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Wireless Access and the Local Telephone Network
Abstract
From the Publisher:This book analyzes the wireless revolution: from applications to technology, and from economics to system engineering.
... The current policies for increasing telecommunications deployment in rural areas are considered to be insufficient or unsuccessful, and the plans for expansion of local telephone networks are considered to be imprecise considering the scope of the investment (Malecki, 2003;Melody 1999;Strover, 2003, Calhoun, 1992. For instance, telecom privatization has been related to telephone deployment growth but not to universal service. ...
... For this reason, the cost to provide a telephone line to a rural subscriber could be ten times the cost for an urban subscriber (Calhoun, 1992). ...
... Telecom planning using a long-term and non-linear system dynamics approach as compared to 'tactical' approaches, which are reactive, short-term, and linear, has been advocated (Lyneis, 1994). In addition, new modeling practices, like System Dynamics, has been suggested for the telecommunications industry, which can incorporate the trade-offs raised by the emergence of wireless access alternatives, especially when applied to rural environments (Calhoun, 1992). System Dynamics is used in this dissertation, specifically for investigating the impact of Universal Service Obligations and International Cross-Subsidies on the growth of rural telecom infrastructure. ...
... In so doing, it continues the exploration of architectural differences in (Gillett, Lampson and Tennenhouse, 1994) and (Tennenhouse, Lampson, Gillett et al., 1995), but with a narrower focus on cable and ISDN as the infrastructures, and Internet access as the application. It also extends the qualitative discussion of architectural differences between bus and star networks found in (Calhoun, 1992). In exploring the question of architectural differences stated above, this report takes existing infrastructure costs as given, except for capital investments specifically needed to support the Internet access application. ...
... Wireless networks are also a possibility but are beyond the scope of this report. 34 As Reed writes on page 1 of (Reed, 1993): ÒThe high costs of optical systems have so far ruled out the widespread deployment of fiber-to-the-home and fiber-to-the-curb networks.Ó See also (Calhoun, 1992), pp. 547-8. ...
... 35 Professor David Tennenhouse suggested thinking about the problem in this way. Flexibility of the cost structure of the needed investment is also discussed in (Calhoun, 1992), pp. 549-50; (Lu, Eiger and Lemberg, 1990), p. 1063; and (Faulkner, Payne, Stern and Ballance, 1989). ...
... This report describes the technologies and evaluates qualitative differences between the two approaches. It presents quantitative results of capital cost models based on case studies of the PSICable deployment in Cambridge, MA, and the Internet over ISDN service offered by Internex, Inc. in the San Francisco, CA area. The report finds that cables shared-bandwidth approach has superior economic characteristics. For example, 500 Kbps Internet access over cable can provide the same average bandwidth and four times the peak bandwidth of ISDN access for less than half the capital cost per subscriber. The economy of the shared bandwidth approach is most evident when comparing the persubscriber cost per bit of peak bandwidth: 16 for ISDN. Cable-based access also has better service characteristics: it can support both full-time Internet connections and higher peak bandwidths, such as a 4 Mbps cable service that provides thirty-two times the peak bandwidth of ISDN. The report concludes with an analysis of the barriers to diffusion of cable and ISDN Internet access, including business and policy factors. It finds that the closed market structure for cable subscriber equipment has not been as effective as the open market for ISDN equipment at fostering the development of needed technology. Furthermore, monopoly control of residential communications infrastructurewhether manifest as high ISDN tariffs or simple lack of interest from cable operatorslimits business opportunities for Internet service providers.
... Typically the unbundling occurred along the subscriber loop between the local exchange carrier's central office and the subscriber's equipment with costly hard-wired connections. With the increasing popularity of wireless networks, however, service providers gained access to customers without wired connections to their local loops (Bates 2001, Calhoun 1992, Vacca 2001, Webb 2000. ...
... Estimating the FWB Market New service providers must estimate the market for an FWB access network (Calhoun 1992, Webb 2000. To do so, they must collect information on business buildings in the area, their tenants, and the tenants' telecommunications needs. ...
