Ch1 Introduction to Wireless

Communications & Networks

Reading materials:[1]Overview of wireless communications[2] 移动通讯词汇（中英）

Outline

Part 1 Introduction to Wireless Communication & Networks

Part 2 Applications of Wireless Networks

Part 1 Introduction to Wireless

Communication & Networks

The Wireless Vision

Technical Challenges

Current Wireless Systems

Emerging Wireless Systems

Spectrum Regulation

Standards

Wireless History

First Mobile Radio Telephone 1924

Pre-Cellular Wireless

One highly-elevated antenna in a large service area

Small number of channels

Very low capacity

Examples: MJ and MK systems in the United States

The Cellular Concept

Basic Principles

Frequency Reuse

Cell Splitting

First proposed by D.

H. Ring at Bell Laboratories in 1947

Cellular - Implementation

Cellular - Implementation

Cellular Systems:Reuse channels to maximize

capacity Geographic region divided into cells Frequencies/timeslots/codes reused at spatially-separated locations. Co-channel interference between same color cells. Base stations/MTSOs coordinate handoff and control functions Shrinking cell size increases capacity, as well as networking burden

BASESTATION

MTSO

GSM System Architecture

Cellular Phone Networks

BSBS

MTSOPSTN

MTSO

BS

San Francisco

New YorkInternet

The Wireless Revolution

Cellular is the fastest growing sector of communication industry (exponential growth since 1982, with over 2 billion users worldwide today)

Three generations of wireless First Generation (1G): Analog 25 or 30 KHz FM,

voice only, mostly vehicular communication Second Generation (2G): Narrowband TDMA and

CDMA, voice and low bit-rate data, portable units.2.5G increased data transmission capabilities

Third Generation (3G): Wideband TDMA and CDMA, voice and high bit-rate data, portable units

World Telecom Statistics

Crossover has happened in May 2002!

World Cellular Subscribers by Technology

as of June 20062.41 Billion Cellular Customers Worldwide

GSM/UMTS Totals 82.3%

World Cellular Subscriber Distribution as of June

2006

GSM Growth - 1993 to June 2006

Exciting Developments

Internet and laptop use exploding2G/3G wireless LANs growing rapidlyHuge cell phone popularity worldwideEmerging systems such as Bluetooth,

UWB, Zigbee, and WiMAX opening new doors

Military and security wireless needsImportant interdisciplinary applications

Future Wireless Networks

Wireless Internet accessNth generation CellularWireless Ad Hoc NetworksSensor Networks Wireless EntertainmentSmart Homes/SpacesAutomated HighwaysAll this and more…

Ubiquitous Communication Among People and Devices

•Hard Delay Constraints•Hard Energy Constraints

Design Challenges

Wireless channels are a difficult and capacity-limited broadcast communications medium

Traffic patterns, user locations, and network conditions are constantly changing

Traffic is nonstationary, both in space and in time

Energy and delay constraints change design principles across all layers of the protocol stack

Evolution of Current Systems

Wireless systems today2G Cellular: ~30-70 Kbps.WLANs: ~10 Mbps.

Next Generation3G Cellular: ~300 Kbps.WLANs: ~70 Mbps.

Technology Enhancements Hardware: Better batteries. Better

circuits/processors.Link: Antennas, modulation, coding, adaptivity,

DSP, BW.Network: Dynamic resource allocation. Mobility

support.

Migration to 3G

CDMA

GSM

TDMA

PHS (IP-Based)

64 Kbps

GPRS

115 Kbps

CDMA 1xRTT

144 Kbps

EDGE

384 Kbps

cdma20001X-EV-DV

Over 2.4 Mbps

W-CDMA (UMTS)

Up to 2 Mbps

2G2.5G

2.75G 3G

1992 - 2000+2001+

2003+

1G

1984 - 1996+

2003 - 2004+

TACS

NMT

AMPS

GSM/GPRS

(Overlay) 115 Kbps

9.6 Kbps

9.6 Kbps

14.4 Kbps/ 64 Kbps

9.6 Kbps

PDC

Analog Voice

Digital Voice

Packet Data

IntermediateMultimedia

Multimedia

PHS

TD-SCDMA

2 Mbps?

9.6 Kbps

iDEN

(Overlay)

iDEN

Source: U.S. Bancorp Piper Jaffray

3G: ITU-Developed IMT-2000

Satellite

MacrocellMicrocell

UrbanIn-Building

Picocell

Global

Suburban

Basic TerminalPDA Terminal

Audio/Visual Terminal

Future Generations

Rate

Mobility

2G

3G

4G802.11b WLAN

2G Cellular

Other Tradeoffs: Rate vs. Coverage Rate vs. Delay Rate vs. Cost Rate vs. Energy

Fundamental Design Breakthroughs Needed

Current Wireless Systems

Cellular Systems Wireless LANs Satellite Systems Paging Systems Bluetooth Ultrawideband radios Zigbee radios

