Adaptive decision feedback equalization for multi-Gbps data links

Channel equalization combats the effects of the imperfection of wire channels. This dissertation deals with adaptive decision feedback channel equalization. The dissertation starts with an in depth study of the challenges encountered in the design of adaptive DFE and techniques that address these challenges. Various 2-dimensional eye-opening monitors (EOMs) based adaptive DFE are proposed and implemented. A novel 2-dimensional hexagon EOM is proposed and its effectiveness is validated using simulation. A simplified and power efficient 2-dimensional hexagon EOM is also introduced. Both EOMs are capable of differentiating the severity of the violation of the minimum eye-opening so as to allow the DFE to take different actions adaptively and achieve desired eye-opening more rapidly. A maximum-jitter EOM-based adaptive DFE is also introduced to greatly reduce system complexity. The adaptive DFE is taped out in a 130nm 1.2V CMOS technology and finally an improved adaptive engine that outperforms DFE utilizing sign-sign least-mean-square is proposed.

Adaptive decision feedback equalization for multi-Gbps data links

Channel equalization combats the effects of the imperfection of wire channels. This dissertation deals with adaptive decision feedback channel equalization. The dissertation starts with an in depth study of the challenges encountered in the design of adaptive DFE and techniques that address these challenges. Various 2-dimensional eye-opening monitors (EOMs) based adaptive DFE are proposed and implemented. A novel 2-dimensional hexagon EOM is proposed and its effectiveness is validated using simulation. A simplified and power efficient 2-dimensional hexagon EOM is also introduced. Both EOMs are capable of differentiating the severity of the violation of the minimum eye-opening so as to allow the DFE to take different actions adaptively and achieve desired eye-opening more rapidly. A maximum-jitter EOM-based adaptive DFE is also introduced to greatly reduce system complexity. The adaptive DFE is taped out in a 130nm 1.2V CMOS technology and finally an improved adaptive engine that outperforms DFE utilizing sign-sign least-mean-square is proposed.

Improved Signal Detection Techniques for QOSTBC System in Fast Fading Channel

Most existing quasi-orthogonal space time Block coding (QO-STBC) schemes have been developed relying on the assumption that the channel is at or remains static during the length of the code word symbol periods to achieve an optimal antenna diversity gain. However, in time-selective fading channels, this assumption does not hold and causes intertransmit-antenna-interferences (ITAI). Therefore, the simple pairwise maximum likelihood decoding scheme is not sufficient to recover original transmitted signals at the receiver side. To avoid the interferences, we have analyzed several signal detection schemes, namely zero forcing (ZF), two-step zero forcing (TS-ZF), minimum mean square error (MMSE), zero forcing - interference cancelation - decision feedback equalizer (ZF-IC-DFE) and minimum mean square error - interference cancelation { decision feedback equalizer (MMSE-IC-DFE). We have proposed two efficient iterative signal detection schemes, namely zero forcing - iterative interference cancelation - zero forcing { decision feedback equalization (ZF-IIC-ZF-DFE) and minimum mean square error - parallel interference cancelation - zero forcing – decision feedback equalization (MMSE-IIC-ZF-DFE). The simulation results show that these two proposed detection schemes significantly outperform all conventional methods for QOSTBC system over time selective channel.