Transcript Introduction to Wireless - University of Wisconsin–Parkside

Introduction to Wireless
CS 477
Technologies
Tech.
Primary
Appl.
Data Rates
QoS Goals
WLAN:
802.11
Wireless
Ethernet
Best Effort
+
WLL:
LMDS/
MMDS
Wireless
Cable:
Business
Hot spot
11, 54
Mbps
50, 100,
150 Mbps
WPAN:
Bluetooth
Tetherless
Computing
Cellular
Mobile
Comm.
ATM classes
Mastercontrolled
8, 144 kb/s RT & Best
- 2Mb/s
Effort
Transmission Techniques
Distributed/Hierarchical
FDMA/TDMA/CDMA
TDD/FDD
Network Types

Distributed Network:
Users interface with
each other
• Ad Hoc Network: Selfcreating

Hierarchical network:
Users interface with
Base Station or Access
Point
• Polled: Master-Slave
MT
MT
MT
MT
MT
BS
MT
MT
Hierarchical Networks
Base Station
Uplink
Downlink
Terminal
Equipment
Time Division Duplex (TDD)
Base Station & Terminal Equipment
alternate transmissions
 Good when amount of downlink data
> amount of uplink data

Frequency Division Multiple Access
Frequency Division Duplex (FDD)
Example: First Generation Cellular
Time Division Multiple Access
TDMA - FDD
Time Division Multiple Access
Channels allocated by Frequency &
Timeslot
 A Multiframe defines who & what
transmits during a timeslot (E.g.:)

• Broadcast / Paging / Synchronization
Channel
• Random Access Channel
• Signaling Channels
• Traffic Channel
Frequency Hopped Spread
Spectrum (FHSS)
EDGE Technology
EDGE Technology

Finds Optimal Bit Rate
• Selects modulation & coding scheme
based on environment
• Uses Link Quality Control

Varies Modulation Scheme
• GMSK, 8-PSK

Code Rate varies form .37 to 1.0
EDGE Modulation & Coding
MCS-9
MCS-8
MCS-7
MCS-6
MCS-5
MCS-4
8PSK
8PSK
8PSK
8PSK
8PSK
GMSK
1
0.92
0.76
0.49
0.37
1
59.2
54.4
44.8
29.6
22.4
17.6
kbps
kbps
kbps
kbps
kbps
kbps
MCS-3
MCS-2
MCS-1
GMSK
GMSK
GMSK
0.85
0.66
0.53
14.8 kbps
11.2 kbps
8.8 kbps
Direct Sequence Spread Spectrum
(DSSS)
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
Code Division Multiple Access
(CDMA)

Each bit is transmitted multiple times
at different frequencies, called ...
• Direct Sequence Spread Spectrum
• Fast Frequency Hopping

Message x spreading signal
• Pseudo-noise code sequence @ chip
rate
• Codewords are orthogonal to each other

Interference Limited
Multi-Carrier vs. Direct Sequence
CDMA 2000 Technology
Multi-Carrier
Direct Sequence
CDMA Enhancements
CDMA2000:
 Chip rates of N=1, 3, 6, 9, 12
 Reduced spreading
-6 vs 10-3
 Turbo codes: 10
 QPSK on Forward (v) Link
• BPSK on Reverse (^)
Spatial Diversity Multiple Access
SDMA or Smart Antennas
• Forms a focused beam
• Allows channels to be reused within a
cell

Multibeam Type
• Multiple fixed beams with a narrow
focus

Adaptive Array
• Uses Spatial & Angle Diversity
• Separates signal from its path
SDMA
Varied Cell Sizes
picocell
microcell
macrocell
megacell
Diameter
0
100 m
2 km
70 km
200-1000km
Frequency Allocations
Licensed: Cellular, Satellite,
WLL
Unlicensed: WLAN, WPAN
Licensed, Cellular Frequencies
.824 - .894 US-DC, IS-95
.890 - .960 ETACS / NMT / GSM
1.71-1.88 DCS 1800
1.85-1.99 US-DC, IS-95
1.92-2.17 UMTS - W-CDMA
Wireless Cable
MMDS
Frequency 2.1 & 2.5-2.686 GHz
Cell Size
25-35 miles
LMDS
27.5-28.35 GHz
31-31.3 GHz
1-3 km
Wireless LAN / PAN
IEEE 802.11B
BLUETOOTH
Wireless LAN
Unlicensed Frequencies
 Low Maximum Transmit Power
 Possible Contention Problems
 Frequencies Used:

• Industrial, Scientific, Manuf. (ISM): 2.4
GHz
• Unlicenced Nat. Info. Infrastructure
(UNII):
5.2 GHz 300 MHz
 5.725 - 5.825 GHz

IEEE 802.11B
192 us
1 Mbps
Data: 1 of 4 rates
Uses multiple subcarriers
Header
Training
Data
IEEE 802.11
Simultaneous Transmissions Possible
Hidden
Terminal
CSMA/CA
MT A
MT B
RTS
CTS
Data
ACK
MT C
IEEE 802.11 Protocol
S
I
F
S
P
I
F
S
D
I
F
S
IEEE 802.11 Protocol
Possible Simultaneous TX
 CSMA/CA
 RTS/CTS notifies all in area of TX
 SIFS: Short delay before ack.
 PIFS: Poll time-sensitive data

