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
Routing technology has been forced to evolve towards higher capacity and per port packet processing speed. The ability to achieve high forwarding speed is due to either software or hardware technology. TCAM (Ternary C...Routing technology has been forced to evolve towards higher capacity and per port packet processing speed. The ability to achieve high forwarding speed is due to either software or hardware technology. TCAM (Ternary Content Addressable Memory) provides a performance advantage over other software or hardware search algorithms, often resulting in an order of magnitude reduction of search time. But slow updates may affect the performance of TCAM based routing lookup. So the key is to design a table management algorithm, which supports high speed updates in TCAMs. This paper presented three table management algorithms, and then compared their performance. Finally, the optimal one after comparing was given.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
This In the past decade there has been an increasing need for designs to address the time and cost efficiency issues from various computer network applications such as general IP address lookup and specific network in...This In the past decade there has been an increasing need for designs to address the time and cost efficiency issues from various computer network applications such as general IP address lookup and specific network intrusion detection. Hashing techniques have been widely adopted for this purpose, among which XOR-operation-based hashing is one of most popular techniques due to its relatively small hash process delay. In most current commonly used XOR-hashing algorithms, each of the hash key bits is usually explicitly XORed only at most once in the hash process, which may limit the amount of potential randomness that can be introduced by the hashing process. In [1] a series of bit duplication techniques are proposed by systematically duplicating one row of key bits. This paper further looks into various ways in duplicating and reusing key bits to maximize randomness needed in the hashing process so as to enhance the overall performance further. Our simulation results show that, even with a slight increase in hardware requirement, a very significant reduction in the amount of hash collision can be obtained by the proposed technique.展开更多
Interference cancellation system (ICS) for 3GPP/LTE system is the broadband cancellation system, which receives forward signal through the donor antenna. We proposed new algorithm of received signal with pilot and non...Interference cancellation system (ICS) for 3GPP/LTE system is the broadband cancellation system, which receives forward signal through the donor antenna. We proposed new algorithm of received signal with pilot and non-pilot design. Although repeater design needs our project, so in this paper we discuss about interference cancellation algorithm for 2x2 MIMO systems without pilot in LTE. First explain the general principle structure of 3GPP/LTE, next determine our new design and algorithm. Finally, we simulated our mathematic extraction of proposed new algorithm on MATLAB.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(ΔR^(2)=0.20~0.26),RF相对稳定(ΔR^(2)=0.14~0.20),LUT加入红边波段RE_(2)(B,R,RE_(2),RE_(3),NIR,RE,SW_(2))可在提高精度的同时保持抗干扰性(均值ΔR^(2)=0.18);(2)移除异常数据后,LUT反演精度最高(R^(2)=0.88,RMSE=0.31),GA次之,RF加入RE_(2)波段表现显著提升(R^(2)=0.65~0.79,RMSE=0.64~0.53);(3) 3种模型在高LAI区间(2.5~5.0;LUT:R^(2)>0.84;GA:R^(2)>0.71;RF:R^(2)>0.57)反演精度均显著优于低LAI区间(0.5~2.5),其中RF结合RE_(2)波段R^(2)从0.57提高至0.82。综上所述,物理模型反演方法以及RE_(2)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
文摘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.
文摘Routing technology has been forced to evolve towards higher capacity and per port packet processing speed. The ability to achieve high forwarding speed is due to either software or hardware technology. TCAM (Ternary Content Addressable Memory) provides a performance advantage over other software or hardware search algorithms, often resulting in an order of magnitude reduction of search time. But slow updates may affect the performance of TCAM based routing lookup. So the key is to design a table management algorithm, which supports high speed updates in TCAMs. This paper presented three table management algorithms, and then compared their performance. Finally, the optimal one after comparing was given.
文摘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.
文摘This In the past decade there has been an increasing need for designs to address the time and cost efficiency issues from various computer network applications such as general IP address lookup and specific network intrusion detection. Hashing techniques have been widely adopted for this purpose, among which XOR-operation-based hashing is one of most popular techniques due to its relatively small hash process delay. In most current commonly used XOR-hashing algorithms, each of the hash key bits is usually explicitly XORed only at most once in the hash process, which may limit the amount of potential randomness that can be introduced by the hashing process. In [1] a series of bit duplication techniques are proposed by systematically duplicating one row of key bits. This paper further looks into various ways in duplicating and reusing key bits to maximize randomness needed in the hashing process so as to enhance the overall performance further. Our simulation results show that, even with a slight increase in hardware requirement, a very significant reduction in the amount of hash collision can be obtained by the proposed technique.
文摘Interference cancellation system (ICS) for 3GPP/LTE system is the broadband cancellation system, which receives forward signal through the donor antenna. We proposed new algorithm of received signal with pilot and non-pilot design. Although repeater design needs our project, so in this paper we discuss about interference cancellation algorithm for 2x2 MIMO systems without pilot in LTE. First explain the general principle structure of 3GPP/LTE, next determine our new design and algorithm. Finally, we simulated our mathematic extraction of proposed new algorithm on MATLAB.
文摘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。
文摘介绍了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。
