Randy H. Katz. Adaption and mobility in wireless information systems. IEEE Personal Communications, 1(1):6--17, 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... level contextual reconfiguration has been examined in [8] Infrastructure issues in location aware computing are described in [11, 4, 12] and issues of information dissemination for context aware software is presented in [9] Situation awareness for mobile communication systems is advocated in [5]. 4 Acknowledgments A number of people worked on the location systems in our lab, including Marvin Theimer, Mike Spreitzer, Karin Petersen, David Nichols and Phil James. Thanks to Rich Gold for Figure 1. John Ellis wrote the ParcTab voting application. David Nichols and Marvin Theimer wrote the ....

Randy H. Katz. Adaption and mobility in wireless information systems. IEEE Personal Communications, 1(1):6--17, 1994.

.... emerging UMTS (Universal Mobile Telecommunications System) 9] Compatibility with multiple standards for mobile communications as listed inTable1 istherefore expected, but there is also a potential for compatibility with other emerging systems, such as PCN, PBX, or satellite communications [17]. TABLE 1: Selected Wireless Communication Systems [1, 23, 34] Wireless Access Frequency Channel Frequency Modulation Data Rate Per Peak Standard Scheme Spectrum Spacing Accuracy Technique RF Channel Power DECT TDMA TDD 1.880 1.900MHz 1.728MHz 50kHz GFSK 1.152Mbs 250mW DCS 1800 TDMA ....

....PAGE 2 R 96 1005 Troels Emil Kolding December 1996 standard capability. Current wireless systems are characterized by such terms as voice data, real time delayed, interactive one way, and in building out of doors. The technology must constantly adapt to an increasing requirement for mobility [17]. To simplify the demodulation process, it is an advantage that the modulation characteristics of the various standards are quite similar (constant envelope) Further, the sensitivity is also similar and resides typically around a value of 145dBm Hz. However, there are still significant ....

R. H. Katz. Adaption and Mobility in Wireless Information Systems. IEEE Personal Communications Magazine, 1(1):6 -- 17, 1st quarter 1994.

....application designed specifically to operate in this type of environment. Such applications must avoid assumptions about their underlying support environment which may prevent them from operating effectively across a range of networks. Applications of this type are termed adaptive applications [Katz94]. The potential of adaptive applications is considerable. Firstly, they can fully exploit the available level of connectivity at any given time. Secondly, adaptive applications are, by definition, more portable. For example, the same applications could be used on a workstation connected to a high ....

Katz, R.H. "Adaption and Mobility in Wireless Information Systems." IEEE Personal Communications Vol. 1 No. 1. Pages 6-17, 1994.

....Approximation . 36 REFERENCES. 6 7 I. INTRODUCTION In the last few years there have been much discussion on future Personal Communications Services (PCS) [1]. The existing mobile communication systems mainly support speech services. Also in future systems speech is expected to be the main service, but with higher quality than in the systems of today, and maybe in conjunction with video. Other expected services are image transmission (facsimile) with ....

R. H. Katz, "Adaption and mobility in wireless information systems," IEEE Personal Commun. , First Quarter 1994, pp. 6-17.

....the other schemes. Furthermore multi chip rate, parallel combinatory spread spectrum (PC SS) pulse position modulation (PPM) and variable duty cycle schemes are discussed briefly. I. INTRODUCTION In the last few years there has been much discussion on future Personal Communications Services (PCS) [1]. The existing mobile communication systems mainly support speech services. Also in future systems speech is expected to be the main service, but with higher quality than in the systems of today, and maybe in conjunction with video. Other expected services are image transmission (facsimile) with ....

R. H. Katz, "Adaption and mobility in wireless information systems," IEEE Personal Commun., Vol. 1, No. 1, pp. 6-17, First Quarter 1994.

....been done in the distributed file system context [Levy90] There has been a lot of work on caching in these environments, much of which has focused on the maintenance of cache consistency in the face of updates. More recently, there has been work on data management issues for wireless environments [Katz94]. Some of work in this area has focused on satellite based systems [Dao96, Dire96] in which the downstream bandwidth is quite high. The idea of the publish subscribe model as a dissemination mechanism has been used in many contexts including SIFT [Yan95] and the Information Bus[Oki93] There has ....

R. Katz, "Adaption and Mobility in Wireless Information Systems", IEEE Personnal Comm., 1st Quarter, 1994.

....while clients cannot transmit or can do so only over a lower bandwidth cellular link. Systems with these characteristics have been proposed for many application domains, including traffic information systems, hospital information systems, public safety applications, and wireless classrooms (e.g. [Katz94, Imie94a]) We refer to such environments as Asymmetric Communications Environments. Communications asymmetry can arise in two ways: the first is from the bandwidth limitations of the physical communications medium. An example of physical asymmetry is the wireless environment as described above; ....

R. Katz, "Adaption and Mobility in Wireless Information Systems", IEEE Personal Communications, First Quarter, 1994.

....communication technology gives rise to the possibility that anybody can get any data anytime and anywhere because users can be freed from being physically connected to the underlying network. This vision implies that the distinction between communications and computing will continue to be blurred [Katz 94] Thus, in our age of integration of telecommunication networks, multimedia, distributed (database) systems and information highways there will be no clear separation between data management and communication technology problems anymore. For example: is querying the WWW a database problem, a ....

....systems but each focusing on a certain property. Ubiquitous computing expects a world in which a huge amount of very cheap computers is widely spread among all the domains of our everyday life. Connecting that many computing devices by a wired network would be a time consuming and expensive task [Katz 94] leading to wireless computing. Decoupled computing denotes the ability to compute disconnectedly from servers and even communication networks. Frequent disconnections in turn are predicted to be common in wireless computing since the unreliability of wireless channels or the need to save energy ....

