Standard voice encoding is characterized by using 20-ms interval between voice packets and 160 ms during comfort silence packets, while the radio interface in LTE is divided into transmission time intervals (TTIs) of 1 ms duration. Since VoLTE packet size is small compared to the high capacity in LTE, it is typically possible to send one packet in a single TTI which allows the UE to remain inactive until the next packet will become available. The eNodeB controls the use of radio resources both in the uplink and downlink, which allows optimizing the scheduling of packets. LTE packet scheduler may even some- times increase the time between two allocations, forcing two packets to be transmitting together, in order to increase capacity and power savings. That feature is called packet bundling. Connected state DRX functionality in LTE network tries to exploit the gaps between con- secutive packets in order to allow the UE to switch off its receive chain during short periods of time, reducing its overall power consumption. However, as VoLTE traffic pattern is very different from other applications, there is a need to modify the DRX settings for the UE when a new VoLTE call is established; SO specific DRX settings are sent when a new dedicated bearer with QCI1 QoS class is created. The target behaviour of DRX with VoLTE is illustrated in Figure 16.30. From the power consumption point of view, if both uplink and downlink packets are sent at the same time within one TTI, there is maximum time available for the power-saving DRX sleep mode. However, when downlink and uplink packets are not synchronized, the probability of obtaining gains is significantly reduced. Silence periods also increment the probability of battery savings, since the interval between packets increases to 160 ms. Figure 16.31 shows a comparison between the average current consumed by a SIP VoIP client using AMR WB codec with a predefined voice pattern looped between the two UEs in the call. The voice pattern is shown in Figure 16.32. The reference curre