Precoded pilot transmission for multi-user and single user mimo communications

Abstract

The disclosed method and apparatus include an WTRU-specific reference signal scheme that provides efficient precoded pilot transmission and effective channel estimation using dedicated pilot signals. The disclosed methods are efficient for both a single user (SU) and a multi user (MU) Multiple Input Multiple Output (MIMO) system.

What is claimed is: 
     
         1 . A method for transmitting data and reference symbols in a wireless orthogonal frequency division multiplexing system using a plurality of transmit antennas coupled to a plurality of antenna outputs, wherein the reference symbols facilitate channel estimation at a receiving device, the method comprising:
 for each transmitting antenna, transmitting data of a single stream, precoded reference symbols and antenna specific reference symbols,   wherein the transmitted data, precoded reference symbols and antenna specific reference symbols for each antenna output are transmitted in a same time and frequency resource,   wherein the same time and frequency resource is divided into blocks defined by subcarriers and symbol time intervals,   wherein the antenna specific reference symbols for each antenna output are not transmitted in a same block as the antenna specific reference symbols of another antenna output of the plurality of antenna outputs, and   wherein the precoded reference symbols of the single stream are not transmitted in a same block as any of the antenna specific reference symbols of any of the antenna outputs.   
     
     
         2 . The method of  claim 1 , wherein the precoded reference symbols of the single stream are derived from a scrambling code. 
     
     
         3 . The method of  claim 1 , wherein at least a portion of the reference symbols of the antenna specific reference symbols or the precoded reference symbols are derived from a constant amplitude zero autocorrelation (CAZAC) sequence. 
     
     
         4 . A method for transmitting data and reference symbols in a wireless orthogonal frequency division multiplexing system using a plurality of transmit antennas coupled to a plurality of antenna outputs, wherein the reference symbols facilitate channel estimation at a receiving device, the method comprising:
 for each transmitting antenna, transmitting data of a plurality of precoded data streams, antenna specific reference symbols and for each precoded data stream, precoded reference symbols for that data stream,   wherein the transmitted data, precoded reference symbols and antenna specific reference symbols for each antenna output are transmitted in a same time and frequency resource,   wherein the same time and frequency resource is divided into blocks defined by subcarriers and symbol time intervals,   wherein the antenna specific reference symbols for each antenna output are not transmitted in a same block as the antenna specific reference symbols of another antenna output of the plurality of antenna outputs, and   wherein for each of the plurality of precoded data streams, the precoded reference symbols are not transmitted in a same block as any of the antenna specific reference symbols of any of the antenna outputs.   
     
     
         5 . The method of  claim 4 , wherein the precoded reference symbols are derived from a scrambling code. 
     
     
         6 . The method of  claim 4 , wherein at least a portion of the reference symbols of the antenna specific reference symbols or the precoded reference symbols are derived from a constant amplitude zero autocorrelation (CAZAC) sequence. 
     
     
         7 . A method for use by a user equipment (UE) in a wireless orthogonal frequency division multiplexing (OFDM) system, wherein a base station transmits data to the UE using a plurality of antenna ports, the method comprising:
 receiving an indication of a resource allocation from a base station,   wherein the resource allocation indicates a number of subcarriers assigned to the UE for an OFDM block, and   wherein the OFDM block is divided into sub-blocks defined by subcarriers and symbol time intervals; and   determining a location of antenna specific reference symbols and precoded reference symbols in the OFDM block based on at least the resource allocation,   wherein the antenna specific reference symbols are not in a same sub-block as the antenna specific reference symbols of another antenna output of the plurality of antenna outputs, and   wherein for each received precoded data stream, precoded reference symbols of that stream are included in a plurality of sub-blocks having different symbol time intervals and same subcarriers.   
     
     
         8 . The method of  claim 7 , wherein the antenna specific reference symbols and the precoded reference symbols are used for channel estimation. 
     
     
         9 . The method of  claim 7 , wherein the precoded reference symbols of each data stream are not in a same sub-block as the antenna specific reference symbols of any of the antenna ports. 
     
     
         10 . The method of  claim 7 , wherein the precoded reference symbols of each stream are derived from a scrambling code. 
     
     
         11 . The method of  claim 7 , wherein at least a portion of the reference symbols of the antenna specific reference symbols or the precoded reference symbols are derived from a constant amplitude zero autocorrelation (CAZAC) sequence. 
     
     
         12 . The method of  claim 7 , wherein the indication of the resource allocation is received over a control channel. 
     
     
         13 . The method of  claim 12 , wherein the control channel is included in at least a first transmitted OFDM symbol of the OFDM block. 
     
     
         14 . The method of  claim 7 , wherein for each stream, sub-blocks of the same subcarriers having the precoded reference symbols of that stream have data in the OFDM block. 
     
     
         15 . The method of  claim 7 , wherein a single precoded data stream is received. 
     
     
         16 . The method of  claim 7 , wherein a plurality of precoded data streams are received.