Implications of Antenna Sharing in Colocated 1XRTT and EV-DO Systems: Downtilt Angle Analysis

The impact of antenna downtilt on the forward links of overlayed CDMA2000 1XRTT and EV-DO systems is examined via numerical simulations. A system model for colocated IX / EV-DO networks is proposed and employed to provide a perspective on the issues and trade-off situations derived from using the same cell site antennas and, consequently, the same downtilt angles for the two networks. A set of recommendations regarding the fade margins of both downlink budgets and the optimum antenna downtilt angles as a function of the IX cell load is drawn from the simulations results.