Abstract
MIMO mobile systems, with a large number of antennas at the base-station
side, enable the concurrent transmission of multiple, spatially separated
information streams and, therefore, enable improved network throughput and
connectivity both in uplink and downlink transmissions. Traditionally, to
efficiently facilitate such MIMO transmissions, linear base-station processing
is adopted, that translates the MIMO channel into several single-antenna
channels. Still, while such approaches are relatively easy to implement, they
can leave on the table a significant amount of unexploited MIMO capacity.
Recently proposed non-linear base-station processing methods claim this
unexplored capacity and promise a substantially increased network throughput.
Still, to the best of the authors' knowledge, non-linear base-station
processing methods not only have not yet been adopted by actual systems, but
have not even been evaluated in a standard-compliant framework, involving of
all the necessary algorithmic modules required by a practical system. This
work, outlines our experience by trying to incorporate and evaluate the gains
of non-linear base-station processing in a 3GPP standard environment. We
discuss the several corresponding challenges and our adopted solutions,
together with their corresponding limitations. We report gains that we have
managed to verify, and we also discuss remaining challenges, missing
algorithmic components and future research directions that would be required
towards highly efficient, future mobile systems that can efficiently exploit
the gains of non-linear, base-station processing.