33412339
Conservative Algorithms for Parallel and Sequential Integer Sorting
We present a conservative CRCW parallel algorithm for integer sorting. This algorithm sorts n integers from {0, 1, ..., m−1} in time O(n log log min(m,n)/p + log n) using p processors. The simulation of our parallel algorithm on the sequential machine yields a sequential algorithm for integer sorting which sorts n integers from {0, 1, ..., m−1} in time O(n min(log log n, log log m/log n)).
37059740
Realization of an Arbitrary Permutation on a Hypercube
We present an explicit combinatorial algorithm for constructing a 2-realization for any given permutation on a circuit-switched d-dimensional hypercube (d-cube) such that the total number of directed edges used in the realization (counting every repetition) is bounded by d2d, the total number of directed edges in the d-cube. As a corollary, this result implies a (2d−3) step realization on a packet-switched d-cube (d⩾3).
44324303
Equivalent permutation capabilities between time division optical omega network and non-optical extra stage omega network
Since optical networks must support crosstalk-free (CF) connections, regular N/spl times/N multistage interconnection networks (MINs) cannot be directly used to provide connections between N inputs and N outputs. A solution is to use a 2N/spl times/2N Cube-Type MIN to provide the N/spl times/N connections. C. Qiao (1993) proposed a time domain approach that divides the N optical inputs into several groups such that CF connections can be provided by an N/spl times/N regular MIN in several time slots, one for each group. The set of N-permutations realizable in two slots is defined as class /spl theta/. Qiao proved that the size of /spl theta/ is larger than the size of class /spl Omega/, where /spl Omega/ consists of all N-permutations passible through a regular N/spl times/N Omega network. The paper first presents an optimal O(NlgN) time algorithm for identifying whether a given permutation belongs to class /spl theta/ or not. From this algorithm, the paper proves an interesting fact that the class /spl theta/ is identical to the class /spl Omega/+1 which represents the set of N-permutations admissible by a non-optical N/spl times/N one-extra stage Omega network.
34776029
Embedding between 2-D meshes of the same size
It is shown how to embed an x/sub 1/ /spl times/ 1/sub 1/ mesh M/sub 1/ into an s/sub 2/ /spl times/ t/sub 2/ mesh M/sub 2/, where s/sub 1/ /spl times/ t/sub 2/, s/sub 1/ < t/sub i/ (i = 1,2) such that the dilation is minimized. It is assumed that load = 1 and expansion = 1. For each case there is shown a lower bound on the dilation and a corresponding embedding method. The dilations by these embedding algorithms either match a lower bound or are very close to a lower bound.<<ETX>>
45976743
Improved lightpath (wavelength) routing in large WDM networks
We address the problem of efficient circuit switching in wide area networks. The solution provided is based on finding optimal routes for lightpaths and semilightpaths. A lightpath is a fully optical transmission path, while a semilightpath is a transmission path constructed by chaining several lightpaths together, using wavelength conversion at their junctions. The problem thus is to find an optimal lightpath/semilightpath in the network in terms of the cost of wavelength conversion and the cost of using the wavelengths on links. We first present fast, efficient algorithms both for the general problem and for a natural restricted version. The new algorithms outperform earlier work, providing time improvements amounting to an almost linear time factor in most cases. Also, all our algorithms can be implemented on the network in a distributed way.
9442074
Generalized Latin squares II
Abstract This paper is a continuation of a study on a new class of combinatorial structures called generalized Latin squares or 〈k,l〉-Latin squares. Here, we study the existence question of perfect 〈k,l〉-Latin squares. The main result is an existence theorem for the case M = 2, where M is the multiplicity of the generalized Latin squares. Specifically, we show that for given positive integers N, k = ip, l = iq, where i = gcd(k,l), there exists a perfect 〈k,l〉-Latin square of order N with M = 2 if and only if (i) N = 4k, (ii) pq(p + q)| N, and (iii) q|2.
