  Although frequency range 2 (FR2) systems are an essential part of 5G-Advanced
and future 3GPP releases, the mobility performance of multi-panel user
equipment (MPUE) with hand blockage is still an area open for research and
standardization. In this article, a comprehensive study on the mobility
performance of MPUE with hand blockage is performed for conditional handover
(CHO) and its potential enhancement denoted by fast conditional handover
(FCHO). In contrast to CHO, in FCHO the MPUE can reuse earlier target cell
preparations after each handover to autonomously execute subsequent handovers.
This saves both the signaling overhead associated with the reconfiguration and
re-preparation of target cells after each handover and reduces mobility
failures. Results have shown that FCHO offers considerable mobility performance
gains as compared to CHO for different hand blockage cases that are dependent
on the hand position around the MPUE. For the worst-case hand blockage
scenario, it is seen that mobility failures reduce by 10.5% and 19.3% for the
60 km/h and 120 km/h mobility scenarios, respectively. This gain comes at the
expense of reserving the handover resources of an MPUE for a longer time given
that the target cell configurations are not necessarily released after each
handover. In this article, the longer resource reservation problem in FCHO is
analysed and three different resource reservation optimization techniques are
introduced. Results have shown that these optimization techniques not only
reduce the resource reservation time but also significantly reduce the
signaling overhead at the possible expense of a tolerable degradation in
mobility performance.
