Maximum Transmission Rate Research Articles

Covert Communications in D2D Underlaying Cellular Networks With Power Domain NOMA

A device-to-device (D2D) communication link is vulnerable because it is relatively easy to be compromised by adversaries due to the fact that D2D terminals are power limited nodes. This article proposes a covert communication scheme that allows D2D communication links to transmit covert signals (e.g., privacy sensitive data) to ensure a low probability of detection. We allocate transmit powers of cellular and D2D noncovert signals following a fading D2D channel to add the uncertainty in adversary's background noises. With the help of base station, cooperative power domain nonorthogonal multiple access and successive interference cancellation are used to decode covert signal. Depending on whether a D2D transmitter has the knowledge of adversary's detection threshold, we derive minimum error probability to measure the covertness performance. Furthermore, we evaluate covert throughput, which is defined as a maximum average transmission rate of covert signal, subject to a given covertness performance.

FACEST: feedback-assisted estimation of end-to-end capacity in IP-based communication networks

The end-to-end capacity, defined as the maximal transmission rate of the weakest link on the entire path between two end hosts, plays an important role in efficient network design and management. Although various capacity estimation tools have been proposed in the literature, there is still uncertainty in their accuracy and reliability when they are used in today's IP-based communication networks. The main reason for this is that all current capacity estimation tools only yield a potential candidate for an acceptable estimate, without being aware of its reliability level. In this study, we propose a new feedback-assisted end-to-end capacity estimation (FACEST) procedure that not only produces a candidate for a potentially acceptable estimate but also improves and categorizes its reliability level. Particularly, FACEST follows an ensemble estimation approach which meaningfully utilizes the correlation among the estimates produced by 3 independent capacity estimation tools; namely pathrate, DietTOPP and PBProbe. Through the correlation of 3 individual estimates, additional information about their reliability level is gained and, if necessary, the experiment is iteratively repeated with different sets of measurement parameter values until the required level of estimation accuracy is achieved, or in the worst case a kernel density estimator is applied on the collected experiment results. The proposed ensemble estimation approach has been implemented in a tool called FACEST, the performance of which has experimentally been evaluated on a three-hop testbed using a variety of tests with several scenarios and degrees of cross-traffic. For comparison purposes, individual experiments with pathrate, DietTOPP and PBProbe as well as with other alternative hybrid estimation tool from literature have also been conducted. The results reveal that FACEST outperforms individual and other hybrid capacity estimation tools and yields up to 18.29% lower estimation errors along with additional consistent information about the reliability level of the produced estimates.

An optimal bit-rate allocation algorithm to improve transmission efficiency of images in deep space exploration

As fixed compression ratio is used in traditional deep space exploration image transmission application, the same compression code rate is allocated to each image. However, since the information of each image in a space observation mission is nonuniform, the image with more information will inevitably lead to more compression distortion than the image with less information. Obviously, it's not an efficient way to transmit information in terms of data importance or overall distortion. Therefore, we proposed a combinatorial optimal bit rate allocation algorithm to improve the efficiency of image transmission in space application. Different from traditional method, the rate-distortion model of wavelet coefficients for each image in a transmission task was built, and under the overall maximum transmission rate constraint, an bit-rate optimal allocation was applied for each image to minimize the overall distortion of a batch of images. The proposed algorithm can be widely used in image compression algorithm with embedded code stream characteristics, such as JPEG2000 and SPIHT. Experimental results shows that in the range of 2.6 to 10 compression ratio, the algorithm can reduce image distortion MSB by 40%∼64% at the same overall transmission code rate, which equivalent to improvement of PSNR 3 dB to 5.4 dB.

Construction of EVA/chitosan based PEG-PCL micelles nanocomposite films with controlled release of iprodione and its application in pre-harvest treatment of grapes.

A novel nanocomposite poly(ethylene-co-vinyl acetate) (EVA) film with controlled in vitro release of iprodione (ID) was prepared. Chitosan (CS) was used as the reinforcement which enhances the water and oxygen permeability of films. ID loaded poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) (IPP) micelles were used as the drug carrier which endows the films with antifungal and controlled release ability. IPP micelles with spherical shape and uniform size were obtained, and the maximum encapsulation efficacy (EE) was 91.17±5.03% by well controlling the feeding amount of ID. Incorporation CS could improve the oxygen and moisture permeability of films, and the maximum oxygen permeability (OP) and water vapor transmission rate (WVTR) were 477.84±13.03cc/(m2·d·0.1MPa) and 8.60±0.25gm-2 d-1, respectively. After loading IPP micelles, the films showed an improved antifungal ability and temperature-sensitive drug release behavior, and were found to enhance the quality of grapes by pre-harvest spraying.

