Question: Upon expiration of timer TRAM in the Wait for Retrans Timer state, what actions does the Mobile Station (MS) take when using Point-to-Point Short Message Service (SMS) on the mobile radio interface?
Option 1: The MS resets the RETRANS flag, passes a report indication to SM-TL, and enters the Idle state.
Option 2: The MS forms and transfers an RP-SMMA message with the same RP-Message Reference as before, starts timer TR1M, but remains in the Wait for Retrans Timer state.
Option 3: The MS ignores the timer expiration and waits for an SM-RL-MEMORY-AVAILABLE-Req primitive to proceed.
Option 4: The MS forms and transfers a new RP-SMMA message with a different RP-Message Reference, starts timer TR1M, and enters the Wait for RP-ACK state.
Explanation: This is the correct sequence of actions as per the specified behavior for the SMR entity in the MS when timer TRAM expires in the Wait for Retrans Timer state. Forming a new RP-SMMA message with a different reference ensures uniqueness, starting TR1M initiates a new waiting period for an acknowledgement, and entering the Wait for RP-ACK state aligns with expecting a response to the newly sent message. This process is crucial for reliable SMS transmission over the mobile radio interface.