New Results on Location-Aware Channel Estimation for Multibeam Satellite Links

In order to employ interference mitigation techniques in a multibeam satellite scenario under full frequency reuse, channel estimation is of paramount importance. Even on symbol-synchronous forward links, this is a most challenging task since it must be accomplished before mitigation techniques are applicable. Pilot-aided sequences are normally used in this context, where problems with interfering signals are avoidable, if such sequences satisfy the orthogonality criterion. In case that nonorthogonal schemes have to be employed because of format and/or efficiency reasons, the estimator performance degrades in part tremendously by noise amplification or self-noise effects. Motivated by this background, we derive a maximum-likelihood solution by taking into account the location of the user terminals on ground. A significant improvement of the error performance is achieved with this approach by modifying the interfering components in terms of amplitude and phase such that they constructively contribute to the useful signal part.