智能终端中热IP核的通信方法

片上网络通信架构的改进,使热IP核连接多个路由器,并且原本与热IP核相连的一个路由器的通信量被分配到多个路由器上。基于改进的片上网络通信架构,又设计出新的路由器选择算法。在该算法中,可以根据热IP连接的路由器的当前状态选择数据通信的路由,这样使得热IP能够更加均匀地分配通信量,从而有效地提高了数据传输效率,降低数据传输延时。实验表明,新的算法能够有效减少传输延迟。     

无线传感器网络差分修正定位算法的改进

提出了无线传感器网络中一种基于接收信号指示强度的改进差分修正算法,与传统的差分修正算法相比,在该算法中,通过各个信标节点分别作为差分参考节点进行定位,避免了单个差分参考节点对未知节点定位决定权过大。同时,提出加权因子的概念,体现了各差分参考点对定位效果的决定权。实验结果表明,改进的差分修正算法的定位精度和稳定性有明显提高。     

质心定位中的加权坐标误差修正方法

针对IoT中需求高精度节点定位的问题,提出了一种加权坐标误差修正的质心定位算法。首先对距离无关质心定位算法进行分析,然后使用RSSI测量标记节点与待定位节点的距离,并结合信号衰减度对坐标加权,最后对节点坐标误差修正,进一步精确节点坐标。实验仿真结果表明,本文提出的加权坐标误差修正方法相对于传统定位算法,有更强的抗干扰能力和鲁棒性。     

用微波辐射计测量大气积分水汽的改进算法

提出选择具有最佳频率组合的双通道微波辐射计,通过测量路径上的湿延迟来解算积分水汽含量的改进算法。由于在湿延迟测量模式中,消除了云中液态水对湿延迟测量的"过量"影响,湿延迟测量具有很高的精度。因此,改进算法可提高云天大气积分水汽的测量精度,与由辐射亮温直接解算的传统算法相比测量误差可减小35%以上。     

基于距离修正的DV-Hop改进算法

传统的DV-Hop算法定位精度不高,针对这种情况,提出一种基于距离修正的改进算法。改进算法在两方面对传统算法进行改进。首先修正锚节点间距离,通过修正后计算出的平均跳距更加精确。第二步修正未知节点到锚节点距离,使估算出的未知节点位置更加准确,最终达到高精度定位。修正后在matlab平台上进行仿真,仿真结果表明定位精度有明显提高,是一种简单实用的改进定位算法。     

一种基于IEEE1588协议的同步误差修正算法

为了减小网络传输抖动误差对IEEE1588时间同步协议的影响,提高网络授时精度,本文对IEEE1588协议的原理进行了研究,并提出了卡尔曼平滑滤波修正算法。首先,详细分析了影响同步精度的几个因素,依据IEEE1588延迟请求响应机制,分析推导了偏移测量值的噪声模型,并在此基础上对卡尔曼平滑滤波算法进行仿真,仿真中对比滤波前后的同步精度,验证了该设计的可行性和算法的有效性。     

低仰角对流层折射修正快速算法

大气的折射效应引起电波传播延迟和路径弯曲,测量数据对流层修正的精度直接影响到飞行目标轨（弹）道确定的精度。考虑到对流层折射修正的精度和效率以及5°以下低仰角数据传统修正方法具有较大的误差,通常不对测量数据进行实时对流层折射修正,这使得实时定位的精度受到较大影响。研究设计了一种能够应用于实时数据处理快速有效的对流层折射修正迭代算法。经大量外场实测数据验证,该算法能够有效地消除低仰角对流层折射偏差,对高仰角测量数据的对流层折射修正亦具有较高的精度。     

面向虚拟路由器的基于历史转发开销的资源调度算法

通过研究以Xen为代表的虚拟工具中资源调度算法,得知它们无法保证虚拟路由器中资源共享的公平性。该文提出一种基于历史转发开销的资源调度算法,用来确保路由器实例占用资源的公平性,尤其物理平台的输入/输出(I/O)资源。该算法通过统计路由器实例最近的报文转发开销来计算出路由器实例调度的优先级,确保平均吞吐量较低的路由器实例获得被调度的机会。同时,该算法通过设置优先级计算公式中处理延迟的值,达到对延迟敏感强的路由器实例的支持,以及通过预测报文处理时间决定待处理报文是否丢弃,避免不必要的系统开销。通过实验测试,相对于Credit算法,该文算法在确保虚拟路由器资源共享的公平性方面存在明显优势,并且能为延迟敏感的路由器实例提供支持。     

