Low Rate Communication Research Articles

Application of hybrid SSVEP + P300 brain computer interface to control avatar movement in mobile virtual reality gaming environment

IntroductionThis research evaluated the feasibility of a hybrid SSVEP + P300 brain computer interface (BCI) for controlling the movement of an avatar in a virtual reality (VR) gaming environment (VR + BCI). Existing VR + BCI gaming environments have limitations, such as visual fatigue, a lower communication rate, minimum accuracy, and poor system comfort. Hence, there is a need for an optimized hybrid BCI system that can simultaneously evoke the strongest P300 and SSVEP potentials in the cortex. MethodsA BCI headset was coupled with a VR headset to generate a VR + BCI environment. The author developed a VR game in which the avatar’s movement is controlled using the user's cortical responses with the help of a BCI headset. Specifically designed visual stimuli were used in the proposed system to elicit the strongest possible responses from the user's brain. The proposed system also includes an auditory feedback mechanism to facilitate precise avatar movement. Results and conclusionsConventional P300 BCI and SSVEP BCI were also used to control the movements of the avatar, and their performance metrics were compared to those of the proposed system. The results demonstrated that the hybrid SSVEP + P300 BCI system was superior to the other systems for controlling avatar movement.

CC2530-Based Wireless Data Long-Distance Communication Simulation Design and Application

With the rapid development of IoT, low-power wireless networks are becoming more and more important in engineering applications. For different IoT applications, a variety of corresponding low-power wireless technologies are studied and used. Among them, ZigBee technology is widely used for wireless data long-distance communication networks that require low-power consumption, low communication rate and large capacity self-organizing networks. However, the standard ZigBee module is limited by the large noise factor of the receiver and the small radiation power of the transmitter in the module, which cannot meet the requirements of long-distance communication. In this paper, we combine RF and communication technologies to design a long-range, low-power transceiver based on ZigBee technology for wireless data long-range communication simulation design and application. Experimental results show that the model in the urban area of 500[Formula: see text]m range, the system’s packet loss rate is kept at a low 0.03 or so, and the average Rssi is kept above and below [Formula: see text][Formula: see text]dBm, which can meet the general communication requirements and achieve the expected communication effect. Under the same packet rate, the model combines the improved AODVjr and Cluster_Tree algorithms, and the packet delivery rate can reach 98.5%, which greatly extends the wireless data long-distance communication life.

A consensus-based control for precise reactive power-sharing in AC microgrids

The objective of this work is to propose a control structure for managing the energy of distributed generators connected through a meshed AC network, which supplies a set of distributed loads. To avoid the need for algorithm switching in the event of faults (such as line losses or generator disconnections), all converters operate in grid forming mode. A control strategy based on nonlinear droop control ensures optimal network operation (equal sharing of active and reactive power) even in the presence of uncertainties. Only local voltage measurements are exchanged between neighboring nodes and used by a consensus algorithm to achieve the control objectives. The design of control parameters and hardware-in-the-loop (HIL) validations are presented in the article. The findings demonstrate that a low communication rate network is sufficient to achieve the desired objectives.

Time‐varying state constrained estimators‐based command filtered quantized consensus control for nonlinear multiagent systems

AbstractThis article investigates the command filtered backstepping quantized consensus control for the time‐varying full‐state constrained nonlinear multiagent systems based on unknown system dynamics estimators (USDE). First, different from the intelligent control and the USDE‐based control methods, a novel time‐varying state constrained (TVSC)‐USDE is developed to estimate the unknown nonlinear dynamics and disturbances exactly with fewer parameters, where the states in TVSC‐USDE satisfy the state constraints requirements. The proposed TVSC‐USDE can reduce the computational burdens that caused by the online estimation of weights. Second, distinguish from current state constraints methods, by designing the integral barrier Lyapunov functions (IBLFs), the conservatism feasibility conditions are removed, which is more reasonable for the physical multiagent systems. Furthermore, the explosion of complexity (EOC) is a vital issue to tackle under the IBLFs backstepping control schemes. For this purpose, this article designs the command filters to gain the derivatives and handle the EOC problem. Further, to counterbalance the filtering errors, the error compensation signals are first developed in IBLFs‐based control method. Finally, the input quantized signals are introduced for the limited bandwidth problem in multiagent network systems, and the proposed control approach can attain consensus tracking under low communication rates and small tracking errors.

