Next 5G of mobile wireless systems is expected to employ mmWave antenna arrays at both user-equipment (UE) and base station (BS) side, with the possibility to precisely focus the power on the desired spatial directions and boost communications-based applications at an unprecedented scale. On the other side, the initial access (IA) procedure might entail a high latency due to the need of the BS to scan the surrounding space in order to detect new UEs. In this paper we consider a stand-alone 5G system capable to exploit the memory of past UEs detection to speed-up the IA process for new UEs entering the area. In particular, it considers the creation of a knowledge database that accounts for the UE received power and for both the beamsteering and half power beamwidth (HPBW) set at the BS. Numerical results show that the proposed procedure allows to reduce the average number of scans with respect to traditional approaches adopted in the literature, while preserving the same detection performance.

Devices to support social distancing must be energy-efficient and accurate. Bluetooth Low Energy (BLE) meets the first criteria but falls short on the latter. Ultra-wideband (UWB) measures distances with <10 cm error but with relatively high consumption. Therefore, we built Janus, a dual-radio protocol that uses the strengths of each.