Morales Céspedes, MáximoHaas, HaraldGarcía-Armada, Ana2021-05-122021-05-122021-03-01IEEE Communications Letters, (2021), 25(3), p.: 921-925.1089-7798https://hdl.handle.net/10016/32606We study the performance of linear zero-forcing (ZF) precoding in multiuser multiple-input single-output visible light communications (VLC) when we are able to select the receiving orientation angle (ROA) of each user. For radio-frequency communications, the non-line-of-sight rich scattering environment usually ensures the linear independence among user's channels. However, this condition is less likely to happen in VLC systems, degrading the performance of ZF precoding. In this work, we propose a variable ROA (vROA) photodetector able to modify its orientation vector in order to generate semi-orthogonal channel responses among users. We derive the algorithm for determining the orientation of the vROA photodetector of each user, obtaining optimal and suboptimal solutions with high and low complexity, respectively. Simulation results show that the performance of ZF precoding is improved considerably by managing the users ROA.5eng© 2020 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.Visible light communicationsMultiuser multiple-input single-outputZero forcingOptical channelresearch articleTelecomunicacioneshttps://doi.org/10.1109/LCOMM.2020.3038027open access9213925IEEE COMMUNICATIONS LETTERS25AR/0000026850