Transforming tourism into a successful intervention strategy to decrease income inequality

ABSTRACT This paper analyzes why tourism has failed to reduce income inequality worldwide, despite its success in some countries. While examining the connection between income inequality and tourism development, with an extensive data set of 110 countries for the past 25 years, this study finds that the strength of the relationship between the Gini index and other variables is not high. The low literacy rate and poor communication ability prevented the participation of the illiterate population in tourism activities that demanded higher levels of interaction with the tourists.

Parallel Coded Optical Vortex Beam Free-Space Communication Based on Single-Photon Detection

A free-space communication scheme is proposed based on orbital angular momentum (OAM) states and pulse position modulation (PPM). It can not only improve the channel capacity, but also be suitable for single-photon detection to realize the communication in the case of ultra-weak light. A parallel coding method is proposed to realize high-capacity and low bit error rate (BER) communication under high background. Theoretical simulation and experimental results show that the scheme can effectively suppress the background noise. The BER is as low as 1.27 × 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{-5}$</tex-math></inline-formula> under the condition of 16 OAM states, 16 single-photon detectors (SPDs) coincidence, and the background noise of 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{7}$</tex-math></inline-formula> counts per second. The BER performance is an order of magnitude better than the traditional PPM, and the channel capacity is increased by 12 times. This work provides an effective solution for deep space high-speed and low BER communication.

Waveform Design and Performance Analysis for Full-Duplex Integrated Sensing and Communication

Integrated sensing and communication (ISAC) is a promising technology to fully utilize the precious spectrum and hardware in wireless systems, which has attracted significant attentions recently. This paper studies ISAC for the important and challenging monostatic setup, where one single ISAC node wishes to simultaneously sense a radar target while communicating with a communication receiver. Different from most existing schemes that rely on either radar-centric half-duplex (HD) pulsed transmission with information embedding that suffers from extremely low communication rate, or communication-centric waveform that suffers from degraded sensing performance, we propose a novel full-duplex (FD) ISAC scheme that utilizes the waiting time of conventional pulsed radars to transmit communication signals. Compared to radar-centric pulsed waveform with information embedding, the proposed design can drastically increase the communication rate, and also mitigate the sensing eclipsing and near-target blind range issues, as long as the self-interference (SI) is effectively suppressed. On the other hand, compared to communication-centric ISAC waveform, the proposed design has better auto-correlation property as it preserves the classic radar waveform for sensing. Performance analysis is developed by taking into account the residual SI, in terms of the probability of detection and ambiguity function for sensing, as well as the spectrum efficiency for communication. Numerical results are provided to show the significant performance gain of our proposed design over benchmark schemes.

Event-Based Distributed Frequency Control in Harsh Communication Conditions

In this article, distributed control methods are widely applied in the operation of distributed generators (DGs) in modern power grids. As distributed control, the control operation depends greatly on information exchange among neighboring distributed controllers, where harsh communication conditions (e.g., limited communication rates and accidental communication failures) may cause significant performance deterioration. Therefore, it is necessary to investigate distributed control of DGs under imperfect communication conditions in practical systems. This article proposes an event-based distributed DG frequency control strategy. By introducing an event-based update mechanism for real-time DG data measurements and the communication topology, the adaptability of the control strategy to low communication rates and communication failures is significantly enhanced. Besides, the above-mentioned nonideal communication conditions, the proposed control also shows high adaptability to communication delays. Furthermore, an optimal design method of the control parameters is developed, which ensures proper steady-state performance and optimizes the dynamic performance of the proposed control. Simulations based on MATLAB/Simulink and hardware experimental validations using dSPACE under various conditions verify the effectiveness of the proposed control.

Research on Practical Byzantine Fault Tolerant Algorithm Based on Trust Mechanism

&lt;p&gt;The consensus algorithm is one of the core technologies of the blockchain, which determines how the nodes in the blockchain network reach a consensus and enable them to jointly maintain a piece of data. This paper focuses on the Practical Byzantine Fault Tolerant Algorithm (PBFT Algorithm), and proposes a Practical Byzantine Fault Tolerant Algorithm based on Trust Mechanism (TM-PBFT Algorithm) to solve the problems of its low fault-tolerant rate and high communication cost. This algorithm supports voting for trusted nodes before the consensus cycle starts. In order to make nodes actively vote and vote for reliable nodes, this paper models the trust degree of nodes. In addition, the time factor is added to the Shapley value to design a new reward and punishment scheme, which makes the distribution of income of each node more reasonable and further encourages nodes to vote for reliable nodes. As the system runs for a long time, the probability of malicious nodes becoming master nodes decreases. Finally, a comparison experiment between the proposed algorithm and the PBFT algorithm shows that the fault tolerance and throughput of the TM-PBFT algorithm are higher than that of the PBFT algorithm, and the communication bandwidth overhead is lower than that of the PBFT algorithm.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

