1. A method for state/space estimation, comprising: arranging a network of radio frequency sensors in a space, the network comprising a first pair of radio frequency sensors; calibrating said first pair of radio frequency sensors to determine a first fading condition associated with said first pair of radio frequency sensors; measuring signal strength of at least one signal sent between said first pair of radio frequency sensors; determining a first likelihood model based on said first fading condition, the likelihood model indicating a likelihood that a set of target coordinates will correspond to one or more measured received signal strength values; estimating a first posterior statistical distribution of measured received signal strength values based on said measured signal strength of said at least one signal using said first likelihood model, the first posterior statistical distribution comprising the inverse of the first likelihood model; and determining object information of one or more device-free objects within said space based on said first posterior statistical distribution of measured received signal strength values.