Wifi cuts when Mac is in sleep mode

Hello,

Each time I go in sleep mode with my MacBook Pro (I just close the Mac without shutting down) I loose the wifi connection. Only solution is to re-start the Mac to restore a connection. It doesn't work with just deactivating and reactivating the wifi connection.

According to what I read this is a common issue for some of the users with Lion.

Can you tell me how I can solve this ?

Tx for your help !