Adjustable Extended Discontinuous Reception Cycle for Idle-State Users in LTE-A

In the long term evolution advanced, a user in idle state can activate the discontinuous reception (DRX) to save its energy, and the 3GPP extends the length of a DRX cycle. Therefore, how to configure the extended DRX (eDRX) cycle is a tradeoff between the tracking area update (TAU) cost (the cost of updating a user's location) and the paging cost (the cost of waking up a user). In this letter, we analyze the tradeoff and determine the optimal length for the eDRX cycle under the latency constraint. The objective function is to minimize the total signaling cost considering the tradeoff between TAU cost and paging cost. The analytical and simulation results demonstrate that the proposed mathematical model can mitigate the signaling cost for the networks.