Methods and apparatus for generating and utilizing training codes in a space division multiplexing communication system

Abstract

A communication system is disclosed that comprises first and second communication apparatus. The first communication apparatus is provided with a transmitter for each of the transmission paths, which are capable of sending at least part of a communication signal to the second communication apparatus. The first communication apparatus moreover comprises training mechanisms for generating a training code to be sent to the second communication apparatus enabling a receiver to match a received signal to a corresponding transmitted signal. According to the invention, a training code is used with at least nearly ideal cyclic auto-correlation properties such that its cyclic auto-correction function is at least nearly zero for all cyclic shifts. The transmitter concurrently sends a training code in a mutually shifted manner, while the receiver is capable of performing a cyclic auto-correlation with respect to a received training signal.

1 . A transmitter in a communication system, comprising: 
 a memory; and    at least one processor, coupled to the memory, operative to:    generate a training code with at least nearly ideal cyclic auto-correlation properties such that its cyclic auto-correlation function is at least nearly zero for all cyclic shifts; and    transmit said training code.    
   
   
       2 . The transmitter of  claim 1 , wherein said processor is further configured to generate said cyclic shifts of a received training code and to correlate these cyclic shifts with said training code.  
   
   
       3 . The transmitter of  claim 1 , wherein the training code comprises a concatenation of the rows of a Fourier matrix.  
   
   
       4 . The transmitter of  claim 3 , wherein the training code has a length which is equal to the number of transmission paths or an integer multiple thereof.  
   
   
       5 . The transmitter of  claim 1 , wherein the training code is preceded and followed by a dummy code during operation.  
   
   
       6 . The transmitter of  claim 1 , wherein a training generator generates said training code and comprises a pre-correction filter for processing the training codes.  
   
   
       7 . The transmitter of  claim 1 , wherein a training generator generates said training code and comprises storage means for storage of one or more training codes.  
   
   
       8 . The transmitter of  claim 1 , wherein a training generator generates said training code and during operation issues a number of at least substantially identical training codes and wherein a receiving means comprises summation means to average the received training codes.  
   
   
       9 . The transmitter of  claim 1 , wherein a training generator at least during operation, issues at least substantial training codes at a substantially fixed interval and in that the reception means are provided with auto-correlation means for correlating a received signal with one or more signals received after a delay corresponding to said interval or an integer multiple thereof.  
   
   
       10 . A method for training a receiver in a communication system, comprising the steps of: 
 generating a training code with at least nearly ideal cyclic auto-correlation properties such that its cyclic auto-correlation function is at least nearly zero for all cyclic shifts; and    transmitting said training code.    
   
   
       11 . The method of  claim 10 , further comprising the steps of generating said cyclic shifts of a received training code and correlating said cyclic shifts with said training code.  
   
   
       12 . The method of  claim 10 , wherein the training code comprises a concatenation of the rows of a Fourier matrix.  
   
   
       13 . The method of  claim 12 , wherein the training code has a length that is equal to the number of transmission paths or an integer multiple thereof.  
   
   
       14 . The method of  claim 10 , wherein the training codes are preceded and followed by a dummy code during operation.  
   
   
       15 . The method of  claim 10 , wherein the training code is generated by a pre-correction filter for processing the training codes.  
   
   
       16 . The method of  claim 10 , wherein the training code is generated by a storage means for storage of one or more training codes.  
   
   
       17 . The method of  claim 10 , further comprising the steps of issuing during operation a number of at least substantially identical training codes and averaging the received training codes at a receiver.  
   
   
       18 . The method of  claim 10 , further comprising the steps of at least during operation, issuing at least substantial training codes at a substantially fixed interval and correlating a received signal with one or more signals received at a receiver after a delay corresponding to said interval or an integer multiple thereof.