High-speed Mobile Environment Research Articles

Cooperative transmission of UAV swarm using orthogonal time–frequency space modulation

Unmanned aerial vehicles (UAVs) emerge as versatile aerial nodes capable of dynamically filling coverage gaps and enabling mission-critical communication based on their mobile nature. UAV swarms, characterized by the coordinated operation of multiple drones, are employed for a wide range of applications such as surveillance, environmental monitoring, precision farming, and autonomous delivery. While individual UAVs suffer from limited power, group transmissions of UAV swarms can enhance the data rate, reliability, and energy efficiency. However, their mobility may cause severe Doppler spread. The existing orthogonal frequency division multiplexing (OFDM) system exhibits limitations such as susceptibility to the Doppler effect in high-speed mobile environments. To address this issue, orthogonal time–frequency space (OTFS)-aided cooperative transmission (CT) for UAV swarms is considered, which can surmount the aforementioned limitations. The results show the BER improvement of the order of 103 at the SNR value of 10 dB when OTFS modulation is utilized and even better at the higher SNR values. Furthermore, the analytical framework of OTFS-based CT is presented by identifying the key design considerations on the subcarrier spacing, the number of symbols, and the number of subcarriers, which are subject to the maximum speed of the UAV and the cluster size of the UAV swarm. These results provide a significant platform for advancing research in the field of UAV-based CT, especially with the Doppler-resilient OTFS modulation.

New Bounds of No-Hit-Zone Frequency-Hopping Sequences with Frequency Shift

In quasi-synchronous FH multiple-access (QS-FHMA) systems, no-hit-zone frequency-hopping sequences (NHZ-FHSs) can offer interference-free FHMA performance. But, outside the no-hit-zone (NHZ), the Hamming correlation of traditional NHZ-FHZs maybe so large that the performance becomes not good. And in high-speed mobile environment, Doppler shift phenomenon will appear. In order to ensure the performance of FHMA, it is necessary to study the NHZ-FHSs in the presence of transmission delay and frequency offset. In this paper, We derive a lower bound on the maximum time-frequency two-dimensional Hamming correlation outside of the NHZ of NHZ-FHSs. The Zeng-Zhou-Liu-Liu bound is a particular situation of the new bound for frequency shift is zero.

Multidimensional Heterogeneous Network Link Adaptation Based on Mobile Environment.

With the development of communication technology, train control operation system develops gradually, which significantly improves the reliability and efficiency of train operation. The current mobile Internet has gradually highlighted the many limitations of the mobile Internet in the high-speed mobile environment, which seriously deteriorate the service quality and user experience, and cause a waste of resources. In order to meet the real-time requirements of network communication resource scheduling in the mobile environment, aiming at the multidimensional dynamic adaptation framework constructed in a mobile environment, a service and network adaptation mechanism based on link failure state prediction is proposed in the paper. First, cross-layer theoretical analysis and actual data analysis are combined to construct a wireless link failure probability model. Then, reliable transmission requirements and transmission overhead are applied to optimize goals. Finally, simulation experiments are carried out according to the railway network data to evaluate the E-GCF adaptation algorithm. The experiment results show that compared with the current mainstream algorithms, the prediction accuracy of this adaptation algorithm is improved by 25%. The execution time of the algorithm is reduced by 9.6 seconds and the successful submission rate is as high as 99.99%. The advantages of the algorithm are significantly superior other algorithms. It proves that the research method of this paper can effectively improve the satisfaction rate and utility value of reliable transmission, as well as enhance the throughput performance. It solves the adaptation problems of frequent switching and low utilization of heterogeneous networks in a mobile environment, which contributes to the high-quality communication service of mobile network.

In-Band Full-Duplex Operation in High-Speed Mobile Environments: Not So Fast!

