Figure 3

Outage probability vs robust parameter for MUEs. The variation of MUEs’ outage probability with the increase of parameter ε _m is illustrated, which is compared with worst-case scheme and non-robust scheme when fixing$I_m^t=10N_0$. The worst-case scheme is assumed to totally capture the uncertainty of channel gain where the outage probability is 0. The outage probability decreases steeply from 18% to 1.8% as Ω _m increases from 0 to 0.5. Afterwards, the decreasing rate shows a downward trend till meeting 0 at Ω _m  = 0.7.