27686957
Determining the Global Progress of Parallel Simulation
16848330
A flexible graphical user interface for performance modeling
We identify three goals for the graphical user interface (GUI) of a network simulation environment: user friendliness, model re-usability, and application extensibility. We address the user friendliness issue by proposing a simple yet efficient approach to setup parameters for the simulation models. We address the application extensibility issue by a two-layer GUI architecture. The two layers are loosely-coupled, and the first layer can be easily replaced (without affecting the other components of the simulation environment). We address the model re-usability issue by subnetworks. Unlike most existing simulation packages where subnetwork is simply a method to group the nodes, the subnetwork construct in our approach is an integral part of the simulation environment (i.e., all operations for a basic node also apply to a subnetwork). The port concept is used to explicitly define the I/O relationship between a subnetwork and the outside world. Parameter dialog boxes are used to set up the parameters for a subnetwork conveniently. Finally, a simple stack mechanism is proposed to measure subnetwork-wide output statistics.<<ETX>>
15619003
A Graphical User Interface Design for Network Simulation
Abstract This article describes a prototyping effort of a flexible graphical user interface (GUI) for a simulation tool called COPS. The GUI is designed to allow parameter setup for all modules in simulation model, and can be easily replaced by new GUIs implemented in different languages/graphical tools. This article provides design guidelines and implementation details of the flexible GUI.
5110930
A comparison study of the two-tier and the single-tier personal communications services systems
A two-tier PCS system integrates the high tier PCS system and the low tier PCS systems into a single system to provide the advantages of both tiers. Such a system is expected to provide better service (more available and more cost effective to the users) at the expense of the extra tier switching management. We compare the performance of the two-tier PCS system and the single low tier system in two aspects: the registration traffic and the service availability. Because of the tier management, the two-tier system generates more registration traffic than the single low tier system. Under the range of the input parameters in our study, we show that the two-tier system generates less than 10% extra registration traffic than the single low tier system in most cases and generates less than 20% registration traffic in the worst cases. It is clear that for the service availability, the two-tier system is better than the single one tier system. We also study the probability that a call is forced terminated in the single low tier system because the low tier becomes unavailable during the call (such a call can be continued in the two-tier system).
22500122
Performance of hot billing mobile prepaid service
Abstract Prepaid service has become an important mobile application with rapid growth for subscription rate in the recent years. Implementation of prepaid service may generate large network traffic that significantly affects the performance of a mobile network. This paper studies the hot billing solution for prepaid service. We investigate how the amount of prepaid credit and the frequency of call detail record (CDR) transmissions affect network signaling and potential bad debt that a service provider may bear. Our study suggests that a prepaid service provider should encourage customers to buy large prepaid credits by giving them discounts. Furthermore, based on call traffic, an optimal CDR transmission frequency can be found by using our modeling technique.
16744149
Performance Analysis for Dual Band PCS Networks
In a dual band personal communications services (PCS) network, heavy traffic areas are covered by microcells which overlay macrocells. In such a network, microcells and macrocells utilize different frequency bands. We propose an analytic model to study the performance of a dual band PCS architecture. Our model assumes that a PCS subscriber has a general residence time distribution in a microcell and the macrocell residence time distribution is derived from the microcell residence time distribution. An iterative algorithm is used to compute the overflow traffic from a microcell to its overlaid macrocell. Then, the call incompletion probability is computed by a macrocell model based on the overflow traffic. Our study indicates that the variance of the microcell residence time distribution and the number of microcells covered by a macrocell have significant effects on the call incompletion probability.
26702573
Evolution and Evaluation of Internet Content Delivery
Discover the methods for content delivery and distribution of Web-based media in the Web 2.0 world. The concept of Web caches has existed as long as the Web and evolved from storage of frequently accessed files on an individual's personal computer or proxy server to Internet-based Web cache servers provided by companies as a paid subscription service for content providers. As multimedia has become more prevalent on the Web, content delivery networks (CDNs) have become a critical component of the Internet and an enabler of Web 2.0 applications like IPTV, mobile Web and TV devices, and content-rich Web databases such as Wikimedia.
6763648
An effective methodology for functional pipelining
We address the problem of given a loop behavior, a target initiation interval and resource constraints, scheduling a loop in a pipelined fashion such that the iteration time (turn-around time) is minimized. The iteration time is an important quality measure of a data path design because of its direct correlationship with both the storage and the control costs. Our scheduler starts with performing an As Soon As Possible Pipelined (ASAPp) scheduling without regard to the resource constraint. It then resolves the resource constraint violations, if there are any, by repeatedly rescheduling some operations.
32261160
Channel assignment for GSM half-rate and full-rate traffic
Global System for Mobile Communications (GSM) supports full-rate and half-rate calls. In this paper, we propose analytical and simulation models to study the performance of four channel assignment schemes for GSM half-rate and full-rate traffic. Our study indicates that among the four schemes, the repacking scheme has the best performance for mixing half-rate and full-rate traffic. We also observe that good performance is expected if the standard derivation of the cell residence time for a mobile station is large.
38988284
Perfectly Overlapped Generation of Long Runs for Sorting Large Files
A parallel algorithm is presented for quick generation of long sorted runs as the first phase of sorting a large file. It can generate runs of length about 2(m + 2)p on a linear array of p processors each with a heap of size m. Internal computations can be completely overlapped with I/O, and only n + (m + 2)p steps are required to generate the runs from a file of n items. Experiments with the algorithm show that it can give highly satisfactory results in a real environment. A variant of the algorithm is also presented. It is possible that no merge phase is required for sorting a file occupying a whole disk.
14489226
A performance-driven standard-cell placer based on a modified force-directed algorithm
We propose a performance-driven cell placement method based on a modified force-directed approach. A pseudo net is added to link the source and sink flip-flops of every critical path to enforce their closeness. Given user-specified I/O pad locations at the chip boundaries and starting with all core cells in the chip center, we iteratively move a cell to its force-balanced location assuming all other cells are fixed. The process stops when no cell can be moved farther than a threshold distance. Next, cell rows are adjusted one at a time starting from the top and bottom. After forming these two rows (top/bottom), all movable core cells force-balanced locations are updated. The row-formation-and-update process continues until all rows are adjusted and, hence, a legal placement is obtained.
 We have integrated the proposed approach into an industrial APR flow. Experimental results on benchmark circuits up to 191K-cell (500K-gate) show that the critical path delay can be improved by as much as 11.5%. We also study the effect on both layout quality and CPU time consumption due to the amount of pseudo net added. We found that the introduction of pseudo net indeed significantly improves the layout quality.