MAC. OSI Layer 2 (Data Link) OSI Layer 1 (Physical)

Size: px
Start display at page:

Download "MAC. OSI Layer 2 (Data Link) OSI Layer 1 (Physical)"

Transcription

1 教育部資通訊科技人才培育先導型計畫 無線區域網路媒體存取控 制層協定 任課老師 : 陳懷恩 助理教授兼任資訊工程研究所所長電算中心資訊網路組組長 國立宜蘭大學 wechen@niu.edu.tw 1

2 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 2

3 Introduction to IEEE Wireless networks get rid of tangling and restriction of wired networks. Wireless channels are inherently unreliable and of limited bandwidth Dedicated MAC/PHY protocols are required. IEEE standardizes and boosts the deployment of WLAN. 3

4 IEEE vs. OSI Model IEEE Logical Link Control (LLC) IEEE Media Access Control (MAC) Frequency Hopping Spread Spectrum (FHSS) Direct Sequence Spread Spectrum (DSSS) MAC Infrared a (IR) b g PHY OSI Layer 2 (Data Link) OSI Layer 1 (Physical) 4

5 IEEE Topologies Independent Basic Service Set (also called Ad- Hoc Network) STA: Wireless Station : Wireless Medium : Data Link STA 5

6 IEEE Topologies (cont) Infrastructure Basic Service Set AP STA DS DS: Distribution System AP: Access Point STA: Wireless Station : Distribution System Medium : Wireless Medium : Data Link 6

7 IEEE Topologies (cont) Extended Service Set 7

8 IEEE Network Services IEEE Network Services MAC Service Data Unit (MSDU) delivery Association Disassociation Authentication De-authentication Privacy y( (Wired Equivalent Privacy, WEP) 8

9 IEEE Network Services (cont) Network services are implemented via the exchange of frames by following MAC protocol Data Frame Control Frame Management Frame 9

10 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 10

11 Frame Format PHY Layer Convergence Protocol (PLCP) Data Unit (PPDU) PLCP Preamble 144 bits PLCP Header 48 bits MAC Protocol Data Unit (MPDU) 11

12 Frame Format (cont) MAC Protocol Data Unit (MPDU) Frame Duration Addr 1 Addr 2 Addr 3 Sequence Addr 4 Frame CRC Control or ID Control Body 16 bits 16 bits 48 bits 48 bits 48 bits 16 bits 48 bits 0-16K bits 32 bits Protocol Type Subtype To From More Retry Pwr More WEP Order Version DS DS Frag Mgt Data 2bits 2bits 4bits 1bits 1bits 1bits 1bits 1bits 1bits 1bits 1bits 12

13 Frame Format (cont) Partial List of Type and Subtype Type Type Description Subtype Subtype Description 00 Management 0000 Association Request 1000 Beacon 1011 Authentication 01 Control 1011 Request To Send (RTS) 10 Data 0000 Data 11 Reserved 1100 Clear To Send (CTS) 1101 Acknowledgement (ACK) Reserved 13

14 Frame Format (cont) Inter Frame Space Short Inter Frame Space (SIFS) Point Coordination Inter Frame Space (PIFS) Distributed Inter Frame Space (DIFS) IFSs provide guarding spaces between frames With different durations, IFSs differentiate t frames/entities with different priority Duration: DIFS>PIFS>SIFS Frames follow shorter IFSs have higher priority 14

15 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 15

16 IEEE MAC Protocol IEEE Logical Link Control (LLC) IEEE Media Access Control (MAC) Frequency Direct Hopping Sequence Spread Spread Spectrum Spectrum (FHSS) (DSSS) MAC Infrared a (IR) b g PHY OSI Layer 2 (Data Link) OSI Layer 1 (Physical) 16

17 IEEE MAC Protocol (cont) Functionalities Reliable frame delivery over the wireless PHY media Controlled multiple access to the shared wireless media Protection of the security/privacy of frames being delivered 17

