Field spectrum and degrees of freedom in AdS/CFT correspondence and   Randall Sundrum model
  Compactified AdS space can not be mapped into just one Poincare coordinate chart. This implies that the bulk field spectrum is discrete despite the infinite range of the coordinates. We discuss here why this discretization of the field spectrum seems to be a necessary ingredient for the holographic mapping. For the Randall Sundrum model we show that this discretization appears even without the second brane. 
Henrique Boschi-Filho and Nelson R. F. Braga