Post on 04-Jun-2018
transcript
8/14/2019 Personal Communication Services.pdf reasearch paper
1/48
Chapter 1
Introduction to Personal Communication Services
8/14/2019 Personal Communication Services.pdf reasearch paper
2/48
PCS (personal communications
services) Personal communications services (PCS) refers to a wide
variety of wireless access and personal mobility servicesprovided through a small terminal, with the goal of enablingcommunications at any time, at any place, and in any form.
Business opportunities for such services are tremendous, since
every person not ust every ome cou e equ ppe , as ongas the service is fairly inexpensive. Several PCS systems have been developed to meet rapid
growth prompted by heavy market demand.
Meet of them are connected to the public Switched telephonenetwork (PSTN) to provide access to wire-line telephones.
8/14/2019 Personal Communication Services.pdf reasearch paper
3/48
Examples High-tier digital cellular systems (mobile phone systems ) far widespread vehicular
and pedestrian services.
Global System for Mobile Communication ( GSM ) IS-136 TDMA based Digital Advanced Mobile Phone Service(DAMPS )
Personal Digital Cellular ( PDC ) IS-95(CDMA-based cdmaOne System)
Low-tier telecommunication system standards for residential, business, and publiccordless access applications : Cordless Telephone 2 ( CT2 ) Digital Enhanced Cordless Telephone ( DECT ) Personal Access Communications Systems ( PACS )
Personal Handy Phone System ( PHS ) Wideband wireless systems have been developed to accommodate Internet andmultimedia services. Examples include: cdma2000, evolved from cdmaOne W-CDMA, proposed by Europe
SCDMA, proposed by China/Europe
8/14/2019 Personal Communication Services.pdf reasearch paper
4/48
The PCS umbrella also includes: Special data systems such as Cellular Digital Packet Data,
RAM Mobile Data, and Advanced Radio Data InformationSystem (ARDIS)
Paging system Specialized mobile radio (SMR) access technologies
-Mobile . Satellite Company (AMSC), as well as numerousproposed mobile satellite systems, including S-band, L-band,low-earth orbit (LEO), mid-earth orbit (MEO),geosynchronous orbit, and geostationary earth orbit (GEO), for
both data and voice applications Unlicensed industrial, scientific, and medical (ISM) band
technologies , as well as wireless local area networks (LANs)should also be thrown into the PCS mix
8/14/2019 Personal Communication Services.pdf reasearch paper
5/48
1.1 PCS Architecture
PCS technologies have grown rapidly inthe telecommunications industry.
Two of the most popular are: High-Tier Cellular telephony Cordless and low-Tier PCS telephony
These technologies have similararchitectures, as shown in Figure 1.1.
8/14/2019 Personal Communication Services.pdf reasearch paper
6/48
PCS Architecture
Wireline Transport Network
Radio Network
8/14/2019 Personal Communication Services.pdf reasearch paper
7/48
PCS Architecture basic architecture consists of two parts:
Radio Network. Wireline Transport Network.
8/14/2019 Personal Communication Services.pdf reasearch paper
8/48
PCS Architecture Radio Network
PCS use mobile stations (MSs) to communicate with the basestations (BSs) in a PCS network.
MS is also referred to as handset , mobile phone , subscriber, .
For example, subscriber unit : wireless local loop; portable: low-tier systems (PACS); and mobile station: GSM system.
8/14/2019 Personal Communication Services.pdf reasearch paper
9/48
PCS Architecture Modern MS technology allows the air interface to be
updated (e.g., from DECT to GSM) over the airremotely
The MS can also be remotely monitored by thesystem maintenance and diagnostic capabilities.
Different types of MSs have various power rangesand radio coverage. hand-held MSs have a lower output power (where the
maximum output power can be as low as 0.8 watts forGSM 900) and shorter range compared withvehicle-installed MSs with roof-mounted antennas (wherethe maximum output power can be as high as 8 watts inGSM900).
8/14/2019 Personal Communication Services.pdf reasearch paper
10/48
PCS Architecture The radio coverage of a base station, or a sector in the
base station, is called a cell . For systems such as GSM, cdmaOne, and PACS, the
base station system is partitioned into
radio port control unit in PACS) and radio transmitters/receivers (base transceiver
stations in GSM and radio ports in PACS).
The base stations usually reach the wireline transportnetwork ( core or backbone network ) via land links ordedicated microwave links.