To deploy broadband networks, service providers, such as competing local exchange carriers, need robust plans for providing various types, amounts, and locations of services at competitive prices. Broadband networks generally consist of an access component (wireless access), a concentration component (a wireless aggregation point or hub), a service routing or distribution component (a central office or metro switch), and various combined or separate distribution components (a long-haul backbone data or voice network). Because access, aggregation, and routing or distribution vary greatly in requirements, we developed a method and platform for planning the components of fixed-wireless-broadband (FWB) systems for local loop access. We have helped various service providers to analyze and design many networking scenarios using our methods. The service providers have used these scenarios and their predicted financial outcomes to plan FWB access networks tailored to meet their marketing and financial goals. By implementing our method, one service provider has improved its planning process, achieved a competitive advantage in its markets, and increased its annual service revenues by tens of millions of dollars.
... This also implies that in the immediate future, given current ASR technology and computational resources, complex ASR applications such as dialog systems will only be possible to implement in the network recognition modality, as they rely on sophisticated recognizers and compensation routines, which are currently feasible only with relatively large central speech servers. shows a diagram of an ASR application linked to a user through a mobile network linked to a land-line or Public Switched Telephone Network (PSTN) network, based on the mobile topology presented by Calhoun [9]. The mobile terminal communicates to a radio base station through a wireless channel. ...
... The recognition experiments in the following subsection were performed using the reduced bandwidth and downsampled version of the speaker independent component of the Resource Management RM1 corpus [9]. In order to explore the behavior of these cepstral streams in word accuracy terms under additive noise we also performed experiments adding white Gaussian noise at approximately 18 dB SNR. ...
The growth of cellular telephony combined with recent advances in speech recognition technology results in sizeable potential opportunities for mobile speech recognition applications. Classic robustness techniques that have been previously proposed for speech recognition yield limited improvements of the degradation introduced by idiosyncrasies of the mobile networks. These sources of degradation include distortion introduced by the speech codec as well as artifacts arising from channel errors and discontinuous transmission. In this thesis we focus on characterizing the distortion introduced to the speech signal by the speech codec and we propose methods for reducing the detrimental effect of coding on recognition accuracy. The initial focus of this thesis is on the full rate GSM codec (FRGSM) . We propose a method to generate recognition features directly from codec parameters. It is shown in this work that by selectively constructing a cepstral feature vector from the GSM codec para...
... Since 1988, BIST market trade volume has increased generally. Remarkable growths in transactions have been seen in some years such as 1992, 1995, 2001 The number of transactions has grown 127% in 1992 thanks to some reasons such as board methods and telephone usage, increase in the number of publicly traded companies 216 in 1990 and 1991. Then, computer based system in stock exchange has provided electronic work process in November 1994. ...
In the 18th century The Industrial Revolution has enabled to develop and deployment of science and technology (S & T). Then, the world has faced with an unprecedented picture after the Revolution which was one of the breaking points in the entire history of the world. In the 20th century, the importance of S & T has increased dramatically. Science-based technology, especially ICT, has been very significant within the framework of economic development, sustainability of economic growth, and competitiveness. It is not possible to reject the effects of ICT on relationships among individuals, institutions and between them, as well as on the processes of production and distribution, management structures, the role of governments in innovations and industry, determining the policies of science, technology, and innovation. The progresses in ICT, especially in telecommunications technologies, and transition to information society have been observed in the world. In the second half of the 20th century, the effects of ICT on institutions have been one of the prominent topics in terms of the transformation in the world and Turkey especially.
In this study, the brief history of ICT is overviewed with its place in the world by referring to its effects in the extended introduction. In the second part, I explain the theoretical perspective on technology. Then in the third part, the relationship between ICT and economic institutions is viewed. In the next part, ICT sector situation in the world and Turkey, and some selected economic institutions in Turkey are observed to show ICT effects on. Last part is conclusion which includes some policy recommendations.
