Wireless Communication Transmission Research Articles

APOFDM system design based on all phase FFT technology

The traditional OFDM system as an important part of current wireless communication technology, its advantages are obvious, but one of shortcoming is easily affected by the frequency deviation. An effective solution is to improve data signal processing technology in the front of the system, thus can reduce the effects of system faults and improve the performance of the system. All phase data processing under the research idea of it is in this, after 20 years of research and development, now all phase FFT technology has been applied to image processing, signal processing, signal spectrum analysis, wireless communication transmission, etc. In this paper, using all phase FFT processing technology and detailed the APOFDM, Finally, using MATLAB simulation tools to analyze its advantages.

Swarm robotic network using Lévy flight in target detection problem

One approach in swarm robotics is homogeneous system which is embedded with sensing, computing, mobile and communication components. In this study, a target detection problem, which is one of navigation problems, was employed. Once a robot detects a target, robots immediately communicate with a base station via intermediate relay robots due to the multi-hop transmission of wireless communication. Therefore, this control task is completed with connectivity of the network. In a target detection problem, we must improve the performance of exploration as well as connectivity of the network. This study investigates the performances of the two types of random walk algorithm in navigation while loosely ensuring connectivity of the robotic network based on our previous study.

Effects of radio- and microwaves emitted by wireless communication devices on the functions of the nervous system selected elements

Nervous system is the most "electric" system in the human body. The research of the effects of electromagnetic fields (EMFs) of different frequencies on its functioning have been carried out for years. This paper presents the results of the scientific literature review on the EMF influence on the functioning of the human nervous system with a particular emphasis on the recent studies of the modern wireless communication and data transmission systems. In the majority of the analyzed areas the published research results do not show EMF effects on the nervous system, except for the influence of GSM telephony signal on resting EEG and EEG during patients' sleep and the influence of radiofrequency EMF on the cardiovascular regulation. In other analyzed areas (EMF impact on sleep, the evoked potentials and cognitive processes), there are no consistent results supporting any influence of electromagnetic fields. Neurophysiological studies of the effect of radio- and microwaves on the brain functions in humans are still considered inconclusive. This is among others due to, different exposure conditions, a large number of variables tested, deficiencies in repeatability of research and statistical uncertainties. However, methodological guidelines are already available giving a chance of unifying research that definitely needs to be continued in order to identify biophysical mechanisms of interaction between EMFs and the nervous system. One of the EMF research aspects, on which more and more attention is paid, are inter-individual differences. Med Pr 2016;67(3):411-421.

Switched Phased-Array Transmission Architecture for Secure Millimeter-Wave Wireless Communication

In this paper, we propose a new wireless communication transmission architecture called switched phased-array (SPA), to enhance physical layer security. SPA works as a platform for three different transmission techniques: 1) conventional phased-array transmission; 2) antenna subset transmission (AST) technique; and 3) silent antenna hopping (SAH) transmission technique. SPA consists of a conventional phased-array blacktransmitter followed by antennas with an on–off switching circuit. The proposed solution maintains the objective of scrambling the constellation points in both amplitude and phase in undesired directions, while preserving a clear constellation in the target direction. The proposed solution—SPA—is different from previously used methods in the following ways: 1) SPA is not restricted to the use of phase modulation, and can accept any modulation type including QAM; 2) it does not need to modulate the signal in the radio frequency (RF) domain, where the conventional phased-array transmitter circuits remain unchanged; 3) in the far field, SPA scrambles the signal constellation by randomly switching- off some of the transmitting antennas (AST), or only one of them (SAH); 4) SPA can be easily integrated with the current infrastructure of phased-array transmitters; 5) SPA breaks up the correlation between the data rates and the switching speed; and 6) SPA performs a variety of DM transmission techniques. We present the potential transmission techniques including PA, AST, and SAH. We analyze the performance for all cases and derive an exact expression of the bit error probability, and also we analyze the secrecy capacity. The results show that SPA, and its variants AST and SAH, are simple and very efficient solutions to improve the physical layer security of mm-wave communication.

The Evolution of LTE Physical Layer Control Channels

Physical layer control signals in cellular communications serve the purpose of delivering physical layer control messages in a timely fashion to support cell radio resource management and data transmissions between the network and the mobile users. This article describes the evolution of 3GPP LTE in control channel design. The legacy LTE control channels (Release 8) have proven to be well-designed robust channels for signaling physical layer messages. However, emerging wireless communication transmission technologies continue to challenge the traditional design of LTE control channels. We have reached a point where a totally new design of the control channels has to be provided in order for the new transmission features to be introduced into LTE. In this article we first give an overview of the legacy LTE control channel, and present the new challenges. We then describe in depth the new solutions provided by LTE (Release 11). Finally, we address the limitations of the new design, which are recently identified in certain newly-emerging applications, in particular, the machine-type communications. A new round of evolution is hence imperative. New solutions provided by next release of LTE (Release 13) are presented.

