Various operations may be performed based on distance-related functions associated with two or more devices. For example, one or more distance-based functions may be used to control whether a device is allowed to request another device to perform one or more functions. Similarly, one or more distance-based functions may be used to control whether a device may perform one or more functions requested by another device. A distance-related function may take various form including, for example, a distance between devices, two or more distances between devices, a rate of change in a relative distance between devices, relative acceleration between devices, or some combination of two or more of the these distance-related functions.