Hybrid Beamforming With Switches and Phase Shifters Over Frequency-Selective Channels

Abstract

In recent years, Internet of things (IoT)-enabled health monitoring wearable devices have become a trend in healthcare systems, regularly collecting vital sign data from patients and uploading them to the cloud. Through on-demand search queries, data are shared with third-party healthcare service providers (HSPs) to monitor patients' health status and provide timely diagnoses. To ensure privacy and security, patient health data should be encrypted before being uploaded to the cloud. The cloud can give search encryption services. However, current searchable encryption technologies still have problems with forward privacy security and verifiability. This paper proposes an IoT-cloud-enabled healthcare data system incorporating a searchable encryption method with forward privacy and verifiability. By designing a trapdoor permutation function, we render the resulting output indistinguishable from meaningless random data to the adversary. Thus, the adversary cannot judge the relationship between a newly inserted record and a past search token, and therefore, the system realizes forward privacy or forward secrecy. We propose a multi-keyword search verification mechanism based on a pseudo-random function (PRF). Our approach solves verifying the correctness of search results in the top-k search scenario with partial search results. A formal security analysis proves that our scheme achieves forward privacy preservation, which can help guarantee healthcare data privacy. Additionally, a performance evaluation shows that our method is efficient and effective, providing an information security system to preserve patient privacy in IoT-enabled healthcare systems.

Hybrid Precoding for Mixture Use of Phase Shifters and Switches in mmWave Massive MIMO

“…Based on the low-complexity beamformers derived with close-form expressions, quantized hybrid beamforming and channel estimation are developed [23], while the achievable sum-rates is analyzed for frequency-selective channels [24]. From an energy efficiency (EE) perspective [25], the closed-form expressions are provided to compare several promising hybrid beamforming architectures and the optimal numbers of antennas maximizing the EE are obtained, where significantly higher EE can be achieved by the combination of phase shifters and switches than the conventional phase shifter-only architectures.…”

Developing the First mmWave Fully-Connected Hybrid Beamformer With a Large Antenna Array

“…In a hybrid beamformer, a small number of RF chains are connected to a large number of antennas via a network of phase shifters [13]- [17]. Compared to analog and digital beamformers, hybrid approaches can offer a tradeoff between spatial multiplexing gain, cost, complexity, and power consumption.…”

Microstrip Lens Formulation and Analysis: A Parametric Study

“…In some instances, simultaneous beam scanning with array antennas can be accomplished. However, Typical technologies use phase shifters for antenna arrays [6-8], or array feeds for reflector systems with a switching matrix [9]. Furthermore, the phase-shift approach can be costly for these…”