We are expecting the commercial 5G service available in 2019. It means that our research community already has been one step ahead, now start talking about 6G. This project investigates the promising technologies for 6G System Design & Optimization with the goal of boosting Network Capacity. The capacity increase can be due to more spectrum, more spectral efficiency or more spatial efficiency. What will be the target peak data rate and bandwidth efficiency in 6G? Maybe 1Tbps or more? How about 1Gbps user experienced data rate? Multiple Access techniques, e.g. NOMA, FTN-based MIMO transmission, Multi-Antenna Technologies, such as Massive MIMO, Symbol-level precoding, Spatial Modulation, Interference Alignment & Cancellation, User-centric Coverage techniques, e.g., Distributed Input Distributed Output (aka massive CoMP), pCell Clustering, and Tera-hertz Band Communication like One-bit Quantization & Faster-than-Nyquist (FTN) are some of the directions to be researched for the capacity boost. Everything is open now, so we do not know what it will look like, but we will join the frontline to take shape for 6G.