We propose a powering scheme for tiny wearable devices attached on a cloth without individual one-to-one wires. Devices with a special connector consisting of a tack and a clutch are stuck through a special cloth embroidered with conductive threads. Physical mounting of the devices and electrical connection are integrated into a single action, i.e., just sticking the connector. Combination of microwave/high-frequency circuit technology and recent highly conductive soft fabric materials opens up a new implementation scheme for wearable sensing/display/communication systems.

Presented is a wireless wearable device aimed at continuously monitoring internal temperature a few centimeters deep in the body. A radiometer operating in the 1.4-1.427 GHz quiet band is used with a circular patch probe to measure the thermal radiation emitted by the body, which is proportional to temperature. The output is digitized and transmitted over Bluetooth by a TI CC2541, using a printed inverted-F antenna. The wearable device is powered by a 3.7V Li-Ion battery, through three buck-conversion circuits. The sensor design trades performance (continuous calibration) for simplicity to reduce size and power consumption, however validated measurement data of water temperature inside the cheek demonstrates the feasibility of radiometric internal temperature measurement in a wearable platform.

In this paper, a flexible SIW wearable sensing platform is proposed with a novel 3D printing process enabling fast-prototyping customized wearable devices. SLA 3D printing that enables the fast prototyping and customization of wearable sensing platform. Two different flexible metallization approaches are explored and realized in this paper, which is supplemental to each other and provide an excellent 3D metallization solution together. Two 3D SIW transmission lines are shown with a great flexibility and a great potential of applicability in wearable devices. A proof-of-concept microfluidics sensor based on an SIW slot waveguide antenna, is also presented in the paper with sensitivity of 1.7 MHz/Er, which can be used in the wearable sensing platforms of real-time monitoring of body fluids for Internet-of-Things and distributed healthcare. The proposed SIW-based flexible wearable devices along with the microfluidics sensors can be used in various internet-of-things applications including smart health.

Abstract — This paper presents experimental results of self-interference cancellation of a 2ⅹ2 MIMO in-band full-duplex radio front-end. The proposed RF front-end consists of two rat race coupler and four antennas network, where passive suppression is done, and four self-interference reference generator, where active cancellation is done by making identical signal with residual self-interference signal, then subtracting it from received signal. As every antenna, followed by two rat race couplers, is used for transmitting and receiving simultaneously, MIMO antenna network can be constructed maintaining its own passive suppression. Also, a new type of true time delay circuit, having high dynamic range of variable time and wideband performance, is used to be fit to arbitrary residual self-interference, after the passive suppression, and achieve wideband self-interference cancellation. Experimental results show 50-dB self-interference cancellation over 90-MHz, centered at 2.53 GHz.

A key enabler for high data rates in future wireless systems will be the usage of millimeter waves. Furthermore, Filter Bank Multi-Carrier (FBMC) with its good spectral properties has also been considered as a possible future transmission technique. However, many authors claim that multiple antennas and low-latency transmissions, two of the key requirements in 5G, cannot be efficiently employed in FBMC. This is not true in general, as we will show in this paper. We investigate FBMC transmissions over real world channels at 60 GHz and show that Alamouti’s space time block code works perfectly fine once we spread (code) symbols in time. Although it is true that spreading increases the transmission time, the overall transmission time is still very low because millimeter waves employ a high subcarrier spacing. Therefore, coded FBMC in combination with millimeter waves enables high spectral efficiency, low-latency and allows the straightforward usage of multiple antennas.

Multi-antenna transmitters based on Massive MIMO and beam-forming will be one of the 5G enabler technologies. In order to have suitable commercial architectures for these transmitters, they must be scalable, cost-effective, energy efficient and present a high-level of integration. This paper presents a technique where the circulator (bulky and expensive) is no longer required in the architecture. This paper also addresses the mutual coupling be-tween antennas as one of the main problems associated with the circulator removal and identifies the PA load impedance varia-tion, efficiency degradation, distortion generation and EVM deg-radation as severe consequences. To solve these problems, a digi-tal compensation technique is proposed and verified with meas-urements in a laboratorial setup using 6W ultra-compact 2-stages MMIC PAs. The obtained results show that it is possible to re-move the circulator and keep almost similar performance as in the single antenna operation mode.

Due to the increased demand for data rate, flexibility, and reliability of 5G cellular systems, new modulation formats need to be considered. A recently proposed scheme, Orthogonal Time Frequency Space (OTFS), offers various advantages in particular in environments with high frequency dispersion. Such environments are encountered, e.g, in mm-wave systems, both due to the higher phase noise, and the larger Doppler spreads encountered there. The current paper provides a performance evaluation of OTFS at 5G mm-wave frequencies. Comparisons with OFDM modulation show that OTFS has lower BER than OFDM in a number of situations.

Full duplex communication systems promise to double the available spectrum by enabling simultaneous transmit and receive capabilities. Receiver linearity and its effective isolation from the transmitter must be extremely large to allow detection of any desired signals in the presence of self-interference within the receiver bandwidth. Echoes from the environment may introduce additional distortion that further hinder detection. These challenges are multiplied if full duplex capability is to be achieved over wide bandwidths. This paper describes and demonstrates the performance of a novel wide band transceiver architecture for full duplex applications. The full duplex performance is agnostic to the transmitter hardware in use. Measurements demonstrate simultaneous detection of a complex communication signal and a chirp signal completely uncorrelated with the transmitted signal which delivers 45 dBm to the antenna at the same time in the same bandwidth. To the authors’ knowledge, the novel transceiver architecture demonstrate state-of-the-art full duplex operation.

Static and dynamic control of the limiting threshold in a very low-loss plasma-based microstrip power limiter is investigated in order to prevent receivers from being threatened by high-power microwave (HPM). An analytic model of the microstrip circuit is proposed to derive the influence of its design on the limiting threshold of the microwave power limiter. Experimental results are in good agreement with those expected. Finally, an original approach to allow discrete limiting threshold tunability is presented and validated experimentally.

In this paper, a novel microwave band-pass frequency selective surface based on spoof localized surface plasmons (S-LSPs) resonators is demonstrated, whose center frequency is 11.35GHz with two null points located at 8.8GHz and 11.75GHz. The new frequency selective surface is organized by replacing the conventional frequency selective surface unit cells, using S-LSPs resonators which support multipolar resonance modes. The modes of S-LSPs resonators are controlled by taking advantage of the symmetry and electromagnetic band-gap property of periodic structures; providing an interesting phenomenon: two frequency bands (located at 8.8GHz and 11.35GHz) could be respectively switched as pass or stop-band by changing the angles of incidence wave. Firstly, the single S-LSPs resonator is investigated and designed at X-band frequency range. Then, the X-band frequency selective surface prototype consisting of a 15×15 S-LSPs resonator array is demonstrated. Finally, the performance of the proposed frequency selective surface is measured.