Architectures, Antennas and Circuits for Millimeter-wave Wireless Full-Duplex Applications

Demand for wireless network capacity keeps growing exponentially every year, as a result a 1000-fold increase in data traffic is projected over the next 10 years in the context of 5G wireless networks. Solutions for delivering the 1000-fold increase in capacity fall into three main categories: deploying smaller cells, allocating more spectrum and improving spectral efficiency of wireless systems. Smaller cells at RF frequencies (1-6GHz) are unlikely to deliver the demanded capacity increase. On the other hand, millimeter-wave spectrum (frequencies over 24GHz) offers wider, multi-GHz channel bandwidths, and therefore has gained significant research interest as one of the most promising solutions to address the data traffic demands of 5G. Another disruptive technology is full-duplex which breaks a century-old assumption in wireless communication, by simultaneous transmission and reception on the same frequency channel. In doing so, full-duplex offers many benefits for wireless networks, including an immediate spectral efficiency improvement in the physical layer. Although FD promises great benefits, self-interference from the transmitter to its own receiver poses a fundamental challenge. The self-interference can be more than a billion times stronger than the desired signal and must be suppressed below the receiver noise floor. In recent years, there has been some research efforts on fully-integrated full-duplex RF transceivers, but mm-wave fully-integrated full-duplex systems, are still in their infancy. This dissertation presents novel architectures, antenna and circuit techniques to merge two exciting technologies, mm-wave and full-duplex, which can potentially offer the dual benefits of wide bandwidths and improved spectral efficiency. To this end, two different antenna interfaces, namely a wideband reconfigurable T/R antenna pair with polarization-based antenna cancellation and an mm-wave fully-integrated magnetic-free non-reciprocal circulator, are presented. The polarization-based antenna cancellation is employed in conjunction with the RF and digital cancellation to design a 60GHz full-duplex 45nm SOI CMOS transceiver with nearly 80dB self-interference suppression. The concepts and prototypes presented in this dissertation have also profound implications for emerging applications such as vehicular radars, 5G small-cell base-stations and virtual reality

Four-element phased-array beamformers and a self-interference canceling full-duplex transciver in 130-nm SiGe for 5G applications at 26 GHz

This thesis is on the design of radio-frequency (RF) integrated front-end circuits for next generation 5G communication systems. The demand for higher data rates and lower latency in 5G networks can only be met using several new technologies including, but not limited to, mm-waves, massive-MIMO, and full-duplex. Use of mm-waves provides more bandwidth that is necessary for high data rates at the cost of increased attenuation in air. Massive-MIMO arrays are required to compensate for this increased path loss by providing beam steering and array gain. Furthermore, full duplex operation is desirable for improved spectrum efficiency and reduced latency. The difficulty of full duplex operation is the self-interference (SI) between transmit (TX) and receive (RX) paths. Conventional methods to suppress this interference utilize either bulky circulators, isolators, couplers or two separate antennas. These methods are not suitable for fully-integrated full-duplex massive-MIMO arrays. This thesis presents circuit and system level solutions to the issues summarized above, in the form of SiGe integrated circuits for 5G applications at 26 GHz. First, a full-duplex RF front-end architecture is proposed that is scalable to massive-MIMO arrays. It is based on blind, RF self-interference cancellation that is applicable to single/shared antenna front-ends. A high resolution RF vector modulator is developed, which is the key building block that empowers the full-duplex frontend architecture by achieving better than state-of-the-art 10-b monotonic phase control. This vector modulator is combined with linear-in-dB variable gain amplifiers and attenuators to realize a precision self-interference cancellation circuitry. Further, adaptive control of this SI canceler is made possible by including an on-chip low-power IQ downconverter. It correlates copies of transmitted and received signals and provides baseband/dc outputs that can be used to adaptively control the SI canceler. The solution comes at the cost of minimal additional circuitry, yet significantly eases linearity requirements of critical receiver blocks at RF/IF such as mixers and ADCs. Second, to complement the proposed full-duplex front-end architecture and to provide a more complete solution, high-performance beamformer ICs with 5-/6- b phase and 3-/4-b amplitude control capabilities are designed. Single-channel, separate transmitter and receiver beamformers are implemented targeting massive- MIMO mode of operation, and their four-channel versions are developed for phasedarray communication systems. Better than state-of-the-art noise performance is obtained in the RX beamformer channel, with a full-channel noise figure of 3.3 d

