Patent ID: 8406114

Claim:
A method performed by a base station to allow a mobile device to derive a MIMO channel estimate using transmitted downlink training signals, the method comprising: transmitting first known training signals on first and third subcarrier frequencies by a first antenna during a first OFDM symbol time; transmitting second known training signals on second and fourth subcarrier frequencies by a second antenna during the first OFDM symbol time; transmitting the first known training signals on the second and fourth subcarrier frequencies by the first antenna during a second OFDM symbol time; transmitting the second known training signals on the first and third subcarrier frequencies by the second antenna during the second OFDM symbol time; transmitting the first known training signals on the first and third subcarrier frequencies by the first antenna during a third OFDM symbol time; transmitting the second known training signals on the second and fourth subcarrier frequencies by the second antenna during the third OFDM symbol time; transmitting the first known training signals on the second and fourth subcarrier frequencies by the first antenna during a fourth OFDM symbol time; and transmitting the second known training signals on the first and third subcarrier frequencies by the second antenna during the fourth OFDM symbol time, wherein the method further comprises limiting interference during the transmission of the first and second training signals by: refraining from transmitting any signals on first and third subcarrier frequencies by the second antenna during the first OFDM symbol time; refraining from transmitting any signals on second and fourth subcarrier frequencies by the first antenna during the first OFDM symbol time; refraining from transmitting any signals on the second and fourth subcarrier frequencies by the second antenna during the second OFDM symbol time; refraining from transmitting any signals on the first and third subcarrier frequencies by the first antenna during the second OFDM symbol time; refraining from transmitting any signals on the first and third subcarrier frequencies by the second antenna during the third OFDM symbol time; refraining from transmitting any signals on the second and fourth subcarrier frequencies by the first antenna during the third OFDM symbol time; refraining from transmitting any signals on the second and fourth subcarrier frequencies by the second antenna during the fourth OFDM symbol time; and refraining from transmitting any signals on the first and third subcarrier frequencies by the first antenna during the fourth OFDM symbol time.