一种部分信道响应环境中的多用户MIMO-OFDM自适应子载波分配优化算法

该文提出一种在部分信道响应环境中利用各个用户的信道反馈信息自适应调整多用户子载波分配的优化算法,该算法考虑到实际环境中反馈信息延迟和误差引起的部分信道响应情况,结合各用户的反馈信道信息和动态子载波组分配技术,可实现有效降低自适应子载波分配运算量同时又不明显弱化系统性能的目的。仿真结果表明,该算法可改善部分信道响应带来的负面影响,同时也使子载波分配算法获得较大的简化。     

基于 IMM 的改进去偏转换测量目标跟踪算法

针对机动目标跟踪,提出一种基于交互式多模型的改进去偏转换测量卡尔曼滤波算法（IMM－MDCMKF）,该算法在多模型中使用了改进的去偏转换测量卡尔曼滤波算法（MDCMKF）。 MDCMKF 算法先通过引入状态估计值对转换误差协方差进行修正,有效地降低了测量噪声对此协方差的影响,然后将修正的转换误差协方差用于目标跟踪问题中的去偏转换测量卡尔曼滤波算法。最后进行的 Monte Carlo 仿真结果表明,所提算法跟踪精度优于 IMM－EKF算法和 IMM－DCMKF 算法。     

NOC基于2D MESH的路由算法的比较

NOC设计的目的就是从体系结构上解决片上通信的瓶颈问题和时钟问题,片上网络的每条传输路径都包含若干路由器,经过每个路由器都要消耗数个时钟周期,当网络拥塞时,包传输会产生更大的延时,因此采用合适的路由算法来达到延时、吞吐率等的平衡是关键。本文使用NIRGAM仿真器对XY和OE两种算法在4×4的MESH拓扑上进行算法研究,结果显示OE算法的吞吐率和包延时的比值是2.5358,比XY路由算法的比值2.1126大,因此OE路由算法更适用于Mesh拓扑。     

多分枝trie树路由查找算法研究

为了解决路由器报文转发中路由查找速度慢的瓶颈问题,在分析了路由器中广泛使用的各种典型IP路由算法的基础上．提出一种基于多分枝trie树的改进路由查找算法。在多分枝trie树中取消前缀查找,组成一个大的中间结点。在中间结点之间采用多分支步长查询,中间结点的内部使用二进制trie树来表示。仿真结果表明,改进的多分支trie树具有访存次数少,查询速度快,占用存储空间少,更新开销小等特点,并且对IPv4和IPv6地址都可以适用。     

Congestion Detection in the European Internet

In this paper we present a study about the utilization of one-way delay measurements to detect and characterize network congestion in the european Internet. The experiments have been made using the ETOMIC platform that allows one-way delay measurement with high precision timestamps. We have found a peculiar router behaviour in which the bottleneck is not the available bandwidth but it is the packet processing power of the router (backplane and CPU constraints). This router has been characterized with several network parameters. Some of them are the dependency of this limitation with the input data rate in packets per second, the size of burst packet losses measured in packets or time and the absence of specific scheduling algorithms in the router that could affect to larger flows.     

Improvement of Transmission Control Protocol for High Bandwidth Applications

Transmission control protocol (TCP) is the widely and dominantly used protocol in today’s internet. A very recent implementation of congestion control algorithm is BBR by Google. Bottleneck bandwidth and round-trip time (BBR) is a congestion control algorithm which is created with the aim of increasing throughput and reducing delay. The congestion control protocols mentioned previously try to determine congestion limits by filling router queues. BBR drains the router queues at the bottleneck by sending exactly at the bottleneck link rate. This is done by the BBR through pacing rate which infers the delivery rate of the receiver and uses this as the estimated bottleneck bandwidth. But when the data rate is high, in the startup phase itself pipe becomes full and leads to some degradation in the Access Point of wireless environments by inducing losses specific to this environment. So the current pacing rate is not suitable for producing higher throughputs. Therefore, in the proposed system named R-BBR, this startup gain should be lower than the current startup gain which eventually would reduce pacing rate to reduce queue pressure in the sink node during the startup phase. The startup phase of BBR is modified to solve the problem of pipe full under high data rate. R-BBR has been evaluated over a wide range of wired as well as wireless networks by varying different factors like startup gain, congestion window, and pacing rate. It is inferred that R-BBR performs better than BBR with significant performance improvement.