Symmetrical Full-Duplex Integrated Passive Optical Network and Optical Wireless Communication Transmission System

We propose and experimentally demonstrate a full-duplex integrated passive optical network (PON) and indoor optical wireless communication (OWC) system. For the PON part, an external cavity laser (ECL) and a directly modulated laser (DML) are used as optical sources for downlink and uplink, respectively. The OWC subsystem utilizes a visible light-emitting diode (LED) for downlink and an infrared LED (IR-LED) for uplink transmission. To enable high spectral efficiency (SE), high-speed transmission, and flexible multiple access with simplified optical network unit (ONU)-side digital signal processing (DSP), multilevel, multiband quadrature amplitude modulation (QAM) and hybrid 128/64/16 Nyquist single-carrier frequency domain equalization (N-SC-FDE) modulation are implemented in this paper. In terms of 62.5 MHz OWC N-SC-FDE signals, the system successfully delivered a further 140 cm indoor distance after transmitting over a span of 25 km standard single mode fiber (SSMF) together with three subbands of 250 MHz PON signals. As a proof of concept, an integrated system of symmetrical full-duplex 5 Gb/s PON and 250 Mb/s OWC at each direction for three wired users and one wireless user is successfully achieved. The measured bit error ratios (BERs) for each user are all smaller than the 7% pre-forward-error-correction (pre-FEC) limit of 3.8 × 10−3, which shows the promising potential and feasibility of this proposal to extend multiple services from metro areas to suburban areas.

Wireless Body Area Networks for Healthcare Applications: Protocol Stack Review

Wireless Body Area Networks (WBANs) supporting healthcare applications are in early development stage but offer valuable contributions at monitoring, diagnostic, or therapeutic levels. They cover real-time medical information gathering obtained from different sensors with secure data communication and low power consumption. As a consequence of the increasing interest in the application of this type of networks, several articles dealing with different aspects of such systems have been published recently. In this paper, we compile and compare technologies and protocols published in the most recent researches, seeking WBAN issues for medical monitoring purposes to select the most useful solutions for this area of networking. The most important features under consideration in our analysis include wireless communication protocols, frequency bands, data bandwidth, transmission distance, encryption, authentication methods, power consumption, and mobility. Our study demonstrates that some characteristics of surveyed protocols are very useful to medical appliances and patients in a WBAN domain.

2A1-K06 レヴィフライトを用いたスワームロボットネットワークのターゲット探索

One approach in swarm robotics is homogeneous system which is embedded with sensing, computing, mobile and communication components. In this study, a target detection problem, which is one of navigation problems, was employed. Once a robot detects a target, robots immediately communicate with a base station via intermediate relay robots due to the multi-hop transmission of wireless communication. Therefore, it is important to take connectivity of the network into account. This study investigates the performances of the two kinds of random walk algorithm in navigation while loosely ensuring connectivity of the robotic network based on our previous study.

Wireless Condition Monitoring of Train Traction Systems Using Magnetoelectric Passive Current Sensors

Novel power-supply-free, surface-mount-type magnetoelectric passive current sensors were developed and integrated with a four-channel, 2.4-GHz wireless communication (transmitter and receiver) unit to form a new generation of wireless condition monitor for train traction systems. The wireless condition monitor was deployed in a field study on the East Rail Line in Hong Kong. Four pairs of magnetoelectric passive current sensors and single-channel wireless transmitters were installed, respectively, on and near the electric cables of four electric motor drives located underneath the 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> , 5 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> , 8 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> , and 11 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> cars of a 12-car mainline train. The four-channel wireless receiver was housed in the driver's cab of the train to provide real-time wireless monitoring of the current signatures of the four electric motor drives due to the operation of the train traction system in steady-state and acceleration conditions. The monitored current signatures were post-processed to obtain the distributions of the ratio of harmonic-to-fundamental current, their total harmonic distortions and power factors as well as the frequency spectra. A practical implication and correlation of the post-processed data with the operating conditions of the train traction system was established for application of the proposed wireless condition monitor as train traction system monitor.

Optimised field programmable gate array implementation of a dual‐mode orthogonal frequency division multiplexing optical wireless communication transmitter

This study presents a field programmable gate array (FPGA) implementation of an orthogonal frequency division multiplexing (OFDM) optical wireless communication transmitter. Two OFDM techniques, namely DC biased optical OFDM and asymmetrically clipped optical OFDM, are considered. For each, the dynamic range of the signal is used to optimise signal conversion from digital to analogue domain. A dual-mode transmitter with the same transmission bit rate for both techniques is implemented. The switch from one mode to the other can be performed according to light dimming without reprogramming the FPGA.

