Rate Region of the ZF Precoder in a $2\times2$ Multiuser Optical IM/DD Channel

Energy‐efficient UOWC‐RF systems with SLIPT

“…For communication over the UOWC link, we consider DC biased intensity modulation and direct detection (IM/DD). Let x m represent the message symbol transmitted from S, which modulates the optical intensity of the LD at S. Thus, the instantaneous emitted optical power can be expressed 21 as…”

“…The problem P1 is convex in variable 𝜏 and thus, it can be solved using any standard optimization tools. 24 With obtained 𝜏 by solving (21), the optimization problem in ( 14) can be written as…”

“…For communication over the UOWC link, we consider DC biased intensity modulation and direct detection (IM/DD). Let $$$ {x}_{\mathrm{m}} $$$ represent the message symbol transmitted from S, which modulates the optical intensity of the LD at S. Thus, the instantaneous emitted optical power can be expressed 21 as $$$$ {P}_{\mathrm{t}}=\eta \left({x}_{\mathrm{m}}+B\right), $$$$ where $$$ \eta $$$ is the slope efficiency of the LD, and $$$ B $$$ represents the DC‐bias. Note that $$$ B $$$ is added to $$$ {x}_{\mathrm{m}} $$$ to avoid resulting non‐negative signals 7 .…”