Transcript 行動計算與網路簡介 Introduction to Mobile Computing and Networkin

無線網路與行動計算簡介
Introduction to Wireless Networks
and Mobile Computing
王國禎
PDS
國立交通大學
資訊工程系
行動計算與寬頻網路實驗室
http://mbl.cs.nctu.edu.tw
Email: [email protected]
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無線網路與行動計算發展背景
無線通信本質
電腦的行動性
無線網路技術
行動式電腦技術
研究主題
結論
無線網路與行動計算
發展背景
• 無線數位通信技術快速發展
• 通信及行動電腦成本降低
– 行動計算應用由業者推廣至一般消費者
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• 目標：無遠弗屆及充滿智慧
(Ubiquitous and Intelligent)
– Information seeks people
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無線通信的本質
• 頻寬窄及變動大
• 高位元錯誤率 (BER)
• 電池蓄電的限制
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電腦的行動性
• 新研究課題：對網路、作業系統及資訊
(應用）系統的影響
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– 網路及通信主題
– 位置管理：位置不固定 (Mobile IPv4, IPv6)
– 應用軟體：文脈感測： 如位置相關性
(Context-sensitive applications,
e.g., location-dependent applications)
– 主從架構 (on-demand) ，出版式架構
(publishing) 與 同輩式（peer to peer)
無線與有線環境的最大差異
• 單一頻寬為所有使用者共享
• 無干擾的情況下，同頻道 (channels)
可以再用
• Macrocells → microcells → picocells
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Hierarchical Cell Structure (HCS)
無線網路技術(1)
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1G: Analog cellular systems
2G: Digital cellular systems
Cordless telephony
Wireless LANs: 802.11a/b/g/n
Private wireless data networks and
metropolitan area wireless networks
• Satellite networks
• 3G: IMT-2000: WCDMA, cdma2000
無線網路技術(2)
• WiMax (802.16a/e for MAN) and
MobileFi (802.20- for WAN – Pending)
• ITU 4G: 100 Mbps (when moving)
(2010 or earlier); 1 Gbps (when
standstill)
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無線網路技術(3)
• Principal 4G candidates: LTE (LongTerm Evolution, GSM oriented, 3GPP),
UMB (Ultra Mobile Broadband,
CDMA-oriented, 3GPP2), and IEEE
802.16m (also called WiMax II)
• GSM (2.3 billion); CDMA (450 million)
(Source: IEEE Computer, Nov. 2007)
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下一代無線網路評比
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Wireless Technology Roadmap (Source: Dell)
GSM
WCDMA
EDGE
GPRS 115 kbps
384 kbps
CDMA2000
1xEV-DV
1xEV-DO
1xRTT 144 kbps
HSPDA
(UMTS) 2 Mbps
3.1 Mbps
2.4 Mbps
MobileFi
WPAN
WLAN
BWA
802.20
WiMAX
802.16a 2-60 Mbps
Wi-Fi
802.11g
802.11b
802.11n
54 Mbps
11 Mbps
100+ Mbps
802.11a
Bluetooth
1.1
1 Mbps
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Bluetooth
1.2
Zigbee
802.15.4 250 Kbps
Past
802.16e
2004
Bluetooth
Bluetooth
EDR
2.x
3 Mbps
Zigbee
802.15.4’ 1 Mbps
UWB
802.15.3a
100 Mbps+
2005
2006
NG UWB
480 Mbps
2007+
Increasing Range and Mobility 
WWAN
Wireless technologies, categorized by mobility and range, will continue to
evolve to higher data rates...
