A Framework for Determining Realistic Capacity Bounds for Distributed Antenna Systems

In the current research on future cellular networks, both classical MIMO concepts, such as schemes achieving spatial diversity or spatial multiplexing, and also virtual MIMO concepts are observed. In the latter, multiple base stations serving different cells are grouped to form distributed antenna systems that can be exploited as large MIMO systems. For example, concepts such as joint detection in the uplink and joint transmission in the downlink can be applied in order to cancel or suppress inter-cell interference. In this paper, we focus on the uplink and introduce a framework to investigate capacity bounds in cellular networks that use conventional single-cell links or employ multi-cell joint detection. We observe both an ideal hexagonal cell setup and also the existing GSM cell setup in downtown Dresden, while initially computing the capacities based on idealistic assumptions, and then successively introducing more and more non-idealistic aspects, to finally obtain a good estimate of performance bounds in a real-world system. The paper illustrates capacity bounds and thus the benefits of distributed antenna systems, as well as the methodology of efficiently and realistically modelling the physical layer of future cellular networks.