Introduction to Wireless and Mobile Systems

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CS
6910



Pervasive Computing

Spring 2007


Section 1 (Ch.1):

Introduction to

Wireless and Mobile Systems

P
r
of
. Leszek Lilien

Department of Computer Science

Western Michigan University


Slides based on

publisher’s slides for 1
st

and 2
nd

edition of:

Introduction to Wireless and Mobile Systems
by
Agrawal & Zeng

© 2003, 2006, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved.


Some original slides were modified by L. Lilien, who strived to make such modifications
clearly visible. Some slides were added
by
L. Lilien, and are
©

2006
-
2007
by Leszek T.
Lilien
.
Requests to use
L. Lilien’s

slides for non
-
profit purposes will be

gladly granted upon
a written request.

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

2

Chapter 1

INTRODUCTION

[Image of 2
nd

ed. cover added by L. Lilien.]

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

3


Evolution


Distributed

Computing (
DIST
)


Originally
wireline

only


Wireless

Computing


Originally
non
-
mobile wireless

only


Mobile

Computing (
MOBI
)


Really:
Wireless

&

Mobile
Computing



Pervasive

Computing (
PERV
)



Note: Textbook uses “wireless” and “mobile” as synonyms


Not precise: e.g., can have wireless but not mobile





Q:
Why

to study
Wireless & Mobile Computing
?


A: It is
foundation for PERV
, its critical technology &


building block



Some

other technologies

for Pervasive Computing:


Embedded computing


Sensornets


Opportunistic networks (oppnets) and systems


See Lecture Section 0.B

© 2007 by Leszek T. Lilien

Pervasive vs. Wireless & Mobile Systems

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

4

1.1.

The History of Mobile Radio Communication (1/3)


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)


1933: FCC (Federal Communications Commission)


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 operation

Emphasis (underlines) on this and next 2 slides added by LTL

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

5

The History of Mobile Radio Communication (2/3)


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


operators
(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



[LTL: Dept of Justice]
. All the operators
[LTL: RBOCs]

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
[
LTL: Metropolitan Statistical Area]

and all RSA
[LTL: Rural Service Area
]

licenses


1988: TDMA

(Time Division Multiple Access) voted as a
digital cellular


standard

in North America


1992: GSM

(Groupe Speciale Mobile) operable
in Germany

D2 system

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

6

The History of Mobile Radio Communication (3/3)


1993: CDMA

(Code Division Multiple Access) voted as another digital


cellular standard

in North America


1994
: American
TDMA operable

in Seattle, Washington


1994: PDC (Personal Digital Cellular) operable in Tokyo, Japan


1994: Two of six broadband PCS (Personal Communication Service) license


bands in auction


1995: CDMA operable

in Hong Kong


1996: US Congress passes Telecommunication Reform Act Bill


1996: The
auction

money for six broadband
PCS licensed bands

(120 MHz)


almost reaches 20 billion US dollars


1997: Broadband CDMA

considered as one of the third generation mobile


communication technologies for UMTS (Universal Mobile Telecommu
-
nication Systems)


During the UMTS workshop conference held in Korea


1999
:
ITU
(International Telecommunication Union)
decides the next


generation

mobile communication systems (e.g., W
-
CDMA, cdma2000, etc.)


2001
:
W
-
CDMA

commercial
service

beginning from October in Japan


2002: FCC

approves additional frequency

band for Ultra
-
Wideband (UWB)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

7

[LTL:]

RF = radio
frequency

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

8

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

9

Applications

[LTL:]
Wireless Telephone

Cincinnati, OH

Washington, DC

[LTL:]

User

moves

but phone # unchanged

Maintaining the telephone number across geographical areas in a
wireless and mobile system

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

10


1G

-

First Generation


Primarily for
voice

communication


Using
FDM

(
frequency division

multiplexing
)



2G

-

Second Generation


Emphasis still on
voice

communication but allows for…


… Data

communication


Using
TDM

(
time division

multiplexing
)


Indoor/outdoor and vehicular environment



3G

-

Third Generation



Integrated

voice
,
data
, and
multimedia
communication


Need for:


High volume

of traffic /
Real time

data communication


Flexibility
, incl.


