bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epidemiology of Macrovascular Disease and Hypertension in Diabetes Mellitus
Authors: Tuomilehto Jaakko , Rastenyte Daiva , Qiao Qing , Jakovljevic Dimitrije 
Published: November 2003

AbstractMacrovascular diseases—atherosclerosis, coronary heart disease, cerebrovascular disease or stroke, and peripheral vascular disease—are major causes of morbidity, mortality, and severe disability among diabetic persons. Hypertension is a major contributor to macrovascular disease in diabetic patients. Although late macrovascular complications are common in both type 1 diabetes mellitus and type 2 diabetes mellitus, a somewhat different etiology has been suggested for these two types of diabetes. A number of studies have attempted to answer the basic questions of the epidemiology of hypertension and macrovascular disease in diabetes: (1) What is the occurrence of these disorders in diabetic patients? (2) Are they more common in diabetic patients compared with the general population? (3) Are the risk factors for these disorders the same in diabetic patients as in the general population? (4) Is asymptomatic hyperglycemia an independent risk factor for macrovascular disease? Our ability to diagnose different late complications of diabetes vary. For instance, we may be able to detect retinopathy and increased urinary albumin excretion earlier than clinical macrovascular disease (for which usually 75% stenosis is needed for clinical effects). In addition, the occurrence of macrovascular disease shows a very large geographical variation in the general population. This may also be reflected in between‐population variation in the prevalence of hypertension and macrovascular complications of diabetes. Therefore, the risk of macrovascular disease in diabetic patients must always be interpreted in relation to the risk in the background population. The risk can be expressed in different ways: (1) absolute risk, i.e. as the excess number of cases or excess in the frequency of these complications between diabetic and nondiabetic subjects; (2) relative risk (rate ratio), i.e. ratio of the frequency between diabetic and nondiabetic subjects; (3) population attributable risk, i.e. the proportion of cases of these complications that can be attributed to diabetes, and thereby could possibly be prevented by measures targeted to primary and secondary prevention of diabetes.
Telephone Traffic
Authors: Freeman Roger L. 
Published: November 2003

Abstract

Traffic
denotes the aggregate flow of messages through a telecommunication system.
Traffic engineering
applies mathematical tools for dimensioning telephone facilities so that they can accommodate the message flow in a way that provides satisfactory service to the users while making economical use of the facilities providing the service. In many cases, required trunk and switch capacity can be solved by simple computer programs written in GWBASIC. The coding for these programs is provided.

This chapter provides a basis for sizing groups of shared telecommunications facilities and equipment.
Signaling
Authors: Freeman Roger L. 
Published: November 2003

Abstract

Signaling is defined by CCITT Recommendation
Q.9
as “the exchange of information (other than speech) specifically concerned with the establishment, release and other control of calls, and network management, in automatic telecommunications operation.”

In the broadest sense there are two signaling realms:

Subscriber signaling

Trunk signaling (interswitch or interoffice signaling)

Signaling is also traditionally classified into four basic functions:

Supervision

Address

Call progress (information)

Network management

This chapter treats the signaling interface, a basic telecommunication network issue. Signaling has evolved over the years since 1889, when automatic switching was first introduced. It is difficult to separate signaling and switching disciplines with a clean line of demarcation. Thus some signaling information will be found in Chapter 3, “Switching,” and some switching information will appear in this chapter.
There are about 25 recognized interregister signaling systems worldwide and some fewer number of subscriber signaling techniques. CCITT Signaling System No. 7 has become the international/national standard interregister signaling system. The traditional systems, designed more for the analog network, are being phased out. Thus more emphasis is placed on SSN7. However, some of the more traditional analog signaling systems are covered in necessary detail.
Outside Plant—Metallic Pair Systems
Authors: Freeman Roger L. 
Published: November 2003

Abstract

Outside plant
is defined as “the part of the telephone system that is located physically outside of telephone company buildings. It includes wire‐pair cables, the wire‐pairs themselves, supporting structures, and certain equipment items such as load coils.”

This chapter provides design and interface information on wire‐pair systems including the subscriber loop and subset, wire‐pair trunks (junctions), outside plant construction, and layout.
Wire‐pair systems are just now coming into their own with DSL (digital subscriber line) techniques. For years, wire pair has been undersold even though it was the backbone of the subscriber plant, taking up about 15–20% of the total investment of the local telephone company. There were two driving forces that brought about this new view. First it was the telephone company attempting to compete with entrenched CATV operators to provide a similar service using existing wire‐pair plant. The second force was the need for downstream high‐speed (>1 Mbps) internet service.
Electromagnetic Wave Propagation
Authors: Freeman Roger L. 
Published: November 2003

