waashk/acm huggingface dataset:
quality of service and mobility for the wireless internet our paper explores the issue of how to provide appropriate qualityof service mechanisms closely integrated with flexible mobilitymanagement in wireless local area networks. we consider them asaccess networks of choice for the high performance wireless mobileinternet. we present a hierarchical qos architecture that extends_differentiated services (diffserv)_ to mobile hosts in awireless environment. our approach is based on controlling severalparameters of a wiireless lan cell: the limited geographical spanto ensure the same high bit rate for all hosts, the constrainedrate of traffic sources to limit the use of the channel in functionof the required qos and the limited number of active hosts to keepthe load sufficiently low. the qos management is coupled withmobility management at the ip level. we use a micro- mobility schemeimplemented in the ipv6 layer with fast hand-offs between adjacentcells. micro-mobility avoids address translation, traffictunnelling, and enables fast hand-offs. we give some details ofexperiments to show the quality of service diffferentiation overthe 802.11b network. j. antonio garcia-macias franck rousseau gilles berger-sabbatel leyla toumi andrzej duda
an integrated test center for sl-10 packet networks  the sheer scale and complexity of large data networks makes testing them a daunting task. system commissioning, release acceptance, network troubleshooting, performance testing, host conformance testing, and certification are all operational activities that involve testing. packet switching systems typically provide built-in features to help with hardware level test operations such as modem loopback commands, system failure alarms and system selftests. however, testing system and protocol level functions still required the use of separate tool boxes. typical data product test tools are designed to test single data lines, not multiline distributed networks (1,2,3). considering all of the above, the sl-10 test tools group set out to develop network tools (4). tools have been implemented which are well- integrated into the sl-10 product. the same tools can be used alone, independent of the sl-10 network. this tool set makes the job of network testing more manageable for developer, manufacturer and network operator alike. terminals and host computers, as well as total networks, can now be tested for conformance and performance automatically, instead of manually. as a result, major productivity improvements and quality gains have been observed since the tools were introduced.  the tool set consists of four tools: an interactive protocol tester (ipt) for checking protocol implementations against specifications; the network load test system (nlts) which generates simulated traffic and measures the network's performance; the network process monitor (npm) which examines operating software at the module level; and the network test system (nts) driver which is an automatic or interactive test sequencer for coordinating and controlling distributed network testing. each tool can be operated individually using a standard data terminal. the ipt, nlts and npm tools run on sl-10 rapid* network processors and can be operated remotely via the network or the nts driver. using these tools in combination, a fully integrated and automatic operational test center can be realized, and the need for separate tool boxes can be eliminated.  the design and capabilities of each of these tools are described. this paper describes how these tools meet the special needs of network test operations.  m. w. a. hornbeek
critical path analysis of tcp transactions  improving the performance of data transfers in the internet (such as web transfers) requires a detailed understanding of when and how delays are introduced. unfortunately, the complexity of data transfers like those using http is great enough that identifying the precise causes of delays is difficult. in this paper, we describe a method for pinpointing where delays are introduced into applications like http by using critical path analysis. by constructing and profiling the critical path, it is possible to determine what fraction of total transfer latency is due to packet propagation, network variation (e.g., queueing at routers or route fluctuation), packet losses, and delays at the server and at the client. we have implemented our technique in a tool called tcpeval that automates critical path analysis for web transactions. we show that our analysis method is robust enough to analyze traces taken for two different tcp implementations (linux and freebsd). to demonstrate the utility of our approach, we present the results of critical path analysis for a set of web transactions taken over 14 days under a variety of server and network conditions. the results show that critical path analysis can shed considerable light on the causes of delays in web transfers, and can expose subtleties in the behavior of the entire end-to-end system.  paul barford mark crovella
power-induced time division on asynchronous channels  time division multiple access offers certain well-known advantages over methods such as spread spectrum code division. foremost is the interference immunity provided by dedicated time slots. partly offsetting this is tdma's need for network- wide synchronization. viewing arbitrary time intervals as potential tdma time slots, we ask whether it is possible to obtain some of the benefit of time division without incurring the synchronization cost. in particular, we address the question of whether a tdma-like state can be induced on asynchronous channels in such a way as to reduce interference and energy consumption. through analysis and simulation we find conditions under which it is beneficial to use time division, and then show how autonomous power management may be used as a mechanism to induce a form of time division. in this context a backlog-sensitive power management system is presented.  john m. rulnick nicholas bambos
