Section: 5.4.9 Timing Advance Reporting
Content: The UE may be configured to report information about timing advance during a Random Access procedure and in RRC_CONNECTED Mode. The Timing Advance reporting procedure is used in a non-terrestrial network to provide the eNB with an estimate of the UE's Timing Advance, see TTA in TS 36.211[ Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation ]  [7] clause 8.1. Timing Advance reporting shall be triggered if any of the following events occur: - if triggered by upper layers; - upon configuration of offsetThresholdTA by upper layers, if the UE has not previously reported Timing Advance value to current Serving Cell; - if the variation between current information about Timing Advance and the last reported information about Timing Advance is equal to or larger than offsetThresholdTA, if configured. If the Timing Advance reporting procedure determines that at least one Timing Advance Report has been triggered and not cancelled: - if the MAC entity has UL resources allocated for new transmission for this TTI, and; - if the allocated UL resources can accommodate the Timing Advance Report MAC control element plus its subheader, as a result of logical channel prioritization: - instruct the Multiplexing and Assembly procedure to generate the Timing Advance report MAC control element as defined in clause 6.1.3.20. A MAC PDU shall contain at most one Timing Advance Report MAC CE, even when multiple events have triggered a Timing Advance report. The Timing Advance Report MAC CE shall be generated based on the latest available estimate of the UE's Timing Advance value prior to the MAC PDU assembly. All triggered Timing Advance reports shall be cancelled when a Timing Advance Report MAC CE is included in a MAC PDU for transmission.