Frequent Internet access


Multimedia data transfer


Compatibility

with 2G


Using
compression


Without compromising quality

© 2007 by Leszek T. Lilien

Generations of Wireless Systems & Services

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

11

First Generation Wireless Systems and Services

1970s

Developments of radio and computer technologies for
800/900
MHz

mobile communications
[
1
st

mobile band
]


1976

WARC (World Administrative Radio Conference) allocates
spectrum for cellular radio

1979

NTT (Nippon Telephone & Telegraph) introduces the
first
cellular system in Japan

1981

NMT (Nordic Mobile Telephone) 900 system introduced by
Ericsson Radio System AB and deployed in Scandinavia

1984


AMPS

(Advanced Mobile Phone Service)
[cellular]

introduced by
AT&T
in North America

Emphasis (underlines) and text in square brackets on this and next slide added by LTL

Note: “Cellular systems” called “mobile systems” outside North America.

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

12

Second Generation Wireless Systems and Services

1982

CEPT (Conference Europeenne des Post et Telecommunications)
established
GSM

[global special mobile]

to define future Pan
-
European
Cellular Radio Standards

1990

Interim
Standard IS
-
54

(USDC

[US digital cellular]
) adopted by TIA
(Telecommunications Industry Association)

1990

Interim Std IS
-
19B (NAMPS
[narrowband AMPS]
) adopted by TIA

1991

Japanese PDC (Personal Digital Cellular) system standardized by the
MPT (Ministry of Posts and Telecommunications)

1992

Phase I GSM

system is
operational

1993

Interim
Standard IS
-
95
(
CDMA
) adopted by TIA

1994

Interim Standard IS
-
136 adopted by TIA

1995

PCS

Licenses

[added 2
nd

band (1900 MHz)]

issued in
North America

1996

Phase II GSM operational

1997

North American

PCS deploys
GSM
, IS
-
54, IS
-
95

1999

IS
-
54: in North America

IS
-
95: in North America, Hong Kong, Israel, Japan, China, etc

GSM: in 110 countries

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

13


Basic

technology in the
U.S.


cdma2000



Basic

technology in
Europe
&

Japan


W
-
CDMA



Similar but
design
&
implementation differences


© 2007 by Leszek T. Lilien

Two Basic Technology Choices for 3G

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

14

Third Generation Wireless Systems and Services (1/2)


IMT
-
2000 (International Mobile Telecommunications
-
2000):


-

Fulfill one's dream of
anywhere, anytime communications

a



reality.




Key Features of IMT
-
2000 include:


-

High degree of commonality of design worldwide;


-

Compatibility of services within IMT
-
2000 and with the fixed



networks;


-

High quality;


-

Small terminal for worldwide use;


-

Worldwide roaming capability;


-

Capability for multimedia applications, and a wide range of



services and terminals.

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

15

Third Generation Wireless Systems and Services (2/2)


Important Component of IMT
-
2000 is ability to provide high
bearer rate capabilities:



-

2 Mbps for fixed environment;



-

384 Kbps for indoor/outdoor and pedestrian environments;



-

144 Kbps for vehicular environment.



Standardization Work:



-

Release 1999 specifications



-

In processing



Scheduled Service:




-

Started in October 2001 in Japan (W
-
CDMA)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

16

Future: 4G


4G


Expected to implement
all standards from 2G & 3G


Infrastructure only
packet
-
based
,
all
-
IP


Some of the standards paving the way for 4G:


WiMax


WiBro

(Korean)


3GPP Long Term Evolution


To improves the
UMTS

mobile phone standard


Work
-
in
-
progress technologies


E.g.,
HSOPA
, a part of
3GPP Long Term Evolutionon

© 2007 by Leszek T. Lilien

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

17

Subscriber Growth
for Wireless Phones

3G Subscribers

2G Digital
-
only
Subscribers

1G Analog
-
only
Subscribers

Subscribers

Year

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

18

China Leads World in Mobile Phone Users



Total
[World]

Mobile

Users

>
800

million

[2003]


Total
[World]

Analogue

Users

>
70

million

[2003]



ZDNet UK reports that the number of mobile phone users in
China

reached
167

million in April, 2002, a rise of
6

million
subscribers on March, 2002.



The
US
, which is the
second biggest

market, has
136

million
subscribers.



Mobile phones are the preferred mode of communication in
Japan, with
56.8

million subscribers as of the end of March,
2003.

