Flooring Tile - cemnt b oard over poured concrete ?

Here is my dilemma, I have a freshly almost level poured slab in my new basement washroom,I am concerned about the temp of this cold floor as the heating vents are in the ceiling offering no help to the cold floors in the winter.I want to tile the space floor and walls , A) Do I need to use backer board down on the concrete or do I just tile straight onto the slab.
B) put down a wood sub for warmth then the cement board then the adhesive and tile ? this would add more thickness then I really want but it seems to address my concerns......

Any Thoughts would br greatly apreciated

No cement board on concrete, it won't work. No plywood either. The plywood will absorb any moisture from the slab and swell to the point that will blow the tile off the floor.

have you considered a infloor heating system like Sun Touch?