rm inter-RAT measurements configured by the MN on the SN RAT. When SpCell quality is above the threshold configured by the SN, the UE is not required to perform measure- ments configured by the SN [4]. The measurement reports, configured by the SN, are sent on SRB1 when SRB3 is not con- figured; otherwise, the measurement reports are sent over SRB3. The measurement results related to the target SN can be provided by MN to target SN at MN-initiated SN change procedure. The measurement results of target SN can be forwarded from the source SN to the target SN via MN at SN-initiated SN change procedure. The measurement results corre- sponding to the target SN can be provided by the source MN to the target MN at inter-MN handover with/without SN change procedure [4]. Per-UE or per-FR measurement gaps can be configured, depending on UE capability to sup- port independent FR measurement and network preference. Per-UE gap applies to both FR1 (LTE and NR) and FR2 (NR) bands. For per-FR gap, two independent gap patterns (i.e., FR1 gap and FR2 gap) are configured for FR1 and FR2. The UE may also be configured with a per-UE gap sharing configuration (applying to per-UE gap) or with two separate gap sharing configurations (applying to FR1 and FR2 measurement gaps, respectively). A mea- surement gap configuration is always provided in the following scenarios: for UEs config- ured with LTE inter-frequency measurements; and for UEs that support either per-UE or per-FR gaps, when the conditions to measure SSB-based inter-frequency measurement or SSB-based intra-frequency measurement are satisfied [4]. 2.9 Carrier Aggregation (L2/L3 Aspects) Multiple NR component carriers can be aggregated and simultaneously transmitted to a UE in the downlink or from a UE in the uplink, allowing an increased operating bandwidth and cor- respondingly higher link data rates. The component carriers do not need to be contiguous in New Radio Access Layer 2/3 Aspects and System Operation 281 the frequency domain and can be in the same frequency band or