waashk/acm huggingface dataset:
load-tolerant differentiation with active queue management  current work in the ietf aims at providing service differentiation on the internet. one proposal is to provide loss differentiation by assigning levels of drop procedence to ip packets. in this paper, we evaluate the active queue management (aqm) mechanisms red in and out (rio) and weighted red (wred) in providing levels of drop precedence under different loads. for low drop precedence traffic, fio and wred can be configured to offer sheltering (i.e., low drop precedence traffic is protected from losses caused by higher drop precedence traffic). however, if traffic control fails or is inaccurate, such configurations can cause starvation of traffic at high drop precedence levels. configuring wred to instead offer relative differentiation can eliminate the risk of starvation. however, wred cannot, without reconfiguration, both offer sheltering when low drop precedence traffic is properly controlled and avoid starvation at overload of low drop precedence traffic. to achieve this, we propose a new aqm mechanism, wred with thresholds (wrt). the benefit of wrt is that, without reconfiguration, it offers sheltering when low drop precedence traffic is properly controlled and relative differentiation otherwise. we present simulations showing that wrt has these properties.  u. bodin o. schelen s. pink
host groups: a multicast extension for datagram internetworks  the extensive use of local networks is beginning to drive requirements for internetwork facilities that connect these local networks. in particular, the availability of multicast addressing in many local networks and its use by sophisticated distributed applications motivates providing multicast across internetworks.  in this paper, we propose a model of service for multicast in an internetwork, describe how this service can be used, and describe aspects of its implementation, including how it would fit into one existing internetwork architecture, namely the us dod internet architecture.1 2  david r. cheriton stephen e. deering
code generation of nested loops for dsp processors with heterogeneous registers and structural pipelining  we propose a microcode-optimizing method targeting a programmable dsp processor. efficient generation of microcodes is essential to better utilize the computation power of a dsp processor. since most state-of-the-art dsp processors feature some sort of irregular architectures and most dsp applications have nested loop constructs, their code generation is a nontrivial task. in this paper, we consider two features frequently found in contemporary dsp processors --- structural pipelining and heterogeneous registers. we propose a code generator that performs instruction scheduling and register allocation simultaneously. the proposed approach has been implemented and evaluated using a set of benchmark core algorithms. simulation of the generated codes targeted towards the ti tms320c40 dsp processor shows that our system is indeed more effective compared with a commercial optimizing dsp compiler.  wei-kai cheng youn-long lin
performance study of access control in wireless lans - ieee 802.11 dfwmac and etsi res 10 hiperlan  currently two projects are on their way to standardize physical layer and medium access control for wireless lans---ieee 802.11 and etsi res 10 hiperlan. this paper presents an introduction to both projects focussing on the applied access schemes. further we will present our simulation results, analyzing the performance of both access protocols depending on the number of stations and on the packet size, evaluating them regarding their capability to support qos parameters, regarding the impact of hidden terminals and their range extension strategy.  jost weinmiller morten schläger andreas festag adam wolisz
fast address lookups using controlled prefix expansion  internet (ip) address lookup is a major bottleneck in high-performance routers. ip address lookup is challenging because it requires a longest matching prefix lookup. it is compounded by increasing routing table sizes, increased traffic, higher-speed links, and the migration to 128-bit ipv6 addresses. we describe how ip lookups and updates can be made faster using a set of of transformation techniques. our main technique, controlled prefix expansion, transforms a set of prefixes into an equivalent set with fewer prefix lengths. in addition, we use optimization techniques based on dynamic programming, and local transformations of data structures to improve cache behavior. when applied to trie search, our techniques provide a range of algorithms (expanded tries) whose performance can be tuned. for example, using a processor with 1mb of l2 cache, search of the maeeast database containing 38000 prefixes can be done in 3 l2 cache accesses. on a 300mhz pentium ii which takes 4 cycles for accessing the first word of the l2 cacheline, this algorithm has a worst-case search time of 180 nsec., a worst- case insert/delete time of 2.5 msec., and an average insert/delete time of 4 usec. expanded tries provide faster search and faster insert/delete times than earlier lookup algirthms. when applied to binary search on levels, our techniques improve worst-case search times by nearly a factor of 2 (using twice as much storage) for the maeeast database. our approach to algorithm design is based on measurements using the vtune tool on a pentium to obtain dynamic clock cycle counts. our techniques also apply to similar address lookup problems in other network protocols.  v. srinivasan g. varghese
mimd machine communication using the augmented data manipulator network  there have been many multistage interconnection networks proposed in the literature for interconnecting the processors that comprise large parallel processing systems. in this paper, the use of a multistage network in the mimd mode of operation is considered. a tag based routing scheme is proposed for the augmented data manipulator network. also included is a rerouting scheme that allows a message blocked by a busy link in its present path to dynamically make use of a non-busy link and continue, when possible. finally, a tag based broadcasting scheme is introduced that allows one processor to send messages to a power of two other processors.  robert j. mcmillen howard jay siegel
