618071
iMail: a WAP mail retrieving system
This paper proposes iMail, a WAP mail retrieving system designed for wireless handheld devices to access Internet email service. In mobile data networks, the communication bandwidth is limited and the wireless handsets are constrained by small display, powerless CPU, limited memory, and unhandy input/output interface. To support mail retrieving in a mobile environment, we implement several features for iMail: mail filtering, two-phase fetch and pre-defined list reordering. Based on the user's filter options, mail filtering eliminates non-necessary mails sent to a wireless handheld device. Two-phase fetch is used to reduce transmission overhead of message delivery. We use pre-defined list reordering to speed up text typing in the wireless handheld devices. We also propose three mail notification mechanisms for iMail. When a new mail arrives, the mail notification mechanism informs iMail users immediately. Through the descriptions of the iMail features, this paper provides design and implementation guidelines for WAP applications.
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.
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.
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>>
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.
2805042
A new random walk model for PCS networks
This paper proposes a new approach to simplify the two-dimensional random walk models capturing the movement of mobile users in personal communications services (PCS) networks. Analytical models are proposed for the new random walks. For a PCS network with hexagonal configuration, our approach reduces the states of the two-dimensional random walk from (3n/sup 2/+3n-5) to n(n+1)/2, where n is the layers of a cluster. For a mesh configuration, our approach reduces the states from (2n2-2n+1) to (n/sup 2/+2n+4)/4 if n is even and to (n/sup 2/+2n+5)/4 if n is odd. Simulation experiments are conducted to validate the analytical models. The results indicate that the errors between the analytical and simulation models are within 1%. Three applications (i.e., microcell/macrocell configuration, distance-based location update, and GPRS mobility management for data routing) are used to show how our new model can be used to investigate the performance of PCS networks.
37430657
On the boundary inequality for bandwidth of graphs
15551235
A hardware accelerator for context-based adaptive binary arithmetic decoding in H.264/AVC
We propose a hardware accelerator for context-based adaptive binary arithmetic decoding (CABAC) in H.264/AVC. We also propose an efficient memory system for easy integration with other components such as motion compensation and IDCT. We develop an efficient finite state machine so that our design can generate one bit every 2 to 3 clock cycles. Experimental result with FPGA prototyping shows that our design is sufficient to decode main profile CIF video streams at 30 fps.
6671545
LES: A Layout Expert System
In this paper we describe an expert system for layout generation in a hierarchical VLSI design system. It applies a combination of rule- and algorithmic-based techniques on a new layout style. Experimental results have demonstrated the superiority of this expert system against various standard-cell systems and its competitiveness with human designers.
1945498
An AMBA-compliant deblocking filter IP for H.264/AVC
We propose an efficient hardware architecture for the deblocking filter function in H.264/AVC. We use a novel memory organization that results in significant saving in filtering time. Our design includes two 4/spl times/4 register sets and one 160/spl times/32 two-port SRAM such that filtering and transpose are carried out simultaneously. Synthesis results show that our design is small (19k gates) and high performance (100 MHz @ 0.25 /spl mu/m). An AMBA-compliant interface is added to our design for SOC integration and FPGA prototyping. Experimental results show that our design works well with the reference software JM 7.3 and achieves significant speed up, even with a huge communication overhead between the CPU and the hardware accelerator.
53235373
Performance-optimal clustering with retiming for sequential circuits