SNR Threshold for Distributed Antenna Systems in Cloud Radio Access Networks

A distributed antenna system (DAS) architecture is a key enabler for Cloud Radio Access Networks (CRAN) where geographically separated base stations are connected to a centralized processing and decision making unit. Many schemes have been proposed to leverage Fractional Frequency Reuse (FFR) and co- ordinated joint transmission between base stations to improve cell-edge performance for static network deployments. In this paper, we investigate dynamic decision making that whether co-ordinated joint transmission should be selected in the downlink of a FFR-aided DAS. We derive the transmitting Signal-to- Noise-Ratio (SNR) threshold for making these decisions and we show that this SNR plays a key role in the FFR- aided DAS analysis and can be used as a guide in the evaluation of DAS performance.