Statistically improper signals, in very general terms, are complex signals with I/Q imbalance and correlations between their real and imaginary parts. They hold fundamental applications in communications, including basic modulation schemes such as BPSK and QAM signals. Taking into consideration of the impropriety of complex signals in receiver design (also known as widely-linear receive filters) has shown to be beneficial in the GSM era and currently in voice applications of 3GPP. In contrast, we consider the optimizations of widely-linear transmit filters and relay processing. We will see in this presentation that widely-linear transmit strategies can be used for interference management and physical layer secrecy mechanisms. In a two-user interference channel, widely-linear transmit strategies are shown to improve the achievable rate regions; whereas in a relay-assisted interference channel, widely-linear transmit and relay strategies are shown to improve the secure degrees of freedom: the number of secure data streams supported by the system.
Zuleita Ho received her Ph.D. in wireless communication from EURECOM and Telecom Paris, France in 2010. In 2005 and 2007, She received her Bachelor and Master in Philosophy degree in Electronic Engineering (Wireless Communication) from Hong Kong University of Science and Technology (HKUST). From 2003 to 2004, she studied as a visiting student in Massachusetts Institute of Technology (MIT) supported by the HSBC scholarship for Overseas Studies. From 2011 till now, she has joined the Communications Laboratory at the Dresden University of Technology, Germany. Zuleita's research specializes on fundamental research in optimization of physical layer technologies in wireless communications. In particular, she is interested in performance optimizations in cellular networks, relay-assisted networks utilizing various mathematical tools such as nonlinear optimization, convex optimization, signal processing techniques, game theory, information theory and network coding. She is particularly interested in interference management techniques such as interference alignment and neutralization, improper signaling (widely-linear processing) and physical layer security mechanisms.