Moon-Sik Lee

Design and Performance of a 24-GHz Switch-Antenna Array FMCW Radar System for Automotive Applications

We develop a 24-GHz switch-antenna array frequency-modulated continuous-wave (FMCW) radar system composed of a single transmitter, a single transmitting antenna, four receiving antennas, a single-pole four-throw (SP4T) switch, and a single receiving channel. The antennas are integrated with radio-frequency (RF) and intermediate-frequency (IF) circuits to reduce the interconnection loss and realize a compact whole size. The receiving antennas are periodically switched to the single receiving channel. The performance of the developed system is evaluated using beamforming methods to estimate the angle, range, and velocity.

System modeling and signal processing for a switch antenna array radar

A system composed of a single transmitter, M receiving antennas, and a single receiving channel is studied. Echo radar signals are acquired in a number of the cycles and used for estimation of the angle, velocity, and range in a multiple moving target scenario. The receiving antennas are switched to the single receiving channel periodically once every cycle. The developed algorithms are based on minimum variance (Capon) beamforming. A new nonstationary version of Capon beamforming is developed for the time-varying steering vector model. It is shown in simulations done for an automotive scenario that the proposed algorithms yield very good performance in terms of both estimation accuracy and multiple-target resolution. The Capon-based estimation gives results close to the corresponding Crame/spl acute/r-Rao lower bounds (CRLBs).

An efficient multitarget tracking algorithm for car applications

A new and efficient tracking algorithm for vehicle collision warning and collision avoidance systems using car radar is proposed. The target-to-measurement data association is accomplished using the decision logic algorithm based on order statistics. The simulation and experimental results are presented to demonstrate its performance.

Performance study of the minimax robust phased array for wireless communications

In this paper, new robust M-estimation techniques are developed for combating impulsive noise and multiple-access interference in communication systems. Power functions of the proposed robust estimators are obtained by minimizing a nonquadratic residual function derived from the Hubers minimax robust estimation theory. Maximum peaks of these power functions are used for estimation of communication signals as well as direction of arrival. A strong advantage of the proposed robust M-estimation algorithms is a decreased sensitivity of the estimates with respect to an actual unknown distribution of random noises and interferences. Simulation results demonstrate that the proposed robust algorithms, the robust median, and robust Huber estimators, offer significant performance gain over the conventional and minimum-variance distortionless-response estimators, with the best results given by the robust Huber estimator.

An Efficient Receiver for Preamble Detection in LTE SC-FDMA Systems with an Antenna Array

In this letter, we propose an efficient low complexity receiver for the preamble detection in single-carrier frequency division multiple access (SC-FDMA) systems with an antenna array. The proposed low complexity receiver is derived using a digital mixer and a multistage decimation filter. The signals for each receive antenna are non-coherently combined. Simulations performed in various channel environments validate that the proposed receiver attains a high detection performance equivalent to the full frequency domain approach which provides the optimal performance, while being quite low in computational complexity.

Automotive radar tracking of multi-target for vehicle CW/CA systems

An automotive radar tracking method for vehicle collision warning and collision avoidance (CW/CA) systems is proposed. Currently, the joint probabilistic data association (JPDA) algorithm is a good approach to solve the ambiguity of multi-target data association problem. However, this algorithm might not be easily adapted for a real road application because its computational load is very high. The proposed algorithm provides an optimal method for the track-to-measurement data association by using the decision logic based on order statistics. Simulation results in a cluttered environment show that the tracking performance of the proposed method is better than that of the JPDA filter while maintaining the processing time similar with the probabilistic data association filter, which is a efficient algorithm computationally. To evaluate the performance, the proposed method is implemented using a developed digital signal processing board. Experiments show also the same results as the simulation performances.

Robust L 1 -norm beamforming for phased array with antenna switching

A beamforming method for estimation of the direction-of-arrival (DOA) and distance in the presence of impulsive noise using a phased array with antenna switching is proposed. The proposed robust beamformer is nonlinear in nature and uses the absolute value loss function. Experiment results demonstrate that the proposed method is satisfactorily verified using experimental data from the developed 24 GHz phased array system with antenna switching.

Adaptive Robust DOA Estimation for a 60-GHz Antenna-Array System

Direction-of-arrival (DOA) estimation in a phased-array system is considered for a non-Gaussian noise environment. In this paper, a robust M-estimation scheme based on Hubers loss function with an adaptive threshold is proposed. The method is evaluated using experimental data from the University of California, Los Angeles, 60-GHz antenna-array system. It is shown that the proposed method enables a decreased sensitivity of the DOA estimates with respect to noise components having heavy-tailed distributions.

Extending the reach of WDM networks by combating high channel resolution power divergence using dynamic power equalization

Computer simulations are used to show that a combination of high channel resolution dynamic power equalization along with configurable amplifier gain flattening devices can be used to extend the reach of an optical network from 1700 km to well above 2500 km (a reach improvement of about 50%). This will extend the system or network into the ultra long-haul regime possibly enabling coast-to-coast connectivity. The relatively inexpensive configurable amplifier gain flattening devices can be used at every amplifier stage in the network to provide flat amplifier gain but their resolution is not enough to deal with single channel power variations. The addition of a few high channel resolution dynamic power equalizing devices at strategic points in the network allows combating effects like polarization dependent loss (PDL) induced ripple, shown to be important in networks , as well as dynamic channel add/drops.

A V-Band Current-Reused LNA With a Double-Transformer-Coupling Technique

This letter presents a current-reused V-band low-noise amplifier (LNA) with a double-transformer-coupling technique in 65nm CMOS technology. A couple of common-source (CS) stages are stacked to share current, and the double transformers are used as an RF signal path between the CS stages for both gain and stability considerations. The LNA has three CS-CS stages, and achieves a peak gain of 31.4 dB, a minimum noise figure (NF) of 4.7 dB, and a P1dB of -2 dBm over 62.9-67 GHz with a power consumption of 6 mW. The chip size is 0.66 × 0.90 mm2 including pads.