A Novel 3D Non-Stationary Channel Model for 6G Indoor Visible Light Communication Systems

Abstract

The visible light communication (VLC) technology has attracted much attention in the research of the sixth generation (6G) communication systems. In this paper, a novel three dimensional (3D) space-time-frequency non-stationary geometrybased stochastic model (GBSM) is proposed for indoor VLC channels. The proposed VLC GBSM can capture unique indoor VLC channel characteristics such as the space-time-frequency non-stationarity caused by large light-emitting diode (LED) arrays in indoor scenarios, long travelling paths, and large bandwidths of visible light waves, respectively. In addition, the proposed model can support special radiation patterns of LEDs, 3D translational and rotational motions of the optical receiver (Rx), and can be applied to angle diversity receivers (ADRs). Key channel properties are simulated and analyzed, including the space-time-frequency correlation function (STFCF), received power, root mean square (RMS) delay spread, and path loss (PL). Simulation results verify the space-time-frequency nonstationarity in indoor VLC channels. In addition, the influence of light source radiation patterns, receiver rotations, and ADRs on channel characteristics have been investigated. Finally, the accuracy and practicality of the proposed model are validated by comparing the simulation result of channel 3dB bandwidth with the existing measurement data. The proposed channel model will play a supporting role in the design of future 6G VLC systems.

Pervasive Wireless Channel Modeling Theory and Applications to 6G GBSMs for All Frequency Bands and All Scenarios

“…In IIoT scenarios, apart from the LoS component, specular multipath components (SMCs) and dense multipath components (DMCs) are modeled as h NLoSSMC qp,fc (t, τ ) and h NLoSDMC qp,fc (t, τ ), respectively. The accuracy of channel models can be significantly improved by considering DMCs, which are caused by smaller scatterers and these scatterers are distributed near SMCs [22] Besides, different from traditional radio frequency (RF) communication systems, the transmitted optical signals in VLC systems have extremely short wavelength [36] and no phase since light-emitting diode (LED) lights emit incoherent light [5]. It follows that the superposition of real-valued multipath signals at the Rx will not lead to SSF, but show slow-changing shadowing.…”

“…Also, λ T represents the wavelength range of the light source. Details can be referred to [5]. Note the fact that signals transmitted in VLC channels are real-valued optical power signals instead of complex amplitude signals in RFbased channels.…”

“…MmWave/THz+ ultra-massive MIMO [9] 1) Single-link, single-frequency 2) W E = 1, µ = 1, ψm n = 0, Mn(t) = Mn 3) Generate LSPs without considering spatial consistency Indoor+VLC [5] 1) Single-link, single-frequency 2) Tx is a Mp H × Mp V uniform planar LED array with spacings δ H and δ V , v T = 0 3) W E = 1, AL = 1, Hs = 1, Mn(t) = Mn 4) ∆f BD = 0, ∆t BD = 0, and 2D cluster evolution in space domain LEO [14] 1) Single-link, single-frequency 2) AL = 1, BL = 1, µ = 1, Mn(t) = Mn 3) ∆f BD = 0, γm n = 0, ξn (p, q) = 1 4) LSPs relate to the elevation angle of link…”

“…In the 6G wireless communication systems, all spectra can be utilized, including sub-6 GHz, millimeter wave (mmWave), terahertz (THz), and optical wireless frequency bands [3]- [5]. MmWave and THz channels show new characteristics, e.g., large bandwidth with high delay resolution, frequency non-stationarity, high directivity, diffuse scattering, blockage effects, and atmosphere absorption [6]- [9].…”

“…MmWave and THz channels show new characteristics, e.g., large bandwidth with high delay resolution, frequency non-stationarity, high directivity, diffuse scattering, blockage effects, and atmosphere absorption [6]- [9]. Visible light communication (VLC) channels have no small-scale fading (SSF), negligible Doppler effect, and frequency non-stationarity [5].…”