. Also transmit/receive diversity and beam forming are techniques requiring multiple antennas at transmitter, receiver or both. While diversity and beam forming aim to improve received signal power (reliability) of a single information stream, spatial multiplexing aims to split the signal power between multiple parallel streams. Correspondingly, spatial multiplexing brings most benefits at high SINR regime while diversity and beam forming are useful at low SINR. Since in a real-world network the SINR experienced by UEs varies, practical systems implement some form of dynamic switching between multi- stream and single-stream transmission. An example of a hybrid transmission mode is the 3GPP transmission mode 8 that combines beam forming and spatial multiplexing; the details can be found in [8]. LTE Key Performance Indicator Optimization Factors Impacting Spatial Multiplexing Throughput The classical Shannon channel information capacity for single-stream communication link without modulation constraints is = log2(1+SNR) where C is the maximum achievable information capacity in bits per second per Hertz and SNR = S/N is the signal to noise ratio at output of the receiver, S is the signal power and N is the noise power. For a spatial multiplexing system the corresponding generalization of the classic Shannon formula reads as C=log2(1+SNR1)+log2(1+SNR2)+..+log2(1+SNRk) = where SNR = SKIN now denotes the SNR of the kth information substream. The SNR of a substream depends on the values of the channel impulse responses between receiver and transmitter antenna pairs and on the receiver implementation. In a closed-loop communication scheme the transmitter can use some form of precoding to improve substream SNR and thus capacity. The impulse response of a MIMO system is usually represented as an n by m matrix. For n receive ports and m transmit ports the maximum number of parallel streams is k = min(n, m); for example, a 4Tx/2Rx system can have two parallel streams. With channel fading the SNRs of the substreams also exper