Reliable Cross-Technology Communication With Physical-Layer Acknowledgement

Cross-technology Communication (CTC) is a promising paradigm for efficient coordination and cooperation among heterogeneous wireless technologies. Recent advances in physical-layer CTC (PHY-CTC) approaches the standards' maximum transmission rate by exploring PHY-layer signal features. However, due to the lack of reliable feedback, current PHY-CTC technologies can hardly ensure transmission reliability. This paper presents RAP (Reliable Acknowledged PHY-CTC), a bidirectional CTC design with reliable PHY-CTC feedback. First, we present a novel PHY-CTC technique to efficiently establish a reliable feedback channel (e.g., ACKs or NACKs). Then, based on the feedback, we propose a joint intra-packet coding and inter-packet coding scheme to improve the reliability of CTC. Finally, we present an on-demand data (re)transmission scheme to support unicast, multicast and broadcast more efficiently. We implement and evaluate RAP on USRP N210 with IEEE 802.11g PHY (WiFi) and commodity ZigBee devices. The experiment results show RAP achieves reliable data transmission (>99% packet reception rate (PRR)) and high throughput (over 35kbps) under a wide range of scenarios.

Research on Anti-Jamming for UAV Airborne Jamming Method Based on Relay Optimization Strategy

Aiming at the new threat of Unmanned Aerial Vehicle (UAV) airborne jamming faced by wireless mobile communication networks, a communication network anti-jamming technology method based on relay optimization selection strategy is proposed. In order to achieve the maximum transmission rate of the selected relay node, a system model based on multi-arm bandit (MAB) is established. It is proved by simulation that the method of selecting the best relay node by Upper Confidence Bound (UCB) algorithm is feasible. It can avoid the nodes that are most affected by jamming and improve the anti-jamming ability of the communication system.

Analysis of the effect of cloud thickness on the performance of blue-green laser communication

When the airborne laser transmitter is located above or in the center of the cloud, the cloud will reduce the laser communication performance. In order to solve this problem, the effects of different types of clouds on laser energy attenuation, signal-to-noise ratio (SNR), maximum symbol transmission rate and bit error rate are simulated and analyzed. It is concluded that the cloud mainly causes laser energy attenuation, which affects maximum transmission rate and bit error rate, but has little effect on SNR. For communication systems with link margin greater than 18.9 dB, 4 km cloud cover is allowed on the link. The effect of cloud on the maximum communication rate and bit error rate is mainly caused by inter-symbol crosstalk caused by time extension. Cirrus has little effect on communication performance, cumulus has a great impact on communication performance, and stratus, stratocumulus, and cumulonimbus have a greater influence on the communication performance, but the differences between the three types of clouds are small and could be not be distinguished. Altostratus cloud and nimbostratus have greatest influence on communication performance, of which nimbostratus has greater influence than altostratus cloud.

Refined Asymptotics for a Block Fading Channel Under Energy Harvesting and Fixed Power Constraints

We consider a block fading additive white Gaussian noise (AWGN) channel with perfect channel state information (CSI) at the transmitter (CSIT) and the receiver (CSIR). For a given codeword length and non-vanishing average probability of error, we obtain lower and upper bounds on the maximum transmission rate. First, we derive bounds when the transmitter has a time varying peak power constraint imposed by an energy harvesting device ; such devices power many modern wireless devices. Next, using the same techniques we obtain bounds for the canonical peak and average power constraint cases. The bounds characterize the finite blocklength back-off from the channel capacity, which is in turn achieved by water-filling power allocation across time. Finally, we derive bounds on the moderate deviations constant for the block fading model. We compare the bounds numerically to bring out the efficacy of our results.

LTE Capacity Estimation with Changing Different Planning Parameters

Capacity improvement is the essential advantages in 4th generation mobile systems which called Long-Term Evolution (LTE). The maximum data transmission rate of LTE cell is 100 Mb/s in downlink direction and 50Mb/s in uplink, and this rate can be enhanced with deploying different techniques like MIMO, carrier aggregation, and many others. Because of that 4G-LTE mobile network is considered pure packet switching, there are many parameters which affect the maximum cell capacity. This study will evaluate the result of changing many parameters on the maximum mobile cell capacity. The aim is to extract the best values of the different parameters to maximize LTE mobile cell capacity.

