Solid core PCF-based mode selector for MDM-Ro-FSO transmission systems

Radio-over-free-space (Ro-FSO) technology is a combination of free-space optics (FSO) and radio over fiber. It plays a significant role in radio-frequency signal transmission in mobile network communication through high-speed optical carrier without any licensing and costly cables. Photonic crystal fibers also play a significant role to deliver data at faster rate for short haul communication. This paper, for the first time to the author’s best knowledge, utilizes mode division multiplexing in conjunction with solid core PCFs to transmit \(2 \times 2.5\) Gbps–5 GHz data over 2.5 km free-space link. The results are reported in terms of bit error rate, spatial profiles of received modes, mode spectrum of modes and eye diagrams. Furthermore, proposed PCF-MDM-Ro-FSO transmission system is also reported under the impact of atmospheric turbulences.     

Comparison of Laguerre-Gaussian and Donut modes for MDM-WDM in OFDM-Ro-FSO transmission system

Radio-over-free-space-optics (Ro-FSO) technology may pave the way towards a ubiquitous platform for seamless integration of radio and optical networks without expensive optical fiber cabling. In this paper, to increase the capacity of Ro-FSO, mode division multiplexing (MDM) of two modes has been capitalized in a three-channel WDM system spaced by 1 nm over a FSO link of 80 km, resulting in a 120 Gbps six-channel Ro-FSO system. The SNR and received power of MDM of two Laguerre-Gaussian modes LG00 and LG01 is compared with respect to MDM of two transverse donut modes. The performance of four-level quadrature amplitude modulation (QAM) for orthogonal frequency division multiplexing (OFDM) of radio subcarriers in the WDM-MDMs system is investigated for mitigation of frequency-selective fading under strong atmospheric turbulence.     

A More Precise Empirical Formula for Estimating Normalized Fog Attenuation in the Millimeter-Wave Frequency Range 30 ~ 100 GHz

At millimeter wavelengths, normalized fog attenuation (NFA) in units of (dB/km)/ (g/m³) is generally calculated by the Rayleigh approximation when working wavelengths are much larger than the average diameter of fog droplets. The calculations of the Rayleigh approximation are much less than those of Mie scattering theory, but still complex and heavy. To solve the above problem and facilitate the engineering applications of the Rayleigh approximation, a new empirical formula is discussed to estimate NFA in the frequency range 30?~?100 GHz and the fog common temperature range ?8?~?20 °C. The simulation results of the new formula are compared with those got by other three empirical formulae: the Altshuler empirical formula, the Liebe empirical formula and the Zhao empirical formula. Maximal absolute value of the relative errors (MAVRE) and Pearson correlation coefficient (PCC) indicate the largest deviation of estimated results and the fitting performance of an empirical formula, respectively. Comparisons show that the MAVRE of the new formula is only 4.482 %, which is much smaller than those of the other three formulae. The mean value of the Pearson correlation coefficients (PCCs) of the proposed formula is 0.999943, larger than those of other methods. Additionally, relative error (RE) curves of the four empirical formulae are given at four certain temperatures ?8 °C, 0 °C, 10 °C and 20 °C.     

Radio-over-free space optical space division multiplexing system using 3-core photonic crystal fiber mode group multiplexers

Wireless Networks - Radio over free space optics (Ro-FSO) systems have previously relied on the signal intensity, wavelength and polarization for multiplexing data streams in...     

Design and Optimization of Dual Band Microstrip Antenna Using Particle Swarm Optimization Technique

Dual-frequency operation of antenna has become a necessity for many applications in recent wireless communication systems, such as GPS, GSM services each operating at two different frequency bands. A new technique to achieve dual band operation from different types of microstrip antennas is presented here. An evolutionary design process using a particle swarm optimization (PSO) algorithm in conjunction with the method of moments (MoM) is employed effectively to obtain the geometric parameters of the antenna performance. In this article a PSO based on IE3D®? method is used to design dual band inset feed microstrip antenna. Maximum return loss is obtained at 2.4 GHz is ?43.95 dB and at 3.08 GHz is ?27.4 dB. Its bandwidth, of 33.54 MHz, ranges from 2.38355 GHz to 2.41709 GHz. Simulated and experimental results of the antenna are discussed.     

