  In this paper, a novel coordinated initial access (IA) scheme for clustered
millimeter wave small cells (mmSCs) is proposed for the fifth generation mobile
communication networks (5G). This solution is a method for efficient and fast
initial access for ultra-dense millimeter wave standalone networks without
presence of overlaid legacy networks operating on lower frequency. In contrast
to the current full beam sweep scheme, where time consuming exhaustive
searching is employed, the mmSCs within one cluster will perform the IA
procedure in a coordinated manner based on the power delay profile (PDP)
measurement reports shared with each other via the backhaul links and thereby
avoiding the full beam sweep. The proposed scheme significantly reduces the
initial access time, enhances the access robustness and reduces the cost and
complexity of the mobile terminals.
