Mobility interruption time for L1/L2 Triggered Mobility (LTM) is the time from UE receives the cell switch command to UE performs the first DL/UL reception/transmission on the indicated beam of the target cell.
The latency of the mobility procedure for LTM is characterized by the terms illustrated in
Figure G-1.
Each component of mobility latency is described in the table below. The value of T
RRC is specified in
clause 12 of TS 38.331.
The latency of the RACH-based and RACH-less LTM procedure is characterized by the terms illustrated in
Figure G-2 and
Figure G-3. In particular,
Figure G-2 shows the LTM procedure where the UE performs DL synchronization toward an LTM candidate cell before performing an LTM cell switch which involves a random access procedure. Further,
Figure G-3 shows the LTM procedure where the UE performs the UL and DL synchronization before performing an LTM cell switch which does not involve a random access procedure. In both figures, it is highlighted how the overall mobility latency of LTM can be reduced by early synchronization procedure. Interruption time requirements (not represented by this annex) are specified in
clause 6.3 of TS 38.133.