Keywords: Information and Communications Technology, Economic Institutions, Economic Growth and Development, Technology, Innovation.
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... The ARTour Web Express system described in [elided] focused on various techniques for minimizing data volume and reducing latency of the HTTP protocol when communicating over low-bandwidth, high-latency communication channels such as those used in wide-area wireless networks [4,5,6,7]. We argued that the browser model is becoming the user interface of choice due to its rapid deployment and acceptance and the broad connectivity afforded by the Internet. ...
... It requires the universal availability of public telecommunications networks by individual households, and accompanied by non-discriminatory and affordable prices [12]. USOs and ICSs are telecom subsidies that have been typically applied to those telephone services regulated by governments, and mandated to provide affordable and accessible service, such as fixed 'wired' telephones [4]. At the same time, cellular telephone service, which is generally less regulated, is not significantly affected by such cross-subsidies. ...
This paper re-evaluates the telecommunication policies often applied to create regional dispersion of services in developing countries. We observe that failure to consider the complexities of the regional telecommunication systems in creating policies and investment strategies has increased the telecom gap between urban and rural regions worldwide. In particular, the teledensities of rural telecommunications in developing countries have remained very low in spite of support through universal service obligation fees and cross-subsidization from international services. As traditional methods for economic analysis and modeling have failed to identify mechanisms that improve telephone dispersion in these countries, we use a system dynamics modeling approach to deal with complexities of the situation in order to evaluate how Universal Service Obligations (USOs) and International Cross-Subsidy (ICS) policies affect telephone densities. We demonstrate that these policies may be counterproductive due to the structure of the telecom system itself. We also show that, when market-clearing pricing is combined with USOs once the urban telephone density reaches a minimum threshold, the dispersion of rural telecommunications can be considerably improved.
... RF availability depends on natural environment, infrastructure, and subscriber handsets. There are many research and development results[1,2]in each of the above areas. In this paper, our investigation focuses on RF channel failure recovery in the infrastructure, more specifically, in remote base site. ...
With the increasing penetration of wireless communications systems, customers are expecting the same level of service, reliability and performance from the wireless communication systems as the traditional wire-line networks. Due to the dynamic environment, such as the roaming of mobile subscribers, maintaining a high radio frequency (RF) availability is one of the most challenging aspects in wireless network management. To date, in wireless network management, a call is dropped when the channel it uses goes down. In order to increase system end-to-end availability, an RF channel recovery scheme is proposed in this paper. When an RF channcl Pds, the channcl is replaced by another working channel and the call continues. The methods to replace failed RF channels of ongoing calls and to handle channel failures of handoR and new calls are investigatcd. Markov reward models are developed to compare system availability and performance. Automated generation and solution of Markov reward modcls is facilitatcd by a version of stochastic Petri nets that we call stochastic reward nets. The results show that the rccovcry schcme reduces the dropped calls and the blocked calls significantly under both light and normal trarffics.
... In other words, integrated planning is required to cover interactions among aspects treated separately by conventional planning tools. For instance: Given a multiple access technique based on code division (CDMA, [3]) or space division (SDMA, [11]), the shape of a cell depends on the behavior of the users in the cell as well as on the users of surrounding cells. Furthermore, in such systems, the user distribution directly influences the performance of the system. ...
... There is little dispute about the theoretical impact of the competitive marketplace which the liberalisation of markets is expected to encourage. In theory, markets are expected to evolve to encourage the supply of multiple competing network and service operators and their networks are expected to be seamlessly 'stitched' together by transparent agreements among competitors (Calhoun 1992). The traditional public telecommunication network operators are expected to compete and win business alongside cable and other fixed network operators and suppliers of radio-based infrastructure. ...
... The main obstacle to innovation in the telecommunications network is therefore the installed investment of copper wiring in the local network. The transition towards geodesic architecture—or what Calhoun calls the 'laminar network*—is gathering momentum in the local network as an increasing number of competing and overlapping transmission technologies are used to access the network (Calhoun, 1992, p. 63). By the turn of the twenty-first century, two new access technologies, fibre optics and cellular radio, may overcome the 'access bottleneck" created by the limitations of copper wiring. ...
