How to express tau*W*log2(1+(theta*h)/(tau*sigma))==S in CVX?

Nonconvex
2

tau*W*log2(1+(theta*h)/(tau*sigma)) >= S can be reformulated as
-W*rel_entr(tau,tau+theta*h/sigma)/log(2) >= S.

However, nonlinear equality constraints are non-convex.