AbstractThis chapter provides design data and background material dealing with electromagnetic wave propagation, more commonly calledradio propagation. The material in this chapter will find application principally as support for the specific radio technologies covered in other chapters. The intent here is to keep this chapter generic and general. In many instances there is a fine line between direct applications to a particular technology and discipline and the generalized case.The termwirelesshas been popularized in the trade press. Its meaning is synonymous withradio. We deprecate the use of the term “wireless.”It should be appreciated that different frequency bands have different propagation characteristics. For example, atmospheric absorption is generally not an issue below 10 GHz. That does not mean that there is no absorption below 10 GHz; it means that in most cases it is inconsequential. There are no hard and fast rules. The skip phenomenon of HF propagation takes place below 30 MHz. However, during high sunspot years, skip conditions have occurred on frequencies as high as 100 MHz. Another example is meteor burst propagation. Here we can expect greater returns from meteor trails at the lower frequencies (e.g., <20 MHz), but the tendency is to use higher frequencies (e.g., between 40 and 50 MHz) where man‐made noise is less intense.
Radio Noise
Authors: Freeman Roger L. 
Published: November 2003

Abstract
This chapter deals with ambient noise. It has several components which are frequency critical. These components include atmospheric noise deriving from lightning discharges, man‐made noise, noise that derives from celestial sources, hot earth noise, and emissions from atmospheric gases and hydrometers. Noise is similar to any other electromagnetic (radio) signal. It can be measured in the power domain (dBm, dBW or picowatts), in the voltage or current domain across a known impedance, and in noise temperature (kelvins). Because much of the noise dealt with here is impulsive in character, noise values are often given in a power spectral density format (e.g., dBm/Hz or dBW/Hz).
Tropospheric Scatter and Diffraction
Authors: Freeman Roger L. 
Published: November 2003

Abstract
Tropospheric scatter and diffraction involve propagation phenomenon that allows beyond‐line‐of‐sight (BLOS) for comparatively broadband communication. Prior to the advent of satellite communications, troposcatter communication was common with the world's armed forces, particularly with the US Department of Defense both in fixed plant and for tactical mobile communications. There was also some application in the civilian arena, generally for connectivity with the “outback” or among islands. However, once satellite communications became widespread, tropo/diffraction communication became less attractive with the possible exception of oil rig communications.
Diffraction and troposcatter are simply outgrowths of line‐of‐sight (LOS) microwave where the links are no longer LOS. To achieve beyond‐line‐of‐sight, a tropo/diffraction installation has to be “bigger” in nearly every aspect. LOS Microwave and Tropo/Diffraction are Compared.
The major purpose of the chapter is to provide a substantial database for the design of troposcatter links. Secondarily, information is provided for diffraction link design. Two methods are included to calculate aperture‐to‐medium coupling loss. Many believe that the CCIR method is overly conservative. The information on transmission loss calculations are from NBS. Analog and digital troposcatter are presented. Guidance on quantifying dispersion as provided.
Satellite Communications
Authors: Freeman Roger L. 
Published: November 2003

AbstractSatellite communications have proliferated worldwide. The trend since about 1965 has been to use the geostationary orbit, where a satellite placed over the equator at the proper distance appeared to an earth station to be stationary. A great advantage for geostationary earth orbit (GEO) satellites is that “stationarity” eliminates the need for tracking in many circumstances. Delay is a principal disadvantage. This is due to the distance involved for a signal to reach a GEO satellite, about 125 ms.A new communication satellite series is evolving using low earth orbit (LEO) satellites. Here the distance to a satellite is greatly reduced (about 500–1500 km above the earth's surface), and hence there is much less delay, 1.6 to 5 ms. Expect LEO satellites to be contenders in two arenas: cellular telephony and data transport. Tracking requirements may be listed as a disadvantage, unless some form of omnidirectional antenna is used. Generally there are much higher elevation angles when compared to their GEO counterparts. This must be listed as an advantage. A brief discussion of LEO satellite systems is provided at the end of the chapter.A large portion of the communication satellites over the Western Hemisphere supports entertainment, particularly TV, supplying service to CATV head‐ends, motels/hotels, and the like. The original intent of GEO satellites was to relay over medium and long distances, multichannel telephony. This is now in decline. Fiber optic cable systems with their far‐reduced propagation delay and nearly infinite bandwidth have caused this decline. One may state that communication satellites have limited bandwidth whereas fiber‐optic cables have nearly unlimited bandwidth.Systems using very small aperture terminals (VSATs) have great promise, and many such systems are in operation. VSATs are commonly used for data connectivities, usually from outstations to a centralized hub.There are three important issues of concern to a satellite system designer: coexistence of satellite communications with terrestrial radio communications (in particular, line‐of‐sight microwave); shortage of desirable frequency assignments for use with geostationary satellites, forcing migration to higher frequencies such as the 30/20‐GHz band with the associated propagation limitations; and the actual orbital crowding where physical separation between GEO satellites is down to 2 degrees.The objective of this chapter is to answer the needs of the satellite link and system designer considering the aforementioned concerns. There is notable lack of standardization, and some sort of standards are set inside a particular system and rarely cross system boundaries. INTELSAT (International Telecommunication Satellite [consortium]) is the largest system operation in the world. This group has set its own standards. If a user wishes an earth station to interoperate with an INTELSAT satellite, that earth station must meet certain standard requirements established by INTELSAT. One of the goals of this chapter is to provide a brief outline of INTELSAT requirements.
Land Mobile Communications: Cellular Radio, Paging, and Personal Communication Services
Authors: Freeman Roger L. 
Published: November 2003

