RFID tag antennas with stable performance on the diverse electromagnetic mounting platforms are an integral part of the ubiquitous RFID systems. This research article presents a novel tag antenna design that facilitates the said objective. The proposed antenna consists of a modified H-shaped slot structure that ensures considerable robustness from the application environment through confining the surface current density within the antenna structure. The antenna offers a tunable bandwidth of 40 MHz within the microwave band of (2.4-2.5) GHz. The proposed tag antenna exhibits excellent response on metallic platforms of different sizes and thicknesses with an effective gain of almost four times of that in free space. Furthermore, the designed tag antenna performs adequately well on low-medium permittivity dielectrics (glass, paper, and plastic) and RF absorbers (water). The free space and on-metal performance of the proposed tag antenna are verified by testing a prototype realized on the FR4 substrate.

In this work a quad-band, planar, low-profile and compact antenna envisioned for incorporation into portable wireless devices is presented. The antenna is modeled on flexible Rogers RT/Duroid 5880 substrate of 0.127mm thickness. The proposed antenna structure consists of symmetrically placed F-shaped slits and a curved rectangular shaped ground plane with a CPW feed line. The four bands obtained for the radiator operates at the resonant frequencies 2.8, 3.9, 5.45 and 6.2 GHz with impedance bandwidths of 14%, 14.5%, 5.7%, and 5% respectively. Thus the proposed antenna supports WLAN, LTE, WiMAX, and C-band applications. The peak gain achieved for the antenna is 3.4 dB.

In this paper, we analyze the impact of buffer-aided full-duplex successive relay selection schemes with energy harvesting capability of relay nodes in amplifying and forward (AF) and decode and forward (DF) relaying environments for the Internet of Things networks. We propose to select a relay pair based on the energy harvested and signal strength at relay and destination to receive and transmit in the same time slot, respectively. Contrary to the previous relay pair selection schemes which are based on the signal strength only and cause the relay overuse problem, the proposed scheme ensures the balanced use of energy of relay nodes. The proposed relay selection scheme is implemented with the time switching (TS) and power splitting (PS)-based energy harvesting models in AF and DF relaying environments separately. Furthermore, we derive the closed-form expression of the outage probability and average throughput for both the TS and PS approaches in the DF and AF relaying modes. We compare the proposed relay selection scheme with the S-MMRS scheme and prove that the proposed scheme significantly reduces the outage probability and improves the average throughput. Furthermore, the analytical findings are reinforced with the extensive Monte Carlo simulations.

A compact, flexible antenna for wireless applications, i.e., WLAN/WiMAX/Wi-Fi, UMTS2100, C-Band, and DSRC is presented. The quad-band antenna is designed and analyzed in terms of efficiency, gain, radiation pattern, return loss, and VSWR. The optimized design consists of a CPW fed rectangular ring patch with the semi-circular ground. The cross-lines and the semicircular ground is investigated to ascertain the multiband effect. A concept of inset feed mechanism is also interpolated to enhance impedance matching. The framed antenna is examined under the bent condition as well. The reported work is an apt candidate for the proposed applications because of its high efficiency of 95% with a peak gain of 3.22 dBi along with VSWR less than 2. With stable radiation pattern and bandwidth, there is a justified concurrence between simulated and measured results.

This work ideates a novel approach for designing a QR-incorporated data encoding structure that functions as a fully-passive, chipless radio frequency identification (RFID) tag. Several concentric square-shaped resonant slots embedded strategically within a QR-patterned region constitute the tag. A functional prototype is realized over an ungrounded Duroid (R) 5880 substrate, and the same is evaluated for its electromagnetic performance. The tag performs encoding of up to 118 data bits distributed across spectral and optical domain in a compact form factor measuring 55 x 55 mm(2). Possible applications of the formulated tag include multi-layer authentication for secure access control in smart cities and connected homes.

This work proposes a compact, penta-band, slotted antenna with Defected Ground Structure (DGS). The proposed multiband resonator is intended for integration into microwave circuits and portable RF portable devices. The prototype with spurlines and DGS is designed on thin Rogers RT Duroid 5880 substrate having thickness 0.508 mm. The presented radiator is capable to cover the frequency bands 2.46-2.59 GHz, 2.99-3.78 GHz, 5.17-5.89 GHz, 6.86-7.36 GHz, 9.38-11 GHz. The impedance bandwidths of 5.24%, 23.68%, 12.8%, 7.24% and 16.08% is obtained for the covered frequency bands respectively. The antenna proposed in this work thus supports WLAN, WiMAX, ISM, LTE, Bluetooth, C-band and X-band applications. The radiator attains 4.2 dB peak gain. It is apparent from the radiation performance of the prototype, that it is an effective candidate for current and forthcoming multiband wireless applications.