18 IEEE MAC Protocol (cont) Objectives Reliable Delivery Multiple Access Security/Privacy QoS (Quality of Service) Support Fair Sharing 18

19 IEEE MAC Protocol (cont) Mechanisms Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 19

20 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 20

21 MAC Access Modes Distributed Coordination Function (DCF) Distributed, contention-based Exponential backoff upon collision Optional CSMA/CA Point Coordination Function (PCF) Superframe = Content Free Period + Contention Period (DCF) AP polls STAs in turn in Content Free Period (CFP) CFP is centralized, polling-based, contention-free 21

22 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 22

23 Carrier Sense Multiple Access / Collision Avoidance (Ethernet) adopts Carrier Sense Multiple Access / Collision Detection (CSMA/CD) for medium access control Collision detection by sending and listening Frames Data Data Source 1 Destination 1 Destination 2 Source 2 23

24 Carrier Sense Multiple Access / Collision Avoidance (cont) Collision detection is infeasible in WLAN Hidden Terminal Problem Source 1 Destination Source 2 24

25 Carrier Sense Multiple Access / Collision Avoidance (cont) adopts Carrier Sense Multiple Access / Collision Avoidance (CSMA/CA) for medium access control RTS/CTS/Data/ACK 4-way handshaking and Virtual Carrier Sensing to reduce the chance of collision Network Allocation Vector (NAV), required duration for intended transmission, is carried in the Duration filed of RTS and CTS 25

26 Carrier Sense Multiple Access / Collision Avoidance (cont) 1. RTS: Request To Send 2. CTS: Clear To Send 3. Data 4. ACK: Acknowledgement Source Destination 26

27 Carrier Sense Multiple Access / Collision Avoidance (cont) Channel Previous Competition SIFS SIFS SIFS DIFS Next Cycle Cycle // RTS Data Source Destination CTS ACK Others NAV(RTS) NAV(CTS) Defer Access 27

28 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 28

29 Distributed Coordination Function Distributed Coordination Function No coordinator Contention-based Exponential backoff upon collision Optional CSMA/CA For both infrastructure and ad-hoc topologies 29

30 Distributed Coordination Function (cont) Backoff Algorithm STA randomly yp picks up a Backoff Time (number of Slot Time ) from [0,CW] Backoff timer Freeze when medium is busy Decrease when free period > DIFS Transmission is commenced when timer reaches zero 30

31 Distributed Coordination Function (cont) : Frame : Backoff : MSDU Arrival st: Slot Time DIFS A 19st 9st 4st 2st B 10st C 15st 5st D 7st 2st 31

32 Distributed Coordination Function (cont) Exponential Backoff Slot Time = transmitter turn-on delay + medium propagation delay + medium busy detect response time On collision, CW is increased exponentially till CW max On success, CW is reset to CW min For IEEE b A Slot Time is of 20us CW is in {CW min =31,63,127,255,511,CW max =1023} 32

33 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Distributed Coordination Function Point Coordination Function IEEE e 33

34 Point Coordination Function Point Coordination Function Superframe = Content Free Period + Contention Period (DCF) In Content Free Period (CFP), Point Coordinator (AP in general) polls STAs in turn CFP is centralized, polling-based, contention- free Adequate for time-bounded applications Only for infrastructure topologies Not widely implemented 34

35 Point Coordination Function (cont) B: Beacon, Dx: Downlink, Ux: Uplink, P: CF-Poll, A: CF-Ack, E: CF-End PIFS SIFS SIFS SIFS SIFS SIFS PIFS SIFS SIFS PC B D1/P D2/A/P D3/A/P D4/P E STA 1 U1/A STA 2 U2/A STA 3 STA 4 NAV U4/A Contention Free Period Superframe // Contention Period 35

36 Outline Introduction ti to IEEE Frame Format Medium Access Control Protocol MAC Access Modes Carrier Sense Multiple Access / Collision Avoidance Point Coordination Function Distributed Coordination Function IEEE e 36

