Equalizer coefficient determination in the frequency domain for MIMO/MISO radio

Abstract

A Radio Frequency (RF) receiver includes a RF front end and a baseband processing module coupled to the RF front end that is operable to receive a time domain signal that includes multiple information signals, each having training symbols and time domain data symbols. The baseband processing module includes a channel estimator that processes the training symbols to produce respective time domain channel estimates, a Fast Fourier Transformer converts the time domain channel estimates to the frequency domain to produce frequency domain channel estimates, a weight calculator operable to produce frequency domain equalizer coefficients based upon the frequency domain channel estimates, an Inverse Fast Fourier Transformer operable to convert the frequency domain equalizer coefficients to the time domain to produce time domain equalizer coefficients, and an equalizer operable to equalize the time domain data symbols using the time domain equalizer coefficients. The RF receiver supports STTD, MISO, and MIMO operations.

1 . A method for operating a Radio Frequency (RF) receiver comprising:
 receiving a merged information signal that includes a first information signal and a second information signal, each of the first and second information signals having time domain training symbols and data symbols;   processing the first information signal time domain training symbols and the second information signal time domain training symbols to produce a first information signal time domain channel estimate and a second information signal time domain channel estimate;   converting the first information signal time domain channel estimate and the second information signal time domain channel estimate to the frequency domain to produce a first information signal frequency domain channel estimate and a second information signal frequency domain channel estimate, respectively;   producing first frequency domain equalizer coefficients and second frequency domain equalizer coefficients based upon the first information signal frequency domain channel estimate and the second information signal frequency domain channel estimate;   converting the first frequency domain equalizer coefficients and the second frequency domain equalizer coefficients to the time domain to produce first time domain equalizer coefficients and second time domain equalizer coefficients, respectively;   equalizing the merged information signal time using the first time domain equalizer coefficients to produce equalized first information signal data symbols; and   equalizing the merged information signal time using the first time domain equalizer coefficients to produce equalized second information signal data symbols.   
   
   
       2 . The method of  claim 1 , further comprising:
 despreading the equalized first information signal data symbols; and   despreading the equalized second information signal data symbols.   
   
   
       3 . The method of  claim 1 , wherein:
 the merged information signal comprises a Space Time Transmit Diversity (STTD) signal;   the first information signal data symbols and the second information signal data symbols carry common data; and   the method further comprises STTD decoding the equalized first information signal data symbols and the equalized second information signal data symbols.   
   
   
       4 . The method of  claim 1 , wherein:
 the merged information signal comprises a Space Time Transmit Diversity (STTD) signal;   the first information signal data symbols and the second information signal data symbols carry common data; and   the method further comprises:
 despreading the equalized first information signal data symbols; 
 despreading the equalized second information signal data symbols; and 
 STTD decoding the despread equalized first information signal data symbols and the despread equalized second information signal data symbols. 
   
   
   
       5 . The method of  claim 1 , wherein:
 the merged information signal comprises a Multiple Input Multiple Output (MIMO) signal; and   the first information signal data symbols and the second information signal data symbols carry differing data.   
   
   
       6 . The method of  claim 1 , wherein:
 producing the first information signal frequency domain channel estimate includes:
 cluster path processing the first information signal time domain training symbols; 
 producing the first information signal time domain channel estimate based upon the cluster path processed first information signal time domain training symbols; and 
 Fast Fourier Transforming the first information signal time domain channel estimate to produce the first information signal frequency domain channel estimate; and 
   producing the second information signal frequency domain channel estimate includes:
 cluster path processing the second information signal time domain training symbols of the second time domain signal; 
 producing the second information signal time domain channel estimate based upon the cluster path processed second information signal time domain training symbols; and 
 Fast Fourier Transforming the second information signal time domain channel estimate to produce the second information signal frequency domain channel estimate. 
   
   
   
       7 . The method of  claim 1 , wherein:
 converting the first frequency domain equalizer coefficients to the first time domain equalizer coefficients comprises:
 Inverse Fast Fourier Transforming the first frequency domain equalizer coefficients to produce the first time domain equalizer coefficients; and 
 tap ordering the first time domain equalizer coefficients; and 
   converting the second frequency domain equalizer coefficients to the second time domain equalizer coefficients comprises:
 Inverse Fast Fourier Transforming the second frequency domain equalizer coefficients to produce the second time domain equalizer coefficients; and 
 tap ordering the second time domain equalizer coefficients. 
   
   
   
       8 . The method of  claim 1 , wherein producing the first frequency domain equalizer coefficients and the second frequency domain equalizer coefficients based upon the first frequency domain channel estimate and the second frequency domain channel estimate comprises performing a Minimum Mean Squared Error (MMSE) algorithm to produce the first frequency domain equalizer coefficients and the second frequency domain equalizer coefficients. 
   
