基于三频观测的Multi_GNSS载波相位特性分析

载波相位观测噪声和多径误差是衡量载波相位观测数据质量的重要指标。采用三频消电离层无几何组合对GPS、BDS和Galileo系统的载波相位观测噪声和多径误差进行计算。选取IGS ARHT和MGO2两测站2021年连续30 d的数据,对上述GNSS系统的载波相位观测噪声和多径误差特性进行了分析,采用高阶谐函数对GPS Block IIF卫星的频间钟偏差进行模型化以降低其对DIF的影响,结论显示,各系统的DIF组合均方根值随着仰角的增大逐渐减小,在高仰角区间内比低仰角区间下降约90%;受残余IFCB的影响,GPS系统的DIF组合均方根值最大,约为BDS-2系统的3—7倍,约为BDS-3和GAL系统的20倍。

Reliable Braided Multipath Routing with Network Coding for Underwater Sensor Networks

Owing to the long propagation delay and high error rate of acoustic channels, it is very challenging to provide reliable data transfer for underwater sensor networks. Moreover, network coding is proved to be an effective coding technique for throughput and robustness of networks. In this paper, we propose a Reliable Braided Multipath Routing with Network Coding for underwater sensor networks （RBMR-NC）. Disjoint multi-path algorithm is used to build independent actual paths, as called main paths. Some braided paths on each main path are built according to the braided multi-path algorithm, which are called logic paths. When a data packet is transmitted by these nodes, the nodes can employ network coding to encode packets coming from the same group in order to further reduce relativity among these packets, and enhance the probability of successful decoding at the sink node. Braided multi-path can make the main paths to be multiplexed to reduce the probability of long paths. This paper mainly employs successful delivery rate to evaluate RBMR-NC model with theoretical analysis and simulation methods. The results indicate that the proposed RBMR-NC protocol is valuable to enhance network reliability and to reduce system redundancy.

Multi-Path Routing and Resource Allocation in Active Network

An algorithm of traffic distribution called active multi-path routing (AMR)in active network is proposed. AMR adopts multi-path routing and applies nonlinear optimizeapproximate method to distribute network traffic among multiple paths. It is combined to bandwidthresource allocation and the congestion restraint mechanism to avoid congestion happening and worsen.So network performance can be improved greatly. The frame of AMR includes adaptive trafficallocation model, the conception of supply bandwidth and its' allocation model, the principle ofcongestion restraint and its' model, and the implement of AMR based on multi-agents system in activenetwork. Through simulations, AMR has distinct effects on network performance. The results show AMRisa valid traffic regulation algorithm.

MTSS: multi-path traffic scheduling mechanism based on SDN

Large-scale and diverse businesses based on the cloud computing platform bring the heavy network traffic to cloud data centers.However,the unbalanced workload of cloud data center network easily leads to the network congestion,the low resource utilization rate,the long delay,the low reliability,and the low throughput.In order to improve the utilization efficiency and the quality of services(QoS)of cloud system,especially to solve the problem of network congestion,we propose MTSS,a multi-path traffic scheduling mechanism based on software defined networking(SDN).MTSS utilizes the data flow scheduling flexibility of SDN and the multi-path feature of the fat-tree structure to improve the traffic balance of the cloud data center network.A heuristic traffic balancing algorithm is presented for MTSS,which periodically monitors the network link and dynamically adjusts the traffic on the heavy link to achieve programmable data forwarding and load balancing.The experimental results show that MTSS outperforms equal-cost multi-path protocol(ECMP),by effectively reducing the packet loss rate and delay.In addition,MTSS improves the utilization efficiency,the reliability and the throughput rate of the cloud data center network.

MRBCH: A Multi-Path Routing Protocol Based on Credible Cluster Heads for Wireless Sensor Networks

Wireless sensor networks are widely used for its flexibility, but they also suffer from problems like limited capacity, large node number and vulnerability to security threats. In this paper, we propose a multi-path routing protocol based on the credible cluster heads. The protocol chooses nodes with more energy remained as cluster heads at the cluster head choosing phase, and then authenticates them by the neighbor cluster heads. Using trust mechanisms it creates the credit value, and based on the credit value the multi-path cluster head routing can finally be found. The credit value is created and exchanged among the cluster heads only. Theoretical analysis combined with simulation results demonstrate that this protocol can save the resource, prolong the lifetime, and ensure the security and performance of the network.

