Wireless WAN

เครือข่ายไร้สายระยะไกล

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หวัขอ้

�Cellular Network

�WiMAX

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Cellular Network - Architecture

Radio tower

PSTN

Telephone

Network

Mobile Switching

Center

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A Cellular Network

Public

Switched

Telephone

Network

(PSTN)

Mobile

Telephone

Switching

Center

(MTSC)

Base Transceiver Station (BTS) Mobile User

Cell 1

Cell 2

Cordless connection

Wired connection

HLR VLR

HLR = Home Location Register

VLR = Visitor Location Register 4

Cellular System

Handoffs (typically 30 mseconds):

1. At any time, mobile station (MS) is in one cell and under the control of a BS

2. When a MS leaves a cell, BS notices weak signal

3. BS asks surrounding BSs if they are getting a stronger signal

4. BS transfers ownership to one with strongest signal

5. MTSO assigns new channel to the MS and notifies MS of new boss

Public

Switched

Telephone

Network

(PSTN)

Mobile

Telephone

Switching

Center

(MTSC)

Cell 1

Cell 2

HLR VLR

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Cellular networks: From 1G to 3G

�1G: First generation wireless cellular: Early 1980s�Analog transmission, primarily speech: AMPS (Advanced Mobile Phone Systems) and others

�2G: Second generation wireless cellular: Late 1980s�Digital transmission�Primarily speech and low bit-rate data (9.6 Kbps)�High-tier: GSM, IS-95 (CDMA), etc�Low-tier (PCS): Low-cost, low-power, low-mobility e.g. PACS

�2.5G: 2G evolved to medium rate (< 100kbps) data�3G: future Broadband multimedia

�144 kbps - 384 kbps for high-mobility, high coverage�2 Mbps for low-mobility and low coverage

�Beyond 3G: research in 4G 6

1G

(<1Kbps)

1 Kbps

10 Kbps

100 Kbps

2 Mbps

1 Mbps

Data Rates

1980 1990 2000 2010

2G

(9.6Kbps)

2.5G

(10-150Kbps)

3G

(144Kbps to 2Mbps)

Years

1G to 3G

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Very Basic Cellular/PCS Architecture

Base Station

(BS) Mobile Station

Base Station

Controller

Mobility

Database

Mobile

Switching

Center

(MSC)

Radio Network

Public Switched

Telephone Network

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Duplex Communication - FDD

�FDD: Frequency Division Duplex

Base StationB

Mobile Terminal

M

Forward ChannelReverse Channel

Forward Channel and Reverse Channel use different frequency bands

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Access Methods

Frequency

Time

Frequency

Time

Frequency

Time

FDMA

TDMA

CDMA

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Clusters

�A cluster is a group of cells

�No channels are reused within a cluster

A seven Cell Cluster

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Frequency Reuse

�Cells with the

same number have

the same set of

frequencies

Frequency Reuse

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Frequency Reuse using 7 frequencies allocations

f4

f3f2

f1f6

f7

f5 f4

f3f2

f1f6

f7

f5

f4

f3f2

f1f6

f7

f5

f4

f3f2

f1f6

f7

f5

f4

f3f2

f1f6

f7

f5

Each cell is generally 4 to 8 miles in diameter with a lower limit

around 2 miles.

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Cell Splitting�Allows urban centres to be split into as many areas as necessary for acceptable service levels in heavy-traffic regions, while larger, less expensive cells can be used to cover remote rural regions

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Cellular Concept with Sectors

base station

frequency re-use

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Hand-off

�The final obstacle in the

development of the

cellular network involved

the problem created when

a mobile subscriber

moved from one cell to

another during a call

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InternetPSTN

(Telephone Network)

Looking to PCS from different Angles

Mobile Users-Cell phone users

-Cordless phone users

Mobile Users-Laptop users-Pocket PC users

-Mobile IP, DHCP enabled computers

Wireless Access

Telecom People View Data Networking People View

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Telecom and Data Networking

-Radio Propagation-Link Characteristics-Error Models-Wireless MediumAccess (MAC)- Error Control

-Data Transmission-Mobile IP (integrating mobile hosts to internet) -Ad-hoc Networks-TCP over Wireless-Service Discovery

- Voice Transmission- Frequency Reuse- Handoff Management-Location Tracking-Roaming-QoS-GSM, CDMA, Cordless Phones,-GPRS, EDGE