AI-Empowered Propagation Prediction and Optimization for Reconfigurable Wireless Networks

Vehicular ad-hoc network (VANET) is one of the most important components to realizing intelligent connected vehicles, which is a high-commercial-value vertical application of the fifth-generation (5G) mobile communication system and beyond communications. VANET requires both ultrareliable low latency and high-data rate communications. In order to evolve towards the reconfigurable wireless networks (RWNs), the 5G mobile communication system is expected to adapt the key parameters of its radio nodes rapidly. However, the current propagation prediction approaches are difficult to balance accuracy and efficiency, which makes the current network unable to perform autonomous optimization agilely. In order to break through this bottleneck, an accurate and efficient propagation prediction and optimization method empowered by artificial intelligence (AI) is proposed in this paper. Initially, a path loss model based on a multilayer perception neural network is established at 2.6 GHz for three base stations in an urban environment. Not like empirical models using environment types or deterministic models employing three-dimensional environment models, this AI-empowered model explores the environment feature by introducing interference clutters. This critical innovation makes the proposed model so accurate as ray tracing but much more efficient. Then, this validated model is utilized to realize a coverage prediction for 20 base stations only within 1 minute. Afterward, key parameters of these base stations, such as transmission power, elevation, and azimuth angles of antennas, are optimized using simulated annealing. This whole methodology paves the way for evolving the current 5G network to RWNs.

Remote English Teaching Resource Sharing Based on Internet O2O Model

Aiming at the problems of low success rate, delay, and high communication cost in distance English teaching resource sharing, this paper puts forward a method of distance English teaching resource sharing based on Internet O2O mode. Based on the model of distance English teaching resource sharing, this paper designs four processes: query, reply, resource substitution, and resource sharing optimization. Experimental results show that the proposed method can achieve high success rate of resource sharing, low latency, communication cost, and high transmission efficiency. Therefore, it is an effective method.

Design of DCO-OFDM System for VLC on Chip at the Register-Transfer Level

This paper reports a System-on-Chip (SoC) architecture design for the DC-biased optical OFDM (DCO-OFDM) Visible Light Communication (VLC) transceiver. The proposed SoC comprises several Digital Signal Processing (DSP) blocks, i.e., Fast Fourier Transform (FFT), Convolutional Encoder (CE), Viterbi Decoder, Quadrature Phase-Shift Keying (QPSK) Modulator/Demodulator, Interleaver/Deinterleaver, and Synchronizer. System was designed through the combination of two Intellectual Property (IP) types: designing IP from the scratch (custom-based IP) and employing available core accelerator IP served by the third party, which is Xilinx library (reuse-based IP). All DSP blocks were targeted for the FPGA development board (Xilinx Zynq SoC 7000), then combined with the ARM microprocessor. In this study, ARM microprocessors were used for various tasks, i.e., scheduling process, on-chip memory as a temporary data storage function, Analog-to-Digital Converter (A/D), Digital-to-Analog Converter (D/A), and Ethernet module as communication medium between SoCs and personal computer (PC). Testing was carried out on the Register Transfer Level (RTL) for hardware (H/W) and software (S/W) models implemented on ARM microprocessors. The system performances were measured through the point-to-point data communication scenarios between a PC transmitter and PC receiver. A 77 kbps of data communication speed and 2.9 ms of data processing latency were obtained using 100 MHz clock speed. The VLC on-chip was successfully demonstrated in RTL phase. This system is suitable for a low-rate communication system application, generally for joint VLC and Internet-things (IoT) technology, (then called as VLC/IoT).

Design of Single-lamp Monitoring System for Airfield Lighting Based on Broadband Power Line Carrier Communication

Considering the problems of low communication rate and large communication delay of the traditional single-lamp monitoring system for airfield lighting based on narrow-band power line carrier communication technology, a solution of single-lamp monitoring system for airfield lighting based on broadband power carrier communication technology is proposed. Firstly, this paper has made a comparison of advantages and disadvantages between narrow-band power line carrier communication technology and broadband power line carrier communication technology, and briefed the problems faced by traditional single-lamp monitoring system based on narrow-band power line carrier communication. Taking technical characteristics into consideration, broadband power line carrier communication technology is selected for the development of a new single-lamp monitoring system for airfield lighting. Secondly, this paper articulated the design and development process of new airfield lighting single-lamp monitoring system based on broadband power line carrier communication technology, from the formulation of the overall architecture scheme of the system to the realization of local convergent equipment, and focused on the analysis of hardware and software development process of single-lamp monitoring module. Finally, this paper set up a test environment, and verified the performance index by experiments. The test results show that the system meets the design index requirements, can improve the performance of the single-lamp monitoring system for airfield lighting, effectively solves the problems faced by the traditional system, and can further meet the needs of the airport for airfield lighting monitoring and control.

