star topology with cisco aironet 1200

Hi,
we have bought few wireless router Cisco 1200. Our idea is to make a
wireless network like this :

_____________ _____________
| Cisco 1200 |----radio interface-----| Cisco 1200 |-------( internet )
-------------- --------------
|
radio interface
|
______________
| Cisco 1200 |
--------------
this solution doesn't seem to work.
Is it possible ? can this impossibiliy can come from the fact that a
radio routing involve the reservation of the half of the radio bandwith ?
Our actually working solution is

_____________ _____________
| Cisco 1200 |----radio interface-----| Cisco 1200 |-------( internet )
-------------- --------------
|
radio interface
|
______________
| Cisco 1200 |
--------------


thanks for the reply