Telecom InterestData Networking

Interest

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Major Mobile Radio Standards - USA

Standard Type Year

Intro

MultipleAccess

Frequency Band

(MHz)

Modulation Channel

BW

(KHz)

AMPS Cellular 1983 FDMA 824-894 FM 30

USDC Cellular 1991 TDMA 824-894 DQPSK 30

CDPD Cellular 1993 FH/Packet 824-894 GMSK 30

IS-95 Cellular/PCS 1993 CDMA 824-894

1800-2000

QPSK/BPSK 1250

FLEX Paging 1993 Simplex Several 4-FSK 15

DCS-1900 (GSM)

PCS 1994 TDMA 1850-1990 GMSK 200

PACS Cordless/PCS 1994 TDMA/FDMA 1850-1990 DQPSK 300

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Major Mobile Radio Standards - Europe

Standard Type Year

Intro

MultipleAccess

Frequency Band

(MHz)

Modulation Channel

BW

(KHz)

ETACS Cellular 1985 FDMA 900 FM 25

NMT-900 Cellular 1986 FDMA 890-960 FM 12.5

GSM Cellular/PCS 1990 TDMA 890-960 GMSK 200KHz

C-450 Cellular 1985 FDMA 450-465 FM 20-10

ERMES Paging 1993 FDMA4 Several 4-FSK 25

CT2 Cordless 1989 FDMA 864-868 GFSK 100

DECT Cordless 1993 TDMA 1880-1900 GFSK 1728

DCS-1800 Cordless/PCS 1993 TDMA 1710-1880 GMSK 200

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2G TechnologiescdmaOne (IS-95) GSM, DCS-1900 IS-54/IS-136

PDC

Uplink Frequencies

(MHz)

824-849 (Cellular)

1850-1910 (US PCS)

890-915 MHz (Eurpe)

1850-1910 (US PCS)

800 MHz, 1500 Mhz

(Japan)

1850-1910 (US PCS)

Downlink Frequencies 869-894 MHz (US

Cellular)

1930-1990 MHz (US

PCS)

935-960 (Europa)

1930-1990 (US PCS)

869-894 MHz (Cellular)

1930-1990 (US PCS)

800 MHz, 1500 MHz

(Japan)

Deplexing FDD FDD FDD

Multiple Access CDMA TDMA TDMA

Modulation BPSK with Quadrature

Spreading

GMSK with BT=0.3 π/4 π/4 π/4 π/4 DQPSK

Carrier Seperation 1.25 MHz 200 KHz 30 KHz (IS-136)

(25 KHz PDC)

Channel Data Rate 1.2288 Mchips/sec 270.833 Kbps 48.6 Kbps (IS-136)

42 Kbps (PDC)

Voice Channels per

carrier

64 8 3

Speech Coding CELP at 13Kbps

EVRC at 8Kbps

RPE-LTP at 13 Kbps VSELP at 7.95 Kbps21

GSM and CDMA Coverage Map Worldwide

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WiMax

�Worldwide Interoperability for Microwave Access

�Last mile wireless broadband access

�Alternative to cable and DSL

�Deliver data, voice, video

�Support hundreds to thousands of homes/business

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802.16 Standards History

802.16a(Jan 2003)

• Extension for 2-11 GHz: Targeted for non-line-of-sight, Point-to-Multi-Point applications like “last mile” broadband access

802.16(Dec 2001)

• Original fixed wireless broadband air Interface for 10 – 66 GHz: Line-of-sight only, Point-to-Multi-Point applications

802.16c(2002)

802.16 Amendment

WiMAX System Profiles

10 - 66 GHz

802.16REVd (802.16-2004)

(Oct 2004)

• Adds WiMAX System Profiles and Errata for 2-11 GHz

802.16e(802.16-2005)

(Dec 2005)

• MAC/PHY Enhancements to support

subscribers moving at vehicular speeds

• First standard based on proprietary implementations of DOCSIS/HFC architecture in wireless domain

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Wireless RMF Spectrum

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Applications of 802.16 Standards

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Scope of 802.16 Standards

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Physical Layer SummaryDesignation Applicability MAC Duplexing

WirelessMAN-SC 10-66 GHz Licensed Basic TDD, FDD, HFDD

WirelessMAN-SC 2-11 GHz Licensed Basic, (ARQ),

(STC), (AAS)

