2014/03 64 p.
To boost capacity in coping with the exponential traffic growth, both denser cell deployment and improved cell spectral
efficiency are required. Co-channel interference, either from inter-cell or co-scheduled intra-cell users, is expected to
become the dominant limiting factor for achieving higher network capacity.
Historically much effort has been spent on transmission coordination to mitigate inter-user and inter-cell interference,
for example via enhanced CSI feedback. However, one of the Rel-11 studies (Advanced Receivers) showed promising
performance gain from practical linear interference suppression (IS) receivers that do not require any transmission
coordination. Specifying interference rejection combining (IRC) receiver UE performance requirements in RAN4 is just
a first step towards increasing the receiver role in the system design. In another Rel-11 work item (feICIC), non-linear
interference cancellation receivers that mitigate strong CRS/PSS/SSS/PBCH interference have been shown to provide
significant gain over linear receivers.
Further enhancements to intra-cell and inter-cell interference mitigation at the receiver side could be achieved by
increasing the degree of knowledge about interfering transmissions with possible coordination in the network. For
example, linear IS receivers and iterative/non-iterative explicit IC receivers could be evaluated with participating
transmitters coordinating and providing side knowledge of the interference such as, but not limited to, the presence and
characteristics of interference, its transmission schemes including resource allocation, its reference symbols for possibly
enabling channel estimation, and its modulation format and/or coding rate.
Compared to transmission-side techniques whose performance degrades under imperfect channel knowledge at the
transmitter side due to limited feedback, IS/IC receivers can alleviate the burden of channel feedback.
Network-assisted IS/IC might require standardization effort, especially on the signalling aspects that can enable more
effective and robust UE-side interference cancellation and/or suppression with possible network coordination, as well as
on the physical layer changes that can translate link-level improvement of these advanced receivers to system-level
capacity gain. It is also important to study the trade-off, in terms of performance, complexity, and signalling overhead,
when enabling feasible and robust interference cancellation/suppression at the UE side with and without network
full Table of Contents for TR 36.866 Word version: 12.0.1