| CPC H04W 56/0045 (2013.01) | 15 Claims |

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1. A method performed by a wireless device of a cellular communications system to determine timing advance, TA, validity, the method comprising:
obtaining a TA for a cell of the cellular communications system;
determining that a configuration comprising signaling bits activating a TA validation mechanism of a predefined set of TA validation mechanisms has not been received from a network node; and
responsive to determining that the configuration activating the TA validation mechanism of the predefined set of validation mechanisms has not been received, determining that the TA is valid for an entirety of the cell, wherein the TA validation mechanism is one of a Time Alignment Timer for idle mode, serving cell Reference Signal Received Power (RSRP) or Narrowband RSRP (NSRP) changes.
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