An internal structure of Ternary Content Addressable Memory (TCAM) is designed and a Sorting Prefix Block (SPB) algorithm is presented, which is a wire-speed routing lookup algorithm based on TCAM. SPB algorithm makes...An internal structure of Ternary Content Addressable Memory (TCAM) is designed and a Sorting Prefix Block (SPB) algorithm is presented, which is a wire-speed routing lookup algorithm based on TCAM. SPB algorithm makes use of the parallelism of TCAM adequately, and improves the utilization of TCAM by optimum partitions. With the aid of effective management algorithm and memory image, SPB separates critical searching from assistant searching, and improves the searching effect. One performance test indicates that this algorithm can work with different TCAM to meet the requirement of wire-speed routing lookup.展开更多
In order to classify packet, we propose a novel IP classification based the non-collision hash and jumping table trie-tree (NHJTTT) algorithm, which is based on noncollision hash Trie-tree and Lakshman and Stiliadis p...In order to classify packet, we propose a novel IP classification based the non-collision hash and jumping table trie-tree (NHJTTT) algorithm, which is based on noncollision hash Trie-tree and Lakshman and Stiliadis proposing a 2-dimensional classification algorithm (LS algorithm). The core of algorithm consists of two parts: structure the non-collision hash function, which is constructed mainly based on destination/source port and protocol type field so that the hash function can avoid space explosion problem; introduce jumping table Trie-tree based LS algorithm in order to reduce time complexity. The test results show that the classification rate of NHJTTT algorithm is up to 1 million packets per second and the maximum memory consumed is 9 MB for 10 000 rules. Key words IP classification - lookup algorithm - trie-tree - non-collision hash - jumping table CLC number TN 393.06 Foundation item: Supported by the Chongqing of Posts and Telecommunications Younger Teacher Fundation (A2003-03).Biography: SHANG Feng-jun (1972-), male, Ph.D. candidate, lecture, research direction: the smart instrument and network.展开更多
叶面积指数(Leaf Area Index, LAI)是反映作物生长的重要参数,准确获取对农业监测和产量评估至关重要。Sentinel-2卫星具备多红边与短波红外波段,在LAI反演中具有潜在优势,因此比较不同模型与波段组合的反演能力,对提升玉米LAI估算精度...叶面积指数(Leaf Area Index, LAI)是反映作物生长的重要参数,准确获取对农业监测和产量评估至关重要。Sentinel-2卫星具备多红边与短波红外波段,在LAI反演中具有潜在优势,因此比较不同模型与波段组合的反演能力,对提升玉米LAI估算精度具有重要意义。本文以位于甘肃省张掖市的黑河遥感试验研究站大满观测场为研究区,基于PROSAIL模型敏感性分析,筛选对LAI敏感的波段组合和关键参数,构建模拟数据库,并采用查找表法(Look Up Table, LUT)、遗传算法(Genetic Algorithm, GA)和随机森林(Random Forest, RF)回归模型3种方法反演LAI,结合Sentinel-2影像及实测数据进行精度验证。结果表明:(1)异常数据对反演精度影响显著,LUT对异常值最敏感(ΔR2=0.20~0.26),RF相对稳定(ΔR2=0.14~0.20),LUT加入红边波段RE2(B,R,RE2,RE3,NIR,RE,SW2)可在提高精度的同时保持抗干扰性(均值ΔR2=0.18);(2)移除异常数据后,LUT反演精度最高(R2=0.88,RMSE=0.31),GA次之,RF加入RE2波段表现显著提升(R2=0.65~0.79,RMSE=0.64~0.53);(3) 3种模型在高LAI区间(2.5~5.0;LUT:R2>0.84;GA:R2>0.71;RF:R2>0.57)反演精度均显著优于低LAI区间(0.5~2.5),其中RF结合RE2波段R2从0.57提高至0.82。综上所述,物理模型反演方法以及RE2波段在提升玉米LAI反演精度方面作用突出,能够为玉米的LAI反演工作和生长监测提供有益参考。展开更多
