David Barber, Felix Agakov
The maximisation of information transmission over noisy channels is a common, albeit generally computationally diﬃcult problem. We approach the diﬃculty of computing the mutual information for noisy channels by using a variational approximation. The re- sulting IM algorithm is analagous to the EM algorithm, yet max- imises mutual information, as opposed to likelihood. We apply the method to several practical examples, including linear compression, population encoding and CDMA.