In a cellular network, connections between the Base Station (BS) and Mobile Stations (MS) may fail when the channel is in a deep fade. Shadow fading is large-scale fading which can cause significant received power loss for a wide area. This will lead to lost connections and/or packet loss which is harmful to mobile users, especially to those who are using real-time applications such as video conferencing. Cooperative communication is an efficient way to reduce outage and provide better Quality of Service (QoS) support for delay sensitive applications. A third station, which is often referred as a relay, can be used to forward signals between the BS and the MS.
This paper focuses on a study of the performance of relay deployments under correlated shadow fading. We consider the downlink direction in a single cell deployment, for which the shadowing effect is modeled as an angle and distance based correlated shadowing. The received signal-to- noise ratio (SNR) is then calculated by assuming jointly Gaussian shadow fading at the MS. Simulation results show channel variations over time with fixed user speed under different relay deployments. These results demonstrate that a modest number of relays can improve the performance of real-time applications significantly.