MIMO capacity enhancement beyond that of the ideal rayleigh multipath by virtue of a leaky feeder cable

摘要

The advantages of Multiple Input-Multiple Output (MIMO) wireless communication systems are known for more than a decade. The operational mechanism of a 2 × 2 MIMO system generally reminds either having cross-polarised receiver/transmitter multiport antennas in line-of-sight (LOS), or both co/cross-polarised multiport antennas in non-line-of-sight multipath environments [1]. In contrast to the aforementioned common perception, within the frame of the current paper, for the first time we realise a 2×2 co-polarised MIMO system in a LOS scenario rendering a capacity close to the ideal 2×2 MIMO system having a double capacity with respect to a LOS single input-single output (SISO) system. In this study, two wideband dipoles with different polarisations are used on the receiver side and one or two long leaky feeder cables (LFCs) are used on the transmitter side. We stress that the highlighted MIMO performance does not strictly depend on the separation between the two dipoles. Furthermore, we illustrate the properties of the channel in the foregoing MIMO system, revealing its amplitude distribution, coherence length, ergodic capacity, and distribution of the channel condition numbers. All conclusions extracted in this study are based on measurements at 1790MHz in free space.