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

19


Many
diverse subsystems



Different
requirements
for different needs



Different
characteristics


Corresponding to the requirements



Different
coverage areas



Cell
= area that can be covered by a single

transmitting
station
(usually called
base station
)



Pico
cells,
micro
cells,
macro
cells &
global

“cell”


Figure


next slide



Why
different cell sizes
?


Limited nr of channels per cell


Smaller cells
can

serve more users


E.g. 2x smaller => can serve 2x more users on the same band
(with smaller range)


© 2007 by Leszek T. Lilien

Flexibility & Versatility of 3G

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

20

Coverage Aspect of Next Generation Mobile
Communication Systems

Picocell

Microcell

Macrocell

Global

Urban

Suburban

Global

Satellite

In
-
Building

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

21

Transmission Capacity

as a Function of Mobility

Broadband radio

Global System for Mobile Communications

0.01

0.1

1

10

100

Transmission capacity as a function of mobility in some radio access systems

Mobility

Universal Mobile
Telecommunica
-


tions System


Mobile Broadband System

Broadband Satellite Multimedia

Local Multipoint Distribution System

Satellite Universal Mo
-
bile Telecommunica
-



tions System

Data Rate (Mb/s)

Stationary

Pedestrian

Vehicular

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

22

1.2. Characteristics of Cellular Systems

Wireless Technology & Associated Characteristics



Wireless Technologies



Cellular



WLAN

(Wireless LAN)



GPS



Satellite Based PCS



Campus network (e.g.,

Ricochet
, Carnegie Mellon U.)



Home Networking



Ad Hoc Networks



WPAN

(Wireless PAN =
[personal area network]
)



Incl. Bluetooth



Sensor Networks




Different technologies

needed
for different applications


--

Details on the next slide


[From 1
st

ed. slides


Slightly modified by LTL]

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

23

[
LTL:
Yellow and
red highlights
added]

(phone calls)

(CMU campus)

(also oppnets, IANs)

(WPAN = wireless
personal area network)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

24

Wireless Technologies for Application Classes

[
LTL:

Yellow and red highlights added]


Notice
the following:


Infrastructure
-
based

networks vs.
ad hoc

networks (p.
11/2)



Terms & acronyms:


Access point



AP

(p. 8/
-
1, 10/2)


Mobile station



MS

(p. 11/2)


Handoff

and
switching

radio resources (p. 11/3)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

25

Application Example:

Medical Application


Wireless remote


consultation

ATM backbone
network


Possibility for remote consulting

(including audio visual communication)

ATM switch

ATM switch


Remote

databases

In hospital

physician

Ambulance

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

26

Wireless Features & Their Potential Apps

[LTL:]


Notice
the following (p. 11/
-
1):



Anytime anywhere
” not always required


Often “
many time
” or “
many where
” is adeqate


Permanent connectivity not necessary


MS can:


Start transaction at
AP1
, then move away (loosing connection to it)


Get close to
AP99
& complete transaction at
AP99

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

27

1.3.

Fundamentals of Cellular Systems

Illustration of a cell with a
mobile station

(MS)

and a
base station

(BS)

BS

MS

Cell

Hexagonal

cell area
used in most models

Ideal cell area

(2
-
10 km radius)

(
circle
)

Alterative
shape of a cell

(
square
)

MS

[LTL:]


Cell shapes

(above)


Actually, cell may have a
zigzag

shape


Hexagon

is a good approximation in practice


Also, gives
non
-
overlapping

cells
(used by clever bees for beehives)


E.g., circles would either overlap, or would have gaps in between

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

28


Single BS per cell =>


limited bandwidth
per cell



Increase

bandwidth use


efficiency

by multiplexing



4 +1 basic
multiplexing techniques


FDMA



frequency

division multiple access


TDMA



time

division multiple access


CDMA



code

division multiple access


OFDM



orthogonal frequency

division multiplexing


New:
SDMA



space

division multiple access


Specialized for microwave antennas



© 2007 by Leszek T. Lilien

Cell Bandwidth Limitations & Multiplexing

B
S

Service
area
(Zone)

MS

MS

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

29

FDMA (Frequency Division Multiple Access)

User 1

User 2

User n



Time

Frequency

[LTL:]