Short Baseline Positioning with an Improved Time Reversal Technique in a Multi-path Channel

在水下面的一条多路径隧道的存在极大地减少放系统的短基线的精确性。在这份报纸，到放系统的短基线的一面时间颠倒镜子的申请被调查。时间颠倒镜子技术允许声学的信号更好集中在未知环境，它有效地减少了多路径的扩大声学的信号象一样改进了集中的信号。时间颠倒操作员的 signal-to-noise 比率(SNR ) 极大地增加了并且能被 ensonifying 获得水。这种技术被环境并且因此少些影响对复杂的浅水环境更适用。数字模拟和水池实验被用来表明这种技术的效率。

A new method to estimate DOA in CDMA system in multi-path environment

An algorithm for direction angle of arrival(DOA) estimation and array calibration of signals from multiple mobile users in the CDMA systems and multi-path environment was presented . The main idea is that the algorithm employs code-matched filter and model of the inter-symbol interference and multiple-access interference exactly. The correlation matrices of the received signals before and after code-matched filtering were employed to eliminate the effect of the additive white Gaussian noise, and a new mathematical problem was created, a new maximum likelihood method based on the strong law of large number was derived for DOA estimation and array calibration. Computer simulation results prove that the algorithm is effective.

Novel multi-path routing scheme for UWB Ad hoc network

The routing protocols play an important role for ad hoc networks performance.As some problems with DSR,SMR,and AMR protocols were analyzed,a new routing protocol suitable for UWB Ad hoc networks was proposed in this paper.The new routing protocol utilize an act of orientation of UWB and tries to get sufficient route information and decrease the network load caused by route discovery at the same time.Simulation results show that the routing load of the new protocol is lower and throughput is higher than that of DSR.While the node’s mobility increases,these advantages become more obvious.

Adaptive genetic algorithm for path planning of loosely coordinated multi-robot manipulators

Adaptive genetic algorithm A SA GA, a novel algorithm, which can dynamically modify the parameters of Genetic Algorithms in terms of simulated annealing mechanism, is proposed for path planning of loosely coordinated multi robot manipulators. Over the task space of a multi robot, a strategy of decoupled planning is also applied to the evolutionary process, which enables a multi robot to avoid falling into deadlock and calculating of composite C space. Finally, two representative tests are given to validate A SA GA and the strategy of decoupled planning.

Rotary unmanned aerial vehicles path planning in rough terrain based on multi-objective particle swarm optimization

This paper presents a path planning approach for rotary unmanned aerial vehicles(R-UAVs)in a known static rough terrain environment.This approach aims to find collision-free and feasible paths with minimum altitude,length and angle variable rate.First,a three-dimensional(3D)modeling method is proposed to reduce the computation burden of the dynamic models of R-UAVs.Considering the length,height and tuning angle of a path,the path planning of R-UAVs is described as a tri-objective optimization problem.Then,an improved multi-objective particle swarm optimization algorithm is developed.To render the algorithm more effective in dealing with this problem,a vibration function is introduced into the collided solutions to improve the algorithm efficiency.Meanwhile,the selection of the global best position is taken into account by the reference point method.Finally,the experimental environment is built with the help of the Google map and the 3D terrain generator World Machine.Experimental results under two different rough terrains from Guilin and Lanzhou of China demonstrate the capabilities of the proposed algorithm in finding Pareto optimal paths.

Thermo-Calc based multi-component micro-segregation model and solidification paths calculations

On the basis of a multi-length scale modeling, a mixture-averaged multi-component /multiphase micro-segregation model was proposed without pre-set function for the micro-scale solute profile. The model explains the effect of morphologies of solidifying phases and solid back diffusion (SBD) on segregation, and covers the two limiting solidification cases of Scheil and Lever-rule models. A commercial Thermo-Calc software package/database was linked to the algorithms via its TQ6-interface for instantaneous determination of the related thermodynamic data of the multi-component alloys. The influences of cooling rate and other parameters on the solidification path and micro-segregation behavior were numerically investigated by sample calculation of the ternary Al-Cu-Mg alloys. A parallel experimental investigation on Al-Cu-Si alloys solidified under different cooling conditions was conducted to validate the theoretical model. Reasonable agreements were gained between the predicted solidification paths and the measured results.

Multi-path planning algorithm based on fitness sharing and species evolution

A new algorithm is proposed for underwater vehicles multi-path planning. This algorithm is based on fitness sharing genetic algorithm, clustering and evolution of multiple populations, which can keep the diversity of the solution path, and decrease the operating time because of the independent evolution of each subpopulation. The multi-path planning algorithm is demonstrated by a number of two-dimensional path planning problems. The results show that the multi-path planning algorithm has the following characteristics: high searching capability, rapid convergence and high reliability.

The quickly switching routing algorithm based on multi-path in mobile Ad Hoc networks

This paper proposes a new on-demand multi-alternate-path algorithm, called quickly switching routing algorithm(QSRA). It switches failure routing to an alternate path as quickly as the network can. Like a nervure shape, algorithm QSRA shapes disjoint-alternate-path structure, but is not limited to. It also contains another structure that every primary node has several links to alternate paths. This structure has two advantages, the first one is that primary nodes can select one alternate path immediately when primary routing is failure without going back to source node to re-discover a new routing or choose an alternate path; the second is that it guarantees primary nodes can select another alternate path as quickly as possible once one of alternate paths fails. Strongpoint of algorithm QSRA is reducing frequency of routing re-discovering. Besides, the structure occupies fewer resources than other routing algorithms due to its distributed structure. Simulation shows that QSRA has higher packets received ratio and lower control packet overhead and lower end-to-end delay.