Drawing upon a framework of analysis developed by Thomas Hughes, this paper examines the development of the telecommunications
network as a large technical system, dealing with the ways in which innovation is behind the rate and direction of system
growth. It focuses on developments in the USA and in Europe since the 1960s in a period when a cluster of radical innovations changed the traditional technical and institutional set-up of the telephone
network. The paper argues that an explanation of innovation in large technical systems‘has to account for the economic drive
to realize economies of scale and scope. However, a new concept of economy of system is required to explain the reductions
in cost which stem from innovations that improve the control of traffic, or load, through the telecommunications network and
other large technical systems. The argument of the paper is not that economic forces take priority over issues of social and
political choice but, rather, that a framework is required which accounts for the ways in which technology and economics mix
with politics in the development of telecommunications and other large systems.
... (Calhoun, 1992) The four-good example above is also a simplification with respect to the diversity of services that must be taken into account in an evaluation of the potential for natural monopoly. For example, BUSINESS is not a homogeneous good comprising "local network services." ...
Is the incumbent local exchange carrier (LEC) a natural monopolist? The analysis indicates that the LEC cost function is not supportable: LECs appear to be either nonsustainable natural monopolies or nonnatural monopolies the set of services they currently offer. However, recent technological changes suggest that whether LECs are natural monopolies over their current offerings is immaterial for policy making, because competitors are enjoying economies of scope in offering both LEC and non LEC services. Based on these results, deregulation of LECs is discussed in a Type I/Type II error framework. Copyright 1995 by Kluwer Academic Publishers
... This semi-attentive use of media can, however, itself be used as a reason for the reluctance for more channels. Given the habits that govern media exposure 23 , the overlap of media use with other activities 24 , and the statistics of modest recall of media content 25 , why would the average user be interested in more channels? ...
this paper, I analyze the impact of this transition on the balance of control that rules the communications process.
... In other words, integrated planning is required to cover interactions among aspects treated separately by conventional planning tools. For instance: Given a multiple access technique based on code division (CDMA, [3]) or space division (SDMA, [11]), the shape of a cell depends on the behavior of the users in the cell as well as on the users of surrounding cells. Furthermore, in such systems, the user distribution directly influences the performance of the system. ...
this paper we present a new approach to cellular network planning that integrates teletra#c issues and radio engineering to automatically achieve optimized planning solutions. The core of this technique is the notion of demand nodes. Experiments with the planning tool prototype ICEPT show the feasibility and e#ectivity of the approach. 1 INTRODUCTION
To obtain realistic performance measures for wireless networks, one should consider changes in performance due to failure related behavior. In performability analysis, simultaneous consideration is given to both pure performance and performance with failure measures. SRN is an extension of stochastic Petri nets and provides compact modeling facilities for system analysis. In this paper, a new methodology to model and analyze performability based on stochastic reward nets (SRN) is presented. Composite performance and availability SRN models for wireless handoff schemes are developed and then these models are decomposed hierarchically. The SRN models can yield measures of interest such as blocking and dropping probabilities. These measures are expressed in terms of the expected values of reward rate functions for SRNs. Numerical results show the accuracy of the hierarchical model. The key contribution of this paper constitutes the Petri nets modeling techniques instead of complicate numerical analysis of Markov chains and easy way of performance analysis for channel allocation under SRN reward concepts.
As a result of the convergence of telecommunications and mass communications technologies, American policymakers face a series of critical decisions about infrastructural investment, technical architecture, and regulation that will determine the character of the U.S. electronic industrial base. This article develops the argument that the current policy trajectory will likely lead to some awkward choices. Powerful vested interests have distorted the communications policy process. Regulatory inertia has come to tie the hands of the regulators as well as the hands of industry leaders. We argue that there exists a critical opportunity for independent communications policy research to make a difference and to anticipate and facilitate a paradigm shift in telecommunications regulation.