Performance Optimization for D2D Communications With Opportunistic Relay and Physical-Layer Network Coding

In this paper, we investigate the joint signal to interference plus noise ratio (SINR) thresholds optimization and resource allocation to maximize the sum-rate of Device-to-Device (D2D) communications while still retaining the rate requirements for active cellular users (CUs), when the inactive CUs are used as opportunistic relays under three operational modes: without using network-coding (NNC), using traditional high-layer network-coding (HNC), and using physical-layer network-coding (PNC). Under Rayleigh fading, we show that, given the selections of relays, this sum-rate maximization in no-relay scheme, NNC, HNC, and PNC opportunistic relay schemes can be formulated as a mixed integer non-linear programming (MINLP), which is NP-hard in general. To find the solution to the MINLP, we propose a two-step approach to solve the problem: 1) for each possible pairing of a D2D pair and a CU, we derive the optimal SINR thresholds to obtain the maximum transmission rate of the D2D pair while satisfying the rate requirement of the CU; 2) based on the maximum transmission rates of D2D pairs for each possible pairing in the first step, we develop a bipartite-matching method to find the optimal pairing CUs for D2D pairs. Finally, according to the solution to the MINLP, we propose an iterative relay selection algorithm to find out the relays that can further improve the sum-rate of D2D communications. Extensive simulation results demonstrate that, compared with the scenario without relaying, the NNC, HNC, and PNC opportunistic relay schemes achieve a maximum performance enhancement of 106%, 138%, and 168%, respectively.

Optimum Design of Energy Harvesting Relay for Two-Way Decode-and-Forward Relay Networks Under Max–Min and Max-Sum Criterions

We study the optimum design of an energy harvesting relay for two-way decode-and-forward (DF) relay networks. In the networks, the relay harvests energy as well as decodes information using the received signal from two sources with power splitting relaying (PSR) and time switching relaying (TSR) strategies. Since the two-way relay network has two opposite traffic flows, it can be considered as a special case of multi-user systems. Applying the max–min criterion for fairness and max-sum criterion for maximum resource utilization, we optimize the operations of the energy harvesting relay. Specifically, considering the transmission rate constraints of individual hops, we derive optimum power splitting coefficients and optimum time switching coefficients, respectively, for PSR-based and TSR-based networks under both criterions, and analytically calculate the resulting maximum transmission rates. Numerical results confirm that our analyses exactly match with exhaustive search simulations. The obtained optimum coefficients are given in closed-form, therefore, they can be easily adopted in simple two-way relay networks with limited computational power such as sensor/Internet of Things (IoT) networks and can help two-way DF relay networks.

Differential-Detection Aided Large-Scale Generalized Spatial Modulation is Capable of Operating in High-Mobility Millimeter-Wave Channels

A large-scale differential-detection aided generalized spatial modulation (GSM) system is proposed, which relies on a novel Gram–Schmidt basis set and an adaptive low-complexity detector, and is evidently suitable for high-mobility millimeter-wave (mmWave) channels. We consider nonstationary time-varying mmWave channels and assume that the beam-angles remain relatively fixed, while the channel coefficients vary rapidly. In this scenario, it is a challenging task to find the accurate estimates of channel coefficients for digital beamforming, which becomes an even more severe problem, as the numbers of subarrays and subcarriers increase. Our analog-beamforming-aided nonsquare differentially detected scheme achieves a higher transmission rate than the conventional coherent multiple-input multiple-output schemes because the pilot overhead and the complex-valued feedback are eliminated. Our simulation results following the IEEE 802.11ad specifications show that the performance of our proposed nonsquare differential GSM improved upon increasing the number of subarrays, where the maximum transmission rate of 16 b/s/Hz was considered.

Dynamics of a time-delayed SIR epidemic model with logistic growth and saturated treatment

• A delayed epidemic model with logistic growth and saturated treatment is studied. • Backward bifurcation, Hopf bifurcation and Bogdanov-Takens bifurcation may occur. • Effects of varying parameters are studied in numerical simulations. • Presence of logistic growth and high treatment rate can decrease infection levels. In this paper, we incorporate a nonlinear incidence rate and a logistic growth rate into a SIR epidemic model for a vector-borne disease with incubation time delay and Holling type II saturated treatment. We compute the basic reproduction number and show that it completely determines the local stability of the disease-free equilibrium. Sufficient conditions for the existence of backward bifurcation and Hopf bifurcation are also established. Furthermore, we determine the direction and stability of the Hopf bifurcation around the endemic equilibrium by means of the center manifold theory. Our study reveals that the model admits a Bogdanov–Takens bifurcation when the time delay and the maximal disease transmission rate are varied. Numerical simulations are presented to illustrate the dynamics of the model and to study the effects caused by varying the treatment rate and delay parameters.