RF system model for In-band full duplex communications

Abstract. In recent years by increasing the demands for communication services various technologies are examined in order to improve the throughput and spectrum efficiency of the wireless communication systems. For improving the performance a communication network, system deficiencies such as transmitter and receiver impairments need to be removed or compensated. One way to improve the network efficiency is to employ full duplex technology. Full duplex technology doubles the network capacity compared to the case when typical frequency division duplexing (FDD) or time division duplexing (TDD) are employed in a transceiver design. Although full duplex (FD) technology has enhanced the performance of the radio communication devices, the main challenge in full duplex communication is the leaking self-interference signal from the transmitter to the receiver. Different methods are employed to suppress the self-interference signal in digital and analog domains which are categorized as passive or active cancellations. These techniques are discussed in this thesis in order to understand from which point in the propagation path, the required signal for cancellation can be taken and how those techniques are employed in digital and analog domains. For having a good self-interference cancellation (SIC) both analog and digital cancellation techniques are needed since typical digital suppression method is low complex and somewhat limited. In this thesis, first we start with discussing about the full duplex technology and the reason why it has become popular in recent years and later full duplex deficiencies are examined. In the following chapters different cancellation methods are introduced and some results are provided in Chapter 5

Full Duplex CMOS Transceiver with On-Chip Self-Interference Cancelation

abstract: The demand for the higher data rate in the wireless telecommunication is increasing rapidly. Providing higher data rate in cellular telecommunication systems is limited because of the limited physical resources such as telecommunication frequency channels. Besides, interference with the other users and self-interference signal in the receiver are the other challenges in increasing the bandwidth of the wireless telecommunication system. Full duplex wireless communication transmits and receives at the same time and the same frequency which was assumed impossible in the conventional wireless communication systems. Full duplex wireless communication, compared to the conventional wireless communication, doubles the channel efficiency and bandwidth. In addition, full duplex wireless communication system simplifies the reusing of the radio resources in small cells to eliminate the backhaul problem and simplifies the management of the spectrum. Finally, the full duplex telecommunication system reduces the costs of future wireless communication systems. The main challenge in the full duplex wireless is the self-interference signal at the receiver which is very large compared to the receiver noise floor and it degrades the receiver performance significantly. In this dissertation, different techniques for the antenna interface and self-interference cancellation are proposed for the wireless full duplex transceiver. These techniques are designed and implemented on CMOS technology. The measurement results show that the full duplex wireless is possible for the short range and cellular wireless communication systems.Dissertation/ThesisDoctoral Dissertation Engineering 201

An in-band full-duplex radio receiver with a passive vector modulator downmixer for self-interference cancellation

In-band full-duplex (FD) wireless, i.e., simultaneous transmission and reception at the same frequency, introduces strong self-interference (SI) that masks the signal to be received. This paper proposes a receiver in which a copy of the transmit signal is fed through a switched-resistor vector modulator (VM)that provides simultaneous downmixing, phase shift, and amplitude scaling and subtracts it in the analog baseband for up to 27 dB SI-cancellation. Cancelling before active baseband amplification avoids self-blocking, and highly linear mixers keep SIinduced distortion low, for a receiver SI-to-noise-and-distortionratio (SINDR) of up to 71.5 dB in 16.25 MHz BW. When combined with a two-port antenna with only 20 dB isolation, the low RX distortion theoretically allows sufficient digital cancellation for over 90 dB link budget, sufficient for short-range, low-power FD links

IC-Antenna Co-Integration for Efficient and Scalable Millimeter-Wave Antenna Interfaces

Millimeter-wave (mm-wave) technology promises high speed, high system capacity and low latency interconnects with reduced cost. Applications like high data-rate wireless links, next generation automotive sensors and security body scanners highly depend on mm-wave technology innovations. As operating frequency moves to higher mm-wave bands, shrinking antenna dimensions enable co-integration of IC and antenna. Limited transistor output power at mm-wave requires multi-element arrays to satisfy communication and radar link budgets. This dissertation presents a wafer-scale compatible IC-antenna co-integration for efficient and scalable mm-wave antenna interfaces. The proposed IC-antenna co-integration approach is demonstrated through single antenna transmitters, a concurrent dual-polarization receiver front-end and polarization-duplex transmitter/receiver front-end. Chapter 2 discusses the challenge of mm-wave IC-antenna interfaces with prior art including antenna-in-package (AiP) and on-chip antennas. The 60 GHz efficient, scalable and wafer-scale compatible IC-antenna co-integration approach is presented demonstrating wide bandwidth and large efficiency which are comparable to system-level AiP techniques at a lower cost and fabrication complexity. Chapter 3 extends the proposed approach to a concurrent 60 GHz dual-polarization receiver front-end for short-range imaging/communication applications and polarization diversity based MIMO links. Active cancellation between orthogonal polarizations is adopted to achieve ∼ 30 dB cross-polarization leakage cancellation and concurrent dual-pol reception. Chapter 4 presents a 60 GHz simultaneous transmit and receive front-end to achieve efficient polarization-duplex operation based on dual-polarization IC-antenna co-integration. Transmitter leakage is suppressed at receiver input and output by intrinsic antenna isolation and a feed-forward passive canceller. Total average self-interference cancellation >40 dB is achieved for 1.07 GHz RF bandwidth at 60 GHz in the presence of a reflector

High-Performance Multi-Antenna Wireless for 5G and Beyond

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