AbstractLand mobile communications dates back to the 1920s; and it has served well, although comparatively inconspicuously, ever since. In that period, the majority of land mobile systems were used for public safety and vehicle dispatching. Only since the mid‐1980s have land mobile systems started to really take their place in the business community. Cellular radio began the explosive march. The kickoff event was a description of an analog FM system called AMPS (advanced mobile phone system) in a 1979 issue of Bell System Technical Journal. Since then, it seems, the number of cellular radio subscribers doubles every year. Paging has seen equivalent acceptance as universal worldwide.PCS (personal communication services) is currently experiencing eruptive emergence. From our perspective, it seems no more than an outgrowth of the cellular radio concept with shorter ranges and lower power. Both face the problem of building penetration. Some cordless telephone systems are truly evolving into the PCS category, such as the DECT (digital European cordless telephone). Another application of PCS with great promise is the wireless local loop (WLL). In this case, instead of connecting the local serving exchange to the subscriber by wire pair, a radio technique is employed. Such systems can be implemented very rapidly at about half the cost of an equivalent wired system. Where competition is permitted in the local serving area, it would be advisable to avoid the additional wired approach and use radio instead. [Note:The current popular press uses the wordwireless. The term was widely used in Great Britain. In North America its connotation is slightly different. All of the applications discussed in this chapter would be called wireless. However, we will use the traditional, more meaningful term:radio.]Cellular radio is chronically short of bandwidth and has turned to using many different means to conserve bandwidth (i.e., achieve more users per unit of bandwidth). PCS, although assigned four times as much bandwidth, will eventually suffer the same demise.A drawback of present cellular radio is the lack of a universal standard. Europe is further along in this regard with its GSM, which is digital, uses a TDMA access technique, and is fairly bandwidth conservative. It is even making inroads in North America. Currently, North America has two different TDMA systems, two CDMA systems, and two analog systems (i.e., AMPS and N‐AMPS).Multipath reception has the potential to corrupt performance in both PCS and digital cellular radio. Its corruptive effects increase as bit rate increases. These harmful effects can be mitigated by using direct sequence spread spectrum transmission along with digital signal processing.
Antennas, Towers, and Passive Repeaters
Authors: Freeman Roger L. 
Published: November 2003

AbstractThe antenna is a critical element in a radio system, and the antenna subsystem is a major design driver for the system engineer. The principal objective of this chapter is to provide the system engineer with the necessary design information to size and properly specify an antenna subsystem. Emphasis has been placed on line‐of‐sight (LOS) microwave, satellite communications, and mobile radio applications. A section on the application of passive repeaters is also included.The section on antenna towers has a detailed discussion of wind load and twist and sway requirements.The Radio Regulations and national regulatory authorities continue to tighten down sidelobe radiation specifications. Of course this is being done to improve the EMC environment as radio systems proliferate more and more. A particularly ticklish area is with frequency band sharing, typically LOS microwave, satellite communications, and local multipoint distribution service (LMDS).
Enterprise Networks
I
: Local Area Networks
Authors: Freeman Roger L. 
Published: November 2003

Abstract

We define an enterprise network
as a data network serving either government or industry which is dedicated almost exclusively to data communications
. It might be called a data network serving the office environment, thus the term
enterprise
(a business).

Enterprise networks can be placed in one of two categories: local area networks (LANs) and wide area networks (WANs). The IEEE defines a LAN as “a communication network to interconnect a variety of intelligent devices (e.g., personal computers, workstations, printers, file storage devices) that can transmit data over a limited area, typically within a facility.”
A WAN
is a data network covering a much greater expanse than its LAN counterpart and with a considerably different structure. This chapter deals with LANs.