Diseño e implementación de un sistema de comunicaciones basado en luz visible

Introducción: El artículo es produto de la investigación: “Prototipo de un sistema de telecomunicaciones basado en luz visible”, realizado en la Universidad del Valle en el año 2018. Objetivo: El objetivo de este trabajo fue construir un prototipo funcional de un sistema de telecomunicaciones basado en luz visible a través del cual se pueda realizar el estudio de las características, elementos y comportamientos más relevantes en relación con esta tecnología. Metodología: Para estudiar el comportamiento del prototipo desarrollado, se realizaron diferentes pruebas que variaron algunas de las variables presentadas en este tipo de sistemas de telecomunicaciones. Además, el prototipo desarrollado se probó en los modos simplex y halfduplex. Conclusiones: Los resultados obtenidos al desarrollar este trabajo permitieron encontrar las características principales del prototipo, sus limitaciones, así como los elementos y variables que rigen un papel fundamental en su diseño. Originalidad: El diseño presentado propone el desarrollo de un prototipo de bajo costo, capaz de obtener los datos que se enviarán a través de la conexión a otros dispositivos a través de diferentes periféricos de comunicación o usar el ADC presente en el dispositivo de procesamiento utilizado. Limitación: Debido a los elementos de recepción utilizados en el prototipo, existe una limitación significativa en la velocidad de transmisión máxima alcanzable. Además, es importante mencionar que las condiciones en las que se implementa el prototipo pueden afectar su comportamiento, por ejemplo, los elementos que impiden la línea de visión entre los módulos de telecomunicaciones pueden detener la transmisión.

Prototype of Visible Light Communication Transceiver Using Array Photo Transistor for Real Time Digital Media Transfer

Previous research about low cost visible light communication (VLC) transceiver prototype was conducted which able to reach 98 cm, 70° and 19200 bps of transmitting distance, maximum transmission angle and transmission rate, respectively. The next prototype is built to get better performance by adding a reflector to the array phototransistor and split the power of the transceiver in order to maximize the light of the LED. This new prototype surpasses our target by reaching 134 cm of transmission distance. The system is also able to send digital multimedia files such as text, images, video in MPEG format and audio files in WAV and Mp3 format. The maximum bit rate of our prototype is 9600 bps and acceptance angle is 87°.

Portable visible light communication transmitter and receiver using core‐shell CdSe/ZnS quantum dots white light‐emitting diode

A portable visible light communication (VLC) system using core-shell CdSe/ZnS quantum dots (QDs) as light converter was presented. The absorption peak wavelength of the fabricated QDs locates at 540 nm, and the emission peak wavelength locates at 570 nm. Owning to a short fluorescent life of QDs, a wide modulation bandwidth as well as a fast data transmission rate can be achieved. A portable transmitter and receiver based on digital signal processors (DSPs) were developed and the related communication experiments were carried out. Under an optimum direct bias voltage of 2.70 V, the achieved maximum communication distance is ~ 1.3 m, and the maximum transmission rate is 267 Kb/s under the premise that the bit error ratio (BER) is <;10 -3 due to a slow turnover speed of the DSP input/output pin. At a 133 Kb/s data transmission rate, high stability was observed through measuring the BER results over 5 h at the two communication distances of 0.5 and 0.7 m.

Optimum SWIPT relaying in bidirectional non‐regenerative relay networks

The authors study the optimal design of simultaneous wireless information and power transfer relaying in bidirectional non-regenerative relay networks. They consider both power splitting relaying and time switching relaying. Since there are two opposite traffic flows between two sources, they characterise the transmission rate performance by the minimum rate of two opposite traffic flows. Specifically, they first obtain closed-form expressions for the optimum power splitting and time switching coefficients to maximise the minimum transmission rate of bidirectional non-regenerative relaying. They also derive the resulting maximum transmission rate expressions. Furthermore, they consider a minimum input radio frequency (RF) power level to turn on diodes, and derive the turn-on probability of the RF energy harvesting circuit when two channels experience independent Rayleigh fading. Numerical results confirm that the authors' analyses exactly match with simulation results and that the two relaying strategies with optimum coefficients give almost the same transmission rate performance.