37 IEEE e Limitation of PCF Simple round-robin robin algorithm Limited QoS support Transmission time of the polled stations is not under control IEEE e Enhanced QoS supports for service differentiation Different Arbitration Inter Frame Space (AIFS) and CW min /CW max for different Access Categories (ACs) Controlled Transmission Opportunity (TXOP) 37

38 IEEE e (cont) IEEE e Superframe = (Optional) Point Coordination Function (PCF) + Hybrid Coordination Function (HCF) HCF = Mixture of Enhanced DCF channel access (EDCA) HCF controlled channel access (HCCA) Hybrid Coordinator (HC) has total control over the mixture of EDCA/HCCA 38

39 IEEE e (cont) Enhanced DCF Channel Access (EDCA) Prioritized QoS support 4 Access Categories AC_VO (voice), AC_VI (video), AC_BE (best effort), AC_BG (background) Different AIFS and CW min /CW max for different ACs ACs with higher priorities have better chance to gain access right 39

40 IEEE e (cont) 40

41 IEEE e (cont) HCF controlled channel access (HCCA) Parameterized QoS support HC polls and assigns TXOP to Traffic Stream (TS) according to its Traffic Specification (TSPEC) HC can gain control of medium after PIFS 41

Mobile & Wireless Networking. Lecture 7: Wireless LAN

Mobile & Wireless Networking. Lecture 7: Wireless LAN 192620010 Mobile & Wireless Networking Lecture 7: Wireless LAN [Schiller, Section 7.3] [Reader, Part 6] [Optional: "IEEE 802.11n Development: History, Process, and Technology", Perahia, IEEE Communications

More information

Chapter 6 Wireless and Mobile Networks. Csci 4211 David H.C. Du

Chapter 6 Wireless and Mobile Networks. Csci 4211 David H.C. Du Chapter 6 Wireless and Mobile Networks Csci 4211 David H.C. Du Wireless LAN IEEE 802.11 a, b, g IEEE 802.15 Buletooth Hidden Terminal Effect Hidden Terminal Problem Hidden terminals A, C cannot hear each

More information

Topics for Today. More on Ethernet. Wireless LANs Readings. Topology and Wiring Switched Ethernet Fast Ethernet Gigabit Ethernet. 4.3 to 4.

Topics for Today. More on Ethernet. Wireless LANs Readings. Topology and Wiring Switched Ethernet Fast Ethernet Gigabit Ethernet. 4.3 to 4. Topics for Today More on Ethernet Topology and Wiring Switched Ethernet Fast Ethernet Gigabit Ethernet Wireless LANs Readings 4.3 to 4.4 1 Original Ethernet Wiring Heavy coaxial cable, called thicknet,

More information

IEEE e Enhanced QoS

IEEE e Enhanced QoS IEEE 802.11e Enhanced QoS 國立中興大學資工系曾學文 Tel : (04)22840497 ext 908 E-mail: hwtseng@nchu.edu.tw Outlines Introduction Traffic Differentiation Hybrid Coordination Function (HCF) Contention-Based Channel Access

More information

Lesson 2-3: The IEEE x MAC Layer

Lesson 2-3: The IEEE x MAC Layer Module 2: Establishing Wireless Connectivity Lesson 2-3: The IEEE 802.11x MAC Layer Lesson Overview This lesson describes basic IEEE 802.11x MAC operation, beginning with an explanation of contention schemes

More information

Data and Computer Communications. Chapter 13 Wireless LANs

Data and Computer Communications. Chapter 13 Wireless LANs Data and Computer Communications Chapter 13 Wireless LANs Wireless LAN Topology Infrastructure LAN Connect to stations on wired LAN and in other cells May do automatic handoff Ad hoc LAN No hub Peer-to-peer

More information

ICE 1332/0715 Mobile Computing (Summer, 2008)

