UE Measurements Relaxation for UE Power Saving in 5G New Radio

The efficient usage of power has become a matter of extreme importance in 5G New Radio. To enhance UE power saving, among other techniques of the 3GPP release 17, it is worth mentioning the relaxation of the measurements required for RLM (Radio Link Monitoring) and BFD (Beam Failure Detection). In this paper, we describe the design of the RLM and BFD measurements relaxation framework and evaluate the power saving gain provided by such relaxation for UEs in low mobility, at cell center and with a short DRX cycle. Our results show that the attainable power saving gain can be approximately between 5% and 40%. The gain greatly depends on factors such as the applied relaxation level, location in time of the reference signals used for the measurements, DRX configuration and whether the UE is also allowed to relax other measurement types (e.g. Radio Resource Management measurements). Furthermore, we study the impact of such relaxation on the mobility and QoS performance through numerical analysis. We conclude that the performance degradation due to relaxation can be bounded to acceptable levels if the applied relaxation level is limited and the UE is able to stop employing relaxation timely, whenever the radio quality deteriorates.