Compound Adaptive Fuzzy Quantized Control for Quadrotor and Its Experimental Verification.

This article aims to realize a precise position and attitude tracking control for the quadrotor using a proposed fuzzy approximator-based compound adaptive fuzzy quantized control scheme. In the control scheme, a quantized output-feedback control for position tracking and a state-feedback quantized control for attitude trajectory tracking are combined to deal with the underactuated and strong coupling problems of the quadrotor. The main contributions are: 1) the adaptive fuzzy quantized control is realized, then the strong nonlinearities caused by the quantizer are effectively mitigated, which implies that the control precision can be improved when a low communication rate is required in the real-time control system of quadrotor; 2) by applying the adaptive fuzzy dynamic surface control (DSC) technique to the underactuated quadrotor control system, the "explosion of complexity" problem in the backstepping method is overcome and the L∞ tracking performance is achieved with the proposed initializing technique inspired by Zhang et al. This guarantees that the attitude signals promptly converge to the desired trajectories, then the underactuated problem of the quadrotor is overcome by solving the designed adaptive fuzzy-quantized control equations; and 3) the experiments on the platform of the Quanser Qball-X4 quadrotor are conducted and the effectiveness of the proposed control scheme is validated.

WITHDRAWN: Performance analysis of VoIP codecs in interactive streaming data environment

Voice over Internet Protocol (VoIP) is a novel interactive telecommunication equipment. A main challenge of telecom engineering is maintaining quality. VoIP suggests shared, cooperative and quality transactions in the form of communications over the internet. VoIP normally contracts from traditional and conventional circuit based networks in the form of low rate communication. Real time voice data transmission is very difficult when compare with ordinary text data transmission. The VoIP transmission faces lot of inconvenience. It suffers from packet loss, low quality, jitter, delay and delivery. These parameters influence and degrades the performance. The codec plays major role in VoIP transmission. This paper reports the elementary functionalities of VoIP, coder, decoder functioning in the form of quality output, the broadcast technology, and set up connections of VoIP, advantages, applications and forthcoming crazes of VoIP.

A Compressed Sensing Method for Joint Radar and Communication System Based on OFDM-IM Signal

Considering the problems of low communication rate and poor reliability of Orthogonal Frequency Division Multiplexing (OFDM) signals in joint Radar and Communication (RadCom) system, a subcarrier Index Modulation (IM) based OFDM RadCom signal scheme (OFDM-IM) and a corresponding radar signal processing algorithm based on Compressed Sensing (CS) are proposed in this paper. In the scheme, IM modulation is adopted at the transmitting end to enhance the communication quality of OFDM signal, CS technology is adopted at the radar receiving end to obtain the range-velocity 2-D super resolution image of radar targets, and the method of rapid piecewise reconstruction and second phase-coherent accumulation are further adopted to reduce the computational complexity of the algorithm. Simulation results show that, compared with the traditional algorithm, this method can significantly improve the processing performance of OFDM-IM RadCom signal and realize ultra-low side lobe in distance, which means the proposed scheme is able to enhance the performance of radar and communication in the same time.

Dynamic Focusing of Large Arrays for Wireless Power Transfer and Beyond

We present architectures, circuits, and algorithms for dynamic 3-D lensing and focusing of electromagnetic power in radiative near- and far-field regions by arrays that can be arbitrary and nonuniform. They can benefit applications such as wireless power transfer at a distance (WPT-AD), volumetric sensing and imaging, high-throughput communications, and optical phased arrays. Theoretical limits on system performance are calculated. An adaptive algorithm focuses the power at the receiver(s) without prior knowledge of its location(s). It uses orthogonal bases to change the phases of multiple elements simultaneously to enhance the dynamic range. One class of such 2-D orthogonal and pseudo-orthogonal masks is constructed using the Hadamard and pseudo-Hadamard matrices. Generation and recovery units (GU and RU) work collaboratively to focus energy quickly and reliably with no need for factory calibration. Orthogonality enables batch processing in high-latency and low-rate communication settings. Secondary vector-based calculations allow instantaneous refocusing at different locations using element-wise calculations. An emulator enables further evaluation of the system. We demonstrate modular WPT-AD GUs of up to 400 elements utilizing arrays of 65-nm CMOS ICs to focus power on RUs that convert the RF power to dc. Each RFIC synthesizes 16 independently phase-controlled RF outputs around 10 GHz from a common single low-frequency reference. Detailed measurements demonstrate the feasibility and effectiveness of RF lensing techniques presented in this article. More than 2 W of dc power can be recovered through a wireless transfer at distances greater than 1 m. The system can dynamically project power at various angles and at distances greater than 10 m. These developments are another step toward unified wireless power, sensing, and communication solutions in the future.

