Adaptive bandwidth framework for provisioning connection-level QoS for next-generation wireless cellular networks

The next generation of wireless cellular networks is expected to support real-time multimedia services with different classes of traffic and diverse bandwidth requirements. Bandwidth is a scarce resource in wireless networking that needs to be carefully allocated amid competing connections with different quality of service (QoS) requirements. In this paper, an adaptive framework for supporting multiple classes of multimedia services with different QoS requirements in wireless cellular networks is proposed. The framework combines the following components: (1) a threshold-based bandwidth allocation policy that gives priority to handoff calls over new calls and prioritizes among different classes of handoff calls by assigning a threshold to each class; (2) an efficient threshold-type call admission control (CAC) algorithm; and (3) a bandwidth adaptation algorithm (BAA) that dynamically adjusts the bandwidth of ongoing multimedia calls to minimize the number of calls receiving lower bandwidth than they had requested. Numerical results show that the proposed adaptive multimedia framework outperforms existing non-adaptive schemes in terms of the handoff call dropping probability and effective utilization.     

Dynamic multicast traffic grooming in WDM networks

Dynamic multicast traffic grooming in wavelength division multiplexing (WDM) networks was analyzed to minimize networkwide costs and to increase the network resource utilization. A network model was developed for dynamic multicast traffic grooming with resource constraints and an algorithm that can provide quality of service (QoS) was proposed. The QoS is measured by the maximum number of lightpaths passing between the source and the destinations. The blocking probability of the algorithm was assessed in simulations. The results show that a higher QoS requirement results in higher blocking probability, and when the QoS requirement is low, changes in the QoS requirements have only small effects on the blocking probability. __________ Translated from Journal of Tsinghua University (Science and Technology), 2005, 45(4): 437–440 (in Chinese)     

Power allocation in opportunistic cooperative relaying systems

To enhance the performance of opportunistic cooperative relaying systems, this paper proposes power allocation algorithms aimed at minimizing the outage probability. The optimization model of the system is constructed and proved to be a convex optimization problem. Then the optimal power allocation algorithm and its operation steps are presented. Furthermore, a simple and effective near-optimal power allocation strategy is developed, which only depends on the average channel gains of the relays and thus incurs little overhead. Simulation and numerical results show that significant performance gains can be achieved by the two proposed power allocation algorithms. __________ Translated from Acta Electronica Sinica, 2008, 36(10): 1944–1948 [译自: 电子学报]     

QoS-aware dynamic bandwidth allocation algorithm for Gigabit-capable PONS

The Gigabit-capable passive optical network (GPON) technology is being considered as a promising solution for the next-generation broadband access network. Since the network topology of the GPON is point-tomultipoint, a media access control called dynamic bandwidth allocation (DBA) algorithm is an important factor for determining the performance of the GPON. In this paper, we propose a new DBA algorithm to effectively and fairly allocate bandwidths among end users. This DBA algorithm supports differentiated services—a crucial requirement for a converged broadband access network with heterogeneous traffic. In this article we first reviewed the signaling and configuration of the DBA, and then proposed a new DBA scheme that implemented QoS-based priority for this need to maximally satisfy the requirements of all optical network units (ONUs) and provide differentiated services. Analyses and simulation results show that the new algorithm can improve the bandwidth utilization and realize the fairness for both different ONUs and services.     

Novel P-Cycle protection strategy for asymmetric traffic in mesh optical networks

A novel prefigured-cycle (P-Cycle) algorithm was proposed to improve the protection success ratio for asymmetric traffic in mesh optical networks. The proposed algorithm was simulated in a Pan-European COST239 network environment under an asymmetric dynamic traffic model. The experimental results show that the proposed algorithm has lower capacity redundancy and higher utilization rate of configured resources than traditional P-Cycle methods. Network performance can be improved when implementing this algorithm under single-link failure circumstances. The system behavior is analyzed under different traffic volumes and the configuration strategy is also investigated for the heavyload and light-load networks respectively. __________ Translated from Journal of Beijing University of Posts and Telecommunications, 2008, 31(1): (1–4) [译自: 北京邮电大学学报]     