8/14/2019 Personal Communication Services.pdf reasearch paper
11/48
PCS Architecture Wire-line Transport Network. The mobile switching center (MSC) connected to the base station
is a special switch tailored to mobile applications. For example, the Lucent 5ESS MSC 2000 is an MSC modified
from Lucent Technologies' 5ESS switching system. The Siemens' D900/1800/1900 GSM switch platform is based on its
EWSD (Digital Electronic Switching System) platform. The Ericsson MSC is based on its AXE switching platform. The MSC is connected to the PSTN to provide services between the
PCS users and the wire-line users. The MSC also communicates with mobility databases to track the
locations of mobile stations.
8/14/2019 Personal Communication Services.pdf reasearch paper
12/48
1.2 Cellular Telephony
This section gives an overview offour popular cellular telephonynetworks:
AMPS, GSM,
DAMPS (IS-136) CDMA (IS-95).
8/14/2019 Personal Communication Services.pdf reasearch paper
13/48
1.2.1 Advanced Mobile PhoneService (AMPS) AMPS was the first cellular system. 1970s in the Bell Laboratories, this first-generation analog cellular system has been
considered a revolutionary accomplishment. The AMPS specification was generated from a laborious
, ,a period of 10 years. From 1974 to 1978, a large-scale AMPStrial was conducted in Chicago.
Commercial AMPS service has been available since 1983 . Based on frequency division multiple access (FDMA)
technology for radio communications, high-capacity system based on a frequency reuse scheme .
8/14/2019 Personal Communication Services.pdf reasearch paper
14/48
1.2.1 Advanced Mobile PhoneService (AMPS) Voice channels are assigned to radio frequencies
using FDMA. A total of 50 MHz in the 824-849 MHz and 869-894
MHz bands is allocated for AMPS. -
channels using 1664 discrete frequencies , 832 downlinks and 832 uplinks.
Downlinks are the transmission paths from basestations to handsets,
Uplinks are the transmission paths from handsets tothe base stations.
8/14/2019 Personal Communication Services.pdf reasearch paper
15/48
1.2.1 Advanced Mobile Phone Service (AMPS) Cells are grouped into clusters. Cells of within a cluster may interfere with each other, and
thus must use different frequencies. Frequencies may be reused by cells in different clusters. In AMPS, the typical frequency reuse plan employs either a
-group requency c uster us ng omn - rect onaantennas or 7-group cluster using three sectors per base station. Thus, there are about 50 channels per cell .
Motorola uses a 4-cell, 6-sector design in its AMPS system. GS1 AMPS follows the EIA/TIA IS-41 standard for roaming
management.
8/14/2019 Personal Communication Services.pdf reasearch paper
16/48
1.2.1 Advanced Mobile Phone Service(AMPS)
Compared with the digital alternatives in the United States, AMPS service offers more complete geographical coverage at
a cheaper service charge (partly due to the low cost of massproduction of handsets).
However, digital networks are replacing AMPS because the,
offer lower costs . In 2000, Taiwan started replacing AMPS with the IS-95
CDMA system. After the replacement, the new system will provide the same
service at less than half the bandwidth of the radio spectrum.
8/14/2019 Personal Communication Services.pdf reasearch paper
17/48
1.2.1 Advanced Mobile Phone Service(AMPS)
Note that after the AMPS voice service is replaced by thedigital systems, the AMPS infrastructure can be utilized tosupport mobile data systems such as Cellular Digital PacketData (CDPD).
8/14/2019 Personal Communication Services.pdf reasearch paper
18/48
1.2.2 Global System for Mobile Communications(GSM)
GSM is a digital cellular system developed by Group SpecialMobile of Conference Europeans des Postes etTelecommunications (CEPT) and its successor EuropeanTelecommunications Standard Institute (ETSI).
An important goal of the GSM development process was tooffer com atibilit of cellular services amon Euro ean
countries. GSM is a revolutionary technology that combines both timedivision multiple access (TDMA) and FDMA.
With TDMA, the radio hardware in the base station can be
shared among multiple users. In GSM, a frequency carrier is divided into eight time slotswhere the speech coding rate is 13 Kbps.
8/14/2019 Personal Communication Services.pdf reasearch paper
19/48
1.2.2 Global System for Mobile Communications(GSM)
In a GSM base station, every pair of radio transceiver-receiversupports eight voice channels , whereas an AMPS base stationneeds one such pair for every voice channel.
The GSM MSs control their RF output power to maintaininterference at low levels.
8/14/2019 Personal Communication Services.pdf reasearch paper
20/48
1.2.2 Global System for Mobile Communications(GSM)
The GSM air interface has been evolved into Enhanced DataRate for GSM Evolution (EDGE) with variable data rate andlink adaptation.