In-band full-duplex (IBFD) technology is promised to deliver us from the scarcity of spectral resources as well as create novel multifunction wireless systems <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . This concept was initially investigated in the 1960s for continuous-wave radar applications <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> , and, in the past decade, it has undergone a shift in research toward communications <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> – <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> <xref ref-type="bibr" rid="ref5" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> <xref ref-type="bibr" rid="ref6" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"/> <xref ref-type="bibr" rid="ref7" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[7]</xref> and converged RF systems <xref ref-type="bibr" rid="ref8" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[8]</xref> , <xref ref-type="bibr" rid="ref9" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[9]</xref> . Since 2010, more than 600 IEEE publications alone have focused on at least one aspect of the technology, including more than 400 conference papers, 200 journal articles, and 20 magazine features <xref ref-type="bibr" rid="ref10" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[10]</xref> . After digesting these numbers, it is fair to ask: Why has IBFD functionality not been incorporated into a wireless standard yet?

Analysis of network topology and deployment mode of 5G wireless access network

Aiming at the characteristics of high-density and random deployment of 5G cellular networks, through efficient network-level deployment methods, the network can quickly and efficiently adapt to large-scale dynamic changes in user traffic. Aiming at the need for 5G systems to meet the requirements of high-speed mobile environment communications, this paper deeply studies the factors that affect communication quality in mobile scenarios and their relationships. Based on this, around the content transmission and distribution of information, a 5G mobile communication network architecture based on content-centric network technology is proposed. To meet the deployment requirements of cross-domain VNF (Virtual Network Function) during the deployment phase, in order to solve the problem that the existing cross-domain deployment algorithms do not take into account node computing resources and link bandwidth resources, this paper proposes a DPSO-K (Discrete Particle Swarm Optimization—Kruskal) 5G cross-domain virtual network function deployment method. Compared with the traditional method, the overall cost is reduced, and the cost is least affected by the number of data fields. In different practical scenarios, the resource reduction gain of the strategy is evaluated. Simulation results verify the impact of different system parameters on the energy efficiency of the network. The results show that this method has obvious advantages in optimizing the energy spectrum efficiency of randomly deployed networks.

High Throughput Mobile Communication Based on OTFS System with the Delay-Doppler Compensation

In this paper, we like to propose a high throughput mobile communication system that can work even at the very high vehicular speed. Generally, mobility and data throughput has inverse relationship. Also, very complicated receiver structure is required and takes a long time processing for compensating the Doppler frequency due to the high speed mobility. Seriously, the communication performance becomes degraded with the increase of the dimension of multiple input and multiple output (MIMO), since the delay Doppler problem becomes bigger the higher dimension of MIMO. So, it is greatly important to design the very robust mobile communication that can provide the high throughput even at the very high vehicular speed system. Design and performance evaluation of the orthogonal time frequency space (OTFS) modulation system and OTFS-based MIMO system are described and analyzed at the very high mobility environment. OTFS modulation can concisely compensate the delay-Doppler spreading effect by using two dimensional inverse discrete Fourier transform and discrete Fourier transform operation. It enables OTFS system to transmit high-speed data. Especially, OTFS-MIMO system can transmit data stream of each antenna without the communication performance degradation even in the high Doppler frequency environments. As simulation results, it is confirmed that the capacity of 1 × 1 OTFS system is a similar to each stream of 2 × 2 OTFS-MIMO system. That is, 2 × 2 MIMO system can completely double the communication capacity in comparison with 1 × 1 OTFS system even in the very high Doppler frequency channel such as high speed mobile environments. This remarkable performance can continue in the very high dimensional MIMO system and simultaneously in the high mobility situation.

Fractional-order algorithms for tracking Rayleigh fading channels

This paper presents the tracking behavior of fractional-order (FO) variants of the normalized least mean square (NLMS) algorithm in a nonstationary environment modeled as time-varying Rayleigh fading sequence. The celebrated recursive least squares (RLS) or its variant extended RLS (E-RLS) algorithms fail in such situations although they exhibit faster convergence but with the undesired feature of higher computational complexity. The FO algorithms are based on the Riemann–Liouville differintegral operator which is used in the gradient calculation; such schemes provide two step sizes and an FO to control the rate of convergence. In evaluation, we consider a high-speed mobile environment with a Rayleigh channel which results in different Doppler frequency shifts depending upon the transmission frequency, relative velocity of the transmitter and receiver. The proposed algorithms are compared with the NLMS, RLS and E-RLS schemes, and numerical experiments show the superiority of the FO variants over these schemes in terms of stability and model accuracy in the steady state. A hybrid scheme is also shown where the weights of an FO variant are initially trained with RLS and then performs self-adaptation; the FO scheme is confirmed to have better performance than all traditional counterparts.

