Performance Analysis of In-Building Distributed Antenna Systems with Frequency Reuse

A major challenge in the design of future
mobile communication systems is providing high data rate
wireless transmissions and ubiquitous coverage to users
located within buildings. One way to solve this problem
is to employ distributed antenna systems (DASs) located
indoors to provide coverage and high data rates. However,
co-channel interference caused by frequency reuse is a restraining
factor as the frequency reuse distances are generally
smaller in in-building DAS. In order to design efficient
and reliable indoor communication systems, knowledge of
the reuse distance is required. This paper investigates the
performance of an in-building DAS where remote antenna
units (RAUs) are deployed on each floor of the building
and connected to a central unit (CU) where received signals
are constructively processed. Frequency reuse is employed
among floors of the building and the impact of co-channel
interference on system performance is investigated by using
a propagation channel model derived from multi-floor, inbuilding
measurement results. The system exploits radio
propagation path loss characteristics in order to reduce
the impact of co-channel interference and hence increase
the spectral efficiency. System performance is evaluated
in terms of average spectral efficiency over a wide range
of potential mobile terminal (MT) locations, various reuse
distances and in-building propagation characteristics.