A robust and efficient transmission technique for the LTE downlink

We present a new robust and efficient feedback and transmit strategy for multiuser MIMO downlink communication systems, termed Rate Approximation (RA), and analyze its performance. Using RA in combination with unitary beamforming the rate loss, due to rate-constrained feedback channel, remains bounded if the SNR increases. A lower bound on the performance of unitary beamforming with partial CSIT based on RA is given. Further, it is shown that the optimal multiuser multiplexing gain can be achieved. System level simulations demonstrate that the RA scheme outperforms other schemes discussed within LTE to enable multiuser MIMO functionalities.