A method and apparatus are disclosed for requesting resources in a wireless communication system. The method includes sending a first SA in a first SA period at a first timing. The method also includes considering a data available in the UE at a second timing, wherein the data needs to be transmitted and the second timing is later than the first timing. The method further includes skipping a resource associated with the first SA for sending the data at a third timing, wherein the third timing is later than the second timing and earlier than a second SA period which is later than the first SA period. In addition, the method includes sending a second SA in the second SA period. Furthermore, the method includes sending the data on a resource associated with the SA.