3G wireless communications for mobile robotic tele-ultrasonography systems

Mobile healthcare (m-health) is a new paradigm that brings together the evolution of emerging wireless communications and network technologies with the concept of 'connected healthcare' anytime and anywhere. In this article, we present the performance analysis of an end-to-end mobile tele-echography using an ultra-light robot (OTELO), over the third-generation (3G) mobile communications network. The experimental setup of the OTELO system over a 3G connectivity link used to measure the system performance is described. The performance of the relevant medical data and the relevant quality of service (QoS) issues defined in terms of the average throughput, delta-time packet delay, and jitter delay are investigated. The real-time 3G performance results show the successful operation of this bandwidth demanding robotic m-health system.     

Markov chain model of fault-tolerant wireless networked control systems

Wireless Networks - Wireless networked control systems (WNCS) are composed of spatially distributed sensors, actuators, and controllers communicating through wireless networks instead of...     

Novel semi-blind ICI equalization algorithm for wireless OFDM systems

Intercarrier interference is deemed as one of the crucial problems in the wireless orthogonal frequency division multiplexing (OFDM) systems. The conventional ICI mitigation schemes involve the frequency-domain channel estimation or the additional coding, both of which require the spectral overhead and hence lead to the significant throughput reduction. Besides, the OFDM receivers using the ICI estimation rely on a large-dimensional matrix inverter with high computational complexity especially for many subcarriers such as digital video broadcasting (DVB) systems and wireless metropolitan-area networks (WMAN). To the best of our knowledge, no semi-blind ICI equalization has been addressed in the existing literature. Thus, in this paper, we propose a novel semi-blind ICI equalization scheme using the joint multiple matrix diagonalization (JMMD) algorithm to greatly reduce the intercarrier interference in OFDM. However, the well-known phase and permutation indeterminacies emerge in all blind equalization schemes. Hence we also design a few OFDM pilot blocks and propose an iterative identification method to determine the corresponding phase and permutation variants in our semi-blind scheme. Our semi-blind ICI equalization algorithm integrating the JMMD with the additional pilot-based iterative identification is very promising for the future high-throughput OFDM systems. Through Monte Carlo simulations, the QPSK-OFDM system with our proposed semi-blind ICI equalizer can achieve significantly better performance with symbol error rate reduction in several orders-of-magnitude. For the 16QAM-OFDM system, our scheme can also improve the performance over the plain OFDM system to some extent.     

无线通信系统通道校准算法研究

多通道无线通信系统中各通道的校准是关键技术,通过设计特定的训练序列,并采用高效的快速算法,在线实时校正阵列天线系统多个通道的幅度和相位.分析了发射通道和接收通道的性能,理论分析和计算机仿真结果表明,该算法能校正通道之间的幅度和相位误差,而且实现简单,具有较好的校准性能.     

Detection of interruption attack in the wireless networked closed loop industrial control systems

Telecommunication Systems - Due to tremendous growth in the network, security is a major concern and it is gaining a high level of attention in the system. In the Industrial control systems such as...     

一种新的MIMO无线通信系统链路自适应算法

提出并分析了一种适用于MIMO系统的新的链路自适应算法。通过接收端估计信噪比,并利用各种编码调制方式的特性,该算法在接收端采用递归的方法确定了每一个发射端子信道所采用的编码调制方式,使反向链路仅传输少量的控制信息,实现了链路的自适应。仿真结果表明,文章所提出的算法大大提高了MIMO系统的吞吐量,且可靠性也显著增加。     

A fast time slot assignment algorithm for TDM hierarchicalswitching systems

A fast (polynomial time) network-flow-based algorithm is presented for time slot assignment in time-division-multiplexing (TDM) hierarchical switching systems. For a nonblocking time-multiplexed central switch the algorithm produces a conflict-free time slot assignment for a given frame (whenever this is possible) on O(M ⁵) time, where M is the system size     

一种适用于多径衰落无线信道的快速盲均衡算法研究

在无线数字通信中,信道衰落和多途传播效应引起的码间干扰,严重影响了通信的有效性和可靠性,盲均衡是对抗码间干扰的有效方法。文章研究了一种适用于无线信道的快速盲均衡算法,并进行了计算机仿真。仿真结果表明,在算法剩余均方误差非常接近的情况下,该算法快于传统的常数模算法。     

一种改进的快速最小K邻居定位算法

根据现有的基于信号强度的室内无线定位算法,结合二分查找的思想,提出了一种具有较低复杂度的室内无线定位算法,即快速最小K邻居定位算法。该算法通过将定位区域划分为多个子区域,利用优化的计算迅速缩小定位区域,再反复利用同样方法进一步缩小定位区域,得到极小的定位区域。最后在最小区域内通过最近K邻居定位算法估计待测点的位置。通过仿真证明,相比于现有的最小K邻居定位算法,该算法在损失极小的定位精度的同时极大的降低了定位复杂度。     

An improvement of DV-Hop localization algorithm for wireless sensor networks

An improved DV-HOP localization algorithm is proposed based on the traditional DV-HOP localization algorithm in the paper. There will be a big error that using the nearest anchor node’s average hop distance instead of the average hop distance of all the anchor nodes that involved in the localizing in the traditional DV-HOP localization algorithm. Therefore, the improved algorithm introduces threshold M, it uses the weighted average hop distances of anchor nodes within M hops to calculate the average hop distance of unknown nodes. In addition, the positioning results are corrected in the improved algorithm. The simulation results show that the new localization algorithm effectively improves the positioning accuracy compared with the traditional DV-HOP localization algorithm, it is an effective localization algorithm in the wireless sensor networks.     

