The main objective of the presented research is to characterize an indoor wireless optical communication channel. Until recently, there have not been any comprehensive published measurements results presenting characteristics of this channel for high data rates, e. g. 1Gbit/s. To this end, a measurement setup is implemented, with a high-power laser diode acting as the optical transmitter and an avalanche photodiode acting as the receiver. Using a network analyzer, the laser is modulated by CW frequencies up to 1 GHz, which is the bandwidth of the receiver, as limited by the intrinsic capacitance and the response-time of the avalanche photodiode. A single collimated optical spot with a small elliptical shape on the ceiling is tested. The impacts of receiver orientation and configuration on the channel frequency response are investigated. These measurements will enable us to explore the possibility of higher data transmission rates, potentially beyond 1 Gbps, on indoor optical wireless channels. These channels can be a viable alternative to inherently insecure and interference-prone RF wireless channels, and therefore, could be the basis of next-generation high data rate wireless local area networks.