The reader is introduced to the seven‐layer OSI (open systems interconnection) model developed by the International Standards Organization (ISO). Nearly every data communications technique invokes the OSI model. Some data systems fit nicely into the model, and they were developed around the model. Others, such as TCP/IP, have been force‐fit into the model. TCP/IP predates OSI by some five years. The model will have application in all subsequent chapters on data networks.
Wireless LANs are also reviewed. These are particularly attractive to IT managers when many office moves and changes are expected.
The final section of the chapter presents a brief overview of IEEE 802 MAC bridges.
Enterprise NetworksII: Wide Area Networks
Authors: Freeman Roger L. 
Published: November 2003

AbstractEarly data networks were based on point‐to‐point or multipoint topologies. They were often of a star structure with a central processing unit (CPU) at the star's hub. Terminals in this network were “dumb” terminals and relied on the CPU's processing power for nearly all network activity.When the personal computer (PC) gained wide acceptance, distributed processing became the rule. As a result, data networks and data networking became much more complex. We now see complex multiple star, mesh, and tree like networks where many of the nodes have multiple inlets and outlets.Data rates were based on the limitations of the analog network. In the period of the 2nd edition of this book, this roughly equated to 9600 bps. Today, it is common to have 56‐kbps access lines to a larger network where the basic channel data rate is 64 kbps. We can bring together these basic building blocks of 64 kbps to form aggregate channels of 128, 256, and 384 kbps up to 1.536 Mbps or 1.984 Mbps.Data protocols instilled order out of contentious chaos in data network operation. These protocols, applying to wide area networks (WANs), are the principal thrust of the chapter. Most are based on shipping user data in packets or frames. We discuss the transport of user data in cells in Chapter 28.Most packet networks are based on CCITT Rec.X.25. If we widen the definition of packet networks to include the transmission control protocol/internet protocol (TCP/IP), certainly X.25 will have a competitor. Both TCP/IP and X.25 have a comparatively high latency (latencyis the time it takes from initiation to completion of a data transaction). Frame relay was introduced in the same period. This is a comparatively low latency system.This section provides design data and brief descriptions of wide area data networking as a whole with hypothetical reference circuits, the archetypical data link layer protocol, high‐level data link control (HDLC), X.25 and its companion, link access protocol B‐layer (LAPB), TCP/IP family of protocols, frame relay family of protocols, and a brief description of SMDS (switched multimegabit data service). Variants of LAPD are discussed in the frame relay section of this chapter.
Integrated Services Digital Networks (
ISDNs
)
Authors: Freeman Roger L. 
Published: November 2003

Abstract
Some say that ISDN arrived before its time. It was based on the premise that the majority of the local plant was copper‐based. It was and is, but the demand for bit rates in excess of ISDN's basic rate has caused certain other technologies to leap frog ISDN (e.g., xDSL, WLL, and ATM). Its acceptance in North America has not been overwhelming. The penetration in Europe is much greater.
On the other side of the coin, ISDN basic rate is showing slow but continuous growth in the United States. To play it down would be a gross error for a basic reference manual such as this text. The reader is advised that there are different flavors of ISDN. We present two: the ITU‐T version and the North American version set forth by ANSI and Bellcore.
ISDN was devised as a common standard for voice, data, and slow‐speed video. It is based on the 64‐kbps digital voice channel. Probably in the 1970s when the ISDN concept was initiated, it met those unifying requirements. Today, ATM certainly gets more to the essence of the matter of integrating voice, data, and video.
ISDN was designed to be compatible with the digital PSTN. This it is, provided that ITU‐T Signaling System No. 7 is implemented and operational in that network.
Broadband
ISDN
(
B
‐
ISDN
) and the Asynchronous Transfer Mode (ATM)
Authors: Freeman Roger L. 
Published: November 2003

Abstract

B‐ISDN
is modestly defined as a service or a system requiring transmission channels capable of supporting (transmission) rates greater than the primary rate (i.e., >1.544 or 2.048 Mbps) (CCITT Rec.
I.121
). ATM and B‐ISDN are designed to work together. ATM provides the underlying digital format; B‐ISDN supplies the necessary transmission facility.

The asynchronous transfer mode (ATM) is a compromise digital format with the design objective of transporting and routing voice, data, and image media. ATM standards have been and are being developed by three agencies: ANSI, ITU‐T, and the ATM Forum.

Conventional ISDN is now commonly called
narrow‐band ISDN
to distinguish it from B‐ISDN. Their basic objectives are similar: the capability of transporting and switching a wide range of media. The approach to reach the objectives is quite different.

There is also a notable similarity in the reference circuit model of each. Whereas in ISDN network elements such as NT1, NT2, TE, and TA appear; in B‐ISDN they are denominated B‐NT1, B‐NT2, B‐TE, and B‐TA. Signaling is handled differently in each technique.
One will note many operational similarities between ATM with frame relay and SMDS.
Narrowband ISDN was designed around the copper pair. In B‐ISDN, fiber‐optic transmission is the medium of choice. We hasten to add that there is no reason why copper pairs cannot be used to transport B‐ISDN signals at the lower data rates. This holds equally for various forms of radio transmission so long as the bandwidth (Hz), with the implied impairments such as group delay, can support the digital transmission rate.