Performance analysis of WAVE communication under high-speed driving

Abstract Although WAVE (Wireless Access in Vehicular Environments) is a technology designed for the high-speed mobile environments, WAVE communication performance in a real road environment is highly dependent on the surrounding environments such as moving vehicles, road shape, and topography. In particular, when a vehicle moves at high speed, the location of the vehicle and its proximity to the road-side device are rapidly changed and thus affect communication performance. Accordingly, we build a performance evaluation system based on the WAVE-LTE network cooperative operation. We also analyzed the performance differences based on external environmental factors, such as information volume and velocity, from the data acquired through actual vehicle tests.

Performance analysis of a novel 5G architecture via Content-Centric Networking

Content-Centric Networking (CCN) is a recent paradigm conceived for future Internet architectures, where communications are driven by contents instead of host addresses. It binds the storage capacity into the network by using the in-network caching, which can reduce the transmission delay in the network. In this paper, a novel architecture of 5G via CCN, named as CCN-5G, is proposed. Meanwhile, the performance of CCN-5G are tested in the high-speed mobile environment. The simulation results show that the CCN-5G can achieve excellent performance and satisfy the future requirements of 5G.

Structured Compressed Sensing for Channel Estimation under High-Speed Mobile Environment

In the fourth generation wireless communication systems, channel estimation technology is very important for orthogonal frequency division multiplexing (OFDM). However, the existing schemes hardly meet the demand for Quality of Service in high-speed mobile environment. To handle this problem, in this paper, the channel sparsity characteristic and temporal correlations are exploited and displayed by the block-sparse system model. Then, the block-based orthogonal matching pursuit (OMP) algorithm is used to obtain the channel state information. Simulation results illustrate the performance of our proposed algorithm superiority.

一种带有ICI自消除的多OFDM符号时变信道估计方法

高速移动环境下，由于多普勒频移增大，信道的时变性破坏了正交频分复用(Orthogonal Frequency Division Multiplexing, OFDM)系统子载波之间的正交性，从而产生子载波间干扰(Inter Carrier Interference, ICI)，导致系统性能严重下降。为了减少待估计量，通常采用基扩展模型(BEM)来近似模拟时变信道。为了提升性能，当信道的相干时间与发送码元的周期可相比拟的时候，本文采用多块(多个OFDM符号)。同时在使用导频符号对参数估计时，忽略了相邻非导频符号的ICI干扰，降低了整个时变信道下的估计准确性。因此我们通过分析子载波所产生的ICI系数变化特点，提出了一种带有ICI自消除的多OFDM符号时变信道估计方法，提高估计的准确性。但是由于基于多OFDM符号的信道估计性能在归一化多普勒频移较大时该方法成立条件不再满足，因此性能呈现明显的衰减，为了解决此问题，我们提出一种带有ICI自消除的自适应OFDM符号个数时变信道估计方法。仿真实验从误码率，归一化均方误差两方面分别验证了该方法的有效性。 In high-speed mobile environment, time-varying channel destroys the orthogonality between subcarriers of orthogonal frequency-division multiplexing (OFDM) systems, giving rise to in-ter-carrier interference (ICI), and degrading the performance of the systems. Basis expansion model (BEM) is usually used to approximate the time-varying channels to reduce the estimators. In order to improve performance, this paper adopts multi block (multiple OFDM symbols) when the coherent time of the channel variations and the symbols can be compared. However, when using pilot-symbol to parameter estimation, the ICI interference from near non-pilot-symbol is ignored, reducing its estimated accuracy of time-varying channel. And in this work the paper proposes a multiple OFDM symbols time-varying channel estimation method with ICI self-cancellation after analyzing the high correlation between subcarriers, improving the accuracy of estimation. But due to the condition of utilizing the multiple OFDM symbols channel estimation method is no longer met in large Doppler frequency shift, the performance of resulting channel estimation attenuates obviously. In order to solve this problem, we put forward a kind of adaptive OFDM symbol time-varying channel estimation method with the ICI self-cancellation. The simulation results show that the proposed method is effective from two aspects of error rate and normalized mean square error.

