optical wireless communication (owc) is an enabling technology for sixth-generation (6g) and beyond communication networks. visible light communication (vlc) is a crucial branch of owc technology expected to meet 6g communication system requirements. the vlc system can facilitate multiple functionalities simultaneously including illumination, ultra-high data rate communications, positioning such as location and navigation services. in vlc systems, a light-emitting diode (led) functions as a transmitter. a photodetector or imaging sensor acts as a receiver and the visible light is used as the transmission medium. researchers have shown a great deal of interest in vlc based positing and localization techniques, as visible light positioning (vlp) systems have shown better localization accuracy than radio frequency (rf) based positioning or global positioning system (gps). this thesis considers the problem of position estimation accuracy in vlc systems in the presence of signal-dependent shot noise (sdsn). we investigate distance and 3d position estimation approaches in different scenarios, focusing on error estimation performance bounds. additionally, this work attempts to resolve the synchronization problem found in vlp systems.