In a signal-based gain control scheme, one or more gain levels used for processing signals are selected based on characteristics of previously received signals. For example, different gain levels may be used to receive sets of signals whereupon certain characteristics of the received sets of signals are determined. One or more gain levels are then selected based on these characteristics whereby another signal is processed based on the selected gain level(s). In some aspects, the signal-based gain control scheme may be employed to facilitate two-way ranging operations between two devices. For example, leading edge detection may involve determining a characteristic of a received signal, determining a threshold based on the characteristic, and identifying a leading edge associated with the received signal based on the threshold. In some aspects, the signal-based gain control scheme may be employed in an ultra-low power pulse-based communication system (e.g., in ultra-wideband communication devices).