TDD, FDD

WirelessMAN-OFDM

2-11 GHz Licensed Basic, (ARQ),

(STC), (AAS)

TDD, FDD

2-11 GHz License-

exempt

Basic, (ARQ),

(STC), (DFS),

(MSH), (AAS)

TDD

WirelessMAN-OFDMA

2-11 GHz Licensed Basic, (ARQ),

(STC), (AAS)

TDD, FDD

2-11 GHz License-

exempt

Basic, (ARQ),

(STC), (DFS),

(MSH), (AAS)

TDD

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Channel Characteristics

�10-66 GHz�Very weak multipath components (LOS is required)�Rain attenuation is a major issue�Single-carrier PHY

�2-11 GHz�Multipath�NLOS�Single and multi-carrier PHYs

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General Downlink Frame Structure

• Downlink Interval Usage Code (DIUC) indicates burst profile30

General Uplink Frame Structure

• Uplink Interval Usage Code (UIUC) indicates burst profile31

Frame Structure – Another View

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Network Entry Process

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Connections

�802.16/WiMAX is connection oriented

�For each direction, a connection identified with a 16 bit

CID

�Each CID is associated with a Service Flow ID (SFID)

that determines the QoS parameters for that CID

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WiMAX connection

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Wireless PAN & Wireless Sensor

เครือข่ายไร้สายส่วนบุคคลและเครือข่ายตรวจจบั

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หวัขอ้

�Bluetooth (IEEE 802.15.1)

�Zigbee (IEEE 802.15.4)

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Bluetooth IEEE 802.15.1

�Adopted the Bluetooth MAC and PHY specifications

�IEEE 802.15.1 and Bluetooth are almost identical

regarding physical layer, baseband, link manager, logical

link control and apdation protocol, and host control

interface

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Personal Ad-hoc Networks

Cable Replacement

Landline

Data/Voice Access Points

(internet access)

Usage♦ three major applications

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Bluetooth Specifications�2.4 GHz ISM Unlicensed band

�Microwave ovens also use this band

�Frequency Hopping Spread Spectrum�Avoid interference

�23/79 channels

�1 MHz per channel

�1 Mbps link rate (GFSK modulation)

�Fast frequency hopping and short data packets avoids interference�Nominally hops at 1600 times a second (vs. 2.5 hops/sec in IEEE 802.11)

�625us per hop (366us for data only)

�3200 times a second during inquiry and paging modes

�Multiple uncoordinated networks may exist and cause interference�CVSD (Continuous Variable Slope Delta Modulation) voice coding (FEC)

enables operation at high bit error rates40

ISM Unlicensed Band

2.4GHz

2.402

Guard band Guard band

2.48 2.483

2.402-2.480 GHz79 hopping channels

ISM unlicensed band

Licensedband

� 79 channels in 2.4GHz (in USA and most Europe)

Licensedband

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Transmit Power�transmit power and range

o 0 dbm (up to 20dbm with power control) o 10-100 m

Power Class Max Output Min Output Power Control

1100mW

(20dBm)

1mW

(0dB)

-4db/time

Max twice

22.5mW

(4dBm)

0.25mW

(-6dBm)Optional

31mW

(0dBm)N/A Optional

�Power 1mW (class 3)•3% power of cellular phone•10meters of transmission distance or 100m by PA

�Power 100mW(class 1)•100 meters of transmission distance

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Frequency Hopping

Time

Frequency

0

78

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FHSS

DataSource

Hopping

CodeGenerator

+d(t)

DigitalModulator

Frequencysynthesizer

Front-endFilter

+

Frequencysynthesizer

DataDetector

d(t)^

Local hoppingcode generator

Receiver

Transmitter

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Modulation and Symbol Rate�Symbol Rate : 1M symbols/sec (1MHz)

�GFSK (Gaussian Frequency Shift Keying)

�Binary One (1) : Positive frequency deviation

�Binary Zero (0) : Negative frequency deviation

�Maximum frequency deviation

�Between 140kHz and 175kHz

fo fo+∆ffo-∆ffrequency

Magnitude

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Network Topology

�Radio Designation�Connected radios can be master or slave�Radios are symmetric (same radio can be master or slave)

�Piconet�Master can connect to 7 simultaneous or 200+ active slaves per piconet

�Each piconet has maximum capacity (1 Msps and 1 Mbps)�Unique hopping pattern/ID

�Scatternet�High capacity system

�Minimal impact with up to 10 piconets within range�Radios can share piconets!

