  Heterogeneous networks (het-nets) - comprising of conventional macrocell base
stations overlaid with femtocells, picocells and wireless relays - offer
cellular operators burgeoning traffic demands through cell-splitting gains
obtained by bringing users closer to their access points. However, the often
random and unplanned location of these access points can cause severe near-far
problems, typically solved by coordinating base-station transmissions to
minimize interference. Towards this direction, the 3rd generation partnership
project Long Term Evolution-Advanced (3GPP-LTE or Rel-10) standard introduces
time-domain inter-cell interference coordination (ICIC) for facilitating a
seamless deployment of a het-net overlay. This article surveys the key features
encompassing the physical layer, network layer and back-hauling aspects of
time-domain ICIC in Rel-10.
