Analysis of discontinuous reception with both downlink and uplink packet arrivals in 3GPP LTE

We mathematically analyze the discontinuous reception (DRX), a power saving mechanism in 3GPP LTE where both downlink and uplink packet arrivals at a user equipment (UE) and an evolved node B (eNB) follow Poisson processes. We construct a 2-dimensional discrete time embedded Markov chain. We obtain the average power consumption, average downlink delay and average uplink delay. The analytical results match with the simulation results very well. We show that there is a tradeoff between the power consumption and the downlink delay, i.e., the average power consumption decreases and the average downlink delay increases as the DRX cycle increases or the inactivity time decreases. We also see that a presence of uplink packet decreases the downlink packet delay, but increases the power consumption.