Determination of a suitable macro-cell model for UMTS system in Istanbul

Macro-cells are large areas with transmitter antennas well above the surrounding buildings and usually there is no direct visibility between the transmitter and the receiver (NLOS). For this purpose, in general, path loss models which consider uniform environmental characteristics are used, as well as the those that are suitable for homogenous urban environments. Istanbul has a complex geographical structure, and is established on seven hills and divided by the Bosphorus. Many old and new buildings with different height and size are located side by side, and there are various types of roads with random shapes and directions. Also, as Istanbul is not a flat area, the most commonly used macro-cell path loss models for GSM 900/1800 are not one to one applicable to UMTS systems. We define different macro-cell propagation models for each MS to MS, BS to MS, BS to BS, MS to BS communications case where the-buildings are assumed to be nearly uniform height, to ensure an efficient UMTS system. In order to improve the system performance, the most appropriate measurement procedure and measurement criteria are examined, as well as filtering intervals in association with handover mechanisms.