Mobile Communications Engineering - Theory and Applications, Second Edition.pdf - Electrical and Electronical - X-files

Source: Mobile Communications Engineering

Introduction

Part I Mobile Radio—The First 100 Years

By definition, the term “mobile-radio communications” describes any

radio communication link between two terminals of which one or both

are in motion or halted at unspecified locations and of which one may

actually be a fixed terminal such as a base station. This definition

applies to both mobile-to-mobile and mobile-to-fixed radio communica-

tion links. The mobile-to-mobile link could in fact consist of a mobile-

to-fixed-to-mobile radio communication link. The term “mobile” applies

to land vehicles, ships at sea, aircraft, and communications satellites.

In tactical situations, mobile-radio systems may include any or all of

these types of mobile terminals.

Mobile-radio systems are classified as radiophones, dispatching sys-

tems, radio paging systems, packet radios, or radiotelephones (also

known as mobile phones), including train phones.

1. Radiophones (or walkie-talkies) are two-way radios, such as CB (cit-

izens band) radios, which are allocated 40 channels for anyone to use

whenever the channels are free. This system affords no privacy to

the user.

2. Dispatching systems use a common channel. Any vehicle driver can

hear the operator’s messages to other drivers in the same fleet. The

drivers can talk only to the control operator. In military applica-

tions, the users can also talk to each other on an open channel.

3. Radio paging customers carry personal receivers (portable radios).

Each unit reacts only to signals addressed to it by an operator. A

beep sounds to alert the bearer, who then must go to a nearby tele-

phone to receive the message.

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Introduction

4. Packet radio requires a form of multiple-access control that permits

many scattered devices to transmit on the same radio channel with-

out interfering with each other’s transmissions. Packet radios can be

configured as either mobile or portable terminals. This system may

become important in the future.* Each terminal is attached to a

transmission control unit equipped with a radio transmitter and

receiver. The data to be transmitted are formed into a “packet” within

the transmission control unit. The packet contains the addresses of

the receiving location and the originating terminal. A receiving

device receives any packet addressed to it and transmits an acknowl-

edgment if the packet appears to be free of error. The sending station

waits a predetermined period for the acknowledgment. If it does not

receive an acknowledgment, it transmits the packet again. For exam-

ple, CDPD (cellular digital packet data) is a packet radio system. †

5. Radiotelephones include MTS (Mobile Telephone Service), IMTS (Im-

proved Mobile Telephone Service), the Metroliner telephone, TACS

(total access communication system), † and AMPS (Advanced Mobile

Phone Service). † The Metroliner telephone is briefly discussed here,

and the other types of radiotelephones are described, in greater detail,

in subsequent paragraphs. The Metroliner telephone operates in the

400-MHz frequency range on the high-speed train between New York

and Washington, D.C. The 225-mi railway distance is divided into

nine zones. Each zone has a fixed radio transceiver located adjacent to

the track right-of-way. As a train moves from one zone to another, calls

that are in progress must be automatically switched from one fixed

radio transceiver to the next without the customer’s being aware of

any changes or interference in communication.

6. Digital Cellular † and PSC (personal communication service) † are for

high capacity and data transmission. Digital Cellular in Europe is

called GSM (Global System Mobile), a standard system using TDMA

(time division multiple access). PCS is a cellular-like system applied

at 1.8–1.9 GHz instead of 800–900 MHz for cellular. Other than that,

the system protocols are the same as cellular systems. Digital cellu-

lar in North America has two standards: IS-136 (TDMA) and IS-95

(CDMA). Digital cellular in Japan is called PDC (personal digital

phone), a TDMA system.

7. TDD (Time Division Duplexing) systems † such as DECT (digital

European cordless telephone), PHS (personal handy-phone system),

* S. Fralick and J. Garrett, “Technology for Packet Radio,” AFIPS Conf. Proc., vol. 44,

1975, AFIPS, Montvale, N.J.; and R. E. Kahn, S. A. Gronemeyer, J. Burchfield, and R. C.

Kunzelman, “Advances in Packet Radio Technology,” Proc. IEEE, vol. 66, no. 11, Novem-

ber 1978, pp. 1468–1496.

† W. C. Y. L e e , Mobile Cellular Telecommunications, Analog and Digital Systems, 2d ed.

McGraw Hill Co., 1995.

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Introduction

and PACS (personal access communication system) use one fre-

quency for both transmission and reception on a time-sharing basis.

These systems are for low mobility and in-building communications.

8. Mobile Broadband Systems* will be the future public land mobile

telecommunication system (FPLMTS). It will operate at a higher

spectrum band (20–60 GHz), using ATM (asynchronous transfer

mode) for broadband packet switching, and it will be compatible

with the B-ISDN (broadband ISDN). It will be the future wireless

information superhighway system.

