respective of DRX cycle, the UE may use the first available RACH opportunity to send a UL measurement report. Immediately after sending a measurement report, the UE may change its DRX cycle (see Figure 6-30). This mechanism can be pre-configured by the eNB. HARQ operation related to data transmission is independent of DRX cycle and the UE wakes up to read the PDCCH for possible re-transmissions and/ or ACK/NACK signaling, regardless of DRX cycle. In the downlink, a timer is used to limit the time the UE can stay awake awaiting for a re-transmission. When the DRX is configured, the UE may be further programmed with an On Duration timer, during which the UE monitors the PDCCHs for possible allocations. When DRX is configured, periodic CQI reports can only be sent by the UE during the Active-Time. The RRC can further restrict periodic CQI reports SO that they are only sent during the On Duration. A timer in the UE is used to detect need for obtaining timing advance. The following definitions apply to DRX in E-UTRAN: On Duration: time interval in downlink subframes that the UE awaits PDCCH after waking up from DRX. If the UE successfully decodes a PDCCH, the UE stays awake and starts the inactivity timer. Inactivity Timer: time interval in downlink subframes that the UE waits to successfully decode PDCCH from the last successful decoding of a PDCCH. The UE re-enters DRX if it fails to Duration DRX Opportunity DRX Cycle UE Monitors PDCCH FIGURE 6-30 An illustration of the DRX cycle 6.13 3GPP LTE radio resource control functions decode PDCCH. The UE restarts the inactivity timer following successful decoding of PDCCH in the first transmission. Active-Time: total time duration that the UE is awake. This includes the On Duration of the DRX cycle, the time UE is performing continuous reception while the Inactivity Timer has not expired, and the time UE is performing continuous reception while waiting for a DL re-transmission. Based on the above, the minimum active time is equal to On Duration. Among the above parameters, 