The present invention relates to a method and arrangement to enhance the communication performance in wireless communication systems. The method of the invention provides better adjustment of reported SINR in MIMO, and PARC-MIMO based communication systems. According to the method information relating to signal-to-interference-plus-noise ratio is determined by the user equipment and reported to the base station. The base station adjust reported SINRs using a model of the SINR dependences of power and code allocation. The dependences is modeled by a function comprising a first parameter relating only to power allocation and a second parameter relating only to code allocation. The first parameter has a power allocation exponent and the second parameter has a code allocation exponent. Both the power allocation exponent and the code allocation exponent are data stream dependent.