A wide range of Internet of Things devices, platforms and applications have been implemented in the past decade. The variation in platforms, communication protocols and data formats of these systems creates islands of applications. Many organizations are working towards standardizing the technologies used at different layers of communication in these systems. However, interoperability still remains one of the main challenges towards realizing the grand vision of IoT. Intergration approaches proven in the existing Internet or enterprise applications are not suitable for the IoT, mainly due to the nature of the devices involved; the majority of the devices are resource constrained. To address this problem of interoperability, our work considers various types of IoT application domains, architecture of the IoT and the works of standards organizations to give a holistic abstract model of IoT. According to this model, there are three computing layers, each with a different level of interoperability needs — technical, syntactic or semantic. This work presents a Web of Virtual Things (WoVT) server that can be deployed at the middle layer of IoT (Fog layer) and Cloud to address the problem of interoperability. It exposes a REST like uniform interface for syntactic integration of devices at the bottom layer of IoT (perception layer). An additional RESTful api is used for integration with other similar WoVT servers at the Fog or the Cloud layer. The server uses a state of the art architecture to enable this integration pattern and provides means towards semantic interoperability. The analysis and evaluation of the implementation, such as performance, resource utilization and security perspectives, are presented. The simulation results demonstrate that an integrated and scalable IoT through the web of virtual things can be realized.

It remains a challenge to run Deep Learning in devices with stringent power budget in the Internet-of-Things. This paper presents a low-power accelerator for processing Convolutional Neural Networks on the embedded devices. The power reduction is realized by exploring data reuse in three different aspects, with regards to convolution, filter and input features. A systolic-like data flow is proposed and applied to rows of Processing Elements (PEs), which facilitate reusing the data during convolution. Reuse of input features and filters is achieved by arranging the PE array in a 3D tiled architecture, whose dimension is 3 x 14 x 4. Local storage within PEs is therefore reduced and only cost 17.75 kB, which is 20% of the state-of-the-art. With dedicated delay chains in each PE, this accelerator is reconfigurable to suit various parameter settings of convolutional layers. Evaluated in UMC 65 nm low leakage process, the accelerator can reach a peak performance of 84 GOPS and consume only 136 mW at 250 Mhz.

A compact, robust, chipless radio frequency identification (RFID) tag is proposed. Resonant elements patterned in a concentric fashion encode data in the spectral domain employing frequency shift encoding. The proposed tag encodes 28.25 data bits over a miniscule physical footprint of 25 x 25 mm(2). The formulated scheme is demonstrated to be viable for encoding of temporal variables. The electromagnetic performance of the presented design is investigated for different laminates: Rogers RT/duroid (R) 5880 and Taconic TLX-0. Multiple tag prototypes employing a variety of substrates are realized and evaluated for in-laboratory performance. The proposed design is compared with existing work reported in literature. Code density of 4.52 bits/cm(2) has been successfully achieved. The tag design operates from 3.07 to 10.6 GHz and is readily realizable on flexible laminates. Smart retail, intelligent packaging, adaptive ticketing, and similar time-related applications can be materialized using the proposed tag.

This work presents a compact, quad-band planar antenna intended for assimilation into flexible and conformal devices. The CPW-fed semicircular shaped prototype with rake-shaped slots is designed, realized and characterized experimentally. The frequency bands covered by the proposed radiator are centered at 2.5, 3.7, 5.5 and 8 GHz with measured impedance bandwidths of 16%, 13.5%, 11.8% and 14.63%, respectively. The proposed antenna is thus enabled to support WLAN, ISM, Bluetooth, WiMAX LTE and X-band applications. The antenna exhibits a significant gain. The radiation characteristics of the proposed radiator are measured in concave and convex bent shapes at various radii to analyze its flexibility. Performance of the antenna remains almost unaffected in the bent situation. Measurements demonstrate good coherence with simulations. The compactness and good performance of the design both in bent and unbent conditions proves it to be the better contender for future multiband conformal wireless applications.