Cellular Systems －1G

Cellular Systems －2G

Cellular Systems 2G －D-AMPS

Cellular Systems 2G －GSM

Cellular Systems 2G －CDMA

Cellular Systems--2.5G

Cellular Systems--3G

Cellular Systems 3G—IMT-2000

Cellular Systems 3G—UMTS

Cellular Systems--4G

Cellular Systems--4G(续 )

WLAN

Wireless Local Area Networks (WLANs)

WLANs connect “local” computers (100m range)

Breaks data into packets Channel access is shared (random

access) Backbone Internet provides best-effort

servicePoor performance in some apps (e.g.

video)

01011011

InternetAccessPoint

0101 1011

Wireless LAN Standards

802.11b (Current Generation)Standard for 2.4GHz ISM band (80 MHz)Frequency hopped spread spectrum1.6-10 Mbps, 500 ft range

802.11a (Emerging Generation)Standard for 5GHz NII band (300 MHz)OFDM with time division20-70 Mbps, variable rangeSimilar to HiperLAN in Europe

802.11g (New Standard)Standard in 2.4 GHz and 5 GHz bandsOFDM Speeds up to 54 Mbps

In 200?,all WLAN cards will have all 3 standards

WPAN

Satellite Systems

Cover very large areas Different orbit heights

GEOs (39000 Km) versus LEOs (2000 Km)

Optimized for one-way transmissionRadio (XM, DAB) and movie (SatTV) broadcasting

Most two-way systems struggling or bankruptExpensive alternative to terrestrial systemA few ambitious systems on the horizon

Inmarsat Satellite

MARITIME

LAND

AERO

NCS

TT&C

RESCUE COORDINATION CENTRE

OCC

SCC

Inmarsat

NOC

LES

National & InternationalTelecom Network

voicefax datatelex

Inmarsat System (海事卫星 )

Inmarsat 卫星覆盖图

车载卫星导航系统

军用卫星指挥系统

中国卫星概况 1970 年 4 月 24 日，第一颗人造卫星“东方

红一号”发射成功，使中国成为世界上第五个独立研制和发射人造地球卫星的国家

1975 年 11 月 26 日，首次发射回收了返回式遥感卫星 使中国成为世界上第三个掌握卫星返回技术的国家

1984 年 4 月 8 日发射成功第一颗“东方红二号”地球静止轨道通信卫星 4 月 16 日定点于东经 125 赤道上空，使中国成为世界上第五个独立研制和发射静止轨道卫星的国家

中国卫星系列返回式遥感卫星系列 “ 东方红”通信广播卫星系列 “ 风云”气象卫星系列 “ 实践”科学探测与技术试验卫星系列 “ 资源”地球资源卫星系列 “ 北斗”导航定位卫星系列

Paging SystemsBroad coverage for short messagingMessage broadcast from all base

stationsSimple terminalsOptimized for 1-way transmissionAnswer-back hardOvertaken by cellular

8C32810.61-Cimini-7/98

Bluetooth

Cable replacement RF technology (low cost)

Short range (10m, extendable to 100m)2.4 GHz band (crowded)1 Data (700 Kbps) and 3 voice channels

Widely supported by telecommunications, PC, and consumer electronics companies

Few applications beyond cable replacement

Ultrawideband Radio (UWB)

UWB is an impulse radio: sends pulses of tens of picoseconds(10-12) to nanoseconds (10-9)

Duty cycle of only a fraction of a percent

A carrier is not necessarily needed

Uses a lot of bandwidth (GHz)

Low probability of detection

Excellent ranging capability

Multipath highly resolvable: good and badCan use OFDM to get around multipath problem.

Why is UWB Interesting?

Unique Location and Positioning properties1 cm accuracy possible

Low Power CMOS transmitters100 times lower than Bluetooth for same range/data

rate

Very high data rates possible500 Mbps at ~10 feet under current regulations

7.5 Ghz of “free spectrum” in the U.S.FCC recently legalized UWB for commercial useSpectrum allocation overlays existing users, but its

allowed power level is very low to minimize interference

“Moore’s Law Radio”Data rate scales with the shorter pulse widths made

possible with ever faster CMOS circuits

IEEE 802.15.4 / ZigBee Radios

Low-Rate WPAN Data rates of 20, 40, 250 kbps Star clusters or peer-to-peer operation Support for low latency devices CSMA-CA channel access Very low power consumption Frequency of operation in ISM bands