expanded delta networks for very large parallel computers  we analyze a generalization of the traditional delta network, dubbed expanded delta network (edn), which provides multiple paths that can be exploited to reduce contention. in massively parallel simd computers, the trend is to put a large number of processors on a chip, but due to i/o constraints only a subset of the processors may have access to the network at any time. this leads to the restricted access expanded delta network of which the maspar mp-1 router network is an example.  brian d. alleyne isaac d. scherson
multibeam cellular communication systems with dynamic channel assignment across multiple sectors  in cellular communication systems, directional multibeam antennas at cell sites can be used to reduce co-channel interference, increase frequency reuse and improve system capacity. when combined with dynamic channel assignment (dca), additional improvement is possible. we propose a multibeam scheme using dynamic channel assignment across multiple sectors. a cell is divided into several sectors, each of which is covered by several directional beams. specific channels are allocated to each sector as in fixed channel assignment (fca). a channel of a sector is dynamically assigned to a wireless user who communicates through one of the several beams of the sector. the assignment is made so that constraints on the allowable co-channel interference are satisfied. limitations due to co-channel interference are analyzed. a tractable analytical model for the proposed scheme is developed using multidimensional birth--death processes. theoretical traffic performance characteristics such as call blocking probability, forced termination probability, hand-off activity, carried traffic and channel rearrangement rate are determined. with the proposed scheme, call blocking probability can be reduced significantly for a fixed offered traffic. alternatively, system capacity can be increased while blocking probability is maintained below the required level. smaller forced termination probability is obtainable in comparison with corresponding fca schemes.  jung-lin pan stephen s. rappaport petar m. djuric
a wireless local area network employing distributed radio bridges  this paper presents a novel distributed wireless local area network (wlan) architecture, where each wireless terminal (wt) accesses a backbone local area network (lan) segment via multiple radio bridges (rb's). we introduce a self- learning routing algorithm for the rb's, which automatically adapts to changes in terminal locations, and prevents multiple copies of each data frame from being forwarded over the backbone lan segment. the distributed wlan architecture eases the management of network topological changes and terminal mobility, compared to centralized cellular architectures. we consider the use of direct-sequence spread-spectrum (ds/ss) signaling and the slotted aloha medium access control (mac) protocol over the wireless links, with multiple uplink receivers and downlink transmitters at the rb's for each mac frame. simulation results for the uplink show that the multi-receiver site diversity and the capture effect of ds/ss signaling effectively combat multipath and multiaccess interference, resulting in high throughput capacity and stable operation for the channel. under overload traffic, the system is able to maintain a high level of throughput with bounded delays. it is shown that the use of multiple receiver reduces the access fairness problem for wt's at different locations caused by the near-far effect.  victor c. m. leung andrew w. y. au
a routing algorithm for connection-oriented low earth orbit (leo) satellite networks with dynamic connectivity  low earth orbit leo satellites move with respect to a fixed observer on the earth surface. satellites in the polar regions and the seam switch off their intersatellite links to the neighbor satellites. as a result, the connectivity pattern of the network changes. ongoing calls passing through these links need to be rerouted. a large number of simultaneous rerouting attempts would cause excessive signaling load in the network. moreover, the handover calls could be blocked because of the insufficient network resources in the newly established routes or large connection re - establishment delay. in this paper, a routing protocol is introduced to reduce the number of routing attempts resulting from link connectivity change. the protocol does not use the links that will be switched off before the connection is over. since the call durations are not known a priori, the proposed protocol utilizes a probabilistic approach. the performance of the protocol is evaluated through simulation experiments. the experimental results indicate that the routing protocol reduces the number of rerouting attempts resulting from connectivity changes of the network.  huseyin uzunalioglu ian f. akyildiz michael d. bender
slotted aloha and cdpa: a comparison of channel access performance in cellular systems  the paper compares the performance of two channel-access schemes suitable for the cellular environment, which, in particular, allow the packet capture and can deal with inter-cell interference. the first scheme is the well known s-aloha while the second one is the capture division packet access, recently proposed. the comparison is analytically performed over a common system with a common analytical model. despite the many analyses appeared on s-aloha, the one we develop is new because a throughput density uniformly distributed on the plane is considered in a multiple cell environment. the analysis clearly shows the effect of intra-cell and inter- cell interference on the aloha system and quantifies the throughput gain achieved by cdpa, which completely avoids intra-cell interference. our analysis also provides insight about the effectiveness of power control on both systems.  flaminio borgonovo michele zorzi