A Multi-pipe Path Planning by Modified Ant Colony Optimization

Path planning in 3D geometry space is used to find an optimal path in the restricted environment, according to a certain evaluation criteria. To solve the problem of long searching time and slow solving speed in 3D path planning, a modified ant colony optimization is proposed in this paper. Firstly, the grid method for environment modeling is adopted. Heuristic information is connected with the planning space. A semi-iterative global pheromone update mechanism is proposed. Secondly, the optimal ants mutate the paths to improve the diversity of the algorithm after a defined iterative number. Thirdly, co-evolutionary algorithm is used. Finally, the simulation result shows the effectiveness of the proposed algorithm in solving the problem of 3D pipe path planning.

An Efficient CSI Feedback Scheme for Dual-Polarized MIMO Systems Using Layered Multi-Paths Information

Massive MIMO is one of the enabling technologies for beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large number of antenna elements in limited space. However,current CSI(channel state information)feedback schemes developed in LTE for conventional MIMO systems are not efficient enough for massive MIMO systems since the overhead increases almost linearly with the number of antenna. Moreover,the codebook for massive MIMO will be huge and difficult to design with the LTE methodology. This paper proposes a novel CSI feedback scheme named layered Multi-paths Information based CSI Feedback(LMPIF),which can achieve higher spectrum efficiency for dual-polarized antenna system with low feedback overhead. The MIMO channel is decomposed into long term components(multipath directions and amplitudes)and short term components(multipath phases). The relationship between the two components and the optimal precoder is derived in closed form. To reduce the overhead,different granularities in feedback time have been applied for the long term components and short term componentsLink and system level simulation results prove that LMPIF can improve performance considerably with low CSI feedback overhead.

SOPA:Source Routing Based Packet-Level Multi-Path Routing in Data Center Networks

Many ＂rich - connected＂ topologies with multiple parallel paths between smwers have been proposed for data center networks recently to provide high bisection bandwidth, but it re mains challenging to fully utilize the high network capacity by appropriate multi- path routing algorithms. As flow-level path splitting may lead to trafl＇ic imbalance between paths due to flow- size difference, packet-level path splitting attracts more attention lately, which spreads packets from flows into multiple available paths and significantly improves link utilizations. However, it may cause packet reordering, confusing the TCP congestion control algorithm and lowering the throughput of flows. In this paper, we design a novel packetlevel multi-path routing scheme called SOPA, which leverag- es OpenFlow to perform packet-level path splitting in a round- robin fashion, and hence significantly mitigates the packet reordering problem and improves the network throughput. Moreover, SOPA leverages the topological feature of data center networks to encode a very small number of switches along the path into the packet header, resulting in very light overhead. Compared with random packet spraying （RPS）, Hedera and equal-cost multi-path routing （ECMP）, our simulations demonstrate that SOPA achieves 29.87%, 50.41% and 77.74% higher network throughput respectively under permutation workload, and reduces average data transfer completion time by 53.65%, 343.31% and 348.25% respectively under production workload.

Link-Vertex Topology Aggregation for Multi-domain Path Computation with Hierarchical PCE Architecture

Inter-domain path computing is one big issue in multi-domain networks. The Hierarchical Path Computing Element (H-PCE) is a semi-central architecture for computing inter-domain path. To facilitate H-PCE in inter-domain path computing, this paper proposed a topology aggregation scheme to abstract the edge nodes and their connected inter-domain link as one vertex to achieve more optimal paths and confidentiality guarantee. The effectiveness of the scheme has been demonstrated on solving wavelength routing in multi-domain Wavelength Division Multiplexing (WDM) network via simulation. Simulation results show that this scheme reduces at least 10% inter-domain blocking probability, compared with the traditional Domain-to-the-Node (DtN) scheme.

Intelligent learning technique based-on fuzzy logic for multi-robot path planning

Soccer robot system is a tremendously challenging intelligent system developed to mimic human soccer competition based on the multi discipline research: robotics, intelligent control, computer vision, etc. robot path planning strategy is a very important subject concerning to the performance and intelligence degree of the multi robot system. Therefore, this paper studies the path planning strategy of soccer system by using fuzzy logic. After setting up two fuzziers and two sorts of fuzzy rules for soccer system, fuzzy logic is applied to workspace partition and path revision. The experiment results show that this technique can well enhance the performance and intelligence degree of the system.