Spectral efficiency analysis of distributed antenna systems for in-building mobile communication

In wireless systems, providing high data rate wireless services is a major challenge particularly in high building environments. The system performance is impaired by co-channel interference due to the need to reuse the limited available spectrum. In this environment, distributed antenna systems (DASs) can provide adequate coverage and high speed data services in the presence of multipath fading and co-channel interference by optimally combining the same signal from several antennas. This paper proposes and investigates the impacts of DAS for uplink transmission in high-rise buildings; where remote antenna units (RAUs) are deployed on each floor to reduce the radio transmission distance while at the same time exploiting spatial diversity. The RAUs are connected to a central unit (CU) where received signals are processed. The performance of the system is analysed in terms of achievable spectral efficiency using a propagation channel model derived from multi-floor in-building path loss values retrieved from measurement data. This model accounts for the propagation between different floors and ceilings and includes possible reflections from surrounding buildings. The effects of different numbers of receive antennas per floor and deployment conditions are investigated. Numerical results obtained suggest that the proposed scheme can facilitate better use of the available radio spectrum and provide higher data rates for indoor mobile terminals (MTs)