EDGE utilizes highly spectrum-efficient modulation for bitrates higher than existing GSM technology.
EDGE requires upgrade of existing base transceiver station,which supports high-speed data transmission in smaller cellsand at short ranges within cells.
EDGE does not support ubiquitous coverage; that is, it
supports island coverage in indoor, pico, and micro cells.
8/14/2019 Personal Communication Services.pdf reasearch paper
21/48
1.2.2 Global System for Mobile Communications(GSM)
The GSM development process was similar to that of AMPS,except that no large-scale trial was conducted.
The intellectual property rights of the GSM radio system fromall vendors were waived, making GSM hugely popular. It took about four years to create the GSM specification. The GSM roaming management protocol is specified by GSM
o e pp ca on ar , w c prov es s m arfunctionality as IS-41.
GSM features include most features a digital switch canprovide, point-to-point short messaging,
group addressing, call waiting, multiparty services, ...
8/14/2019 Personal Communication Services.pdf reasearch paper
22/48
1.2.3 EIA/TIA IS-136 Digital Cellular System
Also referred to as digital AMPS (DAMPS) , American Digital Cellular (ADC), or North American TDMA (NA-TDMA), IS-136, the successor to IS-54,
supports a TDMA air interface similar to that of GSM, and isthus considered an evolutionary technology. It took four months to create the IS-54 specification, and no
significant trial was conducted.
IS-54 was renamed IS-136 when it reached revision C.
8/14/2019 Personal Communication Services.pdf reasearch paper
23/48
1.2.3 EIA/TIA IS-136 Digital Cellular System
Using TDMA , every IS-136 frequency carrier supports threevoice channels, where the speech coding rate is 7.95 Kbps.
IS-136 systems operate in the same spectrum with the samefrequency spacing (30 KHz) used by the existing AMPSsystems.
-, . An existing AMPS system can be easily upgraded to IS-136 on
a circuit-by-circuit basis. In this way, the evolution from AMPS to DAMPS can be made
gracefully.
IS-136 is also defined for the new PCS spectrum allocation at1850 to 1990 MHz.
8/14/2019 Personal Communication Services.pdf reasearch paper
24/48
1.2.3 EIA/TIA IS-136 Digital Cellular System Features of IS-136 include
point-to-point short messaging, broadcast messaging, group addressing, pr va e user groups, hierarchical cell structures, and slotted paging channels to support a "sleep mode"
in the handset, to conserve battery power. Like AMPS, IS-136 uses the IS-41 standard for
mobility management.
8/14/2019 Personal Communication Services.pdf reasearch paper
25/48
1.2.3 EIA/TIA IS-95 Digital CellularSystem This digital cellular system was developed by
Qualcomm, and has been operating in theUnited States since 1996. IS-95 is based on code division multi le
access (CDMA) technology. CDMA allows many users to share a common
frequency/time channel for transmission; theuser signals are distinguished by spreadingthem with different codes . (DSSS)
8/14/2019 Personal Communication Services.pdf reasearch paper
26/48
1.2.3 EIA/TIA IS-95 Digital Cellular System In theory, this technology optimizes the utilization of
the frequency bandwidth by equalizingsignal-to-noise ratio (SNR) among all the users,thereby more equitably sharing the system powerresources among them.
While AMPS users who are near base stationstypically enjoy SNRs in excess of 80 dB, users at theedge of cell coverage areas experience SNRs near thelower limit.
With CDMA, users who are near base stationstransmit less power, maintaining the same SNR asusers at the edge of a cell's coverage.
8/14/2019 Personal Communication Services.pdf reasearch paper
27/48
1.2.3 EIA/TIA IS-95 Digital CellularSystem By utilizing the minimum necessary amount of
power, system-wide co-channel interference iskept at a minimum. IS-95 MSs ma need to maintain links with
two or more base stations continuously duringphone calls, so that, as multi-path varies, thebase station with the best received signal on a
burst-by-burst basis will be selected tocommunicate with the MS.
8/14/2019 Personal Communication Services.pdf reasearch paper
28/48
1.2.3 EIA/TIA IS-95 Digital Cellular System
The channel bandwidth used by IS-95 is 1.25 MHz .
This bandwidth is relatively narrow for a CDMAsystem, which makes the service migration fromanalog to digital within an existing network more
. In the third-generation wideband CDMA proposal,
the bandwidth has been extended to 5 MHz. The speech coding rate for IS-95 is 13 Kbps or 8
Kbps. IS-95's capacity is estimated to be 10 times thatof AMPS .
