Abstract: The proposal of orbital angular momentum(OAM)provides a feasible solution for the carrier required by the next-generation mobile communication technology. Its unique modular division multiplexing(MDM) method greatly increases the transmission capacity. However, with the diversification of the next-generation communication technology services, people have put forward higher requirements for bandwidth and spectrum utilization. In order to effectively improve the channel capacity and spectrum utilization of the system, an orbital angular momentum-multiple input multiple output (OAM-MIMO) multiplexing communication system combining OAM and multiple input multiple output(MIMO)technology is proposed. The OAM-MIMO system can improve channel capacity and spectrum utilization without increasing bandwidth and antenna transmit power. The system uses the Butler matrix as a phase shifter to feed the signal to a uniform circular array antenna(UCA), so that each UCA can simultaneously and independently generate a carrier wave carrying a variety of different OAM modal signal, thereby significantly improving the channel capacity of the system. The experimental results show that the channel capacity and spectrum utilization rate of the OAM-MIMO communication system are greatly improved in the macro cell and micro cell environment.

Key words: orbital angular momentum, orbital angular momentum-multiple input multiple output system, channel capacity, mode division multiplexing, uniform circular array