An Adaptive Discontinuous Reception Mechanism Based on Extended Paging Indicator for Power Saving in UMTS

In this paper, we propose the ADRX (adaptive discontinuous reception) mechanism with the EPI (extended paging indicator) for power saving in the UMTS (universal mobile telecommunications system). Regardless of various traffic patterns and network situations, the conventional FDRX (Fixed DRX) mechanism currently specified by 3GPP (third generation partnership projects) employs only fixed DRX period with a given DRX cycle length of the same length in which each UE (User Equipment) is to have one paging occasion with the uniquely allocated PI. However, improvement of power saving performance cannot be expected since this FDRX does not support longer DRX periods to save more power consumed in the UE for intermittent data packets. In the proposed ADRX mechanism, to solve this problem and efficiently reduce the power consumption, DRX period is easily controlled by the EPI which is decided by Node B considering the current traffic situation. In addition to its original functions to indicate paging messages, the proposed EPI also includes four extended functions; preservation, increase, decrease, and reset of the DRX periods. Simulation results reveal that the proposed ADRX mechanism achieves remarkable improvement of power saving performance as compared to the conventional FDRX mechanism. Furthermore, it is also observed that the proposed ADRX based on the EPI has a trade-off relationship between power saving performance and packet transmission reliability.