With the increasing popularity of wireless communications systems, customers are expecting the same level of service, reliability and performance from the wireless communica-tion systems as the traditional wire-line networks provide. Due to the dynamic environment, such as the roaming of mobile subscribers, maintaining a high radio frequency (RF) availability is one of the most challenging aspects in wireless network management. To date, in wireless net-work management, a call is dropped when the channel it uses goes down. In order to increase system end-to-end availability, an RF channel recovery scheme is proposed in this paper. When an RF channel fails, the channel is replaced by another working channel and the call contin-ues. The methods to replace failed RF channels of ongo-ing calls and to handle channel failures of handoo and new calls are investigated. Stochastic reward net (SRN) models are developed to compare system availability and perfor-mance. The results show that the recovery scheme reduces the dropped calls and the blocked calls signiicantly under both light and normal traacs.
This research investigates the feasibility of applying the wireless transmission of PDA or GPRS as a communication tool to inspection engineers. Application of such tools at construction job-sites can help all inspection engineers make a better construction management. Based on the development, all kinds of information regarding the construction activities such as standard specifications, figures, tables, equations, pictures and so on, can be developed and supplied to construction inspectors right at the construction job-site. This study also evaluates the performance of application result. At the final, a real case evaluation will also be done to illustrate the practice application.
Now that Intelligent Networks (IN) are becoming reality, some new problems have to be considered while implementing these new architectures in real network structures.
One of the main problems is the need for new (advanced) Software (SW) Tools to optimize the dimensioning and planning process of the IN structures.
The objective of this paper is to present a complex of SW tools named POSET that is related to the IN structures dimensioning and planning. POSET allows modelling of the economics of the transition towards an IN. These tools also assist a study of network modification to improve the efficiency of the existing network.
The proposed paper is further development of work started three years ago by the Rubin Research Institute on modernization of existing networks and deployment of IN within the Russian Federal Programme of Advanced Telecommunications Networks Creation in the St. Petersburg region.
This paper describes software technology that makes it possible to run Internet World Wide Web applications in wide area wireless networks. Web technology in conjunction with today's mobile devices (e.g., laptops, notebooks, personal digital assistants) and the emerging wireless technologies (e.g., packet radio, CDPD) offer the potential for unprecedented access to data and applications by mobile workers. Yet, the limited bandwidth, high latency, high cost, and poor reliability of today's wireless wide-area networks greatly inhibits (even to the point of being unfeasible) supporting Web applications over wireless networks. WebExpress significantly reduces user cost and response time of wireless communications by intercepting the HTTP data stream and performing various optimizations including: file caching, forms differencing, protocol reduction, and the elimination of redundant HTTP header transmission. This paper describes these optimizations and presents some experiment results.
This paper describes an application model and software technology that makes it possible to run World Wide Web applications
in wide area wireless networks. Web technology in conjunction with today's mobile devices (e.g., laptops, notebooks, personal
digital assistants) and the emerging wireless technologies (e.g., digital cellular, packet radio, CDPD) offer the potential
for unprecedented access to data and applications by mobile workers. Yet, the limited bandwidth, high latency, high cost,
and poor reliability of today's wireless wide-area networks greatly inhibits (to the point of infeasibility) supporting such
applications over wireless networks. This paper presents the Client/Intercept computational model that makes it possible to run such distributed applications efficiently in wide area wireless networks.
Furthermore, it presents WebExpress, a client/intercept based system for optimizing Web browsing, that reduces data volume and latency of wireless communications
by intercepting the HTTP data stream and performing various optimizations including: file caching, forms differencing, protocol
reduction, and the elimination of redundant HTTP header transmission. This paper describes these optimizations and presents
some experimental results.
