Monthly Archives: January 2015

Congratulations to Mr. Pang-Cheng (Brian) Lan for passing his Qualifying Exam on January 22, 2015. The title of Brian’s thesis proposal is “Enhancing Secrecy in Wireless Environment with Only Channel State Information: Theory and Applications”. His Qualifying Exam committee consisted of Jay Kuo (Chair), Keith Chugg, Andy Molisch, Salman Avestimehr and Wlodek Proskurowski (Outside Member).

In his proposal, Brian shows the advantages of having only transmitter-side channel state information (CSI) but none or limited CSI at the receiver and the eavesdropper in wiretap channels. With CSI only at the transmitter (CSIT), distortion and interference on the main channel can be pre-compensated by the transmitter to facilitate detection at the receiver while leaving the eavesdropper confused by the uncertainties of its own channel. These ideas are first tested in the case of finite-alphabet discrete memoryless wiretap channels, where the secrecy capacity expression is derived, and are then applied to two practical scenarios, namely, fading wiretap channels and those with Gaussian interference. Truncation-based schemes are proposed to ensure that the transmission occurs only when the main channel is sufficiently reliable. Furthermore, a practical unitary modulation scheme is recommended as application of exploiting the benefits of having CSIT in secrecy for multi-antenna communication systems in which Long Term Evolution (LTE) is used as an example. The achievable secrecy rates of the proposed schemes are derived and asymptotic or approximate expressions are proposed for the optimization purpose. The effectiveness of the proposed transmission schemes and the advantages of having only CSIT are demonstrated through numerical simulations.

Two research  findings of the USC Media Communications Lab were presented at the IEEE International Conference on Consumer Electronics (ICCE), which was held from January 9th to 12th 2015, in Las Vegas .

Auto exposure (AE) control is an important function of modern digital cameras. Simple AE algorithms are designed for a specific type of camera sensors. Advanced AE techniques have been developed to tackle a wider class of camera sensors and/or high contrast lighting conditions, yet they are computationally intensive and, thus, difficult to implement in a resource-constrained environment such as phone cameras. Besides, none of existing solutions provides robust performance if erroneous exposure occurs. To address the aforementioned shortcomings, a fast and robust AE algorithm is  in need. The first paper entitled with “Fast and Robust Camera’s Auto Exposure Control Using Convex or Concave Model”, co-authored by Yuanhang Su and C.-C. Jay Kuo, proposed a concave/convex function model for the luminance characteristics of a camera. Based on such a model, a proper parameter value can be computed using a modified secant algorithm with fast convergence. This paper was presented by an MCL member, Joe Lin.

The second paper entitled with “Uncalibrated Multiview Synthesis based on Epipolar Geometry Approximation”, co-authored by Young Ju Jeong, Hyoseok Hwang, Dongkyung Nam and C.-C. Jay Kuo, was mainly conducted in Samsung Advanced Institute of Technology (SAIT) with the input from Professor Kuo. This paper proposed an  efficient multiview rendering algorithm that takes uncalibrated stereo as the input. First, the epipolar geometry of multiple viewpoints is analyzed for multiview display. Then, the camera pose for an arbitrarily selected viewpoint is estimated by algebraic approximation. Finally, by exploiting rectification homographs and disparities of rectified stereo, one can determine multiview images with [...]