Section: 4.3.30 Unlicensed spectrum aggregation (LAA/LWA/LWIP/NR-U)
Content: Unlicensed spectrum aggregation in EPS can use either LTE Licensed-Assisted Access (LAA) that is using the Carrier Aggregation (CA) RAN configuration defined in TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [5], or LWA/LWIP aggregation using WLAN or NR-U as secondary RAT that is using the Dual Connectivity architecture defined in clause 4.3.2a and TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [5]. If the UE has Access Restriction for Unlicensed Spectrum in the form of LAA, LWA/LWIP, or NR-U (either signalled from the HSS, or, locally generated by VPLMN policy in the MME) the MME signals this to the E-UTRAN as part of Handover Restriction List. An eNodeB supporting aggregation with unlicensed spectrum in the form of LAA, LWA/LWIP, or NR-U checks whether the UE is allowed to use unlicensed spectrum. If the UE is not allowed to use Unlicensed Spectrum, the eNodeB shall not establish dual connectivity or carrier aggregation (CA) with LTE in unlicensed spectrum in the form of LAA, WLAN as a secondary RAT in the form of LWA/LWIP, or NR-U as a secondary RAT. At inter-RAT handover from GERAN/UTRAN, the Access Restriction for Unlicensed Spectrum is either already in the MME's UE context, or is obtained from the HSS during the subsequent Tracking Area Update procedure (i.e. not from the source SGSN or source RAN). In both inter-RAT handover cases, any Access Restriction for use of Unlicensed Spectrum is then signalled to the E-UTRAN. NOTE: This signalling of the Access Restriction during the TAU after the inter-RAT handover procedure means that there is a small risk that unlicensed spectrum resources are transiently allocated.