A 0.1–5.0 GHz Reconfigurable Transmitter With Dual-Mode Power Amplifier and Digitally-Assisted Self-Calibration for Private Network Communications

A 0.1-5.0 GHz 65 nm CMOS reconfigurable transmitter for private network wireless communications is presented. The transmitter integrates a 0.1-1.5 GHz high-efficiency dual-mode power amplifier to support low-cost narrowband applications and a 0.45-5.0 GHz efficiency-optimized pre-power amplifier to support high-performance wideband applications. A wideband PLL frequency synthesizer, DACs with reconfigurable sampling rate and the reconfigurable digital baseband processing with standard JESD207 interface are all included to implement the highly-integrated transmitter. Specifically, with the proposed digitally-assisted self-calibration technique for LO leakage and image rejection, the transmitter achieves 52 dBc LO leakage and >53 dBc image rejection ratio (IRR), showing 20 dB and 30 dB improvement compared with the un-calibrated cases, respectively. The system verifications have demonstrated an EVM of 1.7% for 905 MHz EDGE with 19.5 dBm output power, and an EVM of 3.2% for LTE Band42 with 5.5 dBm output power. This proposed transmitter has achieved the comparable or even better performance in linearity, noise floor and power consumption compared with the state-of-the-art reconfigurable transmitters.

An IQ mismatch calibration and compensation technique for wideband wireless transceivers

An IQ mismatch calibration and compensation technique based on the digital baseband for wideband wireless communication transmitters is proposed. The digital baseband transmits the signal used for IQ mismatch calibration. The signal passes through the RF transmitter path, the calibration loop (which is composed of a square power detector and a band-pass filter in the RF transceiver) and the variable gain amplifier of the receiver. The digital baseband samples the signal for IQ mismatch estimation and compensates for it. Compared with the self-calibration technique in the RF chip, the proposed technique saves area and power consumption for the wireless local area network solution. This technique has been successfully used for the 802.11n system and satisfies the requirement of the standard by achieving over 50 dB image suppression.

The Wireless Network Routing Protocols and Data Communication Methods for Multiple Sensor Information Used in Mining Mechanical

In view of the development of wireless sensor system data transmission model in mine mechanical, we construct a ground reflection model of double path combined with the actual background demand based on the analysis of the wireless network routing protocol. Firstly, we put forward the selection strategy on wireless communication transmission power of multiple information sensor nodes. To build a data communication mode, we proposed the selection and evaluation method of network parameters based on graph theory. In consideration of the wireless channel model, combined with the initial random layout problem of network node, we explore whether to be neighbors between any two nodes arranged at random and the constraint relationship of wireless communication distance between nodes. Finally, we make up a dynamic routing selection algorithm with a view to dynamic nodes, and conduct the simulation analysis and experiment design. The research results show that with the increase of the random movement speed about network nodes, the process of depleting the energy of the nodes in the wireless sensor network speeds up, which explain the protocol given in the paper requires more energy to cope with the problem that the network topology changes frequently because of the random motion of nodes in network. The research results provide a reference to the wireless network node research and design in the electromechanical integration design.

Service Self-Organization Based on SON in LTE-Advanced Heterogeneous Networks

Since global service providers consider seamless interworking with existing networks as the most important factor, it is most likely that LTE-Advanced of 3GPP is selected as international standard for 4G wireless communication. As such, we suggest SON based service self-organization which provides users with service continuity even when mobile users have terminal mobility and session mobility, and enable service providers to implement “heterogeneous multi-network of integrated” which guarantees better service in terms of wireless communication access, transmission speed, and Quality of Service (QoS). It is also expected to allow fast handover service such as VOD, and streaming in LTE-Advanced system. Moreover, this study could be conducted with various research institutions and manufacturers, leading joint research and technology transfer in the future.

Averaging time required for measuring the specific absorption rate of a MIMO transmitter

This paper presents a new method to measure electric field (E-field) for human-body exposure to electromagnetic fields from Multi-Input Multi-Output (MIMO) wireless communication transmitters, and an estimation of averaging time required in the E-field measurement. The proposed method is to measure time-averaged E-field, and the averaging time is the duration required for a measurement system to make averaged E-field converged. The estimation is based on averaging the square of amplitude of received signals or measured E-field strength. Several simulation results with different measurement parameters for MIMO wireless communication transmitters are presented and discussed. It is pointed out that the averaging time in E-field measurements for multi-antenna transmitters is considerably longer than that for single antenna transmitters.