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R.H. Katz: "Adaption and Mobility in Wireless Information Systems", IEEE Personal Communications, Vol. 1, No. 1, pp. 6-17, 1994.

....Dissemination based information systems have been proposed and or implemented for both wired and wireless networks for a wide range of applications. Some examples include: stock quotation and trading systems [Oki93] advanced traveler information systems (ATIS) Shek94] wireless classrooms [Katz94], fast database lookup [Herm87, Bowe92] and news delivery in both wireless [Giff90] and wired [Inte96] environments. In previous work, we proposed and analyzed the Broadcast Disks model for disseminating data in a broadcast environment [Zdon94, Acha95b] Specifically, Broadcast Disks are intended ....

R. Katz, "Adaption and Mobility in Wireless Information Systems", IEEE Personal Communications, 1st Quarter, 1994.

....communications quality ofservice. 1: Introduction Future computer environments will include mobile computers which will either be disconnected, weakly interconnected by low speed wireless networks such as GSM, or fully inter connected by high speed networks ranging from Ethernet to ATM ([1, 2]) Two key characteristics of such environments are: i) a heterogeneous processing environment (including relatively low power mobile hosts) and, ii) rapid and massive fluctuations in the quality of service (QoS) provided by the underlying communications infrastructure. The first of these ....

....of the most fundamental problems in the field of mobile computing. In this position paper we address this issue and propose extensions to emerging distributed systems standards to support mobile computing. These extensions are designed to allow the development of adaptive or reactive applications [2, 6] which are able to tailor their behaviour based on changes in their communications infrastructure. Section 2 of this paper presents a rational for developing adaptive services and highlights the role of QoS management in supporting such services. Section 3 then describes a distributed systems ....

Katz, R.H. "Adaption and Mobility in Wireless Information Systems." IEEE Personal Communications Vol. 1 No. 1, Pages 6-17.

.... level contextual reconfiguration has been examined in [8] Infrastructure issues in location aware computing are described in [11, 4, 12] and issues of information dissemination for context aware software is presented in [9] Situation awareness for mobile communication systems is advocated in [5]. 4 Acknowledgments A number of people worked on the location systems in our lab, including Marvin Theimer, Mike Spreitzer, Karin Petersen, David Nichols and Phil James. Thanks to Rich Gold for Figure 2. John Ellis wrote the PARCTAB voting application. David Nichols and Marvin Theimer wrote the ....

Randy H. Katz. Adaption and mobility in wireless information systems. IEEE Personal COmmunications, 1(1):6--17, 1994.

....capability while clients cannot transmit or can do so only over a lower bandwidth (e.g. cellular) link. Such systems have been proposed for many application domains, including traffic information systems, hospital information systems, public safety applications, and wireless classrooms (e.g. [Katz94, Imie94a]) We refer to these environments as Asymmetric Communications Environments. Communications asymmetry can arise in two ways: the first is from the bandwidth limitations of the physical communications medium. An example of physical asymmetry is the wireless environment as described above; ....

R. Katz, "Adaption and Mobility in Wireless Information Systems", IEEE Personal Comm., 1st Quarter, 1994.

....also in the mobile. A multi modulation scheme is also possible, but the performance for the users with the high data rates is significantly worse than for the other schemes. I. INTRODUCTION In the last few years there have been much discussion on future Personal Communications Services (PCS) [1]. The existing mobile communication systems mainly support speech services. Also in future systems speech is expected to be the main service, but with higher quality than in the systems of today, and maybe in conjunction with video. Other expected services are image transmission (facsimile) with ....

....computing will be necessary services in any future system. There have been some proposals for systems supporting PCS. They are known as Personal Communications Networks (PCN) Future Public Land Mobile Telecommunication Systems (FPLMTS) and Universal Mobile Telecommunication Systems (UMTS) [1]. The main focus has been on the access method, and the competitors seem to be Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA) However, in this paper we consider Direct Sequence CDMA (DS CDMA) as access method and focus on how to support the services in PCS. As seen ....

R. H. Katz, "Adaption and mobility in wireless information systems," IEEE Personal Commun., First Quarter 1994, pp. 6-17.

....Dept. of Computer Science, University of Maryland, College Park, MD 20742, franklin cs.umd.edu) z Dept. of Computer Science, Brown University, Providence, RI 02912 (sbz cs.brown.edu) information systems, hospital information systems, public safety applications, and wireless classrooms (e.g. [Katz94, Imie94a]) We refer to these environments as Asymmetric Communications Environments. Communications asymmetry can arise in two ways: the first is from the bandwidth limitations of the physical communications medium. An example of physical asymmetry is the wireless environment as described above; ....

R. Katz, "Adaption and Mobility in Wireless Information Systems", IEEE Personal Communications, 1st Quarter, 1994.

....for linear amplifiers. A multi modulation scheme is also possible, but the performance for the users with the high data rates is significantly worse than for the other schemes. I. INTRODUCTION In the last few years there has been much discussion on future Personal Communications Services (PCS) [1]. The existing mobile communication systems mainly support speech services. Also in future systems speech is expected to be the main service, but with higher quality than in the systems of today, and maybe in conjunction with video. Other expected services are image transmission (facsimile) with ....

R. H. Katz, "Adaption and mobility in wireless information systems," IEEE Personal Commun., First Quarter 1994, pp. 6-17.

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Katz, R.H. "Adaption and Mobility in Wireless Information Systems." IEEE Personal Communications Vol. 1 No. 1. Pages 6-17.

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