Location service for wireless network using improved RSS-based cellular localisation

Value-added services, especially in mobile environments, have recently become the key component of making more profit and attracting more subscribers. One of the most commonly used such service is location-based advertiser services. The main issue which should be considered in providing such services is determining the position of the mobile terminals precisely. In this paper, one pattern recognition localisation method based on the signal strength appropriated for implementing a location-based service is presented. The main aim is to introduce some practical solutions to decrease error and computational load and also eliminate the necessity of updating the database. Practical results illustrate high accuracy of this technique and its suitability to apply in such services. The mean error declines to 9.7 m and mean error corresponding to CDF = 67% and CDF = 95% are less than 11 m and 23 m, respectively. We also present a location-based advertising service, in which the customer’s interests and local time are considered, in order to enhance the efficiency and individualism of this service.     

钙硼硅系LTCC材料性能研究

在低软化点钙硼硅玻璃(LG)[r(Ca:Si)>1]中添加高软化点钙硼硅玻璃(HG)[r(Ca:Si)<1],经低温烧结制备了钙硼硅(CaO-B2O3-SiO2,CBS)LTCC材料(又称CBS微晶玻璃)。利用XRD和SEM,研究了HG的添加量及烧成温度对钙硼硅LTCC材料的物相和微观结构的影响。结果表明,HG玻璃的引入有效提高了LG的烧结性能及拓宽了烧结范围,且有效降低了该材料的相对介电常数。w(HG)为20%时,CBS微晶玻璃能够在850～910℃烧结致密;在1MHz测试频率下,相对介电常数小于7.25,介质损耗小于2×10–3。     

An Energy-Efficient Load Balancing Approach for Scientific Workflows in Fog Computing

Wireless Personal Communications - Fog computing provides cloud services at the user end. User requests are processed on the fog nodes deployed near the end-user layer in a fog computing...     

MIMO-enabled integrated MGDM–WDM distributed antenna system architecture based on plastic optical fibers for millimeter-wave communication

Design of a low-cost fiber–wireless communication architecture is desirable by network operators. Therefore, we demonstrate the transmission of \(2 \times 2\) MIMO spatial streams, each having 2 Gbps DPSK signal to two different radio access units (RAUs) in a distributed antenna system architecture. The proposed architecture employs mode group division multiplexing in combination with wavelength division multiplexing to transport RF DPSK signals centered at 10 GHz. The RF signals are used to modulate optical carriers that are centered at 1300 nm and transmitted toward the RAUs over perfluorinated graded-index plastic optical fiber. Heterodyne detection is performed at the RAUs to transmit mm-wave signals at 60 GHz to the end users. Furthermore, wireline access is also achieved at each RAU to support simplex services. A cost-efficient multiple wavelength source is generated from a single laser by employing a dual-drive Mach–Zehnder modulator. An increase in multiplexing gain is achieved using the two LP modes, LP01 and LP11, of each generated wavelength. The proposed architecture gives acceptable BER results for practical implementation.     

Quality of service‐aware approaches in fog computing

In recent years, fog computing, a novel paradigm, has emerged for location and latency‐sensitive applications. It is a powerful complement for cloud computing that enables provisioning services and resources outside the cloud near the end devices. In a fog system, the existence of several nonhomogenous devices, which are potentially mobile, led to quality of service (QoS) worries. QoS‐aware approaches are presented in various parts of the fog system, and several different QoS factors are taken into account. In spite of the importance of QoS in fog computing, no comprehensive study on QoS‐aware approaches exists in fog computing. Hence, this paper reviews the current research used to guarantee QoS in fog computing. This paper investigates the QoS‐ensuring techniques that fall into three categories: service/resource management, communication management, and application management (published between 2013 and October 2018). Regarding the selected approaches, this paper represents merits, demerits, tools, evaluation types, and QoS factors. Finally, on the basis of the reviewed studies, we suggest some open issues and challenges which are worth further studying and researching in QoS‐aware approaches in fog computing.     

Authenticated key agreement scheme for fog-driven IoT healthcare system

The convergence of cloud computing and Internet of Things (IoT) is partially due to the pragmatic need for delivering extended services to a broader user base in diverse situations. However, cloud computing has its limitation for applications requiring low-latency and high mobility, particularly in adversarial settings (e.g. battlefields). To some extent, such limitations can be mitigated in a fog computing paradigm since the latter bridges the gap between remote cloud data center and the end devices (via some fog nodes). However, fog nodes are often deployed in remote and unprotected places. This necessitates the design of security solutions for a fog-based environment. In this paper, we investigate the fog-driven IoT healthcare system, focusing only on authentication and key agreement. Specifically, we propose a three-party authenticated key agreement protocol from bilinear pairings. We introduce the security model and present the formal security proof, as well as security analysis against common attacks. We then evaluate its performance, in terms of communication and computation costs.

