Polarization Angle Diversity for Highly-Reliable Machine-to-Machine Radio

A radio architecture is proposed for the wireless monitoring and control of infrastructure equipment. The proposed architecture is useful for machine-to-machine communication using non line-of-sight waves that are multiply reflected by electromagnetic scatters, i.e., with equipments that is much larger than the radio. The proposed radio transmits the signal, which is expanded by orthogonal codes, on different wireless paths using different polarization directions at different times. This communication approach results in good resistance against outer interferences and unexpected interruption, which enables it to achieve highly-reliable wireless communication. We designed a prototype radio in 400MHz band. Simulation results indicate that 100kHz data could be successfully reconstructed through 46MHz coding/decoding and 93MHz modulation/demodulation. The 5x up-conversion is enabled by the band-pass delta-sigma circuit that contains digital parts in a commercial field programmable gate array. The prototype radio exhibited a carrier to noise ratio of more than 30dB.