Energy-Efficient Water-Filling with Order Statistics

This paper proposes a methodology based on order statistics to study the energy-efficient (EE) power allocation for wireless communication transmitters. Water-filling power allocation maximizes the EE when transmitting and processing power consumption is considered. Solutions are typically presented in an iterative form, which complicates analysis and adaptive implementation. Time-consuming simulations are rather required to assess their performance. Order statistics allows analyzing the solution without knowledge of the channel realization. We analytically show how the EE depends on the system parameters. The computing efficiency of our proposal, which is executing one or two orders of magnitude faster than the state-of-the-art algorithms with a performance loss of less than 1 dB, facilitates its applicability in vehicular environments.

Feed-Forward Scheme Considering Bandwidth Limitation of Operational Amplifiers for Envelope Tracking Power Supply Using Series-Connected Composite Configuration

Wireless communication transmitters have a low efficiency because of the utilization of linear radio frequency (RF) power amplifiers (PAs) while the RF input signal is with a variant envelope. The envelope tracking (ET) technique is a very promising approach to improve the PA efficiency. For this application, this paper proposes an ET power supply consisting of a multilevel converter in series with a linear amplifier, where the multilevel converter provides the most load power with its essential high efficiency, and the linear amplifier, features of high bandwidth, improves the linearity of the output voltage. A feed-forward scheme is proposed to cancel the spikes in the output voltage caused by the step-wave voltage of the multilevel converter. In practical implementation, due to the bandwidth limitation of the operational amplifiers, a frequency-compensation scheme by adding a zero and a stability pole is proposed to extend the effective bandwidth. Furthermore, the output voltage high-frequency spike-elimination scheme using the transfer function matching concept is also proposed, removing the additional spikes at the output side of the ET power supply. A prototype for 300-kHz sine-wave tracking, with a 10–32-V output voltage and 50-W peak output power, is fabricated and tested. The experimental results validate the proposed schemes.

Information Rate of OFDM-Based Optical Wireless Communication Systems With Nonlinear Distortion

In this paper, a piecewise polynomial function is proposed as a generalized model for the nonlinear transfer characteristic of the transmitter for optical wireless communications (OWC). The two general multicarrier modulation formats for OWC based on orthogonal frequency-division multiplexing (OFDM), direct-current-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM), are studied. The nonlinear distortion of the electrical signal-to-noise ratio (SNR) at the receiver is derived in closed form, and it is verified by means of a Monte Carlo simulation. This flexible and accurate model allows for the application of pre-distortion and linearization of the dynamic range of the transmitter between points of minimum and maximum radiated optical power. Through scaling and DC-biasing the transmitted signal is optimally conditioned in accord with the optical power constraints of the transmitter front-end, i.e., minimum, average and maximum radiated optical power. The mutual information of the optimized optical OFDM (O-OFDM) schemes is presented as a measure of the capacity of these OWC systems under an average electrical power constraint. When the additional DC bias power is neglected, DCO-OFDM is shown to achieve the Shannon capacity when the optimization is employed, while ACO-OFDM exhibits a 3-dB gap which grows with higher information rate targets. When the DC bias power is counted towards the signal power, DCO-OFDM outperforms ACO-OFDM for the majority of average optical power levels with the increase of the information rate target or the dynamic range. The results can be considered as a lower bound on the O-OFDM system capacity.

Structural Health Monitoring: Alarming System

There is a huge investment in our infrastructure that is vital to our social and economic life. However, the aging and deterioration of the structures require implementing a damage detection system to monitor their structural integrity. In this study, a new alarming system was developed as part of a structural health monitoring system and installed in a scaled-down structure models. The designed system incorporated microprocessors, wireless communication, transducer, and cellular transmission that allow remote monitoring. The developed system facilitates continuous monitoring process of any part of structures and controlled remotely from any location. The system was equipped with data processing subsystem that detects structural behavior irregularity, defects, and potential failures. The system was tested using Linear Variable Differential Transformer (LVDT) for deflections and using strain gages to measure the developed axial and flexural strains in different structural models. Filtering algorithm was used to filter graphs and the data gathered in each loading stage was averaged and plotted to show the abrupt change in the values. The filtering system helps the alarming system to have a clear prediction of possible irregularities. The developed system provides the desired features of low cost, low power, small size, flexibility and easy implementation, remote accessing, early detection of problems, and simplified representation of the results.

New System of Structural Health Monitoring

Monitoring of structures is an important challenge faced by researchers worldwide. This study developed a new structural health monitoring system which utilized the use of microprocessors, wireless communication, transducer, and cellular transmission that allows remote monitoring. The developed system will facilitate the monitoring process at any time and in any location with less human interference. The system is equipped with data processing subsystem which works on detection of structural behavior irregularity, defects, and potential failures. The system was tested using strain gages to measure the developed strains in different applications and structural models. The results developed using the new system showed that the generated readings from the system followed correctly the expected trend according to structural concepts. The developed system accomplished the desired features of lower cost, less power, reduced size, flexibility and easier implementation, remote accessing, early detection of problems, and simplified representation of the results.