Utility-Based Optimal Resource Allocation in LTE-A Networks by Hybrid ACO-TS with MFA Scheme

In mobile broadband technology, advanced long term evolution (LTE-A) networks support for a wide domain of communication services with various prerequisites. Resource allocation for each user equipment (UE) is one of the major and unique issues in wireless communication networks in which improper allocation of resource blocks (RBs) could minimize the throughput in LTE-A networks. RBs with aggregated carriers are deployed in these networks for the enhancement of bandwidth to achieve high speed and high rate data transmission. In this paper, utility-based optimal resource allocation scheme by hybrid ant colony optimization-tabu search (ACO-TS) with modified fit algorithm (MFA) is proposed. The proposed methodology involves three stages, (i) selection of UE with maximum data transmission rate, (ii) choosing RB with best channel quality indicator (CQI) index and (iii) assignment of RBs to each UE. The proposed framework is implemented in the working platform JAVA and the experimental results show that the proposed method attains better performance in terms of utilization rate and overall throughput.

Achieving Maximum Spectrum Efficiency for Full-Duplex MIMO: The Fractal Array-Element Based Self-Interference Mitigation Approach

Full-duplex (FD), where the terminal transmits and receives signals simultaneously using the same frequency-band and time-slots, has been treated as one of the potential candidate techniques to enhance the spectrum efficiency of wireless communications. To achieve the maximum transmission rate for FD multiple input multiple output (MIMO) terminal, all antennas equipped on the terminal need to not only work in FD mode, but also in multiplexing mode. However, the most challenging problem in wireless FD MIMO communications is how to efficiently mitigate the self-interference (SI). In this paper, we propose the correlation-based digital mitigation scheme, the positive-negative array-element (PNAE) block, and the fractal array-element-based mitigation approach to mitigate the SI within one antenna. Then, we integrate the FD into the multiplexing MIMO. The large SI among the different antennas and array-elements are mitigated using the proposed adaptive diagonal loading (ADL)-based beamforming SI mitigation scheme. The simulation results verify our theoretical analyses and show that our developed SI mitigation schemes can significantly reduce the SI for FD MIMO.

ЕФЕКТИВНІСТЬ ВПРОВАДЖЕННЯ ТЕХНОЛОГІЇ VDSL2 З ОПЦІЄЮ «ВЕКТОРИНГ» НА МЕРЕЖІ ПАТ «УКРТЕЛЕКОМ»

The modernization of the PJSC «Ukrtelecom» telecommunication network provides the implementation of the FTTC concept on the access network using VDSL2 technology. The efficiency of the VDSL2 technology implementation on the PJSC «Ukrtelecom» access network is determined by the transmission rate that can be provided by the transmission system (TS) which is implementing this technology. The transmission rate depends on many factors, the main of which are the subscriber line length, the cable type and the number of transmission systems that parallel operate in cable. This paper focuses on research of the dependence of the transmission rate limiting values of the transmission systems using the VDSL2 technology (VDSL2 TS) on the variation of the parameters values for different pairs of the TPPep 10x2x0.4 cable and efficiency evaluation of the implementation of the VDSL2 technology with the «vectoring» option on the PJSC «Ukrtelecom» access network. It was determined that the main factor affecting the achievable transmission rate of the VDSL2 TS without using the «vectoring» option is crosstalk, the level of which increases in proportion to the cable load coefficient by the transmission systems. The estimates of the average, maximum and minimum transmission rates of the VDSL2 TS depending on the subscriber line length, the external additive noises and the number of transmission systems that operate in parallel over TPPep 10x2x0.4 telephone cable for the VDSL2 TS without crosstalk compensation and VDSL2 TS using the «vectoring» option operation variants are provided. It was determined that the variation of the parameters values for different cable pairs significantly affects the achievable transmission rate of the VDSL2 TS operating by these pairs. The «vectoring» application efficiency in the implementation of VDSL2 technology on the PJSC «Ukrtelecom» access network is proved. It is necessary to consider near-end crosstalk in the method of calculating the transmission rate when applying the «vectoring» compensation crosstalk algorithm is determined. The possibility of the efficiency increasing of the implementation of VDSL2 technology without using the «vectoring» option by selecting pairs of the multi-pair cable with better characteristics in cases where the number of transmission systems that parallel operate in that cable does not exceed 50% is substantiated.