  The millimeter wave frequencies (roughly above 10 GHz) offer the availability
of massive bandwidth to greatly increase the capacity of fifth generation (5G)
cellular wireless systems. However, to overcome the high isotropic pathloss at
these frequencies, highly directional transmissions will be required at both
the base station (BS) and the mobile user equipment (UE) to establish
sufficient link budget in wide area networks. This reliance on directionality
has important implications for control layer procedures. Initial access in
particular can be significantly delayed due to the need for the BS and the UE
to find the initial directions of transmission. This paper provides a survey of
several recently proposed techniques. Detection probability and delay analysis
is performed to compare various techniques including exhaustive and iterative
search. We show that the optimal strategy depends on the target SNR regime.
