RFSoft vs. Softer Handover in Wireless Communication
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This article explains the difference between soft handover and softer handover, concepts used in wireless communication systems, specifically when the Radio Resource Control (RRC) layer is in the CELL_DCH state. Both soft and softer handovers involve maintaining multiple active radio links.
With multiple radio links active, adding and removing them becomes much easier, leading to several advantages:
- Antenna Diversity: Alternate radio links can leverage antenna diversity techniques (refer to our diversity page for more details).
- Reduced Call Drop Rate: Maintaining multiple connections greatly reduces the likelihood of dropped calls.
- Seamless Handovers: Provides a smoother handover experience with minimal interruption to voice or data flow.
Soft Handover
A soft handover occurs when a mobile device (User Equipment or UE) switches between two sectors within the same cell of a NodeB (base station). Imagine the NodeB as a pie, and the sectors as slices of that pie. The UE is moving from one slice to another, still served by the same “pie”.
Softer Handover
A softer handover, on the other hand, happens when the mobile device switches between two different cells, each belonging to a different NodeB. Think of it as moving from one “pie” to another.
Softer handovers are further categorized into two types:
- Intra RNC Handover: This occurs when the two different NodeBs are controlled by the same Radio Network Controller (RNC).
- Inter RNC Handover: This occurs when the two different NodeBs are controlled by different Radio Network Controllers (RNCs).
Reference: 3GPP TS 25.331
