The TM500 test mobile allows engineers developing LTE base stations (eNodeB) or physical layers (PHY) for eNodeB to perform beamforming and 4 x 2 MIMO (transmit diversity and spatial multiplexing) measurements either in the laboratory or over the air in a trial LTE network. Beamforming and transmit diversity techniques are used in LTE networks to improve cell coverage and spectrum efficiency. Dual-layer beamforming (Rel-9) can also boost cell average throughput by allowing multiple devices, under the appropriate operating conditions, to share the same base station resources.
The TM500 test mobile is the most widely used instrument worldwide for testing the performance of base stations, and this latest software upgrade reaffirms Aeroflex’s commitment to tracking each new development in the 3GPP standards ahead of the market requirement. It also represents an important milestone on the roadmap towards LTE-Advanced new transmission modes.
Designated as Transmission (Tx) Mode 7 in LTE Release 8 (Rel-8), beamforming is very important to achieving the best performance from LTE. Although the technique is mainly applicable to Time Division Duplex (TDD) modulation, the TM500 can support beamforming in both TDD and Frequency Division Duplex (FDD) modulation schemes. MIMO is applicable to both TDD and FDD, and the TM500 supports the 4 x 2 MIMO feature when operating in either mode.
“This latest upgrade to the TM500 enables it to support all the special measurements and test features that are required to verify the beamforming and 4 x 2 MIMO performance of the eNodeB,” commented Stamatis Georgoulis, product manager at Aeroflex Test Solutions. “It also prepares the TM500 to upgrade for dual-layer Rel-9 beamforming and LTE-A features as soon as these are required.”
The TM500 test mobile with beamforming support features channel estimation based on UE-specific reference symbols (RS) or demodulation RS (DM-RS). In over-the-air tests or using a fading channel simulator, it provides data on beamforming gain by comparing cell-specific RS and DM-RS power. This allows the engineer to assess the efficiency of the weighting vectors selected by the eNodeB. Advanced eNodeB designs may utilize different weighting vectors across resource blocks (RB), and for verifying performance of these eNodeBs, the TM500 provides a per-RB channel estimation.