Wireless communication networks with increased demand for higher speed in data transfer have paved way for device-to-device (D2D) wireless communications. This paper, investigates the radio link characteristics of D2D communication network in an indoor environment utilizing radio frequency experiments and ray-tracing based simulations at frequencies of 2.4, 3.4, 5.2, 28 and 60 GHz. The path loss exponent and standard deviation are estimated and compared with free space path loss, log normal shadowing, International Telecommunication Union model and compared with other research works. This work also studied the impact of indoor environments on D2D communications.