Focus is primarily on radio and access techniques

Data rate

10 kbits/sec

100 kbits/sec1 Mbit/sec

10 Mbit/sec

100 Mbit/sec

0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz

802.11a

UWBZigBee

Bluetooth

ZigBee

802.11b

802.11g

3G

UWB

Range

1 m

10 m

100 m

1 km

10 km

0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz

802.11a

UWB

ZigBee BluetoothZigBee

802.11b,g

3G

UWB

Power Dissipation

1 mW

10 mW

100 mW

1 W

10 W

0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz

802.11a

UWB

UWBZigBee

Bluetooth

ZigBee

802.11bg3G

Emerging Systems

Ad hoc wireless networks

Sensor networks

Distributed control networks

Ad-Hoc Networks

Peer-to-peer communications. No backbone infrastructure. Routing can be multihop. Topology is dynamic. Fully connected with different link

SINRs

Design Issues Ad-hoc networks provide a flexible network

infrastructure for many emerging applications.

The capacity of such networks is generally unknown.

Transmission, access, and routing strategies for ad-hoc networks are generally ad-hoc.

Crosslayer design critical and very challenging.

Energy constraints impose interesting design tradeoffs for communication and networking.

Sensor NetworksEnergy is the driving

constraint

Nodes powered by nonrechargeable batteriesData flows to centralized location.Low per-node rates but up to 100,000 nodes.Data highly correlated in time and space.Nodes can cooperate in transmission,

reception, compression, and signal processing.

Energy-Constrained Nodes

Each node can only send a finite number of bits.Transmit energy minimized by maximizing bit timeCircuit energy consumption increases with bit time Introduces a delay versus energy tradeoff for each bit

Short-range networks must consider transmit, circuit, and processing energy.Sophisticated techniques not necessarily energy-

efficient. Sleep modes save energy but complicate networking.

Changes everything about the network design:Bit allocation must be optimized across all protocols.Delay vs. throughput vs. node/network lifetime tradeoffs.Optimization of node cooperation.

Spectrum Regulation

Spectral Allocation in US controlled by FCC (commercial) or OSM (defense)

FCC auctions spectral blocks for set

applications.

Some spectrum set aside for universal use

Worldwide spectrum controlled by ITU-R

Regulation can stunt innovation, cause economicdisasters, and delay system rollout

Standards Interacting systems require standardization

Companies want their systems adopted as standardAlternatively try for de-facto standards

Standards determined by TIA/CTIA in USIEEE standards often adoptedProcess fraught with inefficiencies and

conflicts

Worldwide standards determined by ITU-TIn Europe, ETSI is equivalent of IEEE

Main Points

The wireless vision encompasses many exciting systems and applications

Technical challenges transcend across all layers of the system design.

Cross-layer design emerging as a key theme in wireless.

Existing and emerging systems provide excellent quality for certain applications but poor interoperability.

Standards and spectral allocation heavily impact the evolution of wireless technology

Some Acronyms in this lecture

OFDM: Orthogonal Frequency Division Multiplexing DAB: Digital Audio Broadcasting UAV: Unmanned Aerial Vehicle OSM: Office of Spectrum Management FCC: Federal Communications Commission TIA: Telecommunications Industry Association CTIA: Cellular Telecommunications Industry

Association ISM: Industrial, Scientific, and Medical ETSI: European Telecommunications Standards

Institute EDGE: Enhanced Data services for GSM Evolution HDR: High Data Rate DSP: Digital Signal Processing SINR: Signal-to-Interference-plus-Noise Ratio

Part 2 Applications of Wireless Networks

概况美国欧洲亚洲重要厂商

概况 -- 无线通信网络的发展

概况 -- 无线网络应用

概况 -- 无线网络应用现状

概况 -- 无线热点

美国现状

美国星巴克

欧洲现状

欧洲—“ The Cloud”

欧洲—“ MAGNET”

亚洲现状

亚洲现状

亚洲现状

重要厂商 -Cisco

重要厂商 -Intel

重要厂商 -Intel( 续 )

重要厂商 -Microsoft

重要厂商 -IBM

重要厂商 - 手机厂商

重要厂商 - 宠物服务 (1)

重要厂商 - 宠物服务 (2)

重要厂商 - 宠物服务 (3)

“ PetsCell” ，兼容现有的蜂窝网络和卫星GPS 技术。

能够让宠物的主人与他们的宠物讲话，以及在必要时请求别人提供帮助。

如果宠物走失，有人发现这个宠物在大街上徘徊，按一下宠物身上佩带的设备，自动拨号功能就可以把电话打到宠物主人的家里，让主人找回宠物。