MUTUAL COUPLING EFFECT ON REALISTIC MIMO TRANSMISSION

Multi-antenna transmission (multiple-input multiple-output, MIMO) allows for high data rates and improved quality of wireless transmission. Theoretically, the best performance requires independent antenna elements; however in practice, mutual coupling (MC) is an unavoidable phenomenon when the physical size of the communication device is small, leading to small interelement spacing. When two antennas are placed close to each other, irrespective of whether one or both are transmitting or receiving, some of the energy that is primarily intended for one end up at the other. Some theoretical studies showed that MC increases correlation between subchannels, resulting in less capacity [1]. Contrary to this, some other theoretical studies have shown that MC can increase the system capacity through its decorrelation effect in poor scattering environments [2]. To this end, measurement becomes the ultimate way to verify the MC effect. In this work, mutual coupling MIMO measurements have been carried out in various indoor environments. Our measurements provide a practical framework for MIMO antenna designs. The MC channel data was acquired using a MIMO-OFDM channel sounder developed at the CSIRO ICT Centre. The channel sounder is equipped with four transmitters and four receivers consisting of full RF chains, operating at 5.24 GHz. In this study three MC scenarios were considered t