ICE 1332/0715 Mobile Computing (Summer, 2008) ICE 1332/0715 Mobile Computing (Summer, 2008) IEEE 802.11 Prof. Chansu Yu http://academic.csuohio.edu/yuc/ Contents Overview of IEEE 802.11 Frame formats MAC frame PHY frame IEEE 802.11 IEEE 802.11b IEEE

More information

Analysis of IEEE e for QoS Support in Wireless LANs

Analysis of IEEE e for QoS Support in Wireless LANs Analysis of IEEE 802.11e for QoS Support in Wireless LANs Stefan Mangold, Sunghyun Choi, Guido R. Hiertz, Ole Klein IEEE Wireless Communications, December 2003 Presented by Daeseon Park, Student No.2005-30231

More information

Chapter 6 Medium Access Control Protocols and Local Area Networks

Chapter 6 Medium Access Control Protocols and Local Area Networks Chapter 6 Medium Access Control Protocols and Local Area Networks 802.11 Wireless LAN CSE 3213, Winter 2010 Instructor: Foroohar Foroozan Wireless Data Communications Wireless communications compelling

More information

Computer Networks. Wireless LANs

Computer Networks. Wireless LANs Computer Networks Wireless LANs Mobile Communication Technology according to IEEE (examples) Local wireless networks WLAN 802.11 Personal wireless nw WPAN 802.15 WiFi 802.11a 802.11b 802.11h 802.11i/e/

More information

04/11/2011. Wireless LANs. CSE 3213 Fall November Overview

04/11/2011. Wireless LANs. CSE 3213 Fall November Overview Wireless LANs CSE 3213 Fall 2011 4 November 2011 Overview 2 1 Infrastructure Wireless LAN 3 Applications of Wireless LANs Key application areas: LAN extension cross-building interconnect nomadic access

More information

standard. Acknowledgement: Slides borrowed from Richard Y. Yale

standard. Acknowledgement: Slides borrowed from Richard Y. Yale 802.11 standard Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale IEEE 802.11 Requirements Design for small coverage (e.g. office, home) Low/no mobility High data rate applications Ability to

More information

4.3 IEEE Physical Layer IEEE IEEE b IEEE a IEEE g IEEE n IEEE 802.

4.3 IEEE Physical Layer IEEE IEEE b IEEE a IEEE g IEEE n IEEE 802. 4.3 IEEE 802.11 Physical Layer 4.3.1 IEEE 802.11 4.3.2 IEEE 802.11b 4.3.3 IEEE 802.11a 4.3.4 IEEE 802.11g 4.3.5 IEEE 802.11n 4.3.6 IEEE 802.11ac,ad Andreas Könsgen Summer Term 2012 4.3.3 IEEE 802.11a Data

More information

Unit 7 Media Access Control (MAC)

Unit 7 Media Access Control (MAC) Unit 7 Media Access Control (MAC) 1 Internet Model 2 Sublayers of Data Link Layer Logical link control (LLC) Flow control Error control Media access control (MAC) access control 3 Categorization of MAC

More information

Certified Wireless Network Administrator (CWNA) PW Chapter Medium Access. Chapter 8 Overview

Certified Wireless Network Administrator (CWNA) PW Chapter Medium Access. Chapter 8 Overview Certified Wireless Network Administrator (CWNA) PW0-105 Chapter 8 802.11 Medium Access Chapter 8 Overview CSMA/CA vs. CSMA/CD Distributed Coordination Function (DCF) Point Coordination Function (PCF) Hybrid

More information

IEEE MAC Sublayer (Based on IEEE )

IEEE MAC Sublayer (Based on IEEE ) IEEE 802.11 MAC Sublayer (Based on IEEE 802.11-1999) Wireless Networking Sunghyun Choi, Associate Professor Multimedia & Wireless Networking Lab. (MWNL) School of Electrical Engineering Seoul National

