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第 2 讲 无线网络与移动终端. §2.1 无线通信与网络 §2.2 移动终端及接入. Mobile Computing Architecture. Server. MU (mobile unit). Fixed network. MSS (mobile support station). Wireless radio cell (19.2Kbps). WLAN. 无线通信技术. 调制解调技术 DSSS FHSS OFDM 无线接入技术 CSMA/CA ALOHA TDMA CDMA OFDMA …. 无线网络. P31 图

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slide1

第2讲 无线网络与移动终端

§2.1 无线通信与网络

§2.2 移动终端及接入

mobile computing architecture
Mobile Computing Architecture

Server

MU

(mobile unit)

Fixed network

MSS

(mobile support station)

Wireless radio cell (19.2Kbps)

WLAN

slide3
无线通信技术
  • 调制解调技术
    • DSSS
    • FHSS
    • OFDM
  • 无线接入技术
    • CSMA/CA
    • ALOHA
    • TDMA
    • CDMA
    • OFDMA
slide4
无线网络

P31图

无线个域网

无线局域网络

无线城域网

无线广域网

卫星通信网络

slide5
无线个域网

红外技术

蓝牙技术

UWB

ZigBee

NFC

slide6
红外通信技术
  • Low cost and not interfered by radio signal.
  • Can connect up to 2 miles with line-of-sight.
  • There are two standards: IrDA and 802.11 IR.
  • IrDA (Infrared Data Association) compatible:
    • Use regular Infrared.
    • Data rate from 9.6 kbps to 4 Mbps.
    • Must follow the IrDA specification.
  • Wireless Ethernet 802.11 IR:
    • Use diffused Infrared, without line-of-sight.
    • Can connect to LAN.
    • Standard not updated for a while.
    • Signal can be swamped by sunlight.
    • Bandwidth is still limited.
bluetooth
Bluetooth
  • Also defined as 802.15b.
  • Variation 802.15c at higher data rate and 802.15d consuming little power.
  • Connect devices up to a distance of 10m.
  • Use master/slave design, known as a piconet.
  • Built upon scattered net with many piconets.
  • Support up to 7 active slaves, and 255 in total.
  • Support 13 specific applications, including service discovery, LAN access and FTP.
  • Bandwidth 1 to 10 Mbps.
  • Low power consumption.
  • Higher cost than infrared, but low cost compared with wireless LAN.
bluetooth network topology

A

P

M

M

P

P

A

P

A

P

A

  • Scatternet
  • Multiple pico-nets co-located
  • Device can be on multiple pico-nets (Performance tradeoff)
Bluetooth Network Topology
  • Radio Design
    • All radios are symmetric (can be master or slave)
  • Pico-net
  • 1 master:
    • 7 active slaves
    • 200+ parked slaves
  • Each network has a unique hopping pattern / ID
zigbee
ZigBee
  • IEEE 802.15.4, brother of Bluetooth
  • Low cost, low power consumption
  • High node density, long range
  • Low data rate
  • Mainly used for
    • Human Input Devices
      • Remote controller
      • Mouse, keyboard…
    • Sensors (WSN)
slide11

Time-domain behavior

Frequency-domain behavior

1

1

0

Ultrawideband

frequency

time

3

10

GHz

(FCC Min=500Mhz)

1

0

1

0

Narrowband

2.4

GHz

UWB(超宽带)

IEEE 802.15.3

Short distance: 2m-10m,

Very low power consumption

Impulse based waveforms (simple)

near field communication nfc
Near Field Communication (NFC)

Very simple wireless communication setup

Very small distance (<20cm)

Low data rate (~400k)

Similar to Infrared (using RF instead)

slide13
比较

NFC:消费支付;红外:设备控制;蓝牙:设备通信互联; ZigBee:大量节点(WSN)

slide14
无线局域网(WLAN)

Most common variant is 802.11n, with data rate up to 150Mbps.

Alternative version 802.11a/b/g.

Compatible with Ethernet using access point.

Can also support ad hoc networking.

High bandwidth.

Initially high cost, but now becomes very affordable.

slide16
网络拓扑
  • Infrastructure networks
    • Access point + mobile station
    • Medium access:
      • collision: wireless nodes and AP are not coordinated
      • collision free: AP controls medium access
  • Ad-hoc (peer-to-peer) networks
    • medium access: collision
    • wireless node may transfer data (router)

wired network

AP

BSS (Basic Service Set)