A new fast polling algorithm in wireless mesh network for narrowband Internet of Things

Telecommunication Systems - We present a new fast polling algorithm (FPA) in a wireless mesh network (WMN) for Narrowband Internet of Things systems using multi-hop WMNs. We focus on wireless...     

一种改进的一维Otsu快速算法

阈值分割是众多图像分割方法中使用最普遍的一种方法,阈值的求解也是图像处理的重心。传统Otsu算法属于穷举式的阈值求解方法,需遍历每个灰度值并计算以其为阈值的类间方差,在此进行了大量不必要的计算,可能无法应用于某些实时性要求较高的环境中。对此提出一种快速的Otsu改进算法,在引入图像复杂度及其相关性质缩小了灰度的搜索范围,同时在搜索范围内使用了一种快速计算方法,较传统Otsu算法进行了二次加速。实验结果证明,该算法较传统Otsu算法提高了计算速度,且两种算法的图像分割结果相同。     

A low complexity VBLAST OFDM detection algorithm for wireless LAN systems

A low complexity detection algorithm for VBLAST OFDM system is presented. Using the fact that the correlation among neighboring subcarriers is high for wireless LAN channels, this algorithm significantly reduces the complexity of VBLAST OFDM detection. The performance degradation of the proposed algorithm is small compared to conventional detection.     

VEPSD: a novel velocity estimation algorithm for next-generation wireless systems

A novel algorithm called velocity estimation using the power spectral density (VEPSD), which uses the Doppler spread in the received signal envelope to estimate the velocity of a mobile user (MU), is introduced in this paper. The Doppler spread is estimated using the slope of the power spectral density (PSD) of the received signal envelope. The performance of the VEPSD algorithm is evaluated in both Rayleigh and Rician fading environments. The sensitivity of the estimation error to additive white Gaussian noise (AWGN), Rice factor (K), and the angle of arrival of the line-of-sight (LOS) component is analyzed and compared with the level crossing rate (LCR) and covariance-based velocity estimators. Simulation results show that VEPSD estimates the velocity of MUs accurately. It is also shown that VEPSD can be used for velocity estimation under nonisotropic scattering and is well suited for next-generation wireless systems (NGWSs).     

一种快速有效的自适应算术编码

介绍了算术编码的原理和基于模型的自适应算术编码算法,并利用二进制索引树这样一个高效率的数据结构对传统的0阶自适应算术编码进行了改进。实验表明,无论对于高度集中的数据集还是对于分布较为均匀的数据集,在运行时间上新算法都有较大的改进。     

一种改进的快速相关攻击算法

T.Johansson[4]提出了一种基于卷积码维特比(Viterbi)译码方案的快速相关攻击算法。在此基础上, 本文对这个算法进行了改进,提出了一种序列密码的快速相关攻击的改进算法。该改进算法使用了Fano译码方案: 由于它在寻找正确的路径时,力求尽早地排除所有非最大似然路径,这样使译码复杂度比维特比的译码复杂度低, 从而大大地提高了算法攻击成功的速度。     

An evolutionary algorithm for broadcast scheduling in wireless multihop networks

A technical challenge in successful deployment and utilization of wireless multihop networks (WMN) are to make effective use of the limited channel bandwidth. One method to solve this challenge is broadcast scheduling of channel usage by the way of time division multiple access (TDMA). Three evolutionary algorithms, namely genetic algorithm (GA), immune genetic algorithm (IGA) and memetic algorithm (MA) are used in this study to solve broadcast scheduling for TDMA in WMN. The aim is to minimize the TDMA cycle length and maximize the node transmissions with reduced computation time. In comparison to GA and IGA, MA actively aim on improving the solutions and is explicitly concerned in exploiting all available knowledge about the problem. The simulation results on numerous problem instances confirm that MA significantly outperforms several heuristic and evolutionary algorithms by solving well-known benchmark problem in terms of solution quality, which also demonstrates the effectiveness of MA in efficient use of channel bandwidth.     

An adaptive load-aware routing algorithm for multi-interface wireless mesh networks

In wireless mesh networks, the number of gateway nodes are limited, when the nodes access to the internet by fixed gateway node, different requirements of nodes lead to the dataflow shows heterogeneity. Many new routing metrics and algorithms existing in traditional wired networks and the Ad Hoc network, can not be directly applied to wireless mesh networks, so how to design a routing metric and algorithm which can dynamically adapt to current networks topology and dataflow changes, avoid bottleneck node, and select the most stable and least congestion link to establish a route is very important. In this paper, we presented a new dynamic adaptive channel load-aware metric (LAM) to solve the link load imbalance caused by inter-flow and inner-flow interference, designed a self-adaptive dynamic load balancing on-demand routing algorithm through extending and improving AODV routing method with the LAM, to achieve flow balance, reduce the high packet loss ratio and latency because congestion and Packet retransmission, and can increase Network Throughput.     

An hp-shape hexa-band antenna for multi-standard wireless communication systems

Wireless Networks - This paper presents design of an hp-shaped reconfigurable antenna printed on a 1.6 mm thicker FR-4 substrate. The antenna works in four distinct modes frequency modes,...     

An improved two-state turbo-SPC code for wireless communication systems

This letter presents an improved two-state turbo single-parity-check code for applications with rates around 1/3. The new code is compared with the (15,13)/sub 8/ turbo code used in the Third Generation Partnership Project. Simulation results demonstrate that the proposed code can achieve similar performance at reduced decoding complexity.