FlexGrid标准研究进展及应用分析

针对电力企业数据业务流量爆炸性增长所引发的骨干网络带宽资源瓶颈问题,在对国家电网公司光传输网（optical transport network,OTN）大容量骨干传输网络承载业务需求分析基础上,从频谱管理方法、交叉连接设备、混合线速传输、控制平面等方面出发,探索FlexGrid技术在电力通信网络中的应用模式,可为电力通信骨干网络提供光层粒度的精细划分与动态调整能力.在此基础上,提出在多种约束条件下根据频谱资源利用度动态调节调制的信道资源管理方法,可有效改善现有骨干传输网络采用的固定带宽分配和管理模式造成网络灵活性差,带宽资源利用效率低下的现状.     

Application of BP neural networks in non-linearity correction of optical tweezers

The back-propagation (BP) neural network is proposed to correct nonlinearity and optimize the force measurement and calibration of an optical tweezer system. Considering the low convergence rate of the BP algorithm, the Levenberg-Marquardt (LM) algorithm is used to improve the BP network. The proposed method is experimentally studied for force calibration in a typical optical tweezer system using hydromechanics. The result shows that with the nonlinear correction using BP networks, the range of force measurement of an optical tweezer system is enlarged by 30% and the precision is also improved compared with the polynomial fitting method. It is demonstrated that nonlinear correction by the neural network method effectively improves the performance of optical tweezers without adding or changing the measuring system. __________ Translated from Optics and Precision Engineering, 2008, 16(1): 6–10 [译自: 光学精密工程]     

适用于IEC 61850标准的以太网无源光网络DBA算法

在分析IEC 61850标准下网络报文传输特性的基础上,提出一种适用于IEC 61850标准网络报文传输的以太网无源光网络动态带宽分配算法。首先,该算法采用固定轮询周期,将带宽划分为采样值(SMV)、面向对象的变电站通用事件(GOOSE)、制造报文规范(MMS)这三类及三个优先级,优先保证SMV报文、GOOSE报文的实时传输,减少网络时延抖动。然后,采用改进的REPORT上传和GATE下发机制,提高了带宽利用率,并简要介绍了算法的典型应用系统及测试验证方案。最后,测试结果表明,该算法满足IEC 61850标准网络报文传输的实时性和快速性要求。     

An improved hypothesis-feedback equalization algorithm for multicode direct-sequence spread-spectrum underwater communications

In underwater acoustic communication, because the available bandwidth of the channel is severely limited, the direct-sequence spread-spectrum scheme can only be realized at low bit rates. To improve the transmission speed, a multicode spread-spectrum scheme is considered. However, in this case, due to the rapid time-variability of the underwater channel, and the influence of inter-symbol interference (ISI) and inter-channel interference (ICI), the conventional rake receiver may fail to function. The hypothesis-feedback equalization algorithm has been proposed for the direct-sequence spread-spectrum system [1]. By updating coefficients at chip rate and feeding back hypothesized chips, it can track time-variability and combat ISI effectively. However, for a multicode system, its performance will be degraded by ICI. An improved algorithm is proposed in this paper, which combines parallel interference cancellation (PIC) with hypothesis-feedback equalization (HFE), with the capabilities of tracking the time-varying channel and suppressing the ISI and ICI at the same time. Simulation results prove that the proposed algorithm can significantly improve the performance of a multicode system. Translated from Journal of Northwestern Polytechnical University, 2006, 24(6): 726–729 [译自: 西北工业大学学报]     

Cross-Layer Design of Dynamic Bandwidth Allocation in DVB-RCS

In this paper, a novel cross-layer framework for optimizing the dynamic bandwidth allocation (DBA) of a digital video broadcast (DVB)-return channel satellite (RCS) system using adaptive coding is proposed. The design of the medium access control (MAC) methods taking into account the adaptive physical layer and higher layers' quality of service (QoS) requirements is cast as an optimization problem by using the network utility maximization (NUM) framework applied within the satellite subnetwork. Hierarchical and global solving procedures fully compliant with the DVB-RCS standard are proposed. They do not only provide minimum bandwidth guarantees but also maximize fairness. Further, they allow a joint optimization of the time slot size and overall system efficiency while minimizing signalling overhead. A reduced computational complexity algorithm to solve the DBA problem is presented. In practical terms, it increases the number of connections with absolute and relative QoS requirements the system can manage and facilitates the interoperability of the satellite network within an Internet protocol (IP) environment.     

