| 摘要 |
A HANDOVER FROM UTRAN procedure is performed to handover a wireless device from the UTRAN to a second network. While attached to the second network, the wireless device sends an INTER RAT HANDOVER INFO message to the UTRAN. The INTER RAT HANDOVER INFO message includes the security START value maintained by the wireless device for ciphering purposes. In response to determining that the security START value equals or exceeds a THRESHOLD value, the UTRAN disables ciphering with the wireless device when performing a HANDOVER TO UTRAN procedure. Similarly, the wireless device disables ciphering when performing the HANDOVER TO UTRAN procedure if the START value equals or exceeds the THRESHOLD value. Alternatively, a new ciphering key set is generated while the wireless device is attached to the second network, and ciphering is performed during the HANDOVER TO UTRAN procedure, utilizing the new key set.
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