Position aided open-loop passive magnetic MIMO transmission

Establishing the passive magnetic multi-input multi-output (MIMO) transmission is seldom reported and still confronts some challenging problems, such as (i) since the sensor energy is induced from the transmitted signals by the sensor coils, only one-round `ping pang access (PPA)' to the access point (AP) is permitted; (ii) Channel state information (CSI) should also be achieved within aforementioned PPA; and (iii) for more applications, both one-dimensional (1D) coil and three-dimensional (3D) coils should be considered. In this study, the magnetic positioning information is employed to solve the above problems and successfully establish the open-loop passive magnetic MIMO transmission, i.e. (i) AP sends the enquiring signal with 3D coils; (ii) sensors with 3D or 1D coils capture the signal and measure the magnetic field from AP. Then, the position and CSI from AP to the sensor are calculated. The access time-slot is determined according to the position; and (iii) sensors send out the response signals within the corresponding time-slots, i.e. according to the space-time mapping procedure. The passive massive MIMO communications can work within the successive PPAs. The proposed scheme gives a promising solution to the magnetic communication and positioning with large magnetic passive sensors in 3D space.