a wireless public access infrastructure for supporting mobile context-aware ipv6 applications  this paper presents a novel wireless access point architecturedesigned to support the development of next generation mobilecontext-aware applications over metropolitan scale areas. inaddition, once deployed, this network will allow ordinary citizenssecure, accountable and convenient access to the internet fromtheir local city and campus environments.  the proposed architecture is based on an approach utilising amodified mobile ipv6 protocol stack that uses packet marking andnetwork level packet filtering at the edge of the wired network toachieve this objective. the paper describes this architecture indetail and contrasts it with existing systems to highlight the keybenefits of our approach.  adrian friday maomao wu stefan schmid joe finney keith cheverst nigel davies
factors in the performance of the an1 computer network  an1 (formerly known as autonet) is a local area network composed of crossbar switches interconnected by 100mbit/second, full-duplex links. in this paper, we evaluate the performance impact of certain choices in the an1 design. these include the use of fifo input buffering in the crossbar switch, the deadlock- avoidance mechanism, cut-through routing, back-pressure for flow control, and multi-path routing. an1's performance goals were to provide low latency and high bandwidth in a lightly loaded network. in this it is successful. under heavy load, the most serious impediment to good performance is the use of fifo input buffers. the deadlock-avoidance technique has an adverse effect on the performance of some topologies, but it seems to be the best alternative, given the goals and constraints of the an1 design. cut-through switching performs well relative to store-and-forward switching, even under heavy load. back- pressure deals adequately with congestion in a lightly-loaded network; under moderate load, performance is acceptable when coupled with end-to-end flow control for bursts. multi-path routing successfully exploits redundant paths between hosts to improve performance in the face of congestion.  susan s. owicki anna r. karlin
an examination of information center implementation and impact  the concept of the information center was developed by ibm in 1976 in response to the large backlogs in applications development facing data processing departments. the concept called for a new degree of cooperation and mutual support between the end user and the data processing department. under the information center concept, the end users were to assume a far greater responsibility in both defining and developing non-production data processing applications, while the data processing department would supply computer and data as well as instruction and support in utilizing these computer resources in meeting end user needs. since that time, explosive growth in microcomputers technology, development of local area networks, advances in database systems, and increased computer literacy among the user community has enlarged demand for computer resources by non-data processing personnel.  despite the fact that large numbers of organizations have made major commitments to the implementation of information centers, there is little in the literature, beyond anecdotal experiences, about the key issues involved in installing an operational information center. this study examines the techniques used by a number of firms in the san diego area to develop information centers and the impact of the information center concept on the organization.  the paper makes the following conclusions:  while there a number of similarities in approaches, as of yet, no distinct pattern of management response to the opportunities or problems created by the information center concept has emerged.  user demands for resource access will continue to increase and many more organizations will adopt the information center concept.  computer science and information systems departments must re-examine their curricula and role, in light of these changing computational support environments.  norman e. sondak madelyn c. phillips
mobile commerce for financial services---killer applications or dead end? since mobile commerce (m-commerce) started to be intensively discussed in the press, financial service companies are said to be the winners of m-commerce. but looking at existing m-commerce applications, you will find _really_ interesting information only on few sites. in addition, there are many of these applications, which are just in a prototype state and not yet available to the customers. based on the lessons we have learned from building prototype and productive m-commerce applications, the following paper briefly discusses some of the problems to be solved by corporations that want to use emerging innovative mobile technologies, such as the wireless application protocol (wap). in particular, we address issues regarding application design and development, security, and infrastructure. michael semrau achim kraiss
sacrio: an active buffer management scheme for differentiated service networks  in this paper, we propose an active resource management approach for d ifferentiated services networks. the proposed approach, sacrio, employs caching and localized packet remarking within a router. it is shown that sacrio is simple and can be implemented transparently within the diff-serv architecture. it is shown that the packet handling cost remains o(1) with sacrio. sacrio is shown to be quite effective and scalable through both ns- based simulations and real-world trace-driven simulations.  saikrishnan gopalkrishnan a. l. narasimha reddy
towards a shared-memory massively parallel multiprocessor  a set of ultra high throughput (more than one gigabits per second) serial links used as processor-memory network can lead to the starting up of a shared-memory massively parallel multiprocessor. the bandwidth of the network is far beyond values found in present shared-memory multiprocessor networks. to feed this network the memory must be serially multiported. such a multiprocessor can actually be build with current technologies.  this paper analyzes the characteristics of such a novel architecture, presents the solutions that must be considered and the practical problems associated with close of experiments. these results show then the way to effectively build this multiprocessor, taking into account main topics such as data coherency, latency time and scalability.  daniel litaize abdelaziz mzoughi christine rochange pascal sainrat
