calculation of a smallest eigen value of a frequency channel response matrix and a smallest element of a diagonal of the matrix and a ratio of the largest and smallest eigen values of the matrix application_number US 89986007 A description the invention concerns a practical time and spatial diversity combination that fits into an ofdm system the ofdm system of the invention can automatically adapt the channel variation and make trade off between time diversity and spatial diversity in an exemplary environment the data rate can be increased 1 8 times for 2 u00d7 2 configuration 2 transmitters 2 receivers which gives 80 mbps and 2 7 times for 3 u00d7 3 configuration 3 transmitters 3 receivers which gives 121 mbps within 6 mhz while keep the robustness of the system turning to the drawing fig1 shows a generic mimo and ofdm transmitter system in the figure sttd and sm are the abbreviations of space time transmitter diversity and spatial multiplexing the mimo ofdm is configured as two level adaptations as shown in fig1 namely space time diversity adaptation and coding modulation adaptation the space time diversity adaptation is determined by the carrier to interference power ratio or signal to noise power ratio information data is fed into adaptive coding modulation the modulation is multiplexed and fed into adaptive space time diversity encoding and assignment a receiver feedback to provide feedback signals to the adaptive coding of modulation multiplexer and adaptive space time diversity is also provided the multiplexed signals in the adaptive space time diversity pass through sttd sm ofdm encoders and the encoded signals transmit to associated antennas the adaptive coding and modulation includes a forward error.