8/14/2019 Personal Communication Services.pdf reasearch paper
29/48
1.2.3 EIA/TIA IS-95 Digital Cellular System
The IS-95 development has been similar to that of
AMPS, but no large-scale trial was conducted; it tooktwo years to generate the specification. Prior to 1997, the most significant IS-95 development
effort was taking place in Korea . In 1991, the Koreangovernment decided to implement IS-95 technology.
The Korean IS-95 system began commercial
operation in April 1996.
8/14/2019 Personal Communication Services.pdf reasearch paper
30/48
1.2.3 EIA/TIA IS-95 Digital Cellular System
The maximum capacity consists of 512 BTS (320
traffic channels per BTS) connected to 12 BSCs.These BSCs are then connected to a mobile switchingcenter (called MX ) using 768 E1 lines.
Like AMPS, IS-95 uses the IS-41 standard formobility management.
One of the third-generation mobile system standards,
cdma2000, is evolved from the narrowband IS-95.
8/14/2019 Personal Communication Services.pdf reasearch paper
31/48
8/14/2019 Personal Communication Services.pdf reasearch paper
32/48
1.3.1 Cordless Telephone, Second Generation (CT2) CT2 was developed in Europe, and has been available
since 1989. CT2 is allocated 40 FDMA channels with a 32-Kbps
speech coding rate. - -
handset-to-base signals are transmitted in the samefrequency. This duplexing mode is referred to as timedivision duplexing (TDD) .
The maximum transmit power of a CT2 handset is 10mW.
8/14/2019 Personal Communication Services.pdf reasearch paper
33/48
1.3.1 Cordless Telephone, Second Generation (CT2) In the call setup procedure, CT2 moves a call path from one
radio channel to another after three seconds of handshake
failure . CT2 also supports data transmission rates of up to 2.4 Kbps
through the speech codec and up to 4.8 Kbps with an increasederror rate.
CT2 does not support handoff call delivery is not supported. Incoming calls have been supported in an enhanced version of
CT2, but its efficiency has not been proven.
8/14/2019 Personal Communication Services.pdf reasearch paper
34/48
1.3.2 Digital European Cordless Telephone(DECT)
DECT specifications were published in 1992 for definitiveadoption as the European cordless standard.
The name Digital European Cordless Telephone has beenreplaced by Digital Enhanced Cordless Telephone to denoteglobal acceptance of DECT.
DECT su orts hi h user densit with a ico-cell desi n.
Using TDMA , there are 12 voice channels per frequencycarrier. Sleep mode is employed in DECT to conserve the power of
handsets. DECT may move a conversation from one time slotto another to avoid interference. This procedure is called timeslot transfer .
DECT also supports seamless handoff.
8/14/2019 Personal Communication Services.pdf reasearch paper
35/48
8/14/2019 Personal Communication Services.pdf reasearch paper
36/48
1.3.3 Personal HandyPhone System(PHS) PHS is a standard developed by the Research and
Development Center for Radio Systems (RCR), a private
standardization organization in Japan . PHS is a low-tier digital PCS system that offers
telecommunications services for homes, offices, and outdoorenvironments usin radio access to the ublic tele hone
network or other digital networks. PHS uses TDMA , whereby each frequency carrier supportsfour multiplexed channels.
Sleep mode enables PHS to support five hours of talk-time , or
150 hours of sta ndby time. PHS operates in the 1895-1918.1 MHz band. This bandwidthis partitioned into 77 channels , each with 300 KHz bandwidth.
8/14/2019 Personal Communication Services.pdf reasearch paper
37/48
1.3.3 Personal HandyPhone System (PHS)
Like DECT, PHS supports dynamic channel allocation . PHS utilizes dedicated control channels : a fixed frequency
that carries system and signaling information is initiallyselected.
The PHS speech coding rate is 32 Kbps .
Like CT2 and DECT, the duplexing mode used by PHS isTDD . Handoff can be included in PHS as an option. PHS supports Group 3 (G3) fax at 4.2 to 7.8 Kbps and a
full-duplex modem with transmission speeds up to 9.6 Kbps.
8/14/2019 Personal Communication Services.pdf reasearch paper
38/48
1.3.4 Personal AccessCommunications System (PACS) PACS is a low-power PCS system developed at Telcordia
(formerly Bellcore). PACS is designed for wireless local loop and for personal
communications services. TDMA is used in PACS with eight voice channels per
frequency carrier. The speech coding rate is 32 Kbps . Both TDD and frequency division duplexing (FDD) are
accommodated by the PACS standard.