面向泛在电力物联网的智能配用电信息采集业务通信分析

泛在电力物联网的建设对配用电通信网的经济性、安全性、可靠性提出了更高的要求,科学合理的通信网络架构和配置方法是亟待研究的问题。文章首先提出了面向泛在电力物联网的智能配用电通信网络架构,分析了智能配用电业务的通信性能约束;然后针对配用电信息采集类业务,建立了基于排队论的通信带宽计算模型及以带宽利用率最大化为目标函数的带宽优化模型,并以某智能配电房改造项目为应用场景,求解并分析了其业务延时、丢包率、带宽利用率与带宽配置关系;最后借助OPNET仿真平台验证了所提方法的可行性。     

Optimal planning of high voltage distribution substations

Aimed at solving the problem of optimal planning for high voltage distribution substations, an efficient method is put forward. The method divides the problem into two sub-problems: source locating and combinational optimization. The algorithm of allocating and locating alternatively (ALA) is widely used to deal with the source locating problem, but it is dependent on the initial location to a large degree. Thus, some modifications were made to the ALA algorithm, which could greatly improve the quality of solutions. In addition, considering the non-convex and non-concave nature of the sub-problem of combinational optimization, the branch-and-bound technique was adopted to obtain or approximate a global optimal solution. To improve the efficiency of the branch-and-bound technique, some heuristic principles were proposed to cut those branches that may generate a global optimization solution with low probability. Examples show that the proposed algorithm meets the requirement of engineering and it is an effective approach to rapidly solve the problem of optimal planning for high voltage distribution substations. Translated from Journal of Tianjin University, 2006, 39(8): 889–894 [译自: 天津大学学报]     

一种基于时隙动态分配的FlexRay系统通信机制

汽车FlexRay总线系统中消息的调度方法直接关系到整车通信实时性。针对FlexRay系统静态段固定分配时隙机制的不足,提出一种静态时隙动态分配的消息调度机制(SDAS),给出该机制下调度器的状态转换模型和运行算法,并定量分析各静态消息最坏响应时间;在对FlexRay帧结构设计基础上,以静态段时间碎片最小为目标,以消息可调度和通信周期有界为约束条件,建立了SDAS机制下相关网络参数的配置方法。实验仿真结果表明,与固定分配时隙相比,SDAS机制能有效提高消息实时性和带宽利用率。     

ASAR: An ant-based service-aware routing algorithm for multimedia sensor networks

Aimed at three basic services (event-driven, data query and stream query), the paper presents a QoS routing model for multimedia sensor networks. Moreover, based on the traditional ant-based algorithm, we propose an ant-based service-aware routing (ASAR) algorithm. The ASAR chooses suitable paths to meet diverse QoS requirements from different kinds of services, thus maximizing network utilization and improving network performance. Finally, extensive simulation is conducted to verify the effectiveness of our solution and we give a detailed discussion on the effects of different system parameters. Compared to the typical routing algorithm in sensor networks and the traditional ant-based algorithm, our ASAR algorithm has better convergence and significantly provides better QoS for multiple types of services in the multimedia sensor networks. __________ Translated from Acta Electronica Sinica, 2007, 35(4): 705–711 [译自: 电子学报]     

Research on run-time overhead of RM and improvement

The rate-monotonic (RM) algorithm is a classic fixed priority real-time scheduling algorithm. However, in most embedded real-time systems where the workload is composed of many tasks of high frequency and short execution time, the overheads from preemptions of the real-time operating system will lead to a low resource utilization rate if the RM algorithm is directly used. By studying the preemption relationship of the tasks scheduled by RM algorithm, a model of preemption overheads is established with task attributes, based on which the run-time preemption overheads of RM algorithm are reduced by optimizing the start time of the tasks in embedded real-time systems. Finally, the experimental results show the validity of the proposed strategy. __________ Translated from Journal on Communications, 2008, 29(2): 79–86 [译自: 通信学报]     

