A Special Open-Loop Transmit Antenna Selection Mode in the SC-FDMA Systems for 3G LTE
29 October 2007
This work investigates the open-loop transmit antenna selection (OL-TAS) modes in the uplink of the long term evolution (LTE) of 3G standard. The uplink subframe is composed of two slots based on single-carrier frequency-division multiple access (SC-FDMA) system. The conventional OL-TAS mode switches the antennas alternatively for every slot. A non-neglectable performance loss is resulted from the hardware switch of transmit antennas. To reduce the number of antenna switches, a special OL-TAS mode is proposed in this work for LTE uplink, where the antenna switch is only performed in the middle of the subframe. Thus the loss of antenna switches reduces half compared to the conventional mode. In addition, it provides more advantageous interpolation for channel estimation algorithms, since every two slots are transmitted consecutively at one antenna. Benefit from the interpolation, the special OL-TAS mode achieves remarkable performance gain, especially at high velocities.