hyper-erlang distribution model and its application in wireless mobille networks this paper presents the study of the hyper-erlang distribution model and its applications in wireless networks and mobile computing systems. we demonstrate that the hyper-erlang model provides a very general model for users' mobility and may provide a viable approximation to fat-tailed distribution which leads to the self-similar traffic. the significant difference from the traditional approach in the self-similarity study is that we want to provide an approximation model which preserves the markovian property of the resulting queueing systems. we also illustrate that the hyper- erlang distribution is a natural model for the characterization of the systems with mixed types of traffics. as an application, we apply the hyper-erlang distribution to model the cell residence time (for users' mobility) and demonstrate the effect on channel holding time. this research may open a new avenue for traffic modeling and performance evaluation for future wireless networks and mobile computing systems, over which multiple types of services (voice, data or multimedia) will be supported.
client-server computing in mobile environments  recent advances in wireless data networking and portable information appliances have engendered a new paradigm of computing, called mobile computing, in which users carrying portable devices have access to data and information services regardless of their physical location or movement behavior. in the meantime, research addressing information access in mobile environments has proliferated. in this survey, we provide a concrete framework and categorization of the various ways of supporting mobile client- server computing for information access. we examine characteristics of mobility that distinguish mobile client-server computing from its traditional counterpart. we provide a comprehensive analysis of new paradigms and enabler concepts for mobile client-server computing, including mobile-aware adaptation, extended client-server model, and mobile data access. a comparative and detailed review of major research prototypes for mobile information access is also presented.  jin jing abdelsalam sumi helal ahmed elmagarmid
performance evaluation of packet data services over cellular voice networks  in this paper we develop a markov chain modeling framework for throughput/delay analysis of data services over cellular voice networks, using the dynamic channel stealing method. effective approximation techniques are also proposed and verified for simplification of modeling analysis. our study identifies the average voice call holding time as the dominant factor to affect data delay performance. especially in heavy load conditions, namely when the number of free voice channels becomes momentarily less, the data users will experience large network access delay in the range of several minutes or longer on average. the study also reveals that the data delay performance deteriorates as the number of voice channels increases at a fixed voice call blocking probability, due to increased voice trunking efficiency. we also examine the data performance improvement by using the priority data access scheme and speech silence detection technique.  young yong kim san-qi li
a model for the design of distributed databases (abstract only)  this research is addressed towards solving a problem which falls under the general class of file allocation problems (fap). the main purpose here is to provide a tool for the designer of a distributed database system. with an increasing number of enterprises tending towards distributed systems, a major research question that has come up is how to allocate resources (databases and programs) in a distributed environment. this question has been addressed by formulating a nonlinear integer programming model. though the same issue has been addressed several times in the past, there is a major difference between the model developed here and all the other models. none of the models in the past have tried to solve the fap by taking into account the concurrency control mechanism being used. this is a major deficiency of these models because allocation of files is partly based on the communication flows in a network of computers. the communication flows in turn are based on the concurrency control mechanism. it is this weakness that the research here has attempted to overcome by designing a more realistic model.  sudha ram geneva g. belford
optimal allocation of programs and data in distributed systems (abstract only)  the problem of allocating programs and data to minimize total cost (communication cost + local processing cost + storage cost) subject to storage, availability, response time and policy/security constraints is formulated and solved. the problem formulation takes into account the complex interactions between data, programs and transactions, and includes the effect of update synchronization algorithms, query processing options, network topologies and queuing delays due to device-busy and locking conflicts. a wide variety of operations research techniques are integrated into a single optimization algorithm which yields, in polynomial time, exact optimal solutions for simplified cases and near optimal solutions for more complex situations. the solution approach lends itself very easily to application of "distributed" optimization, where portions of the algorithm can be executed in parallel by several computers, thus significantly reducing the total optimization time.  amjad umar