Let’s pause momentarily to review some of the historical highlights

of mobile-radio communication. The first practical use of mobile-radio

communication was demonstrated in 1897 by Marchese Guglielmo

Marconi, who is credited with first successfully establishing radio

transmission between a land-based station and a tugboat, over an 18-

mi path. The following summary shows some of the important mile-

stones in the history of mobile-radio communication:

1880: Hertz—Initial demonstration of practical radio communication

1897: Marconi—Radio transmission to a tugboat over an 18-mi path

1921: Detroit Police Department—Police car radio dispatch (2-MHz

frequency band)

1932: New York Police Department—Police car radio dispatch (2-MHz

frequency band)

1933: FCC—Authorized four channels in the 30- to 40-MHz range

1938: FCC—Ruled for regular service

1946: Bell Telephone Laboratories—152 MHz (simplex)

1956: FCC—450 MHz (simplex)

1959: Bell Telephone Laboratories—Suggested 32-MHz band for

high-capacity mobile-radio communication

1964: FCC—152 MHz (full duplex)

1964: Bell Telephone Laboratories—Active research at 800 MHz

1969: FCC—450 MHz (full duplex)

1974: FCC—40-MHz bandwidth allocation in the 800- to 900-MHz

range

1981: FCC—Release of cellular land mobile phone service in the 40-

MHz bandwidth in the 800- to 900-MHz range for commercial oper-

ation

*W.C.Y.Lee, Mobile Cellular Telecommunications, Analog and Digital Systems, 2d ed.

McGraw Hill Co., 1995.

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Introduction

1981: AT&T and RCC (Radio Common Carrier) reach an agreement

to split 40-MHz spectrum into two 20-MHz bands. Band A belongs to

nonwireline operators (RCC), and Band B belongs to wireline opera-

tors (telephone companies). Each market has two operators.

1982: AT&T is divested, and seven RBOCs (Regional Bell Operating

Companies) are formed to manage the cellular operations.

1982: MFJ (modified final judgment) is issued by the government

DOJ. All the operators were prohibited to (1) operate long-distance

business, (2) provide information services, and (3) do manufacturing

business.

1983: Ameritech system in operation in Chicago

1984: Most RBOC markets in operation

1986: FCC allocates 5 MHz in extended band

1987: FCC makes lottery on the small MSA and all RSA licenses

1988: TDMA voted as a digital cellular standard in North America

1992: GSM operable in Germany D2 system

1993: CDMA voted as another digital cellular standard in North

America

1994: American TDMA operable in Seattle, Washington

1994: PDC operable in Tokyo, Japan

1994: Two of six broadband PCS license bands in auction

1995: CDMA operable in Hong Kong

1996: U.S. Congress passes Telecommunication Reform Act Bill.

“Apparently anyone can get into anyone else’s business.”

1996: The auction money for six broadband PCS licensed bands (120

MHz) almost reaches 20 billion U.S. dollars.

1997: Broadband CDMA considered as one of the third-generation

mobile communication technologies for UMTS (universal mobile

telecommunication systems) during the UMTS workshop conference

held in Korea.

In 1970, the FCC allocated the following frequencies for domestic

public mobile-radio use on land:

Number

Channel

Total

Base transmit

Mobile transmit

channels spacing bandwidth

Name

35.26–35.66 MHz

43.26–43.66 MHz

40 kHz 0.8 MHz

MTS

152.51–152.81 MHz

157.77–158.07 MHz

30 kHz 0.6 MHz

IMTS (MJ)

454.375–454.65 MHz 459.375–459.65 MHz

25 kHz 0.55 MHz IMTS (MK)

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Introduction

Although a total of 33 channels are provided for within these fre-

quency allocations, the actual number of channels used in a specified

area is much smaller on account of restrictions imposed by prevailing

FCC regulations, which are explained later on.

In 1974, the FCC allocated a 40-MHz bandwidth in the 800- to 900-

MHz frequency region for mobile telephone use. During the initial trial

tests, it was utilized as follows:

Number of

Channel

Total

Base transmit

Mobile transmit

channels

spacing

bandwidth

870–890 MHz

825–845 MHz

666

30 kHz

40 MHz

The Bell Telephone System used this narrow band of frequencies in

trial tests of its new, high-capacity Advanced Mobile Phone Service

(AMPS), which is designed for use in a cellular planned network.

Because the system design is based on the reuse of allocated frequen-

cies, the number of customers served is greatly increased; hence the

term “high-capacity” system. Part II of this introduction describes a

cellular system in greater detail.

By 1976, the Bell System served approximately 40,000 mobile-

telephone customers within the United States. Of this number, 22,000

were able to dial directly, whereas 18,000 required operator assistance

to place a call. The various systems that serve mobile radiotelephones

are classified according to their assigned frequency range. For exam-

ple, the MJ system operates in the 150-MHz range, whereas the MK

system operates in the 450-MHz range. Each system can provide from

1 to as many as 12 channels, with FCC regulations requiring that 12

channels of an MK system serve an area of 50 miles in diameter.

To illustrate how few channels are available and how overloaded

they are, in 1976 the New York Telephone Company (NYTC) operated

6 channels of the MJ system serving 318 New York City mobile-

telephone subscribers, approximately 53 customers per channel, and

there were 2400 applicants wait-listed for MJ mobile-telephone ser-

vice. NYTC also operated six MK channels serving 225 customers,

approximately 38 customers per channel, and 1300 applicants were

wait-listed for MK mobile-telephone service. New York City was lim-

ited to only six MK channels out of the maximum of 12 available

because of the FCC regulation requiring that 12 channels serve an

area of 50 miles in diameter.

In 1976, there were a total of 1327 mobile-telephone systems in oper-

ation across the United States. The Bell System operated 637 mobile-

telephone systems within its coast-to-coast network, whereas 690 were

operated by independent telephone companies. The market demand for

mobile-telephone service is already much greater than the existing

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