Study on the comparison between MIMO and phased array antenna

By comparing the principle of phased array antenna (PAA) with that of MIMO (Multiple-Input Multiple-Output), it could be found that there are full of inter-contradictions between MIMO and PAA theories. According to Shannon formula, each independent Rayleigh fading channel (IRFC) is determined by the bandwidth and the carrier frequency, or spectrum. In the PAA systems, though all signals are transmitted with the same carrier frequency, some IRFCs still could be achieved by the space division multiplexing (SDM). However the IRFC constructed by each pair of the transmitting and receiving antennas in MIMO systems only could be defined as a virtual IRFC (VIRFC) since the PAA technique is not used in the systems. Moreover, these VIRFCs are almost impossible to be transformed to IRFCs in receiver. Due to the existing of VIRFCs and the non-using of PAA technique, the transmitting beam without required direction would be introduced in MIMO system. In consequence, many blind spots of radio coverage and an unreasonable wireless communication system would be formed. It would be pointed out in the paper that the definition of IRFC in MIMO theory is inappropriate, which makes the channel capacity derived by MIMO theory in mathematics is difficult to be achieved in implementations.