OFDM pre-equalizing

Abstract

For example in case of an OFDM multicarrier transmission system the transmission characteristics of subcarriers of a multicarrier transmission system using a plurality of antenna elements ( 3, 3 ′) can be adjusted. Particularly the power and the phase of the subcarriers can be adapted. To this object the subcarrier frequency channel ( 2, 2 ′) characteristics of the multicarrier transmission are detected ( 11, 11 ′) at the side of the transmitter ( 3 ). The power of each subcarrier is then distributed by a weighting unit ( 14, 14 ′). The subcarriers can be further pre-equalized ( 1, 1 ′) by dividing the subcarrier signal respectively by the sum of the squared magnitude of the frequency channel characteristics of all subcarrier signals or a frequency characteristic of the selected antenna element ( 3, 3 ′).

1 - 20 . (canceled)  
     
     
         21 . A method for transmitting OFDM signals by using a plurality of antenna elements in a wireless transmission system using a plurality of subcarriers for transmitting the OFDM signals, the method comprising the steps of: 
 detecting subcarrier frequency channel characteristics for each of the plurality of subcarriers,    changing a modulation scheme of said OFDM signals in the corresponding subcarrier channels in accordance with the detected characteristics of the corresponding subcarrier frequency channel or all subcarrier frequency channels, and    transmitting the OFDM signals by using the changed modulation scheme.    
     
     
         22 . A transmission device configured to transmit OFDM signals by using a plurality of antenna elements in a multi-carrier transmission system using a plurality of subcarriers for transmitting said OFDM signals, the transmission device comprising: 
 means for detecting the frequency subcarrier channel characteristics for each of the plurality of subcarriers,    means for changing a modulation scheme of said OFDM signals in the corresponding subcarrier channels in accordance with the detected characteristics of the corresponding subcarrier channel, and    means for transmitting the OFDM signals by using the changed modulation scheme via the plurality of antenna elements.    
     
     
         23 . Method for transmitting OFDM transmit signals using a plurality of subcarriers through a plurality of antenna elements in an OFDM multicarrier transmission system, the method comprising the steps of: 
 detecting channel response vectors corresponding to said plurality of antenna elements, wherein each of said channel response vectors has subcarrier related elements corresponding to said plurality of subcarriers, and    changing modulation scheme of said OFDM signals in the corresponding subcarrier channels in accordance with said detected channel response vectors.    
     
     
         24 . Method for transmitting OFDM signals to be transmitted by using a plurality of OFDM subcarriers in an OFDM transmission system, the method comprising the steps of: 
 generating said OFDM signals to be transmitted by using a plurality of antenna elements;    obtaining vector elements indicating channel transmission characteristics of said plurality of OFDM subcarriers at each of said plurality of antenna elements, wherein each of said vector elements is associated with one of said plurality of OFDM subcarrers, and    changing modulation scheme of said OFDM signals in the corresponding subcarrier channels in accordance with said detected channel response vectors.    
     
     
         25 . Method for transmitting OFDM signals to be transmitted by using a plurality of OFDM subcarriers in an OFDM transmission system, the method comprising the steps of: 
 generating said OFDM signals to be transmitted by using a plurality of antenna elements;    changing a modulation scheme of said OFDM signals in the corresponding subcarrier channels on the bases of channel response vectors indicating subcarrier frequency characteristics of said plurality of OFDM subcarriers at each of said plurality of antenna elements.