Used in
all 1G

cellular systems


BS allocates to each of
n

users a
channel

(a frequency
subband) for time the user needs it

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

30

FDMA Bandwidth Structure

1

2

3



n

Frequency

Total bandwidth


[LTL:] Divided into n channels

(frequency subbands)


4

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

31

FDMA Channel Allocation

Channel 1

User 1

Channel 2

User 2

Channel

n

User n

Base Station





Mobile Stations

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

32

TDMA (Time Division Multiple Access)

User 1

User 2

User n



Time

Frequency

[LTL:]


Used in
most 2G

cellular systems


BS allocates to each user
full
bandwidth for duration of a
time slot

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

33

TDMA Frame Structure

1

2

3



n

Time

Frame


[LTL:]

Divided into n time slots

(by a round
-
robin method)

4

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

34

TDMA Frame Illustration for Multiple Users

Time 1

Time 2

Time n





Base Station

User 1

User 2

User n



n

Mobile Stations

[LTL:]


Note:
Non
-
overlapping

time slices


“Time 2” slot starts after “Time 1” slot is over, etc.

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

35


CDMA
a.k.a.

spread spectrum
technique



Used in
some 2G

and
most 3G

cellular systems



Simultaneous

transmission of data from multiple users on
full frequency band


Figure
shows all users using:


Same range of frequencies


Same time range

But


Different codes



CDMA is enabled by

orthogonal


codes
(=
keys
)


One
distinct code

assigned


by BS
to each user

© 2007 by Leszek T. Lilien

CDMA (Code Division Multiple Access)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

36


CDMA transmission


Transmitter
:


Codes (using the key) each user’s data “stream”


Puts all
coded

individual data “streams” on data link


Creates a common “mixed” data stream


Receiver
:


Gets common “mixed” data stream from data link


Uses keys to
decode

(“unmix”) individual data stream from the
“mixed” data stream



# of simultaneous users

limited by # of possible
orthogonal codes



Complex

but
robust

technique

© 2007 by Leszek T. Lilien

CDMA (Code Division Multiple Access)


cont.

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

37

[SKIP:]

Transmitted & Received Signals

in a CDMA System

Information bits

Code at
transmitting end

Transmitted signal

Received signal

Code at
receiving end


Decoded signal

at the receiver

[LTL:] 10
-
bit codewords

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

38

Frequency Ranges used for

FDMA, TDMA & CDMA

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

39


OFDM
idea


to reduce interference


Convert
single high
-
speed data stream

to
multiple low
-
speed data streams


Low
-
speed data streams
sent in parallel

using
(sub)channels working on
multiple
-
frequencies




Frequencies of subchannels

in FDMA vs. OFDM


FDMA



non
-
overlapping

frequen
-


cies of subchannels


Even with gaps between subchannel


bands to reduce interference


OFDM

-

overlapping

frequencies


of subchannels



© 2007 by Leszek T. Lilien

OFDM (Orthogonal Frequency Division
Multiplexing)

Figure:

Copyright © 2003, Dharma P.
Agrawal and Qing
-
An Zeng.

All rights reserved

39

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

40


Many variants & combinations of FDMA, TDMA & CDMA
-

beyond the scope of this discussion



Frequency hopping


combines FDMA & TDMA



Idea:
One user uses
one channel for a time slot
, then
changes to another

channel for another time slot


See the next slide


Receiver

needs to
know

frequency hopping
sequence



Main
advantage

(e.g., in defense applications)
:


Message gets through even if one frequency band
jammed



© 2007 by Leszek T. Lilien

Variants & Combinations of

FDMA, TDMA & CDMA

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

41

Frequency Hopping

Frequency

f
5

f
4

f
3

f
2

f
1

Frame

Slot

Time

[LTL:]

Each user gets one time slot per frame, on a different frequency (round
-
robin
used for frequency selection)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

42

1.4.

