IB-DFE Techniques Applied to Multi-Antenna Systems

Abstract

With the rise of data-hungry mobile services, scientists have struggled to deliver the desired mobile data rates whilst using the limited available bandwidth. As the higher frequencies are yet inaccessible, namely the millimeter wave frequencies (between 60 and 100 GHz), spectral efficiency is becoming the defining factor for future standards. As result of this, MIMO techniques have been gathering interest in the past few years. The basic concept of a MIMO system consists in transmitting different signals through several antennas, using the same frequency band and with at least as many receiving antennas on the receiver. Exploiting the lack of correlation between the multiple channels, it is possible to isolate and detach each received signal at the receiver. While it seems to be a straightforward method to increase the spectral efficiency, as result of multiple signals being squeezed in the same frequency band, the complexity of the signal separation algorithms is awfully high. Additionally, these algorithms fail to separate signals whose power is far inferior than their peers’, imposing limitations to MIMO based systems. This work proposes three independent solutions to improve MIMO uplink communications for single-carrier block-based transmissions with iterative frequency domain equalization (IB-DFE). The first uses magnitude modulation techniques so as to improve the transmitter’s power efficiency. The second employs base station cooperation techniques to improve the user’s performance at cell edges. Lastly, the third solution apply a clusterbased multi-user detection, allowing for an increased number of users to share the same channel without exhausting the computational resources at the receiver.