The constantly increasing demand for wireless services, the scarcity of radio
spectrum and the characteristics of the global wireless market, necessitate
that future wireless systems (Fourth Generation Mobile - 4G) provide higher
peak data rates and better QoS, especially for the cell-edge users. Furthermore
it is essential that they achieve high spectral efficiencies and they are
easily deployed. In order to be able to accomplish these objectives, wireless
systems need to incorporate technologies that increase the cell throughput
without increasing spectral consumption.
A very promising technique that can achieve the aforementioned targets
is Multicell Cooperative Processing (MCP) or Multicell-MIMO. MCP has
the potential to mitigate Inter-Cell Interference (ICI) and augment data
rates without sacrificing additional spectrum but at the cost of some overhead
and complexity. According to the concept of clustered MCP proposed
in this thesis, Base Stations (BSs) are grouped into cooperation clusters,
each of which contains a subset of the network BSs. The BSs of each cluster
exchange information and jointly process signals as they form virtual
antenna arrays distributed in space. In these systems, each user receives
useful signals from several BSs and therefore the notion of a cell transcends
the one of the conventional cellular systems. Although Multicell-MIMO is
a technique that can help meet a lot of the challenges towards 4G systems,
it has some intrinsic drawbacks that need to be addressed in order for it to
be brought into practice; this is the main focus of the present thesis.
Firstly the problem of how to optimally form BS cooperation clusters of
limited size has been investigated. MCP's overheads are proportional to the
size of cooperation clusters, therefore this size should be kept limited. The
straightforward solution of forcing neighboring BSs to collaborate provides
limited gains. In this thesis it is proposed that the BSs which interfere the
most with each other should cooperate rather the ones that are in close
proximity. This is shown to lead to significant spectral efficiency gains while
cluster sizes are kept very small.