Cellular System Infrastructure

BS

Service area
(Zone)

Early wireless system:
Large zone

[LTL:]


Large zone

requires a

high
-
power BS


Better:
replace large zone with

smaller hexagonal zones
(next slide)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

43

Cellular System: Small Zone

BS

BS

BS

BS

BS

BS

BS

Service area

[LTL:]


BS

covers
much smaller area

now


Requires
much less power
(for a given area)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

44


Various kinds of
Mobile Stations

(
MS
s) a.k.a.
wireless devices


Cellphone, PDA, PalmPilot, laptop with WiFi card, …



MSs need
connectivity on the move


E.g., connectivity from BSs in the cells they visit


BS

is a
gateway to wired infrastructure



Typical support for MSs:
Cellular infrastructure


See next slide

© 2007 by Leszek T. Lilien

Cellular System Infrastructure

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

45

Home phone

PSTN

MSC

BSC



BS





MS



BS

MS

BSC

BS

MS



BS

MS

BSC

BS

MS



BS

MS

BSC

BS

MS



BS

MS

MSC

MS, BS, BSC, MSC, and PSTN

[LTL:]


Several BSs

connected via wireline links to one

BSC

(
BS controller
)


Several BSCs

connected via wireline links to one

MSC

(
Mobile Switching
Center
)


Several MSCs

interconnected via wireline links to
PSTN

(
Public
Switched Telephone Network
) and the ATM backbone

wired link

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

46


BS consists of


Base Tranceiver System

(
BTS
)


Includes
tower

&
antenna


BSC


Contains all associated
electronics

© 2007 by Leszek T. Lilien

BS Structure

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

47


MSC
database

for
supporting MS mobility

1)

Home location register
(
HLR
) for MS


Located
at

the
“home MSC”

for MS


Where MS is registered, billed, etc.


Indicates
current location

of MS


Could be within home MSC’s area

OR


Could be in the area of any MSC in the world

2)

Visitor location register
(
VLR
) on each MSC


Contains info on all MSs visiting area of this MSC



Incoming call
scenario


Based on the
called #
, incoming call for an MS is directed
to the HLR of the “home MSC”
for this MS


HLR redirects

the call
to

MSC/BSC/BS

where the MS is
now


VLR

of the “
current MSC
” has info on MS
(one of visiting MSs)

© 2007 by Leszek T. Lilien

MSC Database Supporting MS Mobility


& Incoming Call Scenario

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

48

Control and Traffic Channels

Base Station

Mobile Station

Note:
Forward
/
reverse

in the U.S.,
downlink
/
uplink

elsewhere

[LTL:]


4 simplex channels

needed

for control & traffic


2 control

channels


Exchange control msgs


Forward

channel &
reverse

channel


2 traffic

channels


For data


Forward

channel &
reverse

channel

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

49

More on Control and Traffic Channels

[LTL:]


Traffic channels

used for call duration =>
Large #
of traffic
channels on each BS



Handshake

steps for
call setup

use
control channels





Control channels

used for short duration =>
Small #
of
control channels on each BS


MSs compete

for these few control channels


For call setup, etc.

© 2007 by Leszek T. Lilien

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

50

Steps for a Call Setup from MS to BS

BS

MS

1. Need to establish path

2. Frequency/time slot/code assigned


(FDMA/TDMA/CDMA)

3. Control information acknowledgement

4. Start communic. on assigned traffic channel


[LTL:]



Steps

for a call setup
from MS to BS
-


When
MS initiates a call

Time

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

51

Steps for a Call Setup from BS to MS

BS

MS

2. Ready to establish a path

3. Use frequency / time slot / code


(FDMA/TDMA/CDMA)

4. Ready for communication

5. Start communic on assigned traffic channel

1. Call for MS # pending

[LTL:]


Steps

for a call setup
from BS to MS
:


When
MS responds

to a call
(somebody calls MS)

Time

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

52

A Simplified Wireless Communication System
Representation

Information to
be transmitted
(Voice/Data)

Coding

Modulator

Transmitter

Information
received
(Voice/Data)

Decoding

Demodulator

Receiver

Antenna

Antenna

Carrier

Carrier

[LTL:]


The figure shows
major steps

in
wireless communications


Signal processing operations


beyond the lecture scope


Lecture

will concentrate on
system aspects

of wireless data
communication

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

53

1.5.

Satellite Systems


Application areas of satellite systems


Traditional

Applications


Weather satellite


Radio and TV broadcasting


Military satellites


Navigation and localization (e.g., GPS)



Telecommunication

Applications


Global telephone connections


Backbone for global network


Connections for communication in remote places or
underdeveloped areas


Global mobile communications

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

54

Basic Concepts & Terminology


Only
LOS

communication is possible


LOS = line of sight


Satellites further away from earth cover a wider area


Satelites can emit one or more
satellite beams



Satellites w.r.t. position over earth


Geostationary


Rotating

around the earth



ES



earth station

© 2007 by Leszek T. Lilien

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

55

History of Satellite Systems

50
th

anniversary of the space age on October 4, 2007

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

56

1.6.

