Contents

 

9.0 PCS/PCN

 

9.1 PCS

9.1.1 Services

 

9.2 PCN

9.2.1 Low Tier Systems

9.2.2 High Tier Systems

 

9.3 UMTS

9.3.1 HSCSD

9.3.2 GPRS

9.3.3 CAMEL

 

Assignment Questions

 

For Further Research

 

 

 

 


9.0 PCS/PCN

 

Objectives

This section will:

• Introduce the concept of PCS and PCN

• Examine the capabilities of high tier systems

• Consider the requirements of low tier systems

• Examine the European vision of UMTS

 

For more information:

http://www.pcsdata.com/

AT&T PCS Tutorial

Growth of PCS

 

PCS is a class of cellular phone services and PCN is the network that provides them. In many cases, PCS and cellular technology are one and the same. Some authors make a distinction in terms of frequency, namely that cellular systems operate below 1 GHz and PCS operates above 1 GHz.

The following graphic is from the PCS Tutorial by AT&T Wireless Services.

In our case, the distinction will be on the service offering. Traditional cellular phone systems do not have an infrastructure that enables them to provide full voice and data service over wide areas. PCS systems can provide such services over a continental and even global area.

There are a number of PCS standards being implemented throughout the world. These can be categorized into high and low tier systems.

High Tier Standards

Frequency (MHz): Rx: 1930-1990, Tx: 1850-1910

Multiple Access Method:

PCS TDMA (based on IS-136 cellular)

PCS CDMA (based on IS-95 cellular)

PCS 1900 (based on GSM cellular)

Wideband CDMA

Low Tier Standards

Frequency (MHz): Rx: 1930-1990, Tx: 1850-1910

Multiple Access Method:

PACS (based on PHS cordless)

DCT-U (based on DECT cordless)

Composite CDMA/TDMA

9.1   PCS

PCS† is one of the most talked about areas in modern telecommunications is that of portable and personal communications[1]. The ultimate goal is to contact people and not places. This means that everyone would ideally have a small portable communicator that could access anyone anywhere in the world.

Personal communications services include:

*      Complete portability

*      A single device capable of accessing the network in a variety of environments (fixed, residential, office, mobile)

*      A person oriented numbering plan

*      Network intelligence to implement the plan

*      Package of personal services such as voice telephony, paging, fax, and voice mail

PCS terminals are small, lightweight and low power. They must be capable of conveying both voice and data signals. The numbering plan must be people rather than terminal oriented.

Some of the very complex issues that must be addressed include efficient use of spectrum, network infrastructure, and service offering. The solutions to these problems are not found in one sector of the communications industry, but rather require the cooperation of government, industry and end-users.

It is expected that there will be in excess of 40 million PCS subscribers in the US alone, by the turn of the century.

A number of different proposals have been put forward for implementing PCS. Some of these include[2]:

Proposed Standard

Sponsor

D1900

Siemens

PCS1900

Northern

Omnipoint

Omnipoint

DCS1800

Ericsson

DSC1900

Alcatel

DCT

Ericsson

PHP

Panasonic

PHP

PCSI

IS-54

Ericsson

IS-54

AT&T

IW-CDMA

IDC

CDMA

Qualcomm

W-CDMA

AT&T

A-CDMA

Oki

WACS-8+

Hughes

PPS1800

Motorola

 

Some of these proposals are suitable for advance cellular systems but may not necessarily have defined the entire supporting infrastructure. In 1993 a Joint Technical Committee was established by the Exchange Carriers Standards Association to examine some 17 different proposals for PCS systems. Later the TIA† reduced these to seven. This group contained three Canadian representatives: Stentor, Industry Canada, and Mobility Canada.

9.1.1  Services

PCS networks are expected to compete with cellular phone systems in the US since the FCC may license the frequencies to new carriers. In most other countries, it would seem more natural for the existing cellular phone providers to move into the PCS environment, since they already have so much experience with personal radio systems.

Applications for PCS include:

• Mobile micro cellular phone/messaging

• Wireless PBXs/LANs

• Transaction processing/EDI†

• Alarm monitoring/utility meter reading

• Computer aided dispatch/traffic control

• Environmental monitoring

• Gateway services to wireline/cellular networks

• Value-added network support

Personal Communications Network Services of New York has an FCC experimental license to test PCS services in the 1850 – 1990 MHz band.[3]

9.2   PCN

TIA/JTC Standards for Consideration[4]

 

Hybrid CDMA

IS-95A

PACS

IS-136

PCS1900

PWT

W-CDMA

Based on

 

IS-95

WACS

IS-54

GSM

DECT

IS-95

Access Method

CDMA TDMA

CDMA

TDM TDMA

TDM TDMA

TDMA

TDMA

CDMA

Duplex Method

TDD

FDD

FDD3

FDD

FDD

TDD

FDD

Bandwidth/Ch. Spacing

5 MHz

1.25 MHz

300 KHz

30 KHz

200 KHz

1.728 MHz

5 MHz

Bit Rate [Kbps]

32

8 / 13.3

32

7

13

32

32

# Voice Ch./Carrier

32 (8 Kbps CELP)

