1. E-mail: jhchen@mail.cgu.edu.tw
無線網路 (1)
長庚大學資訊工程所 陳仁暉
Tel : (03) ext. 5990

2. Outline
Midterm Exam 30%
Final Exam 30%
Presentation 40%

3. Course Outline Wireless PAN Wireless LAN Wireless MAN
IEEE (Bluetooth)
IEEE (Ultra-Wide Band, UWB)
IEEE (ZigBee)
Wireless LAN
IEEE a/b/g/n (Wi-Fi)
Wireless MAN
IEEE d/e/j (WiMAX, BWA)
Wireless Networks Research Issues
Routing
Protocol Enhancement
QoS Transmissions

4. Introduction to
Local Area Networks (LANs)

5. What is a LAN ?
A LAN is a data communication system allowing a number of independent devices to communicate directly with each other, within a moderately sized geographic area over a physical communications channel of moderate data rates.

6. Basic Requirements of a LAN
Data rate of 1 to 1000 Mbps
Geographic distances spanning at most 1-5 km
Ability to support several hundred independent devices
Minimal dependence on any centralized components or control
Efficient use of shared resources, including the network channel
Stability under high load
Fair access (bandwidth, delay) to the network by all devices
Reliability and good error characteristics
Easy installation, reconfiguration and maintenance
Low cost

7. LAN Components Computers (Networking devices)
Transmission System (Network Cards, Cabling)
工作站
工作站
傳輸媒介:
同軸電纜, 雙絞線, 光纖, radio
工作站
工作站
工作站

8. LAN Extension
網路區段 1
網路區段 2
訊號增益器

9. Network Topologies Star Bus Tree Ring Mesh
Single Star (IEEE VG-AnyLAN, ATM)
Multiple Star (Snowflake) (ATM)
Bus
Single Bus (IEEE CSMA/CD, IEEE Token-Bus)
Dual Bus (IEEE DQDB)
Tree
Ring
Single Ring (IEEE Token Ring)
Dual Ring (FDDI, FDDI-II)
Mesh
Random (IEEE CSMA/CA)

10. Network Topologies Star Ring Dual Ring Bus Tree Dual Bus B B B A C A CF B D A B C A C E C E F
Bus Tree Dual Bus

11. Network Topologies Dual Bus Dual Bus Mesh Snowflake A B C D A B C B C

12. Network Topologies Wireless LAN ? ... Hub, Switch or Concentrator
橋接器 A C F H A H E D J I
... F B D G C E
橋接器
橋接器 L
Hub, Switch or Concentrator K M
Wireless LAN ? O N
Bridged Ring Networks

13. Open System Interconnection (OSI) Model
Physical Layer. Responsible for transmission of bit streams across a particular physical transmission medium. Retransmission is not supported.
Encoding/Decoding
Scrambling/Descrambling
Data Link Layer. Responsible for providing reliable data transmission from one node to another. Provides error-free transmission of frames.
Network Layer. Concerned with routing data from one network node to another. Provides routing path selection.
Establishing/Maintaining/Terminating network connection
Transport Layer. Responsible for providing data transfer between two end users at an agreed on level of quality.
Establishing/Maintaining/Terminating transport layer connection

14. Open System Interconnection (OSI) Model
Session Layer. Providing services used to organize and synchronize the dialog that takes place between users and to manage the data exchange.
Presentation Layer. Responsible for the presentation of information to the network users.
Character code translation/ Data conversion
Data compression/expansion
Encryption/Decryption
Application Layer. Provides services to application processes or users.
File Transfer Protocol (FTP)
Remote Login (Telnet)
Transaction Server
Network Management
WWW Server/VoD Server

15. Open System Interconnection (OSI) Model - Seven Layers
應用層 (Application Layer)
表達層 (Presentation Layer)
會議層 (Session Layer)
傳輸層 (Transport Layer)
網路層 (Network Layer)
鏈結層 (Data Link Layer)
實體層 (Physical Layer)

16. Layering Protocols 應用層 應用層 表達層 表達層 會議層 會議層 傳輸層 傳輸層 網路層 網路層 鏈結層 鏈結層 實體層
系統 B
應用軟體 X
應用軟體 Y
應用層
應用層通訊協定
應用層
表達層
表達層通訊協定
表達層
會議層
會議層通訊協定
會議層
傳輸層
傳輸層通訊協定
傳輸層
網路層
網路層通訊協定
網路層
鏈結層
鏈結層通訊協定
鏈結層
實體層
實體層通訊協定
實體層
傳輸媒介