• Point Coordinator polls for high priority

DIFS: Anyone may contend to TX
Bluetooth Personal Area
Network
Radio-based cable replacement
• Low-cost, low-power
• Created by IBM, Intel, Ericsson, Nokia,
Toshiba in Feb. ‘98
• Joined by Motorola, Lucent, Microsoft,
3COM
Features
• Piconet: Swaps data at up to 10 meters
• Data Rate: 721 kbps to 1 Mbps, or 3
Voice @ 64 kbps
Bluetooth Applications
Cordless desktop with peripherals
 Cordless phone
 LAN Access - Internet bridge
 File Transfer: PDA synchronization
with PC
 Headset / Intercom / Dial up network
 Home entertainment, lighting,
security

Bluetooth Protocol
IEEE 802.15 Standard defines layers
1&2
 ISM Band: 2.4 GHz
 Spread spectrum: FHSS
 1 Master polls up to 7 Slaves
 Auto-initiation of updates

Cellular Systems
Functions of 2G Network



Cell Search
Location Update
Speech Calls
• Mobile Originated Call
• Paging: Mobile Terminated Call

Handover
• Hard Handover
• Soft Handover

Short Message Service
Features of 3G Cellular







Bit rates to 2 Mbps
Variable Bit Rate
Multiple services multiplexed on single
connection: voice, video, packet data
Real time and Best Effort traffic
FER: 10% to 10-6
Handovers between 2G & 3G systems
Asymmetric uplink and downlink
Services
Class of
Service
Characteristics
Applications
Conversational
Delaysensitive,
Symmetric
Voice,
videotelephony
Streaming
Constant delay, Multimedia,
Asymmetric
web broadcast
Interactive
Request/
Response
Web browsing,
network games
Background
Delayinsensitive
Email
Network Architecture
Universal Mobile
Telecommunications System
(UMTS)
Vocabulary
Control Plane:
 Radio Resource
Control
 Mobility Mgmt
 Call Control
User Plane:
 Speech
 Circuit-Switched
Data
 Packet-Switched
Data
High Level System Architecture
Uu
User
Equipment
(UE)
Iu
UMTS
Terrestrial
Radio
Access
Network
(UTRAN)
Core
Network
(CN)
User Equipment
Uu
Mobile
Equip.
USIM
Subscriber
Identity
Module
Iu
UMTS
Terrestrial
Radio
Access
Network
(UTRAN)
Core
Network
(CN)
Radio Interface Protocols
Control Plane Protocols
User Plane Protocols
Radio Link Control
Logical
Channels
Medium Access Control
Transport Channels
Physical Layer
Logical Channels
Control Channels:
 Broadcast Control (BCCH): Downlink
broadcasts system information
 Paging Control (PCCH): Downlink
incoming call info.
 Dedicated Control (DCCH): Bidirectional
control info (inside call)
 Common Control (CCCH): Bidirectional
control info (outside call)
Logical Channels
Traffic Channels:
 Dedicated Traffic (DTCH):
Bidirectional point-to-point dedicated
channel
 Common Traffic (CTCH): Downlink
point-to-multipoint channel
Radio Link Control
Layer 2:
 Transparent: No protocol
 Unacknowledged Mode
 Acknowledged Mode
UTRAN
Uu
Iu
Mobile
Equip.
Node B
USIM
Subscriber
Identity
Module
Node B
Node B
RNC
RNC
Node B
Core
Network
(CN)
UTRAN Protocols
Uses ATM base:
 ATM AAL5: Control
 ATM AAL2: Speech
 RANAP: Radio Access Network
Application Protocol
Core Network
Uu
Mobile
Equip.
USIM
Subscriber
Identity
Module
Iu
Node B
Node B
RNC
MSC/
VLR
GMSC
PSTN
HLR
Node B
RNC
Node B
SGSN
GGSN
Internet
Core Network Nodes

Circuit-Switched:
• Mobile Switching Center (MSC): switches PCM
speech

Packet-Switched:
• Serving GPRS Support Node (SGSN)
• Gateway Support Node (GGSN): Interface to
global Internet

Common
• Home Location Register (HLR): Permanent
source of subscription information
• Visitor Location Register (VLR): Local source
for user subscription options
GPRS Network Architecture
Serving GPRS Support Node (SGSN)
• Interfaces with MS via BS
• Performs security, mobility / VLR
functions
Gateway GPRS Support Node (GGSN)
• Interfaces to Internet
• Learns MS location via HLR
• Routes data to the SGSN using IP
Network is evolving as 3G/4G
progresses
Physical Layer Channels
Common Channel
Dedicated Channel
Shared Channel
Dedicated Transport Channel


Circuit-switched services: speech,
teleconferencing
Variable bit rate
• Fast data rate change


Soft handover
Physical channels:
• Dedicated Physical Data Channel: User data
• Dedicated Physical Control Channel: Physical
layer control
Common Transport Channels






Broadcast: Downlink cell-specific
information
Forward Access: Downlink control &
packet info.
Paging: Downlink data relevant to paging
Random Access: Uplink request for service
Uplink Common Packet: Extended data
requests
Downlink Shared: Shared for dedicated
data/control