More information

Wireless Local Area Networks (WLANs) Part I

Wireless Local Area Networks (WLANs) Part I Wireless Local Area Networks (WLANs) Part I Raj Jain Professor of CSE Washington University in Saint Louis Saint Louis, MO 63130 Jain@cse.wustl.edu These slides are available on-line at: http://www.cse.wustl.edu/~jain/cse574-08/

More information

Wireless Networked Systems

Wireless Networked Systems Wireless Networked Systems CS 795/895 - Spring 2013 Lec #6: Medium Access Control QoS and Service Differentiation, and Power Management Tamer Nadeem Dept. of Computer Science Quality of Service (802.11e)

More information

Vehicle Networks. Wireless Local Area Network (WLAN) Univ.-Prof. Dr. Thomas Strang, Dipl.-Inform. Matthias Röckl

Vehicle Networks. Wireless Local Area Network (WLAN) Univ.-Prof. Dr. Thomas Strang, Dipl.-Inform. Matthias Röckl Vehicle Networks Wireless Local Area Network (WLAN) Univ.-Prof. Dr. Thomas Strang, Dipl.-Inform. Matthias Röckl Outline Wireless LAN Overview History IEEE 802.11-1997 MAC implementations PHY implementations

More information

CSC344 Wireless and Mobile Computing. Department of Computer Science COMSATS Institute of Information Technology

CSC344 Wireless and Mobile Computing. Department of Computer Science COMSATS Institute of Information Technology CSC344 Wireless and Mobile Computing Department of Computer Science COMSATS Institute of Information Technology Wireless Local Area Networks (WLANs) Part I Almost all wireless LANs now are IEEE 802.11

More information

CS 348: Computer Networks. - WiFi (contd.); 16 th Aug Instructor: Sridhar Iyer IIT Bombay

CS 348: Computer Networks. - WiFi (contd.); 16 th Aug Instructor: Sridhar Iyer IIT Bombay CS 348: Computer Networks - WiFi (contd.); 16 th Aug 2012 Instructor: Sridhar Iyer IIT Bombay Clicker-1: Wireless v/s wired Which of the following differences between Wireless and Wired affect a CSMA-based

More information

Local Area Networks NETW 901

Local Area Networks NETW 901 Local Area Networks NETW 901 Lecture 4 Wireless LAN Course Instructor: Dr.-Ing. Maggie Mashaly maggie.ezzat@guc.edu.eg C3.220 1 Contents What is a Wireless LAN? Applications and Requirements Transmission

More information

Multiple Access Links and Protocols

Multiple Access Links and Protocols Multiple Access Links and Protocols Two types of links : point-to-point PPP for dial-up access point-to-point link between Ethernet switch and host broadcast (shared wire or medium) old-fashioned Ethernet

More information

MAC. Fall Data Communications II 1

MAC. Fall Data Communications II 1 802.11 MAC Fall 2005 91.564 Data Communications II 1 RF Quality (ACK) Fall 2005 91.564 Data Communications II 2 Hidden Terminal (RTS/CTS) Fall 2005 91.564 Data Communications II 3 MAC Coordination Functions

More information

IEEE Wireless LANs

IEEE Wireless LANs Unit 11 IEEE 802.11 Wireless LANs Shyam Parekh IEEE 802.11 Wireless LANs References Standards Basics Physical Layer 802.11b 802.11a MAC Framing Details Management PCF QoS (802.11e) Security Take Away Points

More information

Overview : Computer Networking. Spectrum Use Comments. Spectrum Allocation in US Link layer challenges and WiFi WiFi

Overview : Computer Networking. Spectrum Use Comments. Spectrum Allocation in US Link layer challenges and WiFi WiFi Overview 15-441 15-441: Computer Networking 15-641 Lecture 21: Wireless Justine Sherry Peter Steenkiste Fall 2017 www.cs.cmu.edu/~prs/15-441-f17 Link layer challenges and WiFi WiFi Basic WiFi design Some