20 + SHO1

8

3

8

12

128 (less with SHO)

Capacity x AMPS

16

10

0.8

3

2 - 3

0.2

16 (less with SHO)

Modulation

Cont. Phase Shift QM

OQPSK QPSK

π/4 D-QPSK

π/4 D-QPSK

GSMK

GFSK

OQPSK D-QPSK

Error Control (voice)

none

FEC

none

FEC

FEC

none

FEC

Frequency Reuse

3

1

16

7x32

7 or 3x3

9

1

Max Ave Tx Power

—

200 mW

12.5 mW

100 mW

125 mW

20.8 mW

500 mW

Tx Power in Time Slot

1 W

—

100 mW

600 mW

1 W

250 mW

—

Slot Length

625 ΅s

 

312.5 ΅s

6.7 ΅s

577 ΅s

417 ΅s

—

Frame Length

20 ms

20 ms

2.5 ms

40 ms

4.615 ms

10 ms

—

End to End Speech Delay

80 ms

50 ms

9 ms

110 ms

90 ms

28 ms

13.25 ms

Vocoder

CELP (8 Kbps) ADPCM (16, 24, 32, 40  Kbps)

Variable Rate QCLP (8/4/2/1 Kbps)

ADPCM (32 Kbps)

VSELP (8 Kbps) LDCELP (16 Kbps)

RPE-LTP (13 Kbps)

ADPCM (16-32 Kbps)

ADPCM (32 Kbps)

Equalizer

no

no

no

yes

yes

no

no

 

Note:

•   1 SHO = soft hand-off

•   2 7x3 = 7 cells, 3 sectors per cell

•   3TDD in unlicensed band

 

This committee also identified two PCS environments:

• High tier: for high mobility and/or low-density applications

• Low tier: for low mobility and high-density applications

9.2.1  Low Tier Systems

Microcellular Solutions by Nortel

CDMA Base Station Controller by Nortel

 

The low tier systems are not clearly defined but operate much like the present home cordless phone. The handsets must be low cost, lightweight, and have low transmission power.

These systems would be used in high-density areas and utilize very small pico cells. Handsets would be usable inside buildings equipped with a wireless PBX. In outside environments, radio basestations would be placed on poles or other convenient structures throughout the coverage area.

The radio method used to implement low tier systems does not necessarily have to be the same as used in high tier systems. If however, the objective is to make a comprehensive PCS facility, dual mode phones are necessary. This unfortunately works against the handset objectives.

Frequency Band [MHz]

Rx: 1930-1990         Tx: 1850-1910

Access Method

PACS based on PHS cordless

DCT-U based on DECT cordless

Composite CDMA/TDMA

Cell Size

< 5 km

Terminal Speed

< 50 kph

Terminal Power Level

< 100 mW

Data Rate

32 Kbps

 

Although it appears that much of the world intends to uses GSM for low tier systems, in North America DCT and PACS seem to be preferred.

9.2.2  High Tier Systems

These systems are more clearly defined than low tier systems and are in fact nearly identical to the present cellular networks.

Frequency Band [MHz]

Rx: 1930-1990         Tx: 1850-1910

Access Method

PCS TDMA based on IS-136 cellular

PCS CDMA based on IS-95 cellular

PCS 1900 based on GSN cellular

Cell Size

< 50 km

Terminal Speed

< 200 kph

Terminal Power Level

< 1 W

Data Rate

13 Kbps

 

In Europe, and much of the rest of the world, GSM900 is being deployed. This is expected to migrate to the 1.8 GHz band, where it is called DCS1800.

GSM is suitable for both high and low tier systems.

In North America, it appears that there will be three competing high tier systems: IS-54, IS-95, and PCS1900. Only the last one is based on GSM.

9.3   UMTS

http://www.umts-forum.org/

http://home.intekom.com/cellular/umts.htm

UMTS Brochure from Nortel

Report No. 6 from the UMTS Forum UMTS/IMT-2000 Spectrum

Report No. 7 from the UMTS Forum Candidate Extension Bands for the UMTS/IMT-2000 Terrestrial Component

Report No. 8 from the UMTS Forum The Future Mobile Market

 

One of the European proposals to providing PCS is called UMTS†. It is intended to support:

• 2 Mbps data for indoor users

• 144 Kbps data for WANs

• Mixed traffic [multimedia]

• Wideband local loop enhancement

A number of cell sizes have been identified in order to provide universal access.

Cell Type

Range

Application

Umbrella cells

Hundreds of km

Satellite mobile

Hyper cells

>20 km

Rural areas

Macro cells

1 – 2- km

Highways

Micro cells

100 m – 1 km

Cities

Pico cells

< 100 m

Offices, home

 

It is felt that this can be provided by the natural evolution of GSM and will be fully operational by the year 2005.

As of 1996, there were 153 GSM based networks [GSM 900, DCS 1800, PCS 1900] in operation in 91 countries serving 21 million subscribers. The subscription rate is presently increasing by 1.5 million a month. It is expected that the total number of users will reach 100 million by the end of the century.[5]

In order to provide worldwide coverage, GSM must be adopted by satellite service providers. It appears that this will be the case and Iridium, ICO, and Globestar will support it.

