MIMO Outage Capacity
The ergodic capacity we discussed before is achievable under the assumption of fast fading characteristics of the channel.
And this ergodic capacity is in general not achievable [2] for slow fading channels, where the channel remains constant during the entire transmission but changes from transmission to transmission.
In other words, each information codeword experiences a constant channel realization.
An appropriate metric for such kind of channels is the outage capacity. With outage capacity, the channel capacity is treated as a random variable which depends on the instantaneous channel realization. Whenever the receiver is not capable of supporting a given information rate $C_{\rm{out,q}}$, an outage is declared. The associated outage probability is thus $$ P_{\rm{out}} \left \{ C\leqslant C_{\rm{out,q}} \right \}=q $$ This can be interpreted as the information rate of $C_{\rm{out,q}}$ is guaranteed for $100\cdot (1-q)$% of the channel realizations. Or one may say the highst supportable information rate is $C_{\rm{out,q}}$ if an outage probability of $q$ is desired. Furthermore, the distribution of the channel capacity is needed to compute the outage capacity.
An appropriate metric for such kind of channels is the outage capacity. With outage capacity, the channel capacity is treated as a random variable which depends on the instantaneous channel realization. Whenever the receiver is not capable of supporting a given information rate $C_{\rm{out,q}}$, an outage is declared. The associated outage probability is thus $$ P_{\rm{out}} \left \{ C\leqslant C_{\rm{out,q}} \right \}=q $$ This can be interpreted as the information rate of $C_{\rm{out,q}}$ is guaranteed for $100\cdot (1-q)$% of the channel realizations. Or one may say the highst supportable information rate is $C_{\rm{out,q}}$ if an outage probability of $q$ is desired. Furthermore, the distribution of the channel capacity is needed to compute the outage capacity.