     

Active queue management algorithm focusing on fairness and low delay

The popularity of delay sensitive applications and high throughput applications in the Internet made the caches of routers and switches larger,resulting in the high latency and high jitter rate of network traffic.With the growth of mobile applications based on the high bandwidth non-response flows,the network bottleneck resource utilization becomes more unbalanced,and the resources distribution of the whole network was difficult to be guaranteed.In order to alleviate these problems,considering the delay control and suppression of high bandwidth non-response flow,an active queue management algorithm focusing on fairness and low delay named FLDA was proposed based on Sample-Match,L-LRU cache and probabilistic packets dropping.Experimental results show that under the interference with high bandwidth non-responsive flows,FLDA can better maintain the queue stability,the fairness of resource utilization of the bottleneck link and the low delay.     

MCM routing algorithm based on a compatibility graph approach

A new algorithm for general area multichip module routing using a multi-candidate and compatibility graph approach, which maximises routing density while minimising vias and total wire length, is presented. Experimental results using standard industrial benchmarks show improved results relative to a commercial router and other previously proposed routers while offering flexibility for future incorporation of noise and delay constraints     

基于贝叶斯压缩感知UWB单站定位方法

脉冲超宽带(IR-UWB)能够在无线定位中取得较高的精确度,但是存在ADC瓶颈问题,利用压缩感知理论(CS)对信号压缩采样可以显著降低信号采样速率。本文将贝叶斯压缩感知应用于UWB单站定位,接收节点利用L型天线阵列接收信号,对信号压缩采样,由贝叶斯压缩感知重构算法(BCS)还原信号并估计时延参数,最后由定位算法解算位置信息。基于IEEE 802.15.4a信号模型的仿真结果表明,该方法最低能以20%的奈奎斯特采样速率获得分米级的定位精确度。     

Internet Multicasting of IPTV With Essentially-Zero Delay Jitter

A technology for multicasting packetized multimedia streams such as IPTV over the Internet backbone is proposed and explored through extensive simulations. An RSVP or DiffServ algorithm is used to reserve resources (i.e., bandwidth and buffer space) in each packet-switched IP router in an IP multicast tree. Each IP router uses an Input-Queued (IQ) switch architecture with unity speedup. A recently proposed low-jitter scheduling algorithm is used to pre-compute a deterministic transmission schedule for each IP router. The IPTV traffic will be delivered through the multicast tree in a deterministic manner, with bounds on the maximum delay and jitter of each packet (or cell). A playback buffer is used at each destination to filter out residual network jitter and deliver a very low-jitter video stream to each end-user. Detailed simulations of an IPTV distribution network, multicasting 75 high-definition video streams over a fully-saturated IP backbone are presented. The simulations represent the transmission of 129 billion cells of real video data and where performed on a 160-node cluster computing system. In the steady-state, each IP router buffers approx. 2 cells (128 bytes) of video data per multicast output-port. The observed delay jitter is zero when a playback buffer of 15 milliseconds is used. All simulation parameters are presented.      

Packet classification consuming small amount of memory

In order to provide more value-added services, the Internet needs to classify packets into flows for different treatment. This function becomes a bottleneck in the router. High performance packet classification algorithms are therefore in high demand. This paper describes a new algorithm for packet classification using the concept of independent sets. The algorithm has very small memory requirements. The search speed is not sensitive to the size of the rule table or to the percentage of wildcards in the fields. It also scales well from two-dimensional classifiers to high-dimensional ones. In particular, the algorithm is inherently parallel. Hardware tailored to this algorithm can achieve very fast search speed. The update algorithm proposed is also very fast in general.