In FDD mode , the PACS uplink and downlink utilize differentRF carriers, similar to cellular systems.
8/14/2019 Personal Communication Services.pdf reasearch paper
39/48
1.3.4 Personal Access Communications
System (PACS)
The highly effective and reliable
mobile-controlled handoff (MCHO) completesin less than 20 msec.
IS-41-like protocol. Like GSM, PACS supports both circuit-based
and packet-based access protocols.
8/14/2019 Personal Communication Services.pdf reasearch paper
40/48
1.3.5 Unlicensed Systems In addition to these standardized cordless radio
technologies, unlicensed communications devices forcordless telephony may make use of the industrial,scientific, and medical (ISM) spectrum .
A number of commercially available products(wireless PBXs, wireless LANs, cordless telephones )make use of the ISM spectrum to avoid the delays
associated with spectrum allocation, licensing, andstandardization.
8/14/2019 Personal Communication Services.pdf reasearch paper
41/48
1.3.5 Unlicensed Systems The applicability of the AMPS analog cellular air interface for
cordless telephones and office business phones (using the 800MHz cellular spectrum) has been tested by several cellularservice providers.
From a customer's perspective, these trials have been anoverw e m ng success, n cat ng es re or nteropera tybetween private and public wire-less access.
From a service provider perspective, the service is difficult tooperate and maintain because of hard-to-control interferencefrom the private systems into the public system. The TIAinterim standard IS-94 describes the air interface requirementsfor this application of AMPS.
8/14/2019 Personal Communication Services.pdf reasearch paper
42/48
1.3.5 Unlicensed Systems It also describes the protocol and interface between the
cordless base station and the network, to control the base
station emissions as necessary to limit interference to thepublic system, and to register and deregister the location of thehandsets to and from the private cordless base station at theservice provider's mobility databases for the purpose of routingca s.
Authentication of the handset is included in this protocol. Thenetwork-ing protocol described by IS-94A is extensible todigital cellular systems, and it affects interoperability betweenany public systems using licensed spectrum and any privatesystems using the unlicensed spectrum.
8/14/2019 Personal Communication Services.pdf reasearch paper
43/48
1.4 Third-Generation WirelessSystems Mobile telecommunication systems have been evolving for
three generations. AMPS is the first-generation system ; GSM, IS-136, IS-95, and the low-tier systems described in
Section 1.3 are second-generation technologies.
These systems have been designed primarily for speech withlow-bit-rate data services. They are limited by their vertical architectures. Most system aspects have been specified from services to the
bearer services. Consequently, any enhancements or new services affect the
network from end to end.
1 4 hi d G i i l
8/14/2019 Personal Communication Services.pdf reasearch paper
44/48
1.4 Third-Generation Wireless
Systems Compared with second-generation systems, third-generation
systems offer better system capacity; high-speed, wireless Internet access u to 2 Mb s and
wireless multimedia services, which include audio, video, images, anddata. Several technologies, such as General Packet Radio Service(GPRS ) and EDGE ,
bridge second-generation systems into third generation systems.
1 4 Thi d G i Wi l
8/14/2019 Personal Communication Services.pdf reasearch paper
45/48
1.4 Third-Generation Wireless
Systems In third-generation systems, new network technologies are
integrated into the existing second-generation core networks. ATM (Asynchronous Transfer Mode) backbone, network management, and service creation
Air interfaces such as Wideband CDMA (W-CDMA ) andcdma2000 are major third-generation radio standards.
The increasing number of Internet and multimediaapplications is a major factor driving the third-generationwideband wireless technology.
1 4 Thi d G i Wi l
8/14/2019 Personal Communication Services.pdf reasearch paper
46/48
1.4 Third-Generation Wireless
Systems Some studies indicate that more than 20 percent of the adult
population in the United States are interested in wireless
Internet access . By the end of 1999, wireless data services were marketed asmodem access for laptop.
-
available, and the inexpensive wireless handheld devices (e.g.,wireless personal data assistant and wireless smart phones)become popular, subscribers will begin to enjoy instantwireless Internet access.
1 4 Thi d G ti Wi l
8/14/2019 Personal Communication Services.pdf reasearch paper
47/48
1.4 Third-Generation Wireless
Systems The services include
sales force automation, dispatch, instant content access, an ng, e-commerce, and so on.
8/14/2019 Personal Communication Services.pdf reasearch paper
48/48