Towards Downlink Multi-user Gain

Multi-user gain refers to the potential performance advantage of optimized multi-user downlink schemes over the conventional TDMA, FDMA, and single-user detection based CDMA schemes. In information theory, these conventional schemes are known to be strictly sub-optimal in fading environments. More advanced techniques are necessary to achieve downlink channel capacity. Much progress on this topic has been made in recent years.The main objective of this project is to investigate practical schemes for optimized downlink design. In particular, the researchers propose to investigate whether the above information theoretic assertions can be turned into reality. They will carry out theoretical studies to identify the potential multi-user gain achievable in cellular systems. They will develop practical pre-coding and detection algorithms and identify the realistic level of performance gain that can be achieved while taking account of implementation constraints. The aim is to provide useful guidelines for future cellular systems.The multi-user gain can potentially yield large savings in transmission power (> 10 dB at high transmission rates). It can also be translated into an equivalent gain in spectral efficiency in cellular environments.