/O) conversion of the LEDs, the photodetector (PD) array wavelength-dependent responsivity R(λ), and the defocused beam spot on the PD array.…”