A method ( 400 ) and arrangement for mitigation of intercell and intracell interference in a 3GPP cellular communication system by, in a receiver in a cell of the system, deriving for a first channelin the cell a signal, representative of first channel transfer function (A⁽¹⁾); deriving from at least a second channel originating in a different cell a signal (A^{(2 . . . M)}), representative of second channel transfer function, based on: deriving a cell specific scrambling code (s), deriving a channel impulse response (h), and deriving a channelisation code (c); and performing multi-user detection using the first and second signals. Where the channelisation code is unknown, a substitute channelisation code is preferably substituted. It will be appreciated that the technique can be applied to both downlink and uplink. This provides the advantage that both intra-cell interference and intercell interference are mitigated.