A method and apparatus for using demodulation reference signal (DM-RS) based channel state information (CSI) feedback in Orthogonal Frequency Division Multiplexing-multiple-input multiple-output (OFDM-MIMO) systems is disclosed. The wireless transmit/receive unit (WTRU) receives one or more resource blocks from a base station, wherein the resource blocks (RBs) include demodulating reference signals (DM-RS) and precoder information. The precoder information is sent unicast or broadcasted over a common control channel. The WTRU estimates an effective channel estimate based on the DM-RS, derives an unprecoded channel based on the effective channel and the precoder information, generates CSI feedback based on the unprecoded channel, and transmits the CSI feedback to the base station. Alternatively, the WTRU estimates an effective channel estimate based on the DM-RS, quantizes the effective channel estimate and transmits the CSI feedback to the base station.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A wireless transmit/receive unit (WTRU) comprising: at least one antenna; and a processor, operatively coupled to the antenna, configured to receive from an eNodeB information designating a first plurality of sub-bands; wherein the designated first plurality of sub-bands include a demodulation reference signal (DM-RS) for use by a plurality of WTRUs; wherein a second plurality of sub-bands include data for a single WTRU; wherein the DM-RS for the plurality of WTRUs is transmitted over an antenna port; wherein the antenna port has a selected precoding; and wherein the processor is further configured to utilize the DM-RS to estimate a channel of the designated first plurality of sub-bands; wherein the eNodeB transmits the DM-RS in the first plurality of sub-bands and the data for the single WTRU in the second plurality of sub-bands in a same transmission time interval (TTI).
2. The WTRU of claim 1 wherein the processor is further configured to receive a scrambling indication associated with the DM-RS.
3. The WTRU of claim 1 wherein a plurality of DM-RSs are used to estimate a channel for a plurality of antenna ports of the eNodeB.
4. The WTRU of claim 1 wherein the processor is further configured to receive a channel state information reference signal (CSI-RS) and to estimate a channel using the CSI-RS.
5. A method comprising: receiving, by a wireless transmit/receive unit (WTRU), information designating a first plurality of sub-bands; wherein the designated first plurality of sub-bands include a demodulation reference signal (DM-RS) for use by a plurality of WTRUs; wherein a second plurality of sub-bands include data for a single WTRU; wherein the DM-RS for the plurality of WTRUs is transmitted over an antenna port; wherein the antenna port has a selected precoding; and utilizing, by the WTRU, the DM-RS to estimate a channel of the designated first plurality of sub-bands; wherein an eNodeB transmits the DM-RS in the first plurality of sub-bands and the data for the single WTRU in the second plurality of sub-bands in a same transmission time interval (TTI).
6. The method of claim 5 further comprising receiving, by the WTRU, a scrambling indication associated with the DM-RS.
7. The method of claim 5 wherein a plurality of DM-RSs are used to estimate a channel for a plurality of antenna ports of an eNodeB.
8. The method of claim 5 further comprising receiving a channel state information reference signal (CSI-RS) and to estimate a channel using the CSI-RS.
9. An eNodeB comprising: at least one antenna port; and a processor, operatively coupled to the antenna port, configured to transmit to each of a plurality of wireless transmit/receive units (WTRUs) information designating a first plurality of sub-bands; wherein the processor is further configured to transmit a demodulation reference signal (DM-RS) in the designated first plurality of sub-bands for use by the plurality of WTRUs to estimate a channel of the designated first plurality of sub-bands; and wherein a second plurality of sub-bands include data for a single WTRU; wherein the DM-RS for the plurality of WTRUs is transmitted over an antenna port; wherein the antenna port has a selected precoding; wherein the DM-RS in the first plurality of sub-bands and the data for the single WTRU in the second plurality of sub-bands is transmitted in a same transmission time interval (TTI).
10. The eNodeB of claim 9 wherein the processor is further configured to transmit a scrambling indication associated with the DM-RS.
11. The eNodeB of claim 9 wherein the processor is further configured to transmit a channel state information reference signal (CSI-RS) to the plurality of WTRUs.
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February 24, 2014
February 23, 2016
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