Open loop spatial processing

Abstract

Methods and apparatus for multiple-input multiple-output (MIMO) transmissions are disclosed. A base station may precode wireless transmit/receive unit (WTRU)-specific reference signals and data that are transmitted to a WTRU using a randomly selected precoder. The precoder may be selected based on a predefined precoder selection sequence or by the base station. A different precoder may be applied to different resource blocks (RBs). In addition, a large delay cyclic delay diversity (CDD) or discrete Fourier transform (DFT) spreading may be applied on the WTRU-specific reference signals and the data. For heterogeneous deployed antennas, spatial diversity gain is achieved by dynamically scheduling resources between transmission points. A hopping scheme may be applied across the transmission points as the resources are dynamically partitioned between the transmission points. A different randomly selected precoder may be applied to each RB transmitted from a different transmission point.

1 . A method implemented at a first apparatus having transmit and receive chains and a plurality of antennas configured for multiple-input multiple-output (MIMO) communication, the method comprising:
 randomly selecting at least one precoder;   precoding data and dedicated reference signals specific to the first apparatus using the at least one precoder to generate precoded data and precoded dedicated reference signals; and   transmitting the precoded data and the precoded dedicated reference signals via the plurality of antennas to a plurality of apparatuses, each having transmit and receive chains and one or more antennas configured for MIMO communication.   
     
     
         2 . The method of  claim 1 , wherein the dedicated reference signals are demodulation reference signals. 
     
     
         3 . The method of  claim 1 , wherein precoding data and dedicated reference signals comprises precoding the dedicated reference signals differently than the data. 
     
     
         4 . The method of  claim 1 , wherein the at least one precoder is one of a predefined precoder selection sequence. 
     
     
         5 . The method of  claim 1 , further comprising:
 selecting a first precoder for precoding a first number of resource blocks (RBs); and   selecting a second precoder, different from the first precoder, for precoding a second number of RBs.   
     
     
         6 . The method of  claim 1 , wherein a precoding granularity for the dedicated reference signals is different than a precoding granularity for the data. 
     
     
         7 . A method implemented at a first apparatus having transmit and receive chains and a plurality of antennas configured for multiple-input multiple-output (MIMO) communication, the method comprising:
 randomly selecting at least one precoder;   precoding data and dedicated reference signals specific to the first apparatus using the at least one precoder to generate precoded data and precoded dedicated reference signals, wherein the data is precoded differently than the dedicated reference signals; and   transmitting the precoded data and the precoded dedicated reference signals via the plurality of antennas to at least one second apparatus having transmit and receive chains and one or more antennas configured for MIMO communication.   
     
     
         8 . The method of  claim 7 , wherein the dedicated reference signals are demodulation reference signals. 
     
     
         9 . The method of  claim 7 , wherein the at least one precoder is one of a predefined precoder selection sequence. 
     
     
         10 . The method of  claim 7 , wherein a precoding granularity for the dedicated reference signals is different than a precoding granularity for the data. 
     
     
         11 . An apparatus comprising transmit and receive chains and a plurality of antennas configured for multiple-input multiple-output (MIMO) communication, wherein:
 the transmit chain is configured to:
 randomly select at least one precoder; 
 precode data and dedicated reference signals specific to the first apparatus using the at least one precoder to generate precoded data and precoded dedicated reference signals; and 
 transmit the precoded data and the precoded dedicated reference signals via the plurality of antennas to a plurality of other apparatuses, each having transmit and receive chains and one or more antennas configured for MIMO communication. 
   
     
     
         12 . The apparatus of  claim 11 , wherein the dedicated reference signals are demodulation reference signals. 
     
     
         13 . The apparatus of  claim 11 , wherein the transmit chain is configured to precode the dedicated reference signals differently than the data. 
     
     
         14 . The apparatus of  claim 11 , wherein the at least one precoder is one of a predefined precoder selection sequence. 
     
     
         15 . The apparatus of  claim 11 , wherein the transmit chain is further configured to:
 selecting a first precoder for precoding a first number of resource blocks (RBs); and   selecting a second precoder, different from the first precoder, for precoding a second number of RBs.   
     
     
         16 . The apparatus of  claim 11 , wherein a precoding granularity for the dedicated reference signals is different than a precoding granularity for the data. 
     
     
         17 . An apparatus comprising transmit and receive chains and a plurality of antennas configured for multiple-input multiple-output (MIMO) communication, wherein:
 the transmit chain is configured to:
 randomly select at least one precoder; 
 precode data and dedicated reference signals specific to the first apparatus using the at least one precoder to generate precoded data and precoded dedicated reference signals, wherein the data is precoded differently than the dedicated reference signals; and 
 transmit the precoded data and the precoded dedicated reference signals via the plurality of antennas to at least one second apparatus having transmit and receive chains and one or more antennas configured for MIMO communication. 
   
     
     
         18 . The apparatus of  claim 17 , wherein the dedicated reference signals are demodulation reference signals. 
     
     
         19 . The apparatus of  claim 17 , wherein the at least one precoder is one of a predefined precoder selection sequence. 
     
     
         20 . The apparatus of  claim 17 , wherein a precoding granularity for the dedicated reference signals is different than a precoding granularity for the data. 
     
     
         21 . A method implemented at a first apparatus having transmit and receive chains and a plurality of antennas configured for multiple-input multiple-output (MIMO) communication, the method comprising:
 receiving channel quality feedback for each one of the plurality of transmit antennas; and   transmitting data from the plurality of antennas according to resources dynamically partitioned among the plurality of antennas based on a plurality of domains, wherein transmitting the data from the plurality of antennas comprises transmitting different layers of data from different antennas.   
     
     
         22 . The method of  claim 21 , further comprising:
 assigning each antenna of the plurality of antennas a separate channel state information (CSI) reference signal (RS) resource.   
     
     
         23 . The method of  claim 21 , further comprising:
 applying a randomly selected precoder for each resource block (RB) or resource block group (RBG) transmitted from a different antenna.   
     
     
         24 . The method of  claim 21 , wherein the plurality of domains includes time, frequency and space. 
     
     
         25 . An apparatus comprising transmit and receive chains and a plurality of antennas configured for multiple-input multiple-output (MIMO) communication, wherein:
 the receive chain is configured to receive channel quality feedback for each one of the plurality of transmit antennas; and   the transmit chain is configured to transmit different layers of data from different antennas of the plurality of antennas according to resources dynamically partitioned among the plurality of antennas based on a plurality of domains.   
     
     
         26 . The apparatus of  claim 25 , wherein each antenna of the plurality of antennas is assigned a separate channel state information (CSI) reference signal (RS) resource. 
     
     
         27 . The apparatus of  claim 25 , wherein the transmit chain is further configured to:
 apply a randomly selected precoder for each resource block (RB) or resource block group (RBG) transmitted from a different antenna.   
     
     
         28 . The apparatus of  claim 25 , wherein the plurality of domains includes time, frequency and space.