PC-notebook based mobile networking: algorithms, architectures and implementation

Jain, Rajeev; Short, J.; Nazareth, Sean; Kleinrock, Leonard; Villasenor, John

doi:10.1109/icc.1995.524208

Cited by 16 publications

(12 citation statements)

References 7 publications

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“…An ambitious multimedia multihopped networking project is underway at UCLA [47,48]. It aims to develop design tools to efficiently evaluate the trade-offs in designing a peer-to- peer packet network to support voice, video and data.…”

Section: Multihop Pcs Networkmentioning

confidence: 99%

System design choices in personal communications

Pottie

1995

IEEE Pers. Commun.

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A ssuming that bandwidth is " dear, a reasonable design objective for wireless personal communications systems is to maximize the total throughput (number of users times data rate), subject to constraints on complexity and quality of service. In a conventional time division multiple access system (TDMA), users are assigned time slots which they keep from frame to frame, with the interfering mobiles assigned slots in the same way. As interference levels vary widely between slots due to such factors as shadowing and geographic proximity, some users suffer from persistently poor signal to interference ratios (SIR), and thus low quality of service. To overcome this, the use of frequencies is restricted so that some minimum geographic separation between users sharing a channel is guaranteed. Because systems are designed to tolerate 90 percent or 99 percent worst case conditions, large frequency reuse distances are often required, reducing the bandwidth available in each cell.In this article, we outline some of the many techniques that have been proposed in recent years to deal with the uneven SIR distribution while achieving a higher throughput than conventional TDMA. These may be broadly categorized as either interference averaging or interference avoidance. For example, direct sequence code division multiple access (DS-CDMA) systems with large spreading factors not only yield protection against multipath fading, but average over the interferers. The average interference is exchanged for the worst case, resulting in significantly improved capacity. Dynamic channel and power allocation algorithms on the other hand select either time slots or frequency hopping patterns which avoid strong interferers. As will be seen, this leads to a higher capacity than even synchronous DS-CDMA systems, assuming the interference can be tracked. Interference suppression using antenna arrays, and multiple receiver sites can then be used to improve the performance of either basic system.It is not our purpose to present an exhaustive survey of all possible system design choices, but rather to acquaint the reader with some of the basic trade-offs available for dedicated and multiple access radio systems. In particular, our focus is on the application of digital signal processing techniques to This work supported in part by ARPA contracts DAAB07-92-RX977 and JFB194-222lJ4C942220. improve the capacity of wireless communications systems, with an emphasis on the physical layer. Moreover, while we will compare many types of systems with respect to a common propagation environment by means of simulation, the reader is cautioned that the model chosen is quite simple; such comparisons serve chiefly to motivate more detailed engineering investigation of what is actually required to achieve higher capacity.The remainder of the article is organized as follows. In the following section we outline techniques for dealing with variable propagation conditions for single user channels. In the third section we perform comparisons of interference averagin...

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Section: Multihop Pcs Networkmentioning

confidence: 99%

System design choices in personal communications

Pottie

1995

IEEE Pers. Commun.

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“…There is however, another wireless networking architecture of interest which assumes no base stations [2,6]. Such wireless networks are useful for applications that require "instant" infrastructure, among others.…”

Section: Wireless Networking Issuesmentioning

confidence: 99%

Nomadic computing—an opportunity

Kleinrock

1995

SIGCOMM Comput. Commun. Rev.

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We are in the midst of some truly revolutionary changes in the field of computercommunications, and these offer opportunities and challenges to the research community. One of these changes has to do with nomadic computing and communications. Nomadicity refers to the system support needed to provide a rich set of capabilities and services to the nomad as he moves from place to place in a transparent and convenient form. This new paradigm is already manifesting itself as users travel to many different locations with laptops, PDA's, cellular telephones, pagers, etc. In this paper we discuss some of the open issues that must be addressed as we bring about the system support necessary for nomadicity. In addition, we present some of the considerations with which one must be concerned in the area of wireless communications, which forms one (and only one) component of nomadicity.

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“…5 results, we see that the logical topology synchronization is fairly stable for packet loss rates up to 50%. Experimental results reported in Jain, et al (1995), show that packet loss rates as high as 16% have been observed, with corresponding logical link failure around 1.2%. Note, however, that even though the logical topology is accurate 98.8% of the time, 16% of the data packet transmission still fail.…”

Section: Experimental Studymentioning

confidence: 89%

“…The refined models used in the simulation study described in the next section were ported, without any redesign or programming, to a set of four 486 laptops running WAMISNOS using two different radios: the UCLA Direct Sequence Spread Spectrum radio operating at 32Kbps (Jain, et al 1995), and the Proxim Range-LAN2 Frequency Hop Spread Spectrum radio operating at 1.6Mbps.…”

Section: Integrated Simulation and Implementation Environmentmentioning

confidence: 99%

A hierarchical simulation environment for mobile wireless networks

Bagrodia¹,

Gerla²,

Kleinrock³

et al.

Winter Simulation Conference Proceedings, 1995.

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A hierarchical simulator has been designed for multimedia communication protocols in a wireless mobile environment. The hierarchical approach integrates performa.nce evaluation of protocols with their implementation. The approach supports scalability studies of the protocols in an efficient manner using coarse grain models that abstract implementation details of the protocol and its execution environment by a few key parameters. Fine grain, low-level models that capture implementation details are used for detailed evaluation of small networks and for automatic implementation on radio platforms. The design, evaluation, and implementation cycle is closed by feeding the measurements from the implementation back into the model to improve its accuracy. The paper describer; the use of the environment in the evaluation and implementation of a cluster-based multihop protocol for multimedia traffic.

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PC-notebook based mobile networking: algorithms, architectures and implementation

Cited by 16 publications

References 7 publications

System design choices in personal communications

System design choices in personal communications

Nomadic computing—an opportunity

A hierarchical simulation environment for mobile wireless networks

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