17. Basic Functions of Protocols
Encapsulation/Decapsulation
Segmentation/Reassembly
Connection Establishing
Flow Control
Error Control
Multiplexing/Demultiplexing

18. Encapsulation/Decapsulation Mechanisms
往下送時訊框包裝
往上送時訊框拆裝
應用軟體 X 資料
應用軟體 Y
應用層 AH 資料
應用層
表達層 PH 資料
表達層
會議層 SH 資料
會議層
傳輸層 TH 資料
傳輸層
網路層 NH 資料
網路層
鏈結層
鏈結層
F A C 資料
FCS F
實體層
位元串
實體層
通訊路徑

19. IEEE Project 802 Standards
IEEE High Level Interface
IEEE 802.1D Local Bridge (Spanning Tree Algorithm)
IEEE 802.1G Remote Bridge
IEEE 802.1P Traffic Class Expediting and Dynamic Multicast Filtering
IEEE 802.1Q Virtual LANs
IEEE 802.1X Port Based Network Access Control
IEEE LLC (Logical Link Control)
IEEE CSMA/CD (Carrier Sense Multiple Access with Collision Detection
IEEE Token-Bus
IEEE Token-Ring
IEEE DQDB (Distributed Queue Dual Bus)
IEEE Broadband Technical Advisory Group
IEEE Fiber Optic Technical Advisory Group
IEEE Integrated Voice and Data LAN Working Group
IEEE Interoperable LAN/MAN Security

20. IEEE Project 802 Standards
IEEE CSMA/CA Wireless LAN
IEEE a High-Speed Physical Layer in the 5GHz Band
IEEE b Higher-Speed Physical Layer Extension in the 2.4 GHz Band
IEEE e Medium Access Control (MAC) Enhancements for Quality of Service (QoS) – Draft D2.0
IEEE f Inter-Access Point Protocol (IAPP) – Draft D3
IEEE g Further Higher-Speed Physical Layer Extension in the 2.4 GHz Band – Draft D2.1
IEEE h Spectrum and Transmit Power Management extensions in the 5GHz band in Europe -Draft D1.1
IEEE i Enhanced Security – Draft D1.8
IEEE Demand-Priority (100VG-AnyLAN)
IEEE
IEEE Standard Protocol for Cable-TV Based Broadband Communication Network
IEEE Wireless Personal Area Networks Access Method and Physical Layer Specifications
IEEE Wireless Personal Area Networks (Bluetooth)
IEEE Coexistence
IEEE WPAN Higher Rate
IEEE WPAN Low Rate (Zigbee)
IEEE Broadband Wireless Access Method and Physical Layer Specifications

21. IEEE Project 802 Standards
MAC
WLAN

22. E-mail: jhchen@mail.cgu.edu.tw
無線網路 (2)
長庚大學資訊工程所 陳仁暉
Tel : (03) ext. 5990

23. IEEE 802.3
Carrier Sense Multiple Access with
Collision Detection (CSMA/CD)

24. Typical CSMA/CD NetworkB D
收發器 F
終端器
同軸電纜
收發器電纜
終端器 A C E

25. IEEE 802.3 Architecture OSI參考模式 CSMA/CD 應用層 高層通訊協定 (IP, TCP, HTTP,
FTP, SMTP, etc.,)
表達層
會議層
邏輯鏈結控制
LLC (IEEE 802.2)
傳輸層
媒介擷取控制
MAC (IEEE 802.3)
網路層
實體層訊號處理
PLS
鏈結層
AUI
實體層
MAU
PMA
MDI
傳輸媒介

26. CSMA/CD Protocol Carrier Sense before transmission
Carrier Sense while transmission
Collision: Two or more stations transmitting simultaneously
Backoff: Random delay after collision
Deference: Defers transmission if channel is sensed busy
Collision Window (Slot time): Round-trip propagation delay time plus some carrier sense time. In IEEE 802.3, this value is defined to be 51.2 us.

