Abstract: A mechanism is provided to reduce interference between vehicular radar systems through communicating radar parameters and physical orientation between vehicles and then using directional information to form clusters of radars, which will have consistent modulation parameters. Radar modulation parameters, such as starting frequency, center frequency, bandwidth, slope, ramp direction, timing, and the like for frequency-modulated continuous-wave (FMCW) radars, are adjusted to reduce or eliminate inter-cluster direct interference between clusters oriented in different directions. For other types of radars, in some embodiments, other operational parameters can be adjusted. In some embodiments, some modulation parameters also can be adjusted to reduce or eliminate intra-cluster indirect interference.