sparse communication networks and efficient routing in the plane (extended abstract)  traditional approaches to network design separate the issues of designing the network itself and designing its management and control subsystems. this paper proposes an approach termed routing-oriented network design, which is based on designing the network topology and its routing scheme together, attempting to optimize some of the relevant parameters of both simultaneously.  this approach is explored by considering the design of communication networks supporting efficient routing in the special case of points located in the euclidean plane. the desirable network parameters considered include low degree and small number of communication links. the desirable routing parameters considered include small routing tables, small number of hops and low routing stretch.  two rather different schemes are presented, one based on direct navigation in the plane and the other based on efficient hierarchical tree covers. on a collection of n sites with diameter d, these methods yield networks with maximum degree o(log d) (hence a total of o(n log d) communication links), coupled with routing schemes with constant routing stretch, o(log n log d) memory bits per vertex and routes with at most log n or log d hops.  yehuda hassin david peleg
systems aids in determining local area network performance characteristics  at bethesda, maryland, the national library of medicine has a large array of heterogenous data processing equipment dispersed over ten floors in the lister hill center and four floors in the library building.  the national library of medicine decided to implement a more flexible, expansible access medium (local area network (lan) to handle the rapid growth in the number of local and remote users and the changing requirements. this is a dual coaxial cable communications system designed using cable television (catv) technology. one cable, the outbound cable, transfers information between the headend and the user locations. the other cable, the inbound cable, transfers information from the user locations to the headend. this system will permit the distribution of visual and digital information on a single medium.  on-line devices, computers, and a technical control system network control center are attached to the lan through bus interface units (bius). the technical control system will collect statistical and status information concerning the traffic, bius, and system components. the bius will, at fixed intervals, transmit status information to the technical control. the network control centers (ncc) will provide network directory information for users of the system, descriptions of the services available, etc. a x.25 gateway biu will interface the lan to the public networks (telenet and tymnet) and to x.25 host computer systems.  barbara r. sternick
vertical information technology in the galua's baseÂ-new direction indevelopment of computer machines (abstract only)in the indicated article the stated theoretical basis and structural solutionsof the galua's base for construction of elements of peripheral knotsoperational and microprocessor computer machines. the offered methodology ofrealization of vertical information technology in the galua's base in problemsof programming with a deep level of paralle's data processing inmultiprocessor systems with the associative memory.yaroslav nykolajchuk roman korol
macaw: a media access protocol for wireless lan's  in recent years, a wide variety of mobile computing devices has emerged, including portables, palmtops, and personal digital assistants. providing adequate network connectivity for these devices will require a new generation of wireless lan technology. in this paper we study media access protocols for a single channel wireless lan being developed at xerox corporation's palo alto research center. we start with the maca media access protocol first proposed by karn [9] and later refined by biba [3] which uses an rts-cts-data packet exchange and binary exponential back-off. using packet-level simulations, we examine various performance and design issues in such protocols. our analysis leads to a new protocol, macaw, which uses an rts-cts-ds-data-ack message exchange and includes a significantly different backoff algorithm.  vaduvur bharghavan alan demers scott shenker lixia zhang
adaptive interaction for enabling pervasive services  we describe an architecture that allows mobile users to access a variety of services provided by pervasive computing environments. novel to our approach is that the system selects and executes services taking into account arbitrary contextual information (e.g. location or preferences). our architecture is based on an adaptive service interaction scheme; individual service requests are attributed by context constraints, which specify the adaption policy. context constraints may relate to spatial or temporal concerns. we propose a document- based approach; so called context-aware packets (caps) contain context constraints and data for describing an entire service request. intermediary network nodes route and apply the data to services, which match the embedded constraints. services are identified by characterizing attributes, rather then explicit network addresses. the execution of selected services may be deferred, and triggered by a specific event. service requests carry the context of their use, therefore our system works well in environments with intermitted connectivity, less interaction with the issuing requester is required.  michael samulowitz florian michahelles claudia linnhoff- popien
