tic gain control values, the estimated effective noise power, and the spatial detector used at the receive side. The exten- sion to spatial precoding techniques like CDD or unitary precoding as proposed in 3GPP-LTE [8] is fairly straightforward. The dedicated uplink control channel is protected with rate coding, a CRC, low-order modulation BPSK/QPSK, DFT precoding, and spatial diversity reception using CDD at the UE and MRC at the BS. The uplink bandwidth is limited to a 5-MHz bandwidth. This low uplink bandwidth has been selected in order to achieve a higher spectral power density. The setup allows us to compensate for the imbalance in power budget between uplink and downlink. The UE feedback rate is set to 9 kb/s. By this very basic link adaptation loop, we achieve full flexibility in active antenna numbers at each end of the link. 11.2.1.2 Transmit Mode Selection The measurement prototype supports antenna subset selection. The number of active antennas at each side of the link is varied by disconnecting one BS antenna or one UE antenna, allowing for four basic antenna setups for the downlink transmission: single input, single output (SISO); multiple input, single output (MISO); single input, multiple output (SIMO); and MIMO. A key feature of our implementation is that transmit mode selection and link adaptation are performed jointly. © 2009 by Taylor & Francis Group, LLC Early Real-Time Experiments and Field Trial Measurements In essence, the receiver performs single-stream or dual-stream mode selection. It also calculates the MCS based on achievable SINR for all transmit modes. The best com- bination of transmit mode and MCS that achieves the highest data rate is reported to the base station. This is performed for every resource block. However, a practical imple- mentation issue occurs in transmit mode selection. The transmission power loaded per stream is always fixed. This means that the radiated power from MIMO dual-stream transmission is twice that of single-stream transmission. This constraint has implic