Millimeter-wave and multiple-input-multiple-output (MIMO) technologies combine broad bandwidth with spatial diversity to offer a greater data rate. This paper investigates a flexible millimeter-wave sigma-delta-over-fiber based transmitter solution with digital beamforming MISO and MIMO functionality. Those functions are controlled by a central unit connecting a remote radio head with a standardized QSFP28 fiber link. The central unit generates binary encoded intermediate frequency signals using bandpass sigma-delta modulation. The QSFP28 based fiber link transmits the intermediate frequency bitstreams to the remote radio head. The remote radio head consists of a QSFP28 module, 90°hybrids, and upconverters. The remote radio head feeds four parallel, independent, coherent, and central-unit controlled 28 GHz signals to a linear array transmitting antenna. The transmitter performance is experimentally verified, demonstrating up to 800 Msym/s at an EVM/NMSE of 6.7%/-23.5 dB when tested with a 64 quadrature amplitude modulation (64-QAM) modulation scheme. Digital overthe-air beamforming MISO functionality is demonstrated up to 700 Msym/s across 1 m wireless distance. MIMO communication capabilities is demonstrated by over-the-air transmission of two independent 500 Msym/s to two spatially separated receivers. The results show that the proposed link can be used for realization of scalable, low-cost and flexible transmitter solution for emerging distributed antenna systems.
This paper compares the communication performance for co-located and emerging distributed MIMO in a typical indoor scenario. The simulations, which are verified against experimental measurement data, show that distributed MIMO offers a significantly more uniform capacity for the users. The results also show that the same user capacity can be achieved with half the number of antennas in the distributed MIMO case.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.