     

Energy Efficiency Optimization for Relay Deployment in Multi-User LTE-Advanced Networks

Wireless Personal Communications - Cooperation between the fog and cloud in fog-enabled radio access network&nbsp;could enormously improve the computation offloading services both in terms of...     

Layered data aggregation with efficient privacy preservation for fog‐assisted IIoT

The emergence of fog computing facilitates industrial Internet of Things (IIoT) to be more real‐time and efficient; in order to achieve secure and efficient data collection and applications in fog‐assisted IIoT, it usually sacrifices great computation and bandwidth resources. From the low computation and communication overheads perspective, this paper proposes a layered data aggregation scheme with efficient privacy preservation (LDA‐EPP) for fog‐assisted IIoT by integrating the Chinese remainder theorem (CRT), modified Paillier encryption, and hash chain technology. In LDA‐EPP scheme, the entire network is divided into several subareas; the fog node and cloud are responsible for local and global aggregations, respectively. Specially, the cloud is able to obtain not only the global aggregation result but also the fine‐grained aggregation results of subareas, which enables that can provide fine‐grained data services. Meanwhile, the LDA‐EPP realizes data confidentiality by the modified Paillier encryption, ensures that both outside attackers and internal semi‐trusted nodes (such as, fog node and cloud) are unable to know the privacy data of individual device, and guarantees data integrity by utilizing simply hash chain to resist tempering and polluting attacks. Moreover, the fault tolerance is also supported in our scheme; ie, even though some IIoT devices or channel links are failure, the cloud still can decrypt incomplete aggregation ciphertexts and derive expected aggregation results. Finally, the performance evaluation indicates that our proposed LDA‐EPP has less computation and communication costs.     

Seamless integration of cloud and fog networks

A way to merge cloud computing infrastructures with traditional or legacy network deployments, leveraging the best in both worlds and enabling a logically centralized control. A solution is proposed to extend existing cloud computing software stacks so they are able to manage networks outside the cloud computing infrastructure, the fog, by extending the internal, virtualized network segments. This is useful in a variety of use cases such as incremental legacy to cloud network migration, hybrid virtual/traditional networking, centralized control of existing networks, bare metal provisioning, and even offloading of advanced services from typical home gateways into the operator. Any organization can develop different ‘drivers’ to support new, specific networking equipment, not necessarily tied to a protocol or vendor, and leverage the fog network. Our conceptual solution is prototyped on top of OpenStack, including changes to the API, command‐line interface (CLI), and other mechanisms. Test results indicate that there are low penalties on latency and throughput, and provisioning times are reduced in comparison with similar maintenance operations on traditional computer networks. Copyright © 2016 John Wiley & Sons, Ltd.     

A 4.6 GHz cascade switched biasing LC–QVCO using source-body resistor

This paper presents a 4.6 GHz LC quadrature voltage-controlled oscillator (QVCO) in which the phase noise performance is improved by two methods: cascade switched biasing (CSB) technique and source-body resistor. The CSB topology can reduce the resonator loss caused by MOSFET resistance. Meanwhile, it can maintain the benefits of conventional switched biasing technique. The source-body resistors are utilized to reduce the noise contribution of the substrate related to the cross coupled MOSFETs. The proposed QVCO has been implemented in standard 0.18 μm CMOS technology. With the two methods mentioned above, it consumes 4.9 mW under 1 V voltage supply and achieves a phase noise of ?120.3 dBc/Hz at 1 MHz frequency offset from the carrier of 4.56 GHz. The figure of merit is 186.5 dBc/Hz and the tuning range is from 4.2 G to 5 GHz (17.3 %). When the QVCO operates at 0.8 V voltage supply, the power consumption is 2.88 mW and the phase noise is ?115.7 dBc/Hz at 1 MHz frequency offset from the carrier of 4.58 GHz.     

A wide-locking range ÷3 injection-locked frequency divider using concurrent injection mechanisms

A new wide locking range divide-by-3 injection-locked frequency divider (ILFD) using a standard 0.18 μm CMOS process is presented. The ILFD uses two concurrent injection mechanisms with two independent push–push circuits to extend the locking range. It is realized with a cross-coupled n-core MOS LC-tank oscillator. The core power consumption of the ILFD core is 11.496 mW. The divider’s free-running oscillation frequency is tunable from 4.32 to 3.78 GHz by tuning the varactor’s control bias, and at the incident power of 0 dBm the maximum locking range is 3 GHz (25 %), from the incident frequency 10.5 to 13.5 GHz. The operation range is 3.6 GHz (30.76 %), from 9.9 to 13.5 GHz.     

