https://www.qualcomm.com/media/documents/files/lte-mobility-enhancements.pdf
1. Backward Handover
Backward
handover can be described as network-controlled/UE-assisted mobility.
Handover related information is exchanged between the UE and the
source eNB via the old radio path (thus, the usage of the term ‘backward’). Specifically, the radio conditions need to be good enough
for the source eNB to be able to decode the Measurement Report from
the UE and subsequently prepare the target cell for handover. The radio
conditions also need to be good enough for the UE to be able to decode
the Handover Command from the source eNB.
2. RLC Handover
RLF handover is UE-based mobility and provides a
recovery mechanism when the backward handover signaling with the
source cell partially fails due to poor radio conditions. Specifically, the
radio conditions are good enough for the source eNB to be able to
decode the Measurement Report from the UE and subsequently prepare the target cell for handover, but not good enough for the UE to be able to
decode the Handover Command from the source eNB1.
