  One of upcoming mobility enhancements in 5G-Advanced networks is to execute
handover based on Layer 1 (L1) measurements using the so called lower layer
mobility procedure. In this paper, we provide a system model for lower layer
mobility procedure and we evaluate it against existing higher layer mobility
procedures, such as baseline and conditional handover, using system level
simulations. The benefits and drawbacks of lower layer mobility procedure are
analyzed and compared against higher layer handover mechanisms using the
relevant mobility key performance indicators. It has been shown that lower
layer mobility procedure outperforms the existing handover mechanisms with
respect to radio communication reliability at the expense of higher number of
handovers and ping-pongs. To tackle these drawbacks, additional filtering for
the L1 measurements used in handover decision is introduced to reduce the
fluctuations caused by fast fading and measurement errors. Moreover, lower
layer mobility procedure is enhanced with dynamic switching mechanism enabling
the UE to change cells without being reconfigured by the network. The
evaluations have shown that the introduction of such techniques is beneficial
in reducing the number of ping-pongs and signaling overhead at the expense of
an increase in the delay to react to rapid signal degradation and resource
reservation overhead, respectively.