Recovery Delay with Visual Feedback to Reduce Errors in Single-Switch Scanning Keyboards

PurposeScanning switch keypads are commonly used as augmentative and alternative communication aids for people with complex communication needs. Low communication rates and high error rates are some of the problems that users of scanned keyboards encounter in daily use, which could lead to the abandonment of this type of technology. Thus, this study presents a new configuration system for scanned keyboards using visual feedback recovery time to help the user have a better performance and experience when using this type of alternative communication. MethodsThe system was developed in C#. The control switch is realized by means of a wireless USB mouse button. In order to evaluate the system, 42 participants transcribed sentences using a system based on our recovery delay approach, as well as a second time-delay-free scanning system for comparison purposes. We analyzed the input rate, success rate, and probability of error occurrence. These data were used to compare the performance of the two types of systems. ResultsThe results showed that synchronization and selection errors were lower in the group that used the system with a recovery delay than in the group that used the layout without. ConclusionThe error reduction provided by the recovery delay system, allows for a more stable and enjoyable user experience when using scanned keyboards to communicate. This contribution could improve the use of augmentative and alternative communication devices and therefore contribute to reducing the abandonment of this type of technology.

Wireless Remote Control for Underwater Vehicles

Nowadays, the increasing availability of commercial off-the-shelf underwater acoustic and non-acoustic (e.g., optical and electromagnetic) modems that can be employed for both short-range broadband and long-range low-rate communication, the increasing level of autonomy of underwater vehicles, and the refinement of their underwater navigation systems pave the way for several new applications, such as data muling from underwater sensor networks and the transmission of real-time video streams underwater. In addition, these new developments inspired many companies to start designing hybrid wireless-driven underwater vehicles specifically tailored for off-shore operations and that are able to behave either as remotely operated vehicles (ROVs) or as autonomous underwater vehicles (AUVs), depending on both the type of mission they are required to perform and the limitations imposed by underwater communication channels. In this paper, we evaluate the actual quality of service (QoS) achievable with an underwater wireless-piloted vehicle, addressing the realistic aspects found in the underwater domain, first reviewing the current state-of-the-art of communication technologies and then proposing the list of application streams needed for control of the underwater vehicle, grouping them in different working modes according to the level of autonomy required by the off-shore mission. The proposed system is finally evaluated by employing the DESERT Underwater simulation framework by specifically analyzing the QoS that can be provided to each application stream when using a multimodal underwater communication system specifically designed to support different traffic-based QoSs. Both the analysis and the results show that changes in the underwater environment have a strong impact on the range and on the stability of the communication link.

Power Splitting-Based SWIPT Systems With Full-Duplex Jamming

The simultaneous wireless information and power transfer (SWIPT) has recently attracted much attention since both information and energy are integrated within radio frequency signals, which is considered to be one of the most important technologies for future networks. However, security becomes one of the most critical issues in SWIPT networks due to its broadcasting features over wireless media and the transferring requirements for strong signal strength. To improve the security of SWIPT networks, in this paper, a SWIPT system enabled by full-duplex (FD) jamming is proposed, where an FD energy-limited receiver with the power splitting (PS) structure, powered by a transmitter, generates jamming signals. Both linear and nonlinear energy harvesting (EH) models are considered. To evaluate the secrecy throughput (ST) of the system, we derive the closed-form connection outage probability and secrecy outage probability for the proposed PS-based scheme in the delay-constrained transmission (DCT) mode. The ST is maximized by optimizing the PS ratio based on the asymptotic cases of the high signal-to-noise ratio as well as the perfect self-interference cancellation (SIC). Besides, the exact integral forms of the ergodic secrecy capacity and their closed-form lower bounds are presented for both the PS-based and the time switching (TS)-based schemes in the delay-tolerant transmission (DTT) mode. Simulation results suggest that the PS-based scheme outperforms the TS-based scheme for the DTT mode. For the DCT mode, the PS-based scheme can achieve better performance than the TS-based scheme only in low target communication rate, small PS/TS ratio, high transmit power, and weak path loss. Meanwhile, given a tolerable amount of SIC, the ST obtained in the linear EH model is higher than that achieved in the nonlinear EH model.