Calculation of soft handoff gain for UMTS

Defining "soft handoff gain" is not as trivial as one might think. One reason is because the soft handoff in the uplink direction is different from that in the downlink direction. Another reason is the vague context of this gain. Is it the gain compared to a system without handoff altogether? Or is it the gain compared to a system lacking the softness of the handoff process? We define a frame of reference and explain how soft handoff gain should be calculated.