Cooperative Hybrid VLC-RF Systems with Spatially Random Terminals

In this paper, a cooperative hybrid visible light communication (VLC)-radio frequency (RF) relay system, which includes a transmitter (S) with a cluster of light emitting diodes (LED) lamps, a relay (R) and a destination (D), is taken into consideration. Moreover, decode-forward (DF) and amplifyforward (AF) schemes are considered at R to aid the data transmissions between S and D. Specially, R is randomly located in the coverage of the LED lamps, D is randomly distributed out of the coverage of the LED lamps. Then, VLC is employed for S –R link and traditional radio frequency (RF) communication technology is adopted over R–D link. Considering Nakagami-m fading over R – D link, and the randomness of the locations of R and D, the statistical characteristics of the received signal-tonoise ratio at D under AF scheme, and the ones at R and D under DF scheme are characterized, respectively. Subsequently, approximated analytical and asymptotic expressions for the outage probability of the considered system are derived, as well as the approximated expression for the average symbol error rate of M-ary quadrature amplitude modulation scheme under DF scheme. Finally, simulation and numerical analysis are conducted to verify the correctness of our proposed models.