predictive and adaptive bandwidth reservation for hand-offs in qos-sensitive cellular networks how to control hand-off drops is a very important quality- of-service (qos) issue in cellular networks. in order to keep the hand-off dropping probability below a pre-specified target value (thus providing a _probabilistic_ qos guarantee), we design and evaluate _predictive_ and _adaptive_ schemes for the bandwidth reservation for the existing connections' handoffs and the admission control of new connections.we first develop a method to estimate user mobility based on an aggregate history of hand-offs observed in each cell. this method is then used to predict (probabilistically) mobiles' directions and hand-off times in a cell. for each cell, the bandwidth to be reserved for hand-offs is calculated by estimating the total sum of fractional bandwidths of the expected hand-offs within a mobility-estimation time window. we also develop an algorithm that controls this window for efficient use of bandwidth and effective response to (1) time-varying traffic/mobility and (2) inaccuracy of mobility estimation. three different admission-control schemes for new connection requests using this bandwidth reservation are proposed. finally, we evaluate the performance of the proposed schemes to show that they meet our design goal and outperform the static reservation scheme under various scenarios. sunghyun choi kang g. shin
novanet communications network for a control system  novanet is a control system oriented fiber optic local area network that was designed to meet the unique and often conflicting requirements of the nova laser control system which will begin operation in 1984. the computers and data acquisition devices that form the distributed control system for a large laser fusion research facility need reliable, high speed communications. both control/status messages and experimental data must be handled. a subset of novanet is currently operating on the two beam novette laser system.  j. r. hill j. r. severyn p. j. vanarsdall
gaining efficiency in transport services by appropriate design and implementation choices  end-to-end transport protocols continue to be an active area of research and development involving (1) design and implementation of special-purpose protocols, and (2) reexamination of the design and implementation of general- purpose protocols. this work is motivated by the perceived low bandwidth and high delay, cpu, memory, and other costs of many current general-purpose transport protocol designs and implementations. this paper examines transport protocol mechanisms and implementation issues and argues that general-purpose transport protocols can be effective in a wide range of distributed applications because (1) many of the mechanisms used in the special-purpose protocols can also be used in general-purpose protocol designs and implementations, (2) special-purpose designs have hidden costs, and (3) very special operating system environments, overall system loads, application response times, and interaction patterns are required before general-purpose protocols are the main system performance bottlenecks.  richard w. watson sandy a. mamrak
performance of globally distributed networks  in the design and implementation of computer networks one must be concerned with their overall performance and the efficiency of the communication mechanisms chosen. performance is a major issue in the architecture, implementation, and installation of a computer communication network. the architectural design always involves many cost/performance tradeoffs. once implemented, one must verify the performance of the network and locate bottlenecks in the structure. configuration and installation of a network involves the selection of a topology and communication components, channels and nodes of appropriate capacity, satisfying performance requirements.  this panel will focus on performance issues involved in the efficient design, implementation, and installation of globally distributed computer communication networks. discussions will include cost/performance tradeoffs of alternative network architecture structures, methods used to measure and isolate implementation performance problems, and configuration tools to select network components of proper capacity. the panel members have all been involved in one or more performance issues related to the architecture, implementation, and/or configuration of the major networks they represent. they will describe their experiences relating to performance issues in these areas. methodologies and examples will be chosen from these networks in current use. there will be time at the end of the session for questions to the panel.  stuart wecker robert gordon james gray james herman raj kanodia dan seligman
a unifying methodology for handovers of heterogeneous connections in wireless atm networks the aim of wireless atm is to provide multi-media services to mobile users. while existing research on wireless atm are focussed on handovers of unicast connections, handovers of multicast connections have not been investigated. while conventional multicast join and leave operations occur over the same path, this is not the case during mobile host migrations in a wireless atm network. in this paper, we reveal how handovers of multicast connections can be achieved in a manner irrespective of whether these multicast trees are source-, server- or core-based. more importantly, we demonstrate how the enhanced hybrid handover protocol incorporating crossover switch discovery can be used to support handovers of heterogeneous (i.e., unicast and multicast) connections in a uniform and unified manner, for wireless atm lans employing either the centralised or distributed connection management scheme. c.-k. toh