Slot release is possible only with GPRS mobile nodes. We maintain a release timer (SlotReleaseTimer) at the MS. On receiving a packet (in either direction) the MS checks the IFQ. If the IFQ is empty, the SlotReleaseTimer is started. It is reset if the MS gets another packet (in either direction) within four TDMA frames. Otherwise, on expiry of the timer, the releaseHandler() is called.
Currently, the value of four TDMA frames for the release timer is taken based on simulations performed. It was found optimal in preventing spurious time-outs and avoiding waiting too long. However, the optimal value may differ according to traffic generation pattern and needs to be further explored.