Ultra‐low‐noise large‐bandwidth transimpedance amplifier

Equivalent input current noise and bandwidth are the most relevant parameters qualifying a low‐noise transimpedance amplifier. In the conventional topology consisting of an operational amplifier in a shunt‐shunt configuration, the equivalent input noise decreases as the feedback resistor (R_F), which also sets the gain, increases. Unfortunately, as R_F increases above a few MΩ, as it is required for obtaining high sensitivity, the bandwidth of the system is set by the parasitic capacitance of R_F and reduces as R_F increases. In this paper, we propose a new topology that allows overcoming this limitation by employing a large‐bandwidth voltage amplifier together with a proper modified feedback network for compensating the effect of the parasitic capacitance of the feedback resistance. We experimentally demonstrate, on a prototype circuit, that the proposed approach allows to obtain a bandwidth in excess of 100 kHz and an equivalent input noise of about 4 fA/ , corresponding to the current noise of the 1 GΩ resistor that is part of the feedback network. The new approach allows obtaining larger bandwidth with respect to those obtained in previously proposed configurations with comparable background noise. Copyright © 2014 John Wiley & Sons, Ltd.     

Power allocation scheme for multicell interference coordination in OFDMA systems

To coordinate inter-cell interference, a multicell adaptive power allocation scheme is proposed for downlink orthogonal frequency division multiple access (OFDMA) cellular systems. This scheme uses the difference of the signal to interference plus noise ratio (SINR) between the co-subchannels of adjacent cells to balance SINR for coordinating the transmit power in the co-subchannels. The scheme can improve edge user performance, reduce interference between the co-subchannels of adjacent cells and improve radio resource utility. Simulation results show that the scheme can balance system performance and ensure system throughput. __________ Translated from Journal of Beijing University of Posts and Telecommunications, 2008, 31(1): 71–74 [译自: 北京邮电大学学报]     

Structure of frequency hopping sequences family based on block cipher

A novel family of frequency-hopping (FH) sequences based on iterated block cipher is proposed for frequencyhopping multiple-access (FHMA) communications. The design offers a class of nonlinear FH codes with high security, large linear span and a uniform spread over the entire frequency bandwidth. Moreover, FH sequences among the family are independent from each other and they perform as well as random patterns in terms of multiple access interference in anti-jamming applications. With the performance of packet error and throughput for FHMA network being derived in theory, many numerical results of the 3DES sequences are presented, comparing with those of shift register sequences and chaotic FH sequences. Efficiently implemented in field programmable gate arrays (FPGA), the generator prototype of the proposed sequence has been realized and incorporated into fast FH radio. __________ Translated from Acta Electronic Sinica, 2005, 33(4): 620–623 (in Chinese)     

Efficient and fine scheduling algorithm for bandwidth allocation in ethernet passive optical networks

A novel fine scheduling algorithm is introduced for upstream bandwidth allocation in an Ethernet-based passive optical network. This scheduling algorithm consists of an inter optical network unit (ONU) scheduler at the optical line terminal (OLT) and an intra-ONU scheduler at each ONU. In the inter-ONU scheduling, a novel GATE/REPORT approach is introduced to eliminate the unused remainders without transmission delay and maximize the utilization of bandwidth. Our novel intra-ONU scheduler gives fair bandwidth allocation to the queues of different priorities for each user in a hierarchical and decentralized way. Numerical results have shown that our overall scheduling algorithm can fulfill various requirements of delay and throughput for the transmission of multimedia traffic for each end user.     

Simulation study on delay of end-to-end data communication for protective relaying in substations

The end-to-end delay of protective relaying data flow in a substation was studied by dynamic simulation modeling technology. The distribution characteristics of protective relaying data flow and the constitution of the end-to-end delay of messages were analyzed. The simulation model for digital communication between protective relaying equipment and monitoring equipment of interval layer was suggested. The end-to-end delay of protective relaying data flow in different network configurations was analyzed. It is found that the size and interval of the data frame, utilization of the link background and protocols of higher layer are key factors of real-time performance. Detailed analysis results are presented. A proposal for network configuration is suggested to reduce end-to-end delay of protective relaying data flow. __________ Translated from Journal of North China Electric Power University, 2007, 34(1): 101–105 [译自: 华北电力大学学报]