More information

Outline. CS5984 Mobile Computing. IEEE 802 Architecture 1/7. IEEE 802 Architecture 2/7. IEEE 802 Architecture 3/7. Dr. Ayman Abdel-Hamid, CS5984

Outline. CS5984 Mobile Computing. IEEE 802 Architecture 1/7. IEEE 802 Architecture 2/7. IEEE 802 Architecture 3/7. Dr. Ayman Abdel-Hamid, CS5984 CS5984 Mobile Computing Dr. Ayman Abdel-Hamid Computer Science Department Virginia Tech Outline IEEE 82 Architecture IEEE 82. Wireless LANs Based on Chapter 4 in Wireless Communications and Networks, William

More information

Wireless LAN -Architecture

Wireless LAN -Architecture Wireless LAN -Architecture IEEE has defined the specifications for a wireless LAN, called IEEE 802.11, which covers the physical and data link layers. Basic Service Set (BSS) Access Point (AP) Distribution

More information

Lecture 16: QoS and "

Lecture 16: QoS and Lecture 16: QoS and 802.11" CSE 123: Computer Networks Alex C. Snoeren HW 4 due now! Lecture 16 Overview" Network-wide QoS IntServ DifServ 802.11 Wireless CSMA/CA Hidden Terminals RTS/CTS CSE 123 Lecture

More information

Data Communications. Data Link Layer Protocols Wireless LANs

Data Communications. Data Link Layer Protocols Wireless LANs Data Communications Data Link Layer Protocols Wireless LANs Wireless Networks Several different types of communications networks are using unguided media. These networks are generally referred to as wireless

More information

Wireless Communication and Networking CMPT 371

Wireless Communication and Networking CMPT 371 Wireless Communication and Networking CMPT 371 Wireless Systems: AM, FM Radio TV Broadcast Satellite Broadcast 2-way Radios Cordless Phones Satellite Links Mobile Telephony Systems Wireless Local Loop

More information

ECE442 Communications Lecture 3. Wireless Local Area Networks

ECE442 Communications Lecture 3. Wireless Local Area Networks ECE442 Communications Lecture 3. Wireless Local Area Networks Husheng Li Dept. of Electrical Engineering and Computer Science Spring, 2014 Wireless Local Networks 1 A WLAN links two or more devices using

More information

CSCD 433 Network Programming Fall Lecture 7 Ethernet and Wireless

CSCD 433 Network Programming Fall Lecture 7 Ethernet and Wireless CSCD 433 Network Programming Fall 2016 Lecture 7 Ethernet and Wireless 802.11 1 Topics 802 Standard MAC and LLC Sublayers Review of MAC in Ethernet MAC in 802.11 Wireless 2 IEEE Standards In 1985, Computer

More information

Optional Point Coordination Function (PCF)

Optional Point Coordination Function (PCF) Optional Point Coordination Function (PCF) Time Bounded / Async Contention Free Service PCF Optional DCF (CSMA/CA ) Async Contention Service MAC PHY Contention Free Service uses Point Coordination Function

More information

Mobile Communications Chapter 7: Wireless LANs

Mobile Communications Chapter 7: Wireless LANs Mobile Communications Chapter 7: Wireless LANs Characteristics IEEE 802.11 (PHY, MAC, Roaming,.11a, b, g, h, i, n z) Bluetooth / IEEE 802.15.x IEEE 802.16/.20/.21/.22 RFID Comparison Prof. Jó Ueyama courtesy

More information

CSE 461: Wireless Networks

CSE 461: Wireless Networks CSE 461: Wireless Networks Wireless IEEE 802.11 A physical and multiple access layer standard for wireless local area networks (WLAN) Ad Hoc Network: no servers or access points Infrastructure Network

More information

Page 1. Outline : Wireless Networks Lecture 11: MAC. Standardization of Wireless Networks. History. Frequency Bands