802 11 architecture of an infrastructure

Distribution System

802.11 - Architecture of an infrastructure

802.11 LAN

802.x LAN

BSS1

STA1

Portal

AP

ESS

AP

Extended Service Set

STA3

BSS2

STA2

802.11 LAN

802 11 architecture of an infrastructure1
802.11 - Architecture of an infrastructure
  • Station (STA)
    • terminal with access mechanisms to the wireless medium and radio contact to the access point
  • Basic Service Set (BSS)
    • group of stations using the same radio frequency
  • Access Point
    • station integrated into the wireless LAN and the distribution system
  • Portal
    • bridge to other (wired) networks
  • Distribution System
    • interconnection network to form one logical network (EES: Extended Service Set) based on several BSS
802 11 architecture of an ad hoc network
802.11 - Architecture of an ad-hoc network
  • Direct communication within a limited range
    • Station (STA):terminal with access mechanisms to the wireless medium
    • Independent Basic Service Set (IBSS):group of stations using the same radio frequency

802.11 LAN

STA1

STA3

IBSS

STA2

ieee standard 802 11
IEEE standard 802.11

mobile terminal

infrastructure

network

access point

Fixed terminal

Application

Application

TCP

TCP

IP

IP

LLC

LLC

LLC

802.3 MAC

802.11 MAC

802.3 MAC

802.3 MAC

802.3 PHY

802.11 PHY

802.3 PHY

802.3 PHY

manet
移动自组网(MANET)

Mobile Ad hoc NETworks

Multi-hop wireless links

Peer-to-peer forwarding

802.11based, usually

slide22
无线传感器网络(WSN)

Wireless Sensor Networks

Monitoring

Ad hoc configuration

ZigBee, 802.11…

mesh wmn
无线Mesh网(WMN)

Wireless Mesh Network

Hierarchical, ad hoc backbone

Extension of WLAN

802.11, 802.11s

vanet
车载网VANET

Vehicular Ad-Hoc Network

Hybrid networks

V2V, V2I

802.11p, 3G, etc.

wireless man
无线城域网(Wireless MAN)
  • WiMAX (Worldwide Interoperability for Microwave Access)
    • Also called broadband wireless network.
    • Standard 802.16.
    • Assume service delivery to buildings which will not move.
    • Due to signal attenuation, different modulation schemes give different baud rates and hence bandwidths to clients at different distance.
    • All services are connection-oriented.
      • Constant bit rate service.
      • Real-time variable bit rate service.
      • Non-real-time variable bit rate service.
      • Best-efforts service.
    • Very high aggregate bandwidth.
    • High bandwidth to each subscriber.
slide26
无线广域网
  • 蜂窝通信网络
  • Base station + mobile terminal
  • 1G: AMPS
    • analog access
  • 2G: GSM、CDMA
    • digital access
  • 2.5G:CPCD、EDGE、GPRS
3g technology
3G Technology

WCDMA、CDMA2000、TD-SCDMA

2 Mbps, stationary;384 kbps, walking;144 kbps driving.

Multimedia (music / game playing), Internet

4g technology
4G technology
  • LTE Advanced and/or IEEE 802.16m ?
  • Wireless broadband infrastructure to support multimedia information society.
  • Entirely packet switched networks.
  • All digital network elements.
  • Expectation include
    • High bandwidth of 50 - 100 Mbps.
    • Low system cost.
    • Ubiquitous connection.
    • Seamless integration with wired network and the support of IPv6.
    • Adaptive resource and spectrum management with proper QoS.
    • Software radio.
    • High quality multimedia.
slide31
卫星通信网络
  • Act as transponder for signal and data transfer.
  • Geostationary Earth Orbit (GEO)
    • Satellite at stationary position.
    • Long delay.
    • High energy consumption.
  • Low Earth Orbit (LEO)
    • Satellite at lower orbit.
    • Lower energy consumption, but frequent change of satellite.
slide32
移动终端

Mobile terminal/mobile client/mobile station/mobile node…

Laptop, SmartPhone, Tablet, PDA, Netbook, sensor node, vehicle, ...

slide33
移动终端系统
  • Mobile phone / tablet
    • Android
    • IOS
    • WinPhone
    • Symbian
    • Bada
    • OPhone
  • Others
    • TinyOS:sensor
    • Linux: router、notebook
    • Windows: notebook
    • OS X: notebook
internet
移动Internet接入
  • 基于Cellular网络 vs. 基于Ethernet
  • 网络协议的改进
    • 网络层、传输层
    • 应用层
  • WAP:Open Mobile Alliance
  • iMode:日本DoCoMo公司
characteristics challenges
Characteristics/Challenges
  • Resource constraints
    • Bandwidth, power, memory, CPU power, etc…
  • Failures
    • Link breakage (interference, mobility)
    • Node failures
  • Mobility
  • Openess
summary
Summary
  • Various wireless networks
    • Flat vs. hierarchical
    • Ad hoc vs. infrastructure
  • Various mobile devices
    • Handheld, laptop, vehicle…
review questions
Review Questions

辨析WLAN、IEEE 802.11与WiFi三个概念的关系

什么是LTE?