Secrecy Throughput in Full-Duplex Multiuser MIMO Short-Packet Communications

In this letter, we consider the physical-layer security (PLS) in full-duplex (FD) multiuser multiple-input-multiple-output (MIMO) short-packet communications, where a base station (BS) transmits precoded signals for secure downlink multicast while receiving signals from uplink users. To quantify the PLS performance in the worst-case scenario, we consider the possible maximum wiretapping capability of a multi-antenna eavesdropper. Taking into account the self-interference (SI) in FD mode and the co-channel interference (CCI) from uplink to downlink, we analyse the secrecy throughput in finite blocklength regime and obtain its analytic expression, which perfectly matches asymptotic and simulation results in various scenarios. Moreover, the investigations on secrecy throughput substantiate that the FD multiuser MIMO systems outperform their half-duplex counterparts given the SI being sufficiently suppressed and the CCI being well managed

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

Blind Analog Interference Cancellation

A blind solution to analog interference cancellation is proposed for scenarios where the interference source is known at the receiver. Beyond conventional solutions, the proposed interference cancellation scheme has two merits: 1) it is implemented with analog signal processing, which is suitable for the systems with extremely strong interference and 2) it does not need any training process for adjusting parameters of analog devices, which reduces the computational complexity and time delay. For the purpose of performance evaluation, the power spectral density expressions are formulated in closed form for the desired signal and the interference components after the proposed blind interference cancellation. Furthermore, illustrative numerical results not only substantiate the outstanding performance of the proposed scheme, specifically in the case of strong interference, but also provide useful principles for the pulse shaping filter design in the transceiver