The organization and governance of the transactions that comprise a bundling arrangement depend on the distribution of capabilities among firms and the amount of time during which the window of opportunity for earning rents is expected to remain open. Firms engaged in inter-firm collaboration must undertake 'support' transactions related to billing, marketing customer support and product repair. These support transactions differ from the 'core' transactions that have traditionally been perceived as sufficient to provide a product bundle. Since support transactions create costs of their own, the market may turn out to be an expensive means of governing collaborative arrangements undertaken for bundling purposes. The telecommunications service sector provides an illustration. Copyright 1997 by Oxford University Press.
The pilot pollution interference (PPI) problem occurs when the mobile station conducts handoff process and searches for strong pilot signals from the neighboring cells. The improper handoff search window setting plays a key role in the creation of the PPI problem. Consequently, the existence of the PPI problem affects the progress and termination of the ongoing calls, impacts the origination of fresh calls, delays the handoff process and decreases the system capacity. In this paper, a base station assisted search (BSAS) approach is proposed to minimize the impact of the PPI problem. The proposed BSAS approach is integrated with a modified MAHAR-A approach to alleviate the influence of the PPI as well as improve the system's QoS measured by the call blocking probability and the handoff dropping probability. Simulation experiments clearly indicate the effectiveness of the proposed approach.
Wireless data services and systems represent a rapidly growing and increasingly important segment of the communications industry. We describe the implementation of an interworking system for CDMA wireless data services between the mobile subscriber with a data terminal and the public subscriber in the public switched telephone network (PSTN) with a personal computer or G3 facsimile terminal. This module can be used to make a search of information, which is included in the database of a data network. To adapt this module for the mobile communication network, we suggested the use of a system structure in parallel with the mobile switching system in order to reduce the influence of the network configuration. This system can be used to provide an end to end data communication service and a means of searching for information in databases
The paper describes some access methods for rural
telecommunication using radio links as trunk lines. A comparison is made
between different radio techniques including cellular radio and
satellite. A design is described for a village network connected to the
outside world through fixed cellular radio links. Some economical and
technical aspects are analyzed
“A wireless revolution is set to transform the world's
telecommunications industry.” Key to this discontinuity are three
forces; unparalleled deregulation, privatization and competition in
traditionally monopolistic local access telecommunications markets, the
reallocation of hundreds of MHz of spectrum, and rampant technological
progress in radio-based subscriber access systems. This paper reports on
the third component, wireless technology as the involving transport
mechanism for providing basic telephone service, particularly in
developing countries
In March 1993 the Pacific Advanced Communication Consortium concluded a study of satellite-delivered PCS for thin-route areas. Two of the study's purposes were to ascertain current user communication patterns and, on the basis of those patterns, assess the market potential for PCS in remote and rural areas. Results suggest that thin route residents 1) already are relatively heavy users of mobile communication equipment, 2) are concerned about the cost of new equipment and services, and 3) represent a promising market for PCS
PCS is often identified with mobile/cellular systems, e.g. DCS1800 (sometimes referred to as PCN, it is a standard for GSM on 1800 MHz). Personal Communications Systems aiming for a broad subscriber basis must however comprise many systems (existing and future). As cordless system provides very high capacity (DECT ≈ 10,000 Erlang/km/2floor), they are likely to be considerable part of PCS. Advanced cordless systems as DECT (Digital European Cordless Telecommunications) are easy to adapt to and integrate with other systems as ISDN, GSM, PSTN etc. This paper describes the main features and applications of DECT and the concept of "profiles" in DECT facilitating a deep integration with other systems
Low infrastructure cost is a primary objective of UPC/PCS. A
system infrastructure that is based on a particular modulation type,
TDMA or CDMA for example, may rapidly become obsolete if a different
modulation becomes more desirable. This paper proposes an infrastructure
concept that is modulation insensitive and capable of being adapted to a
wide variety of protocol standards. The infrastructure concept developed
in this paper can simultaneously support a variety of existing
modulations and will be easily adaptable to new modulation types that
may become available in the future. The concept is simple; the
implementation is not. This is the concept: A widely distributed
collection of low-power remote terminals receive and transmit the
signals which form the wireless links with subscriber equipment. These
remote terminals comprise broad-band high-dynamic-range RF-to-digital
converters and digital-to-RF converters that are linked with a few
centralized processing centers via high-speed digital data links. All
signal processing and linking are done digitally within the few
processing centers and are completely software re-configurable. (The
processing centers could be co-located with local POPs to minimize the
cost of interfacing with the PSTN.) System architecture changes can then
be implemented with a software change at the processing centers thereby
affording the possibility of supporting a multiplicity of protocol
