Reconfigurable intelligent surfaces (RISs) are a recent yet revolutionary development in communications systems. Particularly applicable to millileter wave (mmWave) systems, these surfaces can increase localization performance and decrease vulnerability to environmental influences, all by adjusting the incoming signals’ phase. At the same time, manufacturing ideal hardware to be deployed at the transceivers is not feasible nor practical. These non-linearities in hardware, collectively known as hardware impairments (HWIs), cause signal degradation and adversely affect localization. In this paper, the effect of HWIs on RIS-aided localization is examined. Towards that, the mean squared error (MSE) of the user’s position is found through a maximum likelihood estimator (MLE) and its functionality is verified by the position error bounds (PEB), derived from Cramér-Rao lower bounds (CRLB). Our numerical results show that active RISs mitigate the deteriorating effect of HWIs on the user’s PEB. Based on our outcome, increasing the inter-RISs space generally creates more resolvable paths and leads to improved localization.

Location-awareness is expected to be one of the main services in 5G millimeter-wave (mmWave) communication systems. In mm-Wave, multiple-input multiple-output (MIMO) systems will be used, leading to the deployment of antenna arrays in both transmitter and receiver. Hardware components being used in transceiver are commonly modeled as linear filters; but practically, this linearity is not fully satisfied. Power amplifiers and filters applied in antennas mostly show nonlinear behavior, causing loss in spectral efficiency (SE) and signal quality. This non-linearity is referred to hardware impairments (HWIs). Under HWIs model at both the transmitter and receiver, 2D localization performance is examined. Towards that, we derive position and orientation error bounds and study the effect of HWIs on the derived bounds. The numerical results reveal that HWIs have a significant effect on localization and it causes more than 100% degradation in both the transmitter and receiver. Also, the rate of degradation stays the same for both position and orientation error bounds except for the oriented UE.