UCLA

Autonomous driving of vehicles has been becoming a reality and radar is an indispensable feature of this transportation method. However, there will be interference issues due to the multiple signals transmitted from the radars on the adjacent driving vehicles operating in the same area at the same time. Consequently, radar interference mitigation techniques will be essential in such multi-vehicle environment. In order to accurately detect and localize adjacent vehicles, several radars must be carried on each vehicle. A low-cost and highly-integrated CMOS radar sensor could be the best candidate to fulfill this growing industrial need.

Linear frequency-modulated continuous-wave (FMCW) radar with constant envelope

waveform is suitable for low-power/ low-cost CMOS implementation. However, the ghost

targets due to other radars and radio interference generate false alarms and lower the probability of detection. Some interference mitigation techniques allocating frequency sub-bands at different time for different users to avoid concurrent frequency band usage have been proposed in the past. However, the number of users must trade off with the available bandwidth so does the range resolution.

This dissertation presents an interference-tolerant radar which can endure multiple signals transmitted from adjacent vehicles for autonomous driving applications. The interference immunity property has been realized by applying a specific code-division multiplexing method, involved with one-coincidence frequency hopping code, to the continuous-wave radar. A radar prototype has been implemented in 65nm CMOS for operation at 24GHz with 1GHz bandwidth (equivalently with 15cm range resolution). Measurements indicate that the prototype can support up to 22 adjacent vehicles simultaneously by using the optimized Hamming correlation property of the extended hyperbolic congruential code.