standards. The enabling technology for this infrastructure concept is
here today. It is an objective of this paper to demonstrate the
feasibility of this infrastructure concept by comparing the requirements
of a typical UPC system with the specifications of available enabling
technologies
Subcarrier multiplexing (SCM), is a very attractive technology for
future personal communication networks (PCN). The main limitation of
optical links for transport of mobile radio signals, is the linearity of
the laser. We show that in PCN based on microcells, this problem can be
alleviated by a proper carrier/cell assignment to allow the use of
moderate cost lasers in picocellular systems or microcellular with power
control. The design and characterization of a low cost optical link is
then presented with performance adequate for picocell/microcell based
PCN
There have been many advancements in the development and
deployment of portable computing products. The potential offerings of
portable computing have been mostly noticeable in the areas of cellular
communications, and wireless communications technologies. Wireless
communications is still at a very early age, however, many major
international corporations have started to deploy this technology in
specialized applications. This paper provides an overview of the
technologies of the cellular communications and wireless communications.
The advantages and disadvantages of both technologies are discussed. A
survey of some typical laptop computers is provided which perhaps is the
single most important factor that has made portable computing widely
available to many mobile users today
The purpose of this paper is to describe the structure and functions of the selecting system in the base station controller (BSC) for CDMA digital cellular communication. The system mainly manages call processing, handles High-level Digital Link Control (HDLC) protocol, controls soft/softer handoff procedure and provides transcoding channels
Cellular Digital Packet Data (CDPD) is a technology that provides
digital packet-switched data services through standard analog cellular
channels. CDPD is implemented as an overlay to existing cellular
networks allowing data to be sent in packets during idle times on the
cellular voice channels. This overlay implementation makes use of
existing cellular infrastructure, simultaneously transmitting voice and
data from the same device. A cellular communication network has
significant advantages over its wireline counterparts. Mobility and ease
of use are two particularly attractive features to a large population of
field employees. Based upon well known world standards, CDPD will
provide connectivity anywhere anytime-a true realization of the well
sought dream of having “information at your
fingertips”
The preselected title of this paper highlights the misconception
that most engineers, sometimes even communication specialists, still
harbor concerning the central role of channel coding in communication
system performance. More properly descriptive terms are
“error-preventing”, “error-protecting”, or the
more common “error control.” The reason is that in modern
communication systems, designed according to the norms of information
theory, coding is an integral part of the modulation process and the
optimum modulator and demodulator combine the coding and modulation, as
well as the decoding and demodulation, processes into one function at
both the transmitter and the receiver. This viewpoint has become
commonplace for modulation systems which operate in additive Gaussian
noise, with relatively high signal-to-noise ratios, at bit rates
considerably greater than their transmission bandwidth. For such systems
and channels, the evolution and general acceptance of trellis coded
modulation (TCM) has demonstrated how modulation and channel coding can
be integrated to provide superior performance
The paper addresses a two layer resource management model for maintaining a wireless communications network within a LEC. The two layer resource model focuses on the use of element managers to shorten time to market intervals, shield the operations support mechanisms from network complexity, provide data stewards to improve data accuracy, and to improve software update coordination to network elements. This approach does not eliminate the need for the service management layer as a critical portion of the architecture, instead this approach moves the service management functions outside of the area associated with network management
The conversion of terrestrial wireless telephony to digital transmission technology is just beginning. However, with more than four years of experimental laboratory and field testing, one has already learned numerous practical lessons, both positive and negative, relative to the art and science of multiple-access communication by large user populations. Europe, Japan, and North America have each developed digital cellular standards. The North American experience has been the most contentious and diverse. Only here have two alternative and rival approaches been carried through to the development of detailed standards leading to imminent large-scale commercial deployments. In this article, the two alternatives are denoted as orthogonal and random waveform multiple access, and are described and discussed successively.< >
This article describes a wireless local loop system based on
wideband CDMA technology. The unique features of CDMA technology make it
a formidable alternative for fixed wireless telephone applications. The
W-CDMA technology used by this WLL system is selected to provide
primarily ISDN-like services and data rates to subscribers. This
technology also provides a smooth transition into the third generation
wireless technology. The air interface used in this WLL system is an
interim TTA standard, which specifies a CDMA-based protocol operating in
the 2.30-2.40 GHz band. The standard allows two types of bandwidth (5
and 10 MHz). The WLL system described in this article includes the WLL
gateway switch, the radio port controller and the radio interface unit.