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Piconet vs. Scatternet�A scatternet contains two piconets

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Piconet and Scatternet

point-to-point

(piconet)multi-point

(piconet)

scatternet

Master host Slave host

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Basic Baseband Protocol

�Spread spectrum frequency hopping radio

�Hops every packet

�Packets are 1, 3 or 5 slots long

�Frame consists of two packets

�Transmit followed by receive

�Nominally hops at 1600 times a second (1 slot packets)

One

Slot

Packet

Three Slot Packet

Frame

Master

Slave

625 us

One Slot

fk

fk+1

One

Slot

Packet

Frame

Master

Slave

625 usOne Slot

fk

fk+1

One

SlotPacket

(1.25 ms)

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Time Division Duplex (TDD)� Master : even numbered slots

� Slave : odd numbered slots

� The Slot Number ranges from 0- 227-1.

Access code/Header Payload guard time for hopping

Master

Slave

f(2k) f(2k+1) f(2k+2)

Packet

odd (625µs)even (625µs) eventime

slot

guardtime

220 µµµµs+/-10 µµµµs

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Multi-slot Packets� Different packet overhead will result in different throughput

�DH1 : 172.8Kbps in Sym. and Asyn. modes

�DH3 : 390.4Kbps in Sym. mode; 387.2 and 54.4Kbps in Asyn. Mode

�DH5 : 433.9Kbps in Sym. mode; 721 and 57.6Kbps in Aysn.

�DH : without FEC

f(2k+2)f(2k) f(2k+1) f(2k+3) f(2k+4)

f(2k+2)f(2k) f(2k+1) f(2k+3) f(2k+4)

f(2k+2)f(2k) f(2k+1) f(2k+3) f(2k+4)

3-slotPacket(DH3)

5-slotPacket(DH5)

1-slotPacket(DH1)

odd (625µs)even (625µs) odd (625µs)even (625µs) 51

ZigBEE IEEE 802.15.4

�Low Rate WPAN (LR-WPAN)

�Simple

�Low cost

�Low power consumption

�E.g. Sensor networks

�Data rates: 20-250 kbps52

IEEE 802.15.4 – Protocol stack

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IEEE 802.15.4 - DEVs

�2 or more DEVs form a PAN

�2 different types of DEVs

�Full functional Device (FFD)

�Coordinator and simple node

�Any topology

�Talks to any device

�Reduced Functional Device (RFD)

�Simple node only, either source or desination

�Star topology only

�Talks to network coordinator only54

IEEE 802.15.4 - Star

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IEEE 802.15.4 – Peer-to-Peer

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IEEE 802.15.4 - Combined

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Comparison between WPAN

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ZigBee network applications

PERSONAL

HEALTH

CARE

ZigBeeLOW DATA-RATE RADIO DEVICES

HOME

AUTOMATION

CONSUMER

ELECTRONIC

S

TV VCR

DVD/CD

Remote

control

security

HVAC

lighting

closures

PC &

PERIPHERAL

S

consoles

portables

educational

TOYS &

GAMES

INDUSTRIAL

&

COMMERCIAL

monitors

sensors

automation

control

mouse

keyboard

joystick

monitors

diagnostics

sensors

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Wireless technologies

10

100

1,000

10,000

10 100 1,000 10,000 100,000

Bandwidth

kbps

GSM

802.11a/g

GPRS EDGE2000

2003-4

2005

Bluetooth

3G

Hiper

LAN/2Bluetooth 2.0

Range

Meters

802.11b

ZigBee

WiMediaBluetooth 1.5

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ZigBee/802.15.4 architecture� ZigBee Alliance

� 45+ companies: semiconductor mfrs, IP providers, OEMs, etc.

� Defining upper layers of protocol stack: from network to application, including

application profiles

� First profiles published mid 2003

� IEEE 802.15.4 Working Group

� Defining lower layers of protocol stack: MAC and PHY

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ZigBee related to IEEE 802.15.4

�ZigBee takes full advantage of a powerful physical radio

specified by IEEE 802.15.4

�ZigBee adds logical network, security and application

software

�ZigBee continues to work closely with the IEEE to

ensure an integrated and complete solution for the

market

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