  When the future achievable rate is perfectly known, predictive resource
allocation can provide high performance gain over traditional resource
allocation for the traffic without stringent delay requirement. However, future
channel information is hard to obtain in wireless channels, especially the
small-scale fading gains. In this paper, we analytically demonstrate that the
future large-scale channel information can capture almost all the performance
gain from knowing the future channel by taking an energy-saving resource
allocation as an example. This result is important for practical systems, since
large-scale channel gains can be easily estimated from the predicted trajectory
of mobile users and radio map. Simulation results validate our analysis and
illustrate the impact of the estimation errors of large-scale channel gains on
energy saving.