Page 1. Outline : Wireless Networks Lecture 11: MAC. Standardization of Wireless Networks. History. Frequency Bands Outline 18-759 : Wireless s Lecture 11: 80.11 Peter Steenkiste Dina Papagiannaki Spring Semester 009 http://www.cs.cmu.edu/~prs/wireless09/ Peter A. Steenkiste, CMU 1 80 protocol overview Wireless LANs

More information

Wireless Communication

Wireless Communication Wireless Communication Systems @CS.NCTU Lecture 9: MAC Protocols for WLANs Instructor: Kate Ching-Ju Lin ( 林靖茹 ) 1 Reference 1. A Technical Tutorial on the IEEE 802.11 Protocol By Pablo Brenner online:

More information

Introduction to IEEE

Introduction to IEEE Introduction to IEEE 802.11 Characteristics of wireless LANs Advantages very flexible within the reception area Ad hoc networks without previous planning possible (almost) no wiring difficulties more robust

More information

Wireless LANs. ITS 413 Internet Technologies and Applications

Wireless LANs. ITS 413 Internet Technologies and Applications Wireless LANs ITS 413 Internet Technologies and Applications Aim: Aim and Contents Understand how IEEE 802.11 wireless LANs work Understand what influences the performance of wireless LANs Contents: IEEE

More information

Medium Access Control. MAC protocols: design goals, challenges, contention-based and contention-free protocols

Medium Access Control. MAC protocols: design goals, challenges, contention-based and contention-free protocols Medium Access Control MAC protocols: design goals, challenges, contention-based and contention-free protocols 1 Why do we need MAC protocols? Wireless medium is shared Many nodes may need to access the

More information

MAC in /20/06

MAC in /20/06 MAC in 802.11 2/20/06 MAC Multiple users share common medium. Important issues: Collision detection Delay Fairness Hidden terminals Synchronization Power management Roaming Use 802.11 as an example to

More information

Mohamed Khedr.

Mohamed Khedr. Mohamed Khedr http://webmail.aast.edu/~khedr Tentatively Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12 Week 13 Week 14 Week 15 Overview Packet Switching IP addressing

More information

IEEE Medium Access Control. Medium Access Control

IEEE Medium Access Control. Medium Access Control IEEE 802.11 Medium Access Control EECS3214 3 April 2018 Medium Access Control reliable data delivery access control MAC layer covers three functional areas: security 2 1 MAC Requirements To avoid interference

More information

Wireless Communication and Networking CMPT 371

Wireless Communication and Networking CMPT 371 Wireless Communication and Networking CMPT 371 Wireless Systems: AM, FM Radio TV Broadcast Satellite Broadcast 2-way Radios Cordless Phones Satellite Links Mobile Telephony Systems Wireless Local Loop

More information

Wireless Networking & Mobile Computing

Wireless Networking & Mobile Computing Wireless Networking & Mobile Computing CS 752/852 - Spring 2012 Lec #4: Medium Access Control - II Tamer Nadeem Dept. of Computer Science IEEE 802.11 Standards Page 2 Spring 2012 CS 752/852 - Wireless

More information

CMPE 257: Wireless and Mobile Networking

CMPE 257: Wireless and Mobile Networking CMPE 257: Wireless and Mobile Networking Katia Obraczka Computer Engineering UCSC Baskin Engineering Lecture 3 CMPE 257 Winter'11 1 Announcements Accessing secure part of the class Web page: User id: cmpe257.

More information

Data and Computer Communications

Data and Computer Communications Data and Computer Communications Chapter 17 Wireless LANs Eighth Edition by William Stallings Overview of Wireless LANs use wireless transmission medium Wireless LAN were little used issues of high prices,

More information

Introduction to Wireless Networking CS 490WN/ECE 401WN Winter Lecture 4: Wireless LANs and IEEE Part II

Introduction to Wireless Networking CS 490WN/ECE 401WN Winter Lecture 4: Wireless LANs and IEEE