Significant developments are still needed to make this possible. At the moment, GSM can only support 9.6 Kbps data. This is sufficient for faxes and other low speed data service, but is completely inadequate for Internet access or multimedia communication.  These needs are expected to be addressed by HSCSD† and GPRS†.

9.3.1  HSCSD

http://www.option.com/techno/hscsd.htm

http://www.etsi.org/SMG/work/HSCSD_spec.htm

 

High-Speed Circuit Switched Data services can be provided by bundling up to 8 TDMA time slots. This will allow the service provider to offer variable bandwidth on demand. Among other things, it will make mobile videophone possible.

9.3.2  GPRS

http://www.mobileapplicationsinitiative.com/

http://www.cellular.co.za/gprs-intro.htm

http://www.mobilegprs.com/

http://www.pcsdata.com/paprysavy.htm

 

This packet switching technique uses channel coding to provide an effective throughput of 14.4 Kbps per channel. Concatenating 8 of these will results in a maximum throughput of 115 Kbps. This service will be used for bursty traffic. How this will eventually be increased to 2 Mbps remains unknown.

It is expected to operate in a similar way to the present SMS†. Messages will be stored by the service provider if the terminal is powered down. The user is automatically notified once they activate the terminal.

9.3.3  CAMEL†

In order to be universal, it is necessary that the system support worldwide IN services. It is expected that features such as roaming will be provided by CAMEL, which is part of GSM Phase 2+. The intent is to create a system that will provide constant speech quality, data services, security etc. throughout the world.

Assignment Questions

 

Quick Quiz

1.  Some vendors make a distinction between cellular and PCS services based on transmission frequency. [True, False]

2.  High tier PCS is based on cellular technology. [True, False]

3.  Low tier PCS can be based on cordless telephone technology. [True, False]

4.     It is not possible to base high and low tier PCS on the same technology. [True, False]

5.      

Composition Questions

1. 

2. 

3. 

4. 

For Further Research

 

Brody and Ma; “DMS-MTX Cellular Mobile Telephone System”, Telesis 1986 four

Pahalavan, Kaveh and Levesque, Allen H.; Wireless Information Networks, Wiley, 1995

Prentiss, Stan; Introducing Cellular Communications

Lee, William C. Y.; Mobile Communications Design Fundamentals

IEEE Communications, January 1995, a special issue on Wireless Personal Communications

Industry Sites http://www.pcia.com/

http://www.wow-com.com/consumer/

Vendors        http://www.attws.com/

http://www.ameritech.com/

http://www.airtouch.com/

http://www.sprintpcs.com/

http://www.lucent.com/

http://www.nortel.com/

http://www.primeco.com/

http://www.qualcomm.com/

http://www.motorola.com/

http://www.ssc.siemens.com/Welcome.html

http://www.ericsson.com/

Journals        http://www.wirelessdesignonline.com/

Other Sites   www.umts-forum.org

http://www.mitsubishiwireless.com/

http://www.telecom.co.nz

http://www.omnipoint.com/sitemap.htm

http://www.digital-wireless.com/

http://www.einsteinpcs.com/main.htm

http://www.broadband-guide.com/pcsequipserv.html

http://www.cordero2.com/

http://www.volksware.com/mobilis/september.95/cellpcs1.htm

http://sss-mag.com/pcs.html

http://www.wirelessoutpost.com/index-unreg.vtml

http://lgcwireless.com/

http://www.cellworks.com/hmpg.html

http://www.srs-rf.com/resource.htm

http://www.tuanz.gen.nz/

http://elaine.teleport.com/~samc/cable11.html

Comments

http://web.globalserve.net/~punter/Technical%20Comparison.htm

Pointer Sites

http://www.webexpert.net/vasilios/telecom/telecom.htm

PCS

http://www.de.infowin.org/ACTS/ANALYSYS/CONCERTATION/MOBILITY/umts1.htm

http://www.ntia.doc.gov/opadhome/mtdpweb/povrview.htm

http://smartpixel.colorado.edu/~telecom/project3/cellnet/cellnet.html

http://www.radiodesign.com/hwitwrks.htm

http://jura2.eee.rgu.ac.uk/dsk5/eee/mobile+comms/mobile.html

A list of the world’s cellular systems

http://www.teletechnics.com/reference/telecom/cellular.html

 



†     Personal Communications Systems

[1]     Personal Communications Services: Expanding the Freedom to Communicate, IEEE Communications Magazine, February 1991

[2]     TE&M, December 1, 1993

†     Telecommunications Industry Association

†     Electronic Data Interchange

[3]     Interconnection/PCN: a ‘synergistic’ alliance?, TE&M, September 15, 1991

[4]     PCS and the Big Picture, Table A-2, by Kenneth Brown http://strategis.ic.gc.ca

†     Universal Mobile Telecommunications Services

[5]     GSM Evolution towards UMTS, by Greger Ber, www.ericsson.se

†     High Speed Circuit Switched Data

†     General Packet Radio Service

†     Short Message Service

†     Customized Applications for Mobile Networks Enhanced Logic