Empirical analysis of UWB channel characteristics for secret key generation in indoor environments

Recent security methods propose to generate secret keys from Ultra Wide Band (UWB) channels. These solutions rely on the reciprocity and spatial channel correlation principles. This work aims at presenting empirical studies on the aforesaid properties. First, we verify the UWB reciprocity for different multipath scenarios. In these experiences, the reciprocity is always valid independently of distance between the receiver and emitter. However, we show that using an asymmetric hardware in up and down links, can affect the channel similarity. Secondly, we report measurements of spatial correlation in near and far field channel. Various experimental scenarios are tested to validate location channel variations. We observe that in very close and far receiver´s locations, there is no correlation. This variation is not depending on distance but mainly on the indoor environment. In addition, various channel parameters: channel impulse response, channel envelope, and power delay profile have been investigated. We show that channel properties rely on these parameters.