9685849
Adaptive data partition for sorting using probability distribution
Many computing problems benefit from dynamic partition of data into smaller chunks with better parallelism and locality. However, it is difficult to partition all types of inputs with the same high efficiency. This paper presents a new partition method in sorting scenario based on probability distribution, an idea first studied by Janus and Lamagna in early 1980's on a mainframe computer. The new technique makes three improvements. The first is a rigorous sampling technique that ensures accurate estimate of the probability distribution. The second is an efficient implementation on modern, cache-based machines. The last is the use of probability distribution in parallel sorting. Experiments show 10-30% improvement in partition balance and 20-70% reduction in partition overhead, compared to two commonly used techniques. The new method reduces the parallel sorting time by 33-50% and outperforms the previous fastest sequential sorting technique by up to 30%.
449557
Power allocation and scheduling for MAC layer design in UWB networks
This paper proposes a practical joint power allocation and scheduling scheme for medium access control (MAC) layer design in ultra-wideband (UWB) networks. The scheme increases system spectral efficiency and reduces power consumption by fully considering the properties of the UWB, such as its capacity in supporting parallel transmission and providing accurate positioning, and its stringent constraint on computational complexity. Practical implementations of the proposed scheme are achieved by introducing a margin based power allocation scheme and an exclusive region based scheduling scheme. The margin based power allocation scheme is carried out based on each link's own information, and is simple to implement, while the exclusive region based scheduling scheme takes into account the interaction among different links. Simulation results show that the proposed power allocation and scheduling schemes exhibit good performance in terms of the average number of slots per frame and the power consumption reduction
36077313
Developing High-Performance Parallel Applications Using EPAS
In spite of the advent of high performance parallel computers and commodity clusters, complexity of parallel application development remains one of the major obstacles towards the mainstream adoption of parallel computing. Researchers are constantly investigating different approaches to reduce parallel application development time and increase productivity. As re-usable components, patterns have gained popularity in the sequential programming domain. Subsequently, several pattern-based parallel programming environments (PPEs) have been proposed to facilitate parallel application development procedure. Unfortunately, most of these PPEs lack the required flexibility in order to develop real-life parallel applications. In this paper, we describe the features of the EPAS (Extended Parallel Architectural Skeleton) PPE that enables development of complex parallel applications. We investigate and design the required patterns, and then use them to develop a parallel data cube computing application. Finally, we present the performance of the developed applications and discuss the results.
16973693
An adaptive handoff priority scheme for wireless MC-CDMA cellular networks supporting realtime multimedia applications
An adaptive handoff priority scheme is proposed for a packet switching multicode (MC)-CDMA cellular network supporting realtime multimedia applications. The scheme jointly considers the physical, link and network layer characteristics, and gives service priority to handoff calls by exploiting the transmission rate adaptability of multimedia calls to the available radio resources. Based on the scheme, a call admission region is derived with the estimated cell capacity and the proposed packet scheduling and partial packet integration scheme and used for call admission control and handoff management with the satisfaction of quality of service requirements for all multimedia traffic, where the QoS parameters include the wireless transmission bit error rate, packet loss rate and delay requirement. Simulation results are given to demonstrate the viability of the proposed scheme.
302118
A Hierarchical Model of Reference Affinity
To improve performance, data reorganization needs locality models to identify groups of data that have reference affinity. Much past work is based on access frequency and does not consider accessing time directly. In this paper, we propose a new model of reference affinity. This model considers the distance between data accesses in addition to the frequency. Affinity groups defined by this model are consistent and have a hierarchical structure. The former property ensures the profitability of data packing, while the latter supports data packing for storage units of different sizes. We then present a statistical clustering method that identifies affinity groups among structure fields and data arrays by analyzing training runs of a program. When used by structure splitting and array regrouping, the new method improves the performance of two test programs by up to 31%. The new data layout is significantly better than that produced by the programmer or by static compiler analysis.