soft handover : during the call, the mobile is connected to two cells at the same time, or sometimes more than 2 ! The soft HO happens when the mobile actually stops communicating with one of the cells in the “active set” (low level maybe, or bad quality, etc..)
hard handover : it is the type of handovers used in 2G GSM, no doubt about that 🙂
oh, i just found this :
There are following categories of handover (also referred to as handoff):
# Hard Handover
Hard handover means that all the old radio links in the UE are removed before the new radio links are established. Hard handover can be seamless or non-seamless. Seamless hard handover means that the handover is not perceptible to the user. In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover.
# Soft Handover
Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN. Soft handover is performed by means of macro diversity, which refers to the condition that several radio links are active at the same time. Normally soft handover can be used when cells operated on the same frequency are changed.
# Softer handover
Softer handover is a special case of soft handover where the radio links that are added and removed belong to the same Node B (i.e. the site of co-located base stations from which several sector-cells are served. In softer handover, macro diversity with maximum ratio combining can be performed in the Node B, whereas generally in soft handover on the downlink, macro diversity with selection combining is applied.
(cf [url]www.umtsworld.com/technology/handover.htm[/url])