As the density of small cells increases, there is a greater chance of overlapping coverage. It is thus useful to coordinate usage of airlink resources among cells to reduce interference and improve SINR of cell edge users. When neighboring cells experience a difference in load, it is also desirable to balance their load, so as to improve overall network capacity and to match user experience across cells.
The first approach to reducing interference is Tx power management of small cells. Each small cell determines its Tx power based on the measured signal levels at its downlink receiver (Network Listen Module), mobility performance and backhaul quality. This feature also reduces pilot pollution and frequent handovers.
Users near cell-edge are subject to interference by transmission from neighboring cells. This can be avoided via dynamic SFR (soft fractional frequency reuse) so that airlink resource usage between neighboring cells for their respective cell-edge users is orthogonalized.