   
       9 . The method of  claim 1 , wherein the RF receiver supports wireless operations selected from the group consisting of cellular wireless communications, wireless metropolitan area network communications, wireless local area network communications, and wireless personal area network communications. 
   
   
       10 . A method for operating a Radio Frequency (RF) receiver comprising:
 receiving a merged information signal that includes a first information signal and a second information signal, each of the first and second information signals having time domain training symbols and data symbols;   for each of at least two diversity paths:
 processing the first information signal time domain training symbols and the second information signal time domain training symbols to produce a first information signal time domain channel estimate and a second information signal time domain channel estimate; 
 converting the first information signal time domain channel estimate and the second information signal time domain channel estimate to the frequency domain to produce a first information signal frequency domain channel estimate and a second information signal frequency domain channel estimate, respectively; 
 producing first frequency domain equalizer coefficients and second frequency domain equalizer coefficients based upon the first information signal frequency domain channel estimate and the second information signal frequency domain channel estimate; 
 converting the first frequency domain equalizer coefficients and the second frequency domain equalizer coefficients to the time domain to produce first time domain equalizer coefficients and second time domain equalizer coefficients, respectively; 
 equalizing the merged information signal time using the first time domain equalizer coefficients to produce equalized first information signal data symbols; and 
 equalizing the merged information signal time using the second time domain equalizer coefficients to produce equalized second information signal data symbols; 
   combining equalized first information signal data symbols from the at least two diversity paths; and   combining equalized second information signal data symbols from the at least two diversity paths.   
   
   
       11 . The method of  claim 10 , further comprising:
 despreading the combined equalized first information signal data symbols; and   despreading the combined equalized second information signal data symbols.   
   
   
       12 . The method of  claim 10 , wherein:
 the merged information signal comprises a Space Time Transmit Diversity (STTD) signal;   the first information signal data symbols and the second information signal data symbols carry common data; and   the method further comprises STTD decoding combined equalized first information signal data symbols and combined equalized second information signal data symbols   
   
   
       13 . The method of  claim 10 , wherein:
 the merged information signal comprises a Multiple Input Multiple Output (MIMO) signal; and   the first information signal data symbols and the second information signal data symbols carry differing data.   
   
   
       14 . The method of  claim 10 , wherein:
 producing the first information signal frequency domain channel estimate includes:
 cluster path processing the first information signal time domain training symbols; 
 producing the first information signal time domain channel estimate based upon the cluster path processed first information signal time domain training symbols; and 
 Fast Fourier Transforming the first information signal time domain channel estimate to produce the first information signal frequency domain channel estimate; and 
   producing the second information signal frequency domain channel estimate includes:
 cluster path processing the second information signal time domain training symbols of the second time domain signal; 
 producing the second information signal time domain channel estimate based upon the cluster path processed second information signal time domain training symbols; and 
 Fast Fourier Transforming the second information signal time domain channel estimate to produce the second information signal frequency domain channel estimate. 
   
   
   
       15 . The method of  claim 10 , wherein:
 converting the first frequency domain equalizer coefficients to the first time domain equalizer coefficients comprises:
 Inverse Fast Fourier Transforming the first frequency domain equalizer coefficients to produce the first time domain equalizer coefficients; and 
 tap ordering the first time domain equalizer coefficients; and 
   converting the second frequency domain equalizer coefficients to the second time domain equalizer coefficients comprises:
 Inverse Fast Fourier Transforming the second frequency domain equalizer coefficients to produce the second time domain equalizer coefficients; and 
 tap ordering the second time domain equalizer coefficients. 
   
   
   
       16 . The method of  claim 10 , wherein producing first frequency domain equalizer coefficients and second frequency domain equalizer coefficients based upon the first frequency domain channel estimate and the second frequency domain channel estimate comprises performing a Minimum Mean Squared Error (MMSE) algorithm to produce the first frequency domain equalizer coefficients and the second frequency domain equalizer coefficients. 
   
   
       17 . The method of  claim 10 , wherein the RF receiver supports wireless operations selected from the group consisting of cellular wireless communications, wireless metropolitan area network communications, wireless local area network communications, and wireless personal area network communications. 
   
