Method And Arrangements For Signaling Control Information In A Communication System

A method in a first communication device for setting the first communication device to an operational mode according to signalled control information associated with transmission of data over a wireless channel comprising the steps of,

• determining a recommended precoder and a first transmission rank to optionally use when transmitting data from a second communication device,
• transmitting feedback data to a second communication device, wherein the feedback data comprises an indication of recommended precoders and a first transmission rank to use during transmission,
• receiving, from the second communication device, a confirmation message comprising a confirmation that transmission of data from the second communication device is using at least parts of each recommended precoder over frequency used and an indicator of the second transmission rank to use, wherein the parts of each recommended precoder corresponds to a column subset of the recommended precoder and which indicator also indicates which column or number of columns of the recommended precoder column subset to use supporting the second transmission rank. and
• setting up the first communication device in the operational mode to use the at least parts of the confirmed precoder and the second transmission rank to receive and decode the transmission of data from the second communication device.

A first communication device, comprising:

• a control unit arranged to determine recommended precoders and a first transmission rank to optionally use when a second communication device is transmitting data,
• a transmitting arrangement adapted to transmit feedback data to a second communication device, wherein the feedback data comprises an indication of the recommended precoders and the first transmission rank to optionally use during transmission,
• a receiving arrangement arranged to receive, from the second communication device, a confirmation message comprising a confirmation that transmission of data from the second communication device is using at least parts of each recommended precoder over frequency used and an indicator of the second transmission rank that is used. wherein the parts of each recommended precoder corresponds to a column subset of the recommended precoder and which indicator also indicates which column or number of columns of the recommended precoder column subset to use supporting the second transmission rank,
• wherein the control unit is further arranged to setup the first communication device in an operational mode to use the at least parts of each confirmed precoder and the second transmission rank during transmission to receive data from the second communication device.