a simplified approach to the performance evaluation of fdma-cdma systems  this work shows it is possible to apply for the performance evaluation of fdma-cdma cellular mobile systems a simple analytical approximated method, previously successfully proposed by two of the authors with reference to fdma- tdma systems. the distinctive feature of the methodology we describe is that it allows for an immediate determination of both the indexes traditionally employed to define system performance, i.e., average bit error probability \overline p_e and outage probability p_{\mathrm{out} at a very low computational cost. the hypothesis required to apply the proposed approximation is that the examined spread spectrum system be characterized by a bandwidth occupancy lower than the coherence bandwidth of the transmission channel. this could be the case of a wireless ds-cdma system envisioned to provide voice service and exploiting a processing gain of the order of a hundred. we apply our methodology to determine the performance improvements in both \overline p_e and p_{\rm out introduced increasing the protection of the transmitted information through error correcting codes and interleaving, in different operating conditions as regards the functioning of the power control loops. a comparison is also satisfyingly carried out with some other approximated analytical methods found in literature. we strongly point out that the corresponding results are achieved at a much more modest computational cost than in traditional approaches.  gianni immovilli maria luisa merani mohammed kussai shahin
dynamic time windows: packet admission control with feedback  we present a feedback congestion control method, dynamic time windows, for use in high speed wide area networks based on controlling source variance. it is part of the two-level integrated congestion control system introduced in our earlier work[1].  the method consists of a packet admission control system and a feedback system to dynamically control source burstiness. source throughput is not modulated as with traditional packet windows, allowing system throughput to remain high while avoiding congestion. furthermore, the admission control bounds congestion times in the network, allowing feedback to be effective in the face of large bandwidth delay products.  the basic control mechanisms are analogs to traditional packet windows applied to controlling time windows - a new mechanism which allows switches to modulate source variances. the proposed system is simulated, and the results reported and analyzed. enhancements to the basic system are also proposed and analyzed.  we wish to stress that the system described here is the second level of a two- level congestion control. previous work[1] concentrated on the switch queueing mechanism, pulse, while this work is a detailed examination of the feedback system used to adjust time windows to changing network load.  theodore faber lawrence h. landweber amarnath mukherjee
improving the accuracy of static branch prediction using branch correlation  recent work in history-based branch prediction uses novel hardware structures to capture branch correlation and increase branch prediction accuracy. we present a profile-based code transformation that exploits branch correlation to improve the accuracy of static branch prediction schemes. our general method encodes branch history information in the program counter through the duplication and placement of program basic blocks. for correlation histories of eight branches, our experimental results achieve up to a 14.7% improvement in prediction accuracy over conventional profile-based prediction without any increase in the dynamic instruction count of our benchmark applications. in the majority of these applications, code duplication increases code size by less than 30%. for the few applications with code segments that exhibit exponential branching paths and no branch correlation, simple compile-time heuristics can eliminate these branches as code- transformation candidates.  cliff young michael d. smith
a real time transport scheme for wireless multimedia communications in wireless communications systems, a mobile station is typically equipped with limited processing capability and buffer space for transmitting and receiving. the radio link is usually found to be noisy and its propagation delay is sometimes non-negligible as compared with the packet transmission delay. and because of the necessity of flow control and packet retransmission upon error, the delay and throughput performance cannot satisfy the need of a particular traffic type, i.e., real-time multimedia. this paper presents a scheme suitable for the above condition, called the _burst-oriented transfer with time-bounded retransmission (bttr)._ the present scheme uses a large transmission window for sending/receiving a burst of time-sensitive data and, within this window, another smaller observation window is repeatedly used for error status feedback via the backward channel. there is time limitation on each retransmission such that the burst of data can be received in a timely manner, however, with some degradation on the packet loss rate. an analysis is given in terms of the expectations of delay, throughput, and packet drop rate. a comparison with an error-free link protocol will also be given. the result shows that the proposed scheme can meet the delay and throughput requirement under reasonable packet drop rate. jon chiung-shien wu
a service framework for carrier grade multimedia services using parplay apis over a sip system the implementation of new mobile communication technologiesdeveloped in the third generation partnership project (3gpp) willallow to access the internet not only from a pc but also via mobilephones, palmtops and other devices. new applications will emerge,combining several basic services like voice telephony, e-mail,voice over ip, mobility or web- browsing, and thus wiping out theborders between the fixed telephone network, mobile radio and theinternet. offering those value-added services will be the keyfactor for success of network and service providers in anincreasingly competitive market. in 3gpp's service framework theuse of the parlay apis is proposed that allow applicationdevelopment by third parties in order to speed up service creationand deployment. 3gpp has also adopted sip for session control ofmultimedia communications in an ip network. this paper proposes amapping of sip functionality to parlay services and describes aprototype implementation using the sip servlet api. furthermore anarchitecture of a service platform is presented that offers aframework for the creation, execution and management of carriergrade multimedia services in heterogeneous networks. rudolf pailer johannes stadler