The gateway switch connects the radio system to the PSTN and ISDN. The
RPC provides concentration and control functions to a number of base
stations called RPs. The RIU is comprised of the fixed units attached to
the residential or commercial buildings. Also included are the radio
port operation and maintenance (RPOM) unit, which is responsible for
maintaining and managing the radio network elements, and the
interworking function unit, which is used as a gateway to data services
such as the Internet and PSPDN
The coherence of the public switched telephone network (PSTN) was
based on the understanding that, to further common interests, the
terminals and networks were to be coordinated to allow the transparent
flow of traffic. Innovations were evaluated based on the overall system
performance and the potential number of connections. The evolution of
public networks and technological advancements, of course, have allowed
traffic types other than speech to be carried over the PSTN. However,
because stakeholders in multimedia communications often have conflicting
requirements, they usually promote application-specific approaches to
code source information and multiplex the different media streams.
Rarely do they ponder over possible ways to merge all these approaches
in a harmonious way. Multimedia communications straddle the traditions
of both telecommunications and information technologies. As the
technology evolves, it is becoming increasingly difficult to identify
the boundary of “networks”
Seventy-five percent of India's population is in rural villages, yet almost 90 percent of the country's phones are in urban sites. The authors propose a fixed cellular radio system, combined with the existing mobile network, as a cost effective way to extend telecommunications services to India's rural areas.< >
We consider strategies for and performance of a class of
connection-oriented data session services that might be supported using
only the idle times between telephone calls on the channels of a
cellular radio system. Two types of service are envisaged: a short
transaction service and a suspendable data session service. We give
expressions for the mean active and inactive times for data sessions and
show how session assignment and displacement strategies can shape the
distributions of session active and inactive times. We find useful
amounts of capacity in the background of telephony systems even at high
load, but in its raw form the opportunities for data transmission, and
the data session suspension times implied, are rather large-grained for
interactive data sessions. However, enforced time-sharing can improve
these statistics for interactive data uses. With prioritized session
assignment, a number of logical data sessions can be supported providing
a range of service characteristics onto which interactive users, mobile
fax, paging, navigation, and fleet tracking applications can be mapped
in decreasing order of required session availability
We introduce a channel allocation strategy to support both realtime traffic such as voice and video and non-real-time traffic in a wireless CDMA communication system using the internet protocols TCP, UDP and RTP. It is shown by simulation that this approach is useful to achieve fair link sharing, high link utilization, throughput and low blocking probabilities for real-time traffic. Keywords: CDMA, QoS, dynamic bandwidth allocation, wireless internet multimedia. I. Introduction The usability of mobile multimedia applications in cellular radio networks will be one of the most important criteria for the acceptance of future digital cellular radio systems. Spread spectrum technologies as the multiple access technique are possible alternatives to well-known time or frequency division multiple access methods for flexible and efficient usage of radio frequencies in multimedia communications. Direct sequence spread spectrum communication is able to provide good scalability of data rates a...
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