Impact of Path Loss and Delay Spread on Base Station Cooperation
In this paper, the authors investigate the maximum Inter-Site Distance (ISD) for performing joint signal processing between cooperative base stations. As a metric, they use the maximum excess delay measured at 95% point of the cumative power delay profile from all base stations. For the distance-dependent channel parameters, they consider Greenstein's statistical propagation model, which they extended for broadband transmissions. They extract all model parameters from 2.6 GHz multi-cell measurements in their field trial and parametrize the model at a fixed ISD. They also investigate the impact of antenna downtilt and find that when a larger downtilt is used, the rms delay spread and 95% excess delay are smaller.