Simulation and Analysis of Scattering Channel Models in Three-Dimensional High-Speed Mobile Environment

A three-dimensional (3D) statistic channel model based on scattering characteristics is proposed to describe accurately the wireless channel under the scenarios of high-speed train (HST). This paper derives scattering density distribution function and scattering coefficient to represent the channel impulse response (CIR) of HST communication system, and deduces closed expressions of Doppler power spectrum (DPS) of mobile terminal. Expressions are also provided for categorizing and quantizing the scattering characteristics of wireless channels. By analyzing the Doppler spread of HST and comparing the effects of scattering environment and mobile velocity on DPS, these works contribute to understand deeply the wireless scattering channel of HST. Numerical and simulation results demonstrate that the proposed scattering channel models can effectively depict the physical characteristics of HST wireless channel, which provide a reliable method to analyze and estimate channel parameters. Moreover, the channel realization in this paper is more straightforward and concise to study the scattering channel characteristics, which can also be utilized as a reference for experimental measurement campaigns and reducing the modeling errors of scattering channel model effectively.

Iterative Channel Estimation for MIMO-OFDM System in Fast Time-Varying Channels

A practical iterative channel estimation technique is proposed for the multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system in the high-speed mobile environment, such as high speed railway scenario. In the iterative algorithm, the Kalman filter and data detection are jointed to estimate the time-varying channel, where the detection error is considered as part of the noise in the Kalman recursion in each iteration to reduce the effect of the detection error propagation. Moreover, the employed Kalman filter is from the canonical state space model, which does not include the parameters of the autoregressive (AR) model, so the proposed method does not need to estimate the parameters of AR model, whose accuracy affects the convergence speed. Simulation results show that the proposed method is robust to the fast time-varying channel, and it can obtain more gains compared with the available methods.

Research on an optimal selection method for sensor network node under high-speed mobile environment

The traditional selection methods for the selection of sensor network node under high-speed mobile environment is randomness, which cannot effectively use the multiple attributes of nodes, resulting in the irregular distribution of cluster head of nodes, and high energy consumption. An optimal selection method for sensor network node under the high-speed mobile environment based on EERNFS and Naive Bayesian Networks is proposed. By using EERNFS algorithm within each network intercept / sleep cycle, the sensor network node is made processing under high-speed mobile environment, to ensure the stable local connectivity and consistent collaboration intercepts, and reduces energy consumption. Naive Bayes algorithm is used to make optimization of general Bayesian classification method, and set the parameters. In the two-dimensional area, several sensor nodes are randomly placed, and the known two-dimensional area is divided. A certain node is selected arbitrarily in different regions to constitute the original set of Naive Bayes algorithm, and compute the training results and thresholds in the Bayesian system of node set at this moment. On the basis of the threshold, the optimal selection of sensor network node is achieved. Simulation results show that the proposed method not only has higher node coverage, but also the operating efficiency and energy consumption are better than the genetic method.

NDN-GSM-R: a novel high-speed railway communication system via Named Data Networking

To keep up with the rapid development of railway and meet the high demand for communication business in China, Global System for Mobile Communications-Railway (GSM-R) based on General Packet Radio Service (GPRS) ahead of Europe has been developed. However, the current data communication mode of GPRS using TCP/IP has some disadvantages, such as poor mobility, lack of security etc. For this reason, there are some problems for GSM-R, like handover, which makes communication service quality undesirable. Named Data Networking focuses on named data, adopts data-facing communication mode, and does not care where the contents are stored but the contents themselves. It can effectively solve the problems caused by TCP/IP. In this paper, a new high-speed railway communication system with Named Data Networking (NDN) named NDN-GSM-R is proposed. Two simulations, called transmission interference time and end-to-end transmission delay of NDN-GSM-R, have been conducted. The simulation results show that NDN-GSM-R has better performance in high-speed mobile communication environment and can make up the insufficiency of the current GSM-R based on TCP/IP framework.