   
       18 . A Radio Frequency (RF) receiver operable upon a merged information signal that includes a first information signal and a second information signal, each of the first and second information signals having time domain training symbols and data symbols, the RF receiver comprising:
 a RF front end; and   a baseband processing module coupled to the RF front end and comprising:
 at least one channel estimator operable to process the first information signal time domain training symbols and the second information signal time domain training symbols to produce a first information signal time domain channel estimate and a second information signal time domain channel estimate; 
 at least one Fast Fourier Transformer operable to transform the first information signal time domain channel estimate and the second information signal time domain channel estimate to the frequency domain to produce a first information signal frequency domain channel estimate and a second information signal frequency domain channel estimate, respectively; 
 a weight calculator operable to produce first frequency domain equalizer coefficients and second frequency domain equalizer coefficients based upon the first information signal frequency domain channel estimate and the second information signal frequency domain channel estimate; 
 at least one Inverse Fast Fourier Transformer operable to transform the first frequency domain equalizer coefficients and the second frequency domain equalizer coefficients to the time domain to produce first time domain equalizer coefficients and second time domain equalizer coefficients, respectively; and 
   at least one equalizer operable to equalize the merged information signal time using the first time domain equalizer coefficients to produce equalized first information signal data symbols and to equalize the merged information signal time using the first time domain equalizer coefficients to produce equalized second information signal data symbols.   
   
   
       19 . The RF receiver of  claim 18 :
 wherein the merged information signal comprises a Space Time Transmit Diversity (STTD) signal; and   further comprising an STTD decoder operable to STTD decode the equalized first information signal data symbols with the equalized second information signal data symbols.   
   
   
       20 . The RF receiver of  claim 18 , wherein in producing the first frequency domain equalizer coefficients and the second frequency domain equalizer coefficients based upon the first information signal frequency domain channel estimate and the second information signal frequency domain channel estimate, the baseband processing module is operable to perform a Minimum Mean Squared Error (MMSE) algorithm to produce the frequency domain equalizer coefficients. 
   
   
       21 . The RF receiver of  claim 18 , wherein the RF front end and the baseband processing module support wireless operations selected from the group consisting of cellular wireless communications, wireless metropolitan area network communications, wireless local area network communications, and wireless personal area network communications. 
   
   
       22 . A Radio Frequency (RF) receiver operable upon first and second merged information signals, each including a first information signal and a second information signal, each of the first and second information signals having time domain training symbols and data symbols, the RF receiver comprising:
 a RF front end; and   a baseband processing module coupled to the RF front end comprising:
 a first diversity path operable to:
 produce a first information signal time domain channel estimate from the first merged information signal and convert the first information signal time domain channel estimate to the frequency domain to produce a first information signal frequency domain channel estimate; and 
 produce a second information signal time domain channel estimate from the first merged information signal and convert the second information signal time domain channel estimate to the frequency domain to produce a second information signal frequency domain channel estimate; 
 
 a second diversity path operable to:
 produce a first information signal time domain channel estimate from the second merged information signal and convert the first information signal time domain channel estimate to the frequency domain to produce a first information signal frequency domain channel estimate; and 
 produce a second information signal time domain channel estimate from the second merged information signal and convert the second information signal time domain channel estimate to the frequency domain to produce a second information signal frequency domain channel estimate; 
 
 an equalizer weight calculation module operable to produce first frequency domain equalizer coefficients, second frequency domain equalizer coefficients, third frequency domain equalizer coefficients, and fourth frequency domain equalizer coefficients based upon the first information signal frequency domain channel estimate of the first diversity path, the second information signal frequency domain channel estimate of the first diversity path, the first information signal frequency domain channel estimate of the second diversity path, the second information signal frequency domain channel estimate of the second diversity path; 
 the first diversity path further operable to:
 convert the first frequency domain equalizer coefficients to the time domain to produce first time domain equalizer coefficients; 
 equalize the first merged information signal using the first time domain equalizer coefficients; and 
 equalize the first merged information signal using the second time domain equalizer coefficients; 
 
 the second diversity path further operable to:
 convert the second frequency domain equalizer coefficients to the time domain to produce second time domain equalizer coefficients; 
 equalize the second merged information signal using the third time domain equalizer coefficients; and 
 equalize the second merged information signal using the fourth time domain equalizer coefficients. 
 
   
   
   
       23 . The RF receiver of  claim 22 :
 wherein the first and second merged information signals comprises Space Time Transmit Diversity (STTD) signals; and   further comprising an STTD decoder operable to STTD decode data symbols produced by the first, second, third, and fourth equalizations.   
   
   
       24 . The RF receiver of  claim 22 , wherein in producing the first, second, third, and fourth frequency domain equalizer coefficients, the baseband processing module is operable to perform a Minimum Mean Squared Error (MMSE) algorithm to produce the frequency domain equalizer coefficients. 
   
   
       25 . The RF receiver of  claim 22 , wherein the RF front end and the baseband processing module support wireless operations selected from the group consisting of cellular wireless communications, wireless metropolitan area network communications, wireless local area network communications, and wireless personal area network communications.