Network Architectures and Protocols


[LTL:]
Protocol

= basic set of rules followed to provide

systematic signaling steps for information exchange


Other protocols:


Diplomatic protocols, protocol to login, …


[LTL:]
We will cover later following protocol reference
models and protocols:


Open Systems Interconnections

(
OSI
)
reference model


Transmission Control Protocol

(
TCP
)
(on top of IP)


Internet Protocol

(
IP
)


Internet Protocol
Version 4

(
IPv4
)


Internet Protocol
Version 6

(
IPv6
)


work in progress


Mobile IP
(
MIP
)

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

57

1.7.

Ad Hoc Network


[LTL:]
Ad hoc network

(
AHN
)


Def 1: AHN is a local network with
wireless connections
or

temporary plug
-
in

connections
, in which mobile or portable
device are a
part of the network only while

they are in
close

proximity


Def 2: AHN is a collection of wireless MHs forming a
temporary network without

the aid of any
centralized
administration or standard support

services

regularly
available on the wide area network (WAN) to which the hosts
may normally be connected


Examples:


AHN 1: Instructor’s and students’ computers can create an AHN
during lectures


AHN 2: Oppnet used after an earthquake

© 2007 by Leszek T. Lilien

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

58

1.7.

MANET

Source

Destination


[LTL:]
MANET

=
mobile

ad hoc network

-

an autonomous
system of mobile nodes, mobile hosts (
MHs
), or mobile
stations (MSs) connected by
wireless links


MSs

of a MANET also serve as
routers


These routers are
mobile


Route messages from SRC to DEST
-

see Figure


Multihop routing


Store
-
and
-
forward

passing of info in
P2P

(
peer
-
to
-
peer
)
way

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

59

MANETs


cont.1


MANETs are
highly dynamic


All nodes, incl. routers, are mobile


=>
topology highly dynamic, unpredictable


Topology
change

due to MSs mobility
made known to

(some)
other

nodes



Types w.r.t.
infrastructure support


Stand alone

-

no infrastructure support


Limited

infrastructure support


Some routers have access to a fixed infrastructure


E.g., access to Internet


like in oppnets


E.g.,
stub network

(
SN
)




Stub network

= a single LAN which never carries packets
between two remote hosts; all traffic is to and/or from local
hosts


Multiple routers on SN don't route to one another, they
will only route a packet into SN
(if it's destined for SN)
, and
out from SN
(if it originated on SN)

[cf. “stub network“ in Wikipedia]

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

60

MANETs


cont.2


Location of
MSs in a
MANET:


within

buildings, highways, vehicles, on and within human
bodies


MANET nodes

equipped
with a “radio”


“Radio” = wireless transmitter & receiver
(or: wireless transceiver)


With antenna


Types
of antennas:


Omnidirectional


Directional


Steerable


Any
combination

of these


Xmit/rcv parameters affect MANET topology

at any given
moment

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

61

Wireless Sensor Networks

B
ase
S
tation

Antenna

Sensor

Target


[LTL:]

(Ad Hoc)

Wireless Sensor Networks

(
WSNs
)


a specia
-
lized subclass of AHNs



Sensor(s)

in each node in addition to processor and radio


Sensors sense/measure some physical characteristcs


Temperature, humidity, acceleration, pressure, toxicity, …


Can be
planted at random


Even thrown out of a speeding


vehicle, even from a plane


Note: The plane in the Figure


is BS & collects data. Another


one could have dropped


sensor nodes earlier


BS

collects

&


aggregates


sensed info


Example 1 (Fig):


Sensing enemy’s


moves

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

62

Example 2: Sensing a Cloud of Smoke

Copyright © 2003, Dharma P. Agrawal and Qing
-
An Zeng. All rights reserved

63

1.8.

Wireless LAN and PAN


IEEE 802.11

= Wireless Local Area Network (
WLAN
) using the
IEEE 802.11


HiperLAN

is a European Standard


Bluetooth

nets are examples of Wireless Personal Area Networks



(
WPAN
)

End of Section 1 (Ch.1)