MIMO-OFDM Wireless Communication System

Abstract

A MIMO channel frequency response matrix is decomposed into a frequency-related par and a constant part. The constant part is independent of subcarrier index and of number of subcarriers in one symbol interval. Separated QR decomposition and either SVD or GMD is applied to the two parts. A right unitary matrix (R) is obtained from the SVD or GMD applied to the constant part. QR decomposition is applied to the constant part to generate a beamforming matrix (V). In another embodiment, a selection criterion based on a correlation matrix distance is used to select a beamforming matrix that is independent of subcarrier, the selected matrix is retrieved from a local memory and applied to a received signal. Noise covariance is computed for a noise expression which considers interference generated from the applied beamforming matrix. Data detection is performed on the received signal using the noise covariance.

1 - 8 . (canceled) 
     
     
         9 . A method, comprising:
 applying a selection criterion based on correlation matrix distance to select a beamforming matrix that is independent of a subcarrier to which the beamfoiming matrix is to be applied;   obtaining the selected beamfoii ling matrix from a local memory;   applying the obtained beamforming matrix to a received signal;   computing noise covariance for a noise expression which considers interference generated from the applied beamforming matrix; and   performing data detection on the received signal by a multiple input multiple output data detector using the noise covariance.   
     
     
         10 . The method of  claim 9 , further comprising:
 prior to receiving the signal to which the beamforming matrix is applied, sending to a transmitter of the received signal an index that identifies the selected beamforming matrix from among a plurality of beamforming matrices stored in a local memory.   
     
     
         11 . The method of any one of  claims 9 - 10 , wherein the noise expression comprises E{ñ k (n)ñ k (n) H =L k (n)L k (n) H . 
     
     
         12 . The method of  claim 11 , further comprising applying noise whitening to the received signal after computing the noise covariance. 
     
     
         13 . (canceled) 
     
     
         14 . An apparatus, comprising:
 a processor and a non-transitory memory storing a computer program which together are configured to cause the apparatus to:
 apply a selection criterion based on correlation matrix distance to select a beamforming matrix that is independent of a subcarrier to which the beamforming matrix is to be applied; 
 obtain from a local memory the selected beamforming matrix; 
 apply the obtained beamforming matrix to a received signal; and 
 compute noise covariance for a noise expression which considers interference generated from the applied beamforming matrix; and 
   a multiple input multiple output data detector configured to perform data detection on the received signal using the noise covariance.   
     
     
         15 . The apparatus of  claim 14 , further comprising a transmitter configured, prior to when the signal to which the beamforming matrix is applied is received, to send to a transmitter of the received signal an index that identifies the selected beamforming matrix from among a plurality of beamforming matrices stored in a local memory. 
     
     
         16 . The apparatus of any one of  claims 14 - 15 , wherein the noise expression comprises E{ñ k (n)ñ k (n) H =L k (n)L k (n) H . 
     
     
         17 . The apparatus of  claim 14 , wherein the detector is further configured to apply noise whitening when performing data detection on the received signal. 
     
     
         18 . (canceled)