205212938
General Packet Radio Service (GPRS): architecture, interfaces, and deployment
This article provides an overview of General Packet Radio Service (GPRS). GPRS reuses the existing GSM infrastructure to provide end-to-end packet-switched services. Benefits of GPRS include efficient radio usage, fast set-up/access time and high bandwidth with multiple timeslots. GPRS also provides a smooth path for GSM evolution to the third generation mobile network. Specifically, a third generation network can continue to utilize the GPRS IP backbone network. We describe the GPRS network nodes and the interfaces among these nodes. Deployment issues for GPRS are also elaborated. Copyright 2001 John Wiley & Sons, Ltd.
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.
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).
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>>
13450793
On IEEE 802.14 medium access control protocol
In this article we present a comprehensive survey on the architecture, protocol issues, and standard of the hybrid fiber coaxial (HFC) networks which are evolving from the existing residential CATV networks. We first describe the HFC architecture and discuss the problems in providing two-way communication. Then, we identify three important medium access control (MAC) issues in designing the IEEE 802.14 standard; namely, synchronization, upstream channel access modes, and collision resolution. Resolutions adopted by the IEEE 802.14 Committee are illustrated after giving a protocol overview. Key resolutions include compensating round trip correction (RTC), interleaving minislots of data and request concurrently, and resolving collisions by multiple collision resolution engines, using the n-ary tree plus p-persistence algorithm with a first transmission rule. A comparative summary of some draft proposals that lead to the standard is given. Finally, we pinpoint two headend algorithms, minislot allocation and request scheduling, which are left open in the standard. They do not affect interoperability but may have a critical impact on performance.
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.
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.
13768633
Software Defined Radio - A High Performance Embedded Challenge
Wireless communication is one of the most computationally demanding workloads. It is performed by mobile terminals (“cell phones”) and must be accomplished by a small battery powered system. An important goal of the wireless industry is to develop hardware platforms that can support multiple protocols implemented in software (software defined radio) to support seamless end-user service over a variety of wireless networks. An equally important goal is to provide higher and higher data rates. This paper focuses on a study of the wideband code division multiple access protocol, which is one of the dominant third generation wireless standards. We have chosen it as a representative protocol. We provide a detailed analysis of computation and processing requirements of the core algorithms along with the interactions between the components. The goal of this paper is to describe the computational characteristics of this protocol to the computer architecture community, and to provide a high-level analysis of the architectural implications to illustrate one of the protocols that would need to be accommodated in a programmable platform for software defined radio. The computation demands and power limitations of approximately 60 Gops and 100~300 mW, place extremely challenging goals on such a system. Several of the key features of wideband code division multiple access protocol that can be exploited in the architecture include high degrees of vector and task parallelism, small memory footprints for both data and instructions, limited need for complex arithmetic functions such as multiplication, and a highly variable processing load that provides the opportunity to dynamically scale voltage and frequency.
30258464
Contextualising knowledge-making in Linux user groups
A common critique on free/libre open source software (FLOSS) is that FLOSS–oriented products, often mutated from or based on parallel works, are not really innovative. FLOSS’ development process and subsequent products (e.g. software packages, maintaining services, or the formation of user groups, etc.) definitely denote a kind of innovation driving our world towards a knowledge–based society. This perspective challenges the conventional notion of innovation in technological and economic arenas from a glocalised perspective. I argue that software development is not solely a matter of technical engineering or economic progress. Rather, it also involves cultural, social and political factors.

Through interaction and negotiation, FLOSS innovation is embedded in the translation of problems and knowledge–sharing between user and designer, and between lay and expert. Narratives of Linux users groups (LUGs) show that the influence of local knowledge and tacit skills is very much in evidence in the FLOSS innovation system. Practices in LUGs denote the codification of local knowledge and its translation into more formalised and sophisticated expertise. This raises fundamental questions about whether institutional involvement should continue along its techno–economic route of relying entirely on specialists (programmers) to reach developmental decisions, or whether the process should be made more democratic by allowing a broader range of social interests to have some input into software development.

In this paper, I demonstrate the values of local tinkering, soft skills and tacit knowledge in FLOSS innovation. I investigate how locally defined software problems and locally crafted solutions towards the problems are codified and translated into expert knowledge within FLOSS innovation through intense hands–on practices and ongoing debate. The process of translating local knowledge into formal expertise is analysed in light of data collected from the York Linux User Group (YLUG). While FLOSS is gaining unprecedented recognition at an accelerating pace, and more institutional resources are made available, noticeably from national agencies and industry, it is crucial to get a genuine picture of FLOSS development, on which this paper will shed some light.