Soft and Softer handover types are used when RRC layer is in the cell DCH state. Here multiple radio links are kept as active radio links. Hence radio links can be easily added and removed. This helps in many ways as mentioned below.

• Alternate radio link helps by exploiting antenna diversity concepts (refer diversity page to know more)
• Call drop rate can be drastically reduced.
• It helps in smooth handover without any interruption in call/data flow.

Softer handover - handover between two cells (different NodeB) is called softer handover. There are two types of softer handover viz. Intra RNC and Inter RNC handovers.

Soft handover - handover between two sectors of the same cell of a NodeB is called soft handover.

Soft Handoff

• Soft handoff is a "Make before break" handoff. That is, the mobile station (MS) is up on a call and moves from one base station (BS) to another, but the MS starts communicating with a new BS before terminating communications with the old BS.
• Soft handoffs can only be used between BSs on the same frequency. The technique improves reception as MSs move between cells (on cell boundaries).
• During soft handoff the MS actually communicates with more than one BS at a time, so that when it's time to move from the weaker BS to the stronger one, the MS is already in communication with the stronger one.
• During a soft handoff, the mobile station receives independent closed loop power control bits from the two BSs and perform "Or of Downs" logic to determine how to adjust its power. That means the mobile station will increase its power level if and only if both power control bits from the two BSs are 0 (indicating up). If the power control bit from any base station equals to '1' (indicating down), the mobile station shall decrease its power.
• To learn more about how to use the test set to verify the MS behavior on independent closed loop power control from the two BSs, see Verifying Mobile Station (MS) Closed Loop Power Control (CLPC) Behavior in Soft/Softer Handoffs .

Softer Handoffs

 A softer handoff occurs when the MS is communicating with two sectors of a cell. Softer handoff is identical to the soft handoff with the following exceptions.

• The mobile station receives identical power control from both sectors and provides diversity combining of the power control bits to determine whether the BSs are sending an up bit or a down bit (ignore the weaker bits). It's NOT "or of downs" logic.
• To learn more about how to use the test set to verify the MS behavior on identical closed loop power control from two sectors, see Verifying Mobile Station (MS) Closed Loop Power Control (CLPC) Behavior in Soft/Softer Handoffs .