Novel PRACH Scheme for 5G Networks Based on Analog Bloom Filter

5G is expected to support far higher user density and far lower latency than LTE. PRACH is an important procedure for a User Equipment (UE) to initiate a connection with the base station. In this paper, a novel PRACH scheme is proposed, which outperforms the current LTE PRACH in many cases by an order of magnitude measured by the total error ratio. The new scheme is based on the Analog Bloom Filter (ABF), with which a UE transmits multiple orthogonal sequences to the base station, instead of only one sequence according to LTE. The collision probability is greatly reduced, because the number of combinations of sequences is much larger than the number of sequences. The challenges addressed in this paper include a signal processing algorithm that can cope with peak shift and peak energy spreading, as well as a novel scheme that allows the UE to piggyback multiple bits along with the PRACH signal, which will further improve the efficiency of the network.