The Real‐Time Simulation of Doppler Spread in Wireless Mobile Environment by RF Circuits

The time-varying characteristic of wireless channel under the high-speed mobile environments in tunnels causes the Doppler spread to the transmitted signals, which affects the performance of wireless communication systems. The real-time Doppler effect simulation methodology directly based on Radio frequency (RF) circuits is proposed to simulate different Doppler spread effects in real environments. Mixers and a Digital-to-analog (DA) converter circuit are utilized to spread the spectrum of RF signals. A PC platform with the interface written in C# is configured to control the spectrum spread parameters. This radio channel emulator with the proposed methodology can replace the expensive fading simulating instruments with only 25.1ns system delay. Such an emulator has been applied to test the Multi-carrier wireless information local loop (McWiLL) wireless vehicle communication system in the laboratory to meet the requirement of metro Communication based train control (CBTC) system.

Improved Carrier Frequency Offset Estimation Algorithms for PUCCH Format 1 in LTE-Advanced

Physical Uplink Control Channel (PUCCH) is an important narrow-band channel in LTE-Advanced system, which carries the uplink control information, such as acknowledge/non-acknowledge (ACK/NACK) bits, downlink channel quality indicator (CQI), HARQ-ACK feedback information, and it requires much higher transmission quality than the other channels. With the aid of orthogonal CDMA, multiple users share the same time-frequency resource, the multiuser interference has been the main factor that limits the transmission quality of the control information [1]. In the high-speed mobile scenario, there exists a large Doppler frequency shift, which leads to loss of code orthogonality and also introduces inter-carrier interference (ICI) within a single SCFDMA symbol. Besides, the multiuser interference in high-speed mobile environment is severe. In this paper, the carrier frequency offset estimation algorithms are analyzed, and a double-iteration carrier frequency offset (CFO) estimation algorithm is proved to perform the best for PUCCH Format 1 in high-speed mobile scenario. The estimation process is achieved by coarse estimation and fine estimation, which enlarges the estimation range and improves the estimation accuracy.

Dynamic Entropy Based Combination Weighted Clustering Approach for High-Speed Ad hoc Network

Weight based clustering has become the mainstream clustering algorithm in low-speed Ad hoc networks because of its excellent cluster stability. However, due to the dynamic topology changing in high-speed Ad hoc network, the cluster stability (network stability) decreased and the cluster maintenance costs increased sharply. To solve the problem, we propose a dynamic entropy based combination weighted clustering approach (DECW). First, according to the history messages of an evaluation node in the network, the upper bound and the lower bound value of each clustering index will be recorded, so the information entropy deviation of the indexes and dynamic entropy weight of each node can be obtained. After, the linear combination weights set of evaluation nodes is modeled as the second-order norm game , and the weight vector deviation is minimized as the optimization goal to get the multi-node dynamic entropy weights. In the cluster maintenance, a new Monte Carlo optimization is proposed to avoid the frequent clusterheads (CHs) replacement induced of high node mobility of. Simulation results reveal that the proposed approach has the better adaptability in high-speed mobile environment.

Self-Optimization of Handover Parameters for Long-Term Evolution with Dual Wireless Mobile Relay Nodes

In recent years, train passengers have been transferring increasing amounts of data using mobile devices. Wireless networks with mobile relay nodes support broadband wireless communications for passengers of such vehicles using backhaul links. However, the mobility management entity reuses the handover of existing user equipment, resulting in the handover of the Long-Term Evolution network being unsuitable for user equipment within the cabins of vehicles traveling at high speed. In this paper, we propose a self-optimizing handover hysteresis scheme with dual mobile relay nodes for wireless networks in high-speed mobile environments. The proposed mechanism tunes the hysteresis and cell individual offset handover parameters based on the velocity of the vehicle and the handover performance indicator, which affects the handover triggering decision and performance. The results of simulations conducted in which the performance of the proposed scheme was compared to that of an existing scheme show that the proposed scheme can reduce the number of radio link failures and service interruptions during handover procedures.

Bus Safety Regulatory System Design Based on Internet of Vehicles Technology

To provide a reliable system for bus safety regulation, an intelligent bus safety regulatory system based on Internet of Vehicles technology was presented in this paper. By intelligent vehicle terminal and data acquisition sensor platform on the bus, all kinds of sensor data in the bus can be gathered and transferred in high-speed mobile environment. They include interior surveillance video images, bus speed, the number of people getting on or off, and the location of the bus, etc. The number of people aboard bus, getting on or off, vehicle location, the speed of buses and other conditions of real-time monitoring and early warning are realized.