27. CSMA/CD Collision Handling
Collision Signal is generated by Physical layer.
Jam signal (collision enforcement): To make sure that all stations involved in the collision will detect collision. A pattern of 32 bits.
Collision backoff and retransmission method (Truncated Binary Exponential Backoff Algorithm, BEBA):
n : number of collisions experienced (n <= 16)
k : Min (n,10) -- Truncation
r : Random delay time (unit: slot time) between 0 <= r < 2k
Slot time = 51.2 us.
Disadvantage of BEBA:
Last-in-First-out effect: Stations with no or few collisions will have a better chance to transmit before stations that have waited longer.

28. IEEE 802.3 Frame Format 15-位元地址 46-位元地址 7 1 2, 6 2, 6 2 4 位元組
, , 位元組
Preamble SFD DA SA LEN LLC PAD FCS
Preamble: ( ) for Synchronization
SFD: Start Frame Delimiter ( )
DA: Destination Address
SA: Source Address
Length: Length of LLC-Frame
LLC-Frame: Up to 1500 bytes
PAD: Padding when LLC-Frame < 46 bytes
FCS: Frame Check Sequence (CRC-32)
MAC-frame size -- from DA to FCS
Min 64 bytes to distinguish from collision
Max 1518 bytes to prevent dominating bandwidth
I/G
15-位元地址
I/G
U/L
46-位元地址
I/G = 0 Individual Address （個別地址）
I/G = 1 Group Address （群體地址）
U/L = 0 Globally Administered Address （整體性地址）
U/L = 1 Locally Administered Address （區域性地址）

29. Flow Chart 傳送訊框 接收訊框 組成訊框, i=1 開始接收 N Y 線上有 訊號 接收完畢 N Y 傳送訊框 Y 訊框過短
（衝撞） Y N
發生衝撞
送出擾亂訊號 Y
位址辨識 成功 N
i = i + 1 N Y N
檢查碼 正確
傳送完畢 Y
i > 16 Y N
尚有多餘 位元 N
長度欄位
內容正確 N
計算延遲時間 Y Y
刪除訊框頭尾
等待延遲時間
傳送成功
傳送失敗
訊框錯誤
對齊錯誤
接收成功
長度錯誤

30. Collision Detection Window for Baseband CSMA/CD (=2a)
Ａ 開始傳送訊框 B
t0+a-e A
Ｂ 開始傳送訊框 B 衝撞
t0+a A
Ｂ 偵測出衝撞 B
t0+2a-e A
Ａ 偵測出衝撞 B

31. Network Configuration (Single segment)
同軸電纜區段（最長 500 公尺）
（每區段最多接 100 個） B D
收發器 F
終端器
同軸電纜
收發器電纜
終端器 A
（最長 50 公尺） C E

32. Network Configuration (Two segments)
同軸電纜區段（最長 500 公尺） B C A
第一段同軸電纜
收發器電纜
（最長 50 公尺） D
訊號增益器 E F
第二段同軸電纜 G H I
同軸電纜區段（最長 500 公尺）

33. Network Configuration (Five segments, maximum)1 A D
區段 1
區段 2 B E C F
訊號增益器 2 G H 3
區段 3 4
Remind :
Slot Time = 51.2 us
半訊號增益器 L 5 I
半訊號增益器間電纜
區段 5 J
區段 4
（最長 1000 公尺） M 6 K N

34. Alternative Physical Layers
參 數
10BASE BASE BASE BASET BROAD36
同軸電纜
同軸電纜
無遮蔽式
無遮蔽式
同軸電纜
傳輸媒介
（50 歐姆）
（50 歐姆）
雙絞線
雙絞線
（75 歐姆） 基頻
（Manchester） 基頻
（Manchester） 基頻
（Manchester） 基頻
（Manchester） 寬頻
訊號處理技術
（DPSK）
資料傳輸速率
10 Mbps
10 Mbps
1 Mbps
10 Mbps
10 Mbps
每段最大長度
500 公尺
185 公尺
500 公尺
185 公尺
1800 公尺
網路最大長度
2500 公尺
925 公尺
2500 公尺
500 公尺
3600 公尺
每段最多可連接
100 30
工作站數目
工作站間距
2.5 公尺
0.5 公尺
電纜線直徑
10 公厘
5 公厘 公厘 公厘