This paper presents a Medium Access Control (MAC) protocol for broadband wireless LANs based on the ATM transfer mode, together with the evaluation of its performance in terms of throughput and access delay. Important...
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This paper presents a Medium Access Control (MAC) protocol for broadband wireless LANs based on the ATM transfer mode, together with the evaluation of its performance in terms of throughput and access delay. Important characteristics of the MAC protocol are the way information between the Mobile Stations (MSs) and the Base Station (BS) is exchanged and the algorithm used to allocate the bandwidth in order to support the service categories. A detailed analytical evaluation, both on cell level and packet level, leads to an assessment of the efficiency and the access delay of the system.
作者：
Shaikh, Fayaz A.McClellan, StanCenter of Telecommunications
Education and Research Department of Electrical and Computer Engineering University of Alabama at Birmingham 1150 Tenth Avenue South BEC 253 BirminghamAL35294-4461 United States IP Architecture Group
Technology and Systems Engineering Compaq Telecommunications 1255 West Fifteenth Street Suite 8000 PlanoTX75075 United States
The primary challenges in the deployment of Voice over Internet Protocol technology include Quality of Service (QoS) guarantees in the form of stringent bounds on end-to-end delay, jitter and loss, as well as rigorous...
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A heuristic algorithm that maps data processing tasks onto heterogeneous resources (i.e. processors and links of various capacities) is presented. The algorithm tries to achieve a good throughput of the whole data pro...
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A heuristic algorithm that maps data processing tasks onto heterogeneous resources (i.e. processors and links of various capacities) is presented. The algorithm tries to achieve a good throughput of the whole data processing pipeline, taking both parallelism (load balance) and communication volume (locality) into account. It performs well both under computationally intensive and communication-intensive conditions. When all tasks/processors are of the same size and communication is negligible, it quickly distributes the computation load over the processors and finds the optimal mapping. As communication becomes significant and reveals a bottleneck, it trades parallelism for reduction of communication traffic. Experimental results using a topology generator that models the Internet show that it performs significantly better than communication-ignorant schedulers.
The DASUD (Diffusion Algorithm Searching Unbalanced Domains) algorithm belongs to the nearest-neighbours class and operates in a diffusion scheme where a processor balances its load with all its neighbours. DASUD dete...
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The DASUD (Diffusion Algorithm Searching Unbalanced Domains) algorithm belongs to the nearest-neighbours class and operates in a diffusion scheme where a processor balances its load with all its neighbours. DASUD detects unbalanced domains and performs local exchange of load between processors to achieve global balancing. The DASUD algorithm has been evaluated by comparison with another well-known strategy, namely, the SID (Sender Initiated Diffusion) algorithm across a range of network topologies including ring, torus and hypercube where the number of processors varies from 8 to 128. From the experiments we have observed that DASUD outperforms the other strategy as it provides the best trade-of-between the balance degree obtained at the final state and the number of iterations required to reach such a state. DASUD is able to coerce any initial load distribution into a highly balanced global state and also exhibits good scalability properties.
Using a distributed database system as part of a distributed web server architecture has obvious advantages. It is shown that a first phase distributed database system can be build by extending an existing object orie...
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One of the key issues in designing new simulation models for parallel execution, or in the migration of existing models to parallel platforms, is the mapping of the application architecture to the parallel system arch...
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A proper initialization requires starting the process in a state close to the expected steady state. In Web caching, the initialization problem is faced each time a new document enters the cache. Independently of the ...
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A proper initialization requires starting the process in a state close to the expected steady state. In Web caching, the initialization problem is faced each time a new document enters the cache. Independently of the method used to sort the documents into the cache, the newly referenced document is inserted in a so called "removal-list", from which documents are removed when storage space is needed. Often, undesirable documents are assigned a high priority, consequently these documents remain for quite a long time in the cache, leading to a decrease in cache server performances. We investigate one category of undesirable documents, which pass the filters commonly used to control the cache processing.
Web caching has been considered as a powerful solution to deal with the growth of Web traffic. Several studies have shown that caching documents throughout the Internet can save network bandwidth and reduce document a...
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Web caching has been considered as a powerful solution to deal with the growth of Web traffic. Several studies have shown that caching documents throughout the Internet can save network bandwidth and reduce document access latency. However, this technique has introduced new problems such as maintaining the document coherency and selecting the next document to be removed. With the continuous increase in demand for documents, the Web cache servers are becoming the new bottleneck. A need for better resource management is becoming urgent in order to reduce the overhead sustained by Web cache servers. In this paper, a number of Web replacement policies are discussed and compared on the basis of trace-driven simulations. The impact of the Web cache server configuration is pointed out through a set of experiments that use the cache size as a tuning parameter.
Optimization at the early stages of design are crucial. However, due to an overwhelming number of design and optimization options, design exploration is often conducted in a qualitative, ad-hoc manner. This paper pres...
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Optimization at the early stages of design are crucial. However, due to an overwhelming number of design and optimization options, design exploration is often conducted in a qualitative, ad-hoc manner. This paper presents a methodology and interactive environment for guiding the exploration process. A prototype targeting behavioral-level optimization for datapath-intensive ASIC implementations has been developed. The key to the approach is encapsulated knowledge about the various optimizations and a set of techniques to automatically extract the "essence" of a design description. At each stage in the exploration process, the system suggests and ranks potential optimizations, both in terms of immediate and longer-term impact. It also provides evaluations of the design and of the likely affects each optimization will have on metrics like power and performance. In the new approach, the designer is responsible for making the actual optimization selections. However, using the provided guidance, designers can make decisions in a more informed manner, and therefore can explore the design solution space more effectively. The effectiveness of the approach is demonstrated on a number of designs.
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