本文针对传统坐标旋转数字计算机(Coordinate Rotation Digital Computer,CORDIC)算法存在时延长、资源消耗多等问题,提出一种低时延小容量查找表的新型CORDIC实现方案。通过创新性设计,显著优化了算法的时序性能与硬件资源消耗。该方...本文针对传统坐标旋转数字计算机(Coordinate Rotation Digital Computer,CORDIC)算法存在时延长、资源消耗多等问题,提出一种低时延小容量查找表的新型CORDIC实现方案。通过创新性设计,显著优化了算法的时序性能与硬件资源消耗。该方法摒弃传统迭代运算,仅需要构建小容量ROM表,结合简单位移操作,即可实现高精度三角函数输出。经Matlab理论仿真与ModelSim数字验证,该方法处理延迟压缩至2个时钟周期,并且在资源占有率和精度方面也有显著提升,具有一定的理论与实用价值。展开更多
介绍了IP分类技术研究的最新成果,以及IP分类的典型算法。提出了一种基于完全无冲突散列(hash)和跳转表Trie树(NHJTTT)的IP分类算法,通过分析比较,本文提出的算法无论是时间性能还是空间性能均优于无冲突散列查找算法和Grid of Tries算...介绍了IP分类技术研究的最新成果,以及IP分类的典型算法。提出了一种基于完全无冲突散列(hash)和跳转表Trie树(NHJTTT)的IP分类算法,通过分析比较,本文提出的算法无论是时间性能还是空间性能均优于无冲突散列查找算法和Grid of Tries算法,文中通过仿真给出了最终的分类效果。最后对提出的算法在虚拟环境下做了评判。展开更多
摘要An internal structure of Ternary Content Addressable Memory (TCAM) is designed and a Sorting Prefix Block (SPB) algorithm is presented, which is a wire-speed routing lookup algorithm based on TCAM. SPB algorithm makes use of the parallelism of TCAM adequately, and improves the utilization of TCAM by optimum partitions. With the aid of effective management algorithm and memory image, SPB separates critical searching from assistant searching, and improves the searching effect. One performance test indicates that this algorithm can work with different TCAM to meet the requirement of wire-speed routing lookup.
摘要In order to classify packet, we propose a novel IP classification based the non-collision hash and jumping table trie-tree (NHJTTT) algorithm, which is based on noncollision hash Trie-tree and Lakshman and Stiliadis proposing a 2-dimensional classification algorithm (LS algorithm). The core of algorithm consists of two parts: structure the non-collision hash function, which is constructed mainly based on destination/source port and protocol type field so that the hash function can avoid space explosion problem; introduce jumping table Trie-tree based LS algorithm in order to reduce time complexity. The test results show that the classification rate of NHJTTT algorithm is up to 1 million packets per second and the maximum memory consumed is 9 MB for 10 000 rules. Key words IP classification - lookup algorithm - trie-tree - non-collision hash - jumping table CLC number TN 393.06 Foundation item: Supported by the Chongqing of Posts and Telecommunications Younger Teacher Fundation (A2003-03).Biography: SHANG Feng-jun (1972-), male, Ph.D. candidate, lecture, research direction: the smart instrument and network.
摘要本文针对传统坐标旋转数字计算机(Coordinate Rotation Digital Computer,CORDIC)算法存在时延长、资源消耗多等问题,提出一种低时延小容量查找表的新型CORDIC实现方案。通过创新性设计,显著优化了算法的时序性能与硬件资源消耗。该方法摒弃传统迭代运算,仅需要构建小容量ROM表,结合简单位移操作,即可实现高精度三角函数输出。经Matlab理论仿真与ModelSim数字验证,该方法处理延迟压缩至2个时钟周期,并且在资源占有率和精度方面也有显著提升,具有一定的理论与实用价值。
摘要介绍了IP分类技术研究的最新成果,以及IP分类的典型算法。提出了一种基于完全无冲突散列(hash)和跳转表Trie树(NHJTTT)的IP分类算法,通过分析比较,本文提出的算法无论是时间性能还是空间性能均优于无冲突散列查找算法和Grid of Tries算法,文中通过仿真给出了最终的分类效果。最后对提出的算法在虚拟环境下做了评判。