In a method of interference mitigation in a multi user detection capable radio base station in a communication system, which radio base station comprises a set of confined detection modules, at least one of which is capable of handling multiple user connections, first and at least a second subset of detection modules are formed from said set, wherein the second set comprises at least one interference mitigation capable detection module. Interference information from the first subset is communicated to the second subset, interference originating in user connections of the first subset are then mitigated from the user connections of the second subset. Subsequently, interference is mutually mitigated between the connections within the interference mitigation capable detection module.