Fast-Handover Mechanism between 802.11 WLAN and 802.16 WiMax with MIH in PMIPv6

As the wireless Internet services become widely available, users become able to use various Internet services without restriction in location. In particular, the demands on wireless Internet services are becoming greater, because mobile devices that support high mobility are getting smarter. However, if a user uses various wireless networks, much limitation occurs in network setting when they move a network different each other. This is because there are few appropriate handover mechanisms to support a heterogeneous network. We propose a fast-handover for heterogeneous networks that utilizes MIH in PMIPv6 to support heterogeneous networks and to reduce the handover latency time. And the performance evaluation for the proposed method was done separately for low speed and high speed mobility. The result presented shows that the suggested method has reduced latency time by 26 % and packet losses by 90 % (Avg.).     

On the Delay of a CNTFET with Undeposited CNTs by Gate Width Adjustment

This paper deals with the performance of a Carbon Nano Tube Field Effect Transistor (CNTFET) in the presence of undeposited CNTs as defects. A simulation-based analysis of delay degradation due to different features (such as chirality and defective CNT distribution) is initially pursued. Two solutions to mitigate the change in delay are proposed; these approaches are based on adjusting the gate width of the CNTFET by lithography (and removing CNTs) as part of the fabrication process. These two methods reduce the average delay and its deviation, respectively. A probabilistic delay analysis is then presented. The performance of the proposed two adjustment methods is evaluated by considering CNT features (such as chirality and defect distribution) deterministically and probabilistically. By deterministic (probabilistic) simulation, the first method reduces on average the delay by 6.968 % (7.811 %) while the deviation is increased (decreased) by 32.444 % (9.788 %). The second method reduces deterministically (probabilistically) on average the deviation by 44.159 % (47.476 %) with 2.166 % (4.409 %) delay reduction.     

NEST: novel eMBMS scheduling technique

In order to meet the growing demand for mobile multimedia broadcast services 3GPP includes evolved multimedia broadcast and multicast (eMBMS) services in LTE systems. The high data rates, low latency and QoS provisioning makes LTE systems more suitable for mobile broadcast and multicast services than legacy wireless networks. However, the 3GPP standards has not specified any scheduling strategy for this broadcast and multicast services. In this paper, we propose a novel eMBMS scheduling technique (NEST) which focuses on reducing the average waiting time (latency) of the broadcast services offered by LTE system. This paper has twofold contributions. We proffer NEST considering two types of impatience that is user equipment (UE) departure and UE request repetition. Our proposed scheduling strategy estimates the effects originating from the departure of the mobile UEs and UE request repetition case. It intelligently combines the advantages of both flat scheduling and on-demand scheduling in such a way that the overall latency of the system is reduced. We design a suitable modeling framework to analyze the performance of the system. Simulation experiments on typical LTE systems support the performance analysis and demonstrates 10 % gains while comparing with existing eMBMS scheduling available in present LTE systems.     

Low-Power Testing of Losses in Millimeter-Wave Transmission Lines for High-Power Applications

We report the measurement of small losses in transmission line (TL) components intended for high-power millimeter-wave applications. Measurements were made using two different low-power techniques: a coherent technique using a vector network analyzer (VNA) and an incoherent technique using a radiometer. The measured loss in a 140 GHz 12.7 mm diameter TL system, consisting of 1.7 m of circular corrugated waveguide and three miter bends, is dominated by the miter bend loss. The measured loss was 0.3?±?0.1 dB per miter bend using a VNA; and 0.22?±?0.1 dB per miter bend using a radiometer. Good agreement between the two measurement techniques implies that both are useful for measuring small losses. To verify the methodology, the VNA technique was employed to measure the extremely small transmission loss in a 170 GHz ITER prototype TL system consisting of three lengths of 1 m, 63.5 mm diameter, circular corrugated waveguide and two miter bends. The measured loss of 0.05?±?0.02 dB per miter bend may be compared with the theoretical loss of 0.027 dB per miter bend. These results suggest that low-power testing of TL losses, utilizing a small, simple TL system and a VNA, is a reliable method for evaluating performance of low-loss millimeter-wave TL components intended for use in high-power applications.