Title: High-Performance Multi-Antenna Wireless for 5G and Beyond
Description: Over the next decade, multi-antenna radios, including phased array and multiple-input-multiple-output (MIMO) radios, are expected to play an essential role in the next-generation of wireless networks. Phased arrays can reject spatial interferences and provide coherent beamforming gain, and MIMO technology promises to significantly enhance the system performance in the coverage, capacity, and user data rate through the beamforming or diversity/capacity gain which can substantially increase the range in wireless links, that are challenged from the transmitter (TX) power handling, receiver (RX) noise perspectives and a multi-path environment. Furthermore, the multi-user MIMO (MU-MIMO) can simultaneously serve multiple users which is vital for femtocell base stations and access points (AP). Full-duplex (FD) wireless, namely simultaneous transmission and reception at the same frequency, is an emerging technology that has gained attention due to its potential to double the data throughput, as well as provide other benefits in the higher layers such as better spectral efficiency, reducing network and feedback signaling delays, and resolving hidden-node problems to avoid collisions.

However, several challenges remain in the quest for the high-performance integrated FD radios. Transmitter power handling remains an open problem, particularly in FD radios that integrate a shared antenna interface. Secondly, FD operation must be achieved across antenna VSWR variations and a changing EM environment. Finally, FD must be extended to multi-antenna radios, including phased array and multi-input multi-output (MIMO) radios, as over the next decade, they are expected to play an essential role in the next generation of wireless networks. Multi-antenna FD operation, however, is challenged not only by the self-interference (SI) from each TX to its own RX but also cross-talk SI (CT-SI) between antennas. In this dissertation, first, a full-duplex phased array circulator-RX (circ.-RX) is proposed that achieves self-interference cancellation (SIC) through repurposing beamforming degrees of freedom (DoF) on TX and RX. Then, an FD MIMO circ.-RX is proposed that achieves SI and CT-SI cancellation (CT-SIC) through passive RF and shared-delay baseband (BB) canceller that addresses challenges associated with FD MIMO operation.

Wireless radios at millimeter-wave (mm-wave) frequencies enable the high-speed link for portable devices due to the wide-band spectrum available. Large-scale arrays are required to compensate for high path loss to form an mm-wave link. Mm-wave MIMO systems with digitization enable virtual arrays for radar, digital beamforming (DBF) for high mobility scenarios and spatial multiplexing. To preserve MIMO information, the received signal from each element in MIMO RX should be transported to ADC/DSP IC for DBF, and vice versa on the TX side. A large-scale array can be formed by tiling multiple mm-wave IC front-ends, and thus, a single-wire interface is desired between DSP IC and mm-wave ICs to reduce board routing complexity. Per-element digitization poses the challenge of handling high data-rate I/O in large-scale tiled MIMO mm-wave arrays. SERializer – DESerializer (SERDES) is traditionally being used as a high-speed link in computing systems and networks. However, SERDES results in a large area and power consumption.

In this dissertation, a 60~GHz 4-element MIMO TX with a single-wire interface is presented that de-multiplexes the baseband signal of all elements and LO reference that are frequency-domain multiplexed on a single-wire coax cable.