Wireless Application Landscape: Wireless technologies, categorized by
mobility and range, will continue to evolve to higher data rates... (Source: Dell)
Long Range
Text, Graphics,
Internet, Compressed Audio
Multi-channel Video & HDTV
Data, Streaming Video,
Internet, Hi-Fi Audio
MAN
802.16e
802.16a
WAN
GSM/CDMA
GPRS/3G
MMDS/LMDS
802.11b/g
LAN
802.11n
Short Range
802.11g/a
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Zigbee
Bluetooth 2 (MR)
UWB
PAN
Bluetooth 1.1
Low Data Rate
High Data Rate
Very high Data Rate
IMT-2000 的目標
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Expanded range of services
A unified, seamless infrastructure
Integration of mobile and fixed networks
Bridge the telecommunication gap
Broadband transport
Self-adaptive, reprogrammable terminals
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• Virtual home environment (VHE)
IMT-2000 的系統規格
• Hierarchical cell structure
• Global roaming
– Terminal mobility
– Personal mobility
– Service provider portability (via
software radio)
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Expanding
radio
spectrum
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Next generation heterogeneous network services
Frequency allocation
2.5G: GPRS
• GPRS is an extension of existing GSM
bearer services
• Enlarge the data rate from 9.6 kb/s to 170
kb/s
• Uses packet-switch instead of circuit switch
• GPRS is well suited to replace SMS, or
may be as an SMS bearer
• Evolution: GSM → GPRS → EDGE/ EGPRS
P D S (384Kbps, 470 Kbps)
第三代行動電話
• 寬頻高速傳輸
– 顯示即時新聞
– 傳遞數位影像
• 連接網際網路
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– MExE
– 瀏覽首頁
– 收發電子郵件
– 執行電子商務
MExE
• Mobile Station Application Execution
Environment
• Specified in the 3G UMTS to provide
a standard execution environment
for an MS to access Internet and
Intranet services
• A mechanism supporting VHE
P D S concept
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第三代行動網路應用
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即時影像與電子商務
行動式電腦技術
• 電池壽命增長：doze mode
• 儲存技術：flash memory v.s. disks
• 使用者介面：pen-based
– Decoupling the user interface logic and
communication logic from the
processing logic of each application
• 顯示技術：small-size, display
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independence
高能源效率軟體之設計
• CPU scheduling for low power
• New communication protocols
• Energy-aware application designs
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研究主題 (1)
• Mobile networking (DL, NL, TL)
• Information services (mobile wireless clients
 information resources on the fixed networks;
peer-to-peer computing)
• Power management (at the software level as
well as at the hardware level)
• System issues in mobile computing (key
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issues: the issues of disconnection)
– affects file system and database design
研究主題 (2)
• Research prototypes
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– http://www.mobileinfo.com/Education/u
niversities_MobileResearch.htm
– http://www.intel.com/research/explorato
ry/ubiqcomp_research.htm
– http://www.research.ibm.com/Wearable
Computing/
– http://mobileandpervasive.blogspot.com
行動計算之主要研究挑戰
• Mobility (registration vs. searching)
• Variable communication conditions
– fading
– noise
– interference
• Energy limitations
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行動計算與行動通信
• Mobile communications involve
– Physical layer: IR, radio
– MAC layer: CSMA/CA, FDMA, TDMA,
CDMA, W-CDMA, OFDM, OFDMA
• Mobile computing involves
– Mobile networking (DL, NL, TL)
– Software applications (AL)
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IEEE 802.11 vs. HomeRF
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Bluetooth
• Major joint computing and telecomm
industry initiative
• Plan to deliver a revolutionary radiobased solution
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– Cable replacement, no line of sight
restrictions
– Prefect for mobile devices - small, low
power, low cost
– Open specification (license free)
Bluetooth (cont.)
• Basic use of Bluetooth:
– Data/voice access point
– Personal ad hoc network
– Cable replacement
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應用層設計主題
• Application layer
– WAP 2.0 (Wireless Application Protocol)
• XHTML MP (mobile profile)
– I-mode (NTT DoCoMo)
– Context-sensitive applications
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• Ubiquitous intelligent mobile
multimedia computing
PDS Entertainment Subscription Services
•Scroll through the menu of the phone:
Services, Bookmarks, PDS.
•Select PDS. You can change the language if you wish.
•Input your PDS customer ID and password.
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• First you will see the available subscription services menu:
Movie, Train, Airplane, Hotel, Restaurant.
•For example: Select Hotel
•Select the location of the hotel.
•Select the hotel you are interested.
•Select the kind of room you want and the check-in day.
•Send.
•You will receive a confirmation message.
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I-mode
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由 NTT DoCoMo 在1999年2月推出之服務
由封閉的 PDC 系統 至 3G WCDMA
加入JAVA, Jini, Java Card 技術
Three-fold way: subscriber, service
provider, content provider
• 提供一千兩百多個網站, 內容可分為:
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生活資訊: 新聞、氣象
金融服務: 轉帳、查詢
定票服務: 機票、火車票、餐廳訂位
線上訂貨: 超市、百貨
結論
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• Ubiquitous intelligent mobile multimedia computing
and IP-based broadband wireless networking (3G, 4G
(HSDPA, HSUPA), 802.11n, WiMax, WiMax II, NG
UWB)
• Ad hoc and sensor networks
• Actively providing right information at any time, any
place, any terminal (context-sensitive applications)
• Peer to peer computing
• Wearable computing
• Personal web
• Global village
• Digital home (smart home care)
結論 (cont.)
• RFID tags are an example of the embedded
intelligence delivered by ubiquitous wireless
networks (EE Times)
• A high level of computational intelligent
distributed services through the network (EE
Times)
• Obstacles yet to overcome for ubiquitous
intelligent wireless networking (EE Times)
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Regulation
Consumer acceptance
Device scaling
Power consumption
Nanoscaling
結論 (cont.)
(Source: Dr. William C.Y. Lee)
• Future 4G system is based on
selection and integration
• Future 4G system is aiming at the
user-centric
• The lifestyle will be changed due to
the future communications
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結論 (cont.)
(Source: Dr. William C.Y. Lee)
• The future wireless
– In the past – selecting a better system
– In the future – achieving a defined goal
from user’s aspect
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結論 (cont.)
(Source: Dr. William C.Y. Lee)
• The user’s perspective in the future
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– No need to be physically in any meeting
due to digital conferencing technology
– Anything can be found and located by
RFID
– Reducing crime by camera, GPS and
E911
– Mobile office