Mechanisms for reduced density CSI-RS

A method for use in a wireless device of receiving channel state information reference signals (CSI-RS), the method comprising:

• receiving an indication of a subset of physical resource blocks (PRBs) that the wireless device should use to measure CSI-RS, each of the CSI-RS associated with an antenna port, the subset of PRBs comprising a subset of the system bandwidth, wherein the indication of the subset of PRBs that the wireless device should use to measure CSI-RS ports comprises a density value and a comb offset;
• and
• receiving CSI-RS on the indicated subset of PRBs.

A network node operable to transmit channel state information reference signals (CSI-RS), the network node comprising processing circuitry, the processing circuitry operable to:

• transmit, to a wireless device, an indication of a subset of physical resource blocks (PRBs) that the wireless device should use to measure CSI-RS, each CSI-RS associated with an antenna port, the subset of PRBs comprising a subset of the system bandwidth, wherein the indication of the subset of PRBs that the wireless device should use to measure CSI- RS comprises a density value and a comb offset;
• and
• transmit CSI-RS on the indicated subset of PRBs.

A wireless device operable to receive channel state information reference signals (CSI-RS), the wireless device comprising processing circuitry, the processing circuitry operable to:

• receive an indication of a subset of physical resource blocks (PRBs) that the wireless device should use to measure CSI-RS, each of the CSI-RS associated with an antenna port, the subset of PRBs comprising a subset of the system bandwidth, wherein the indication of the subset of PRBs that the wireless device should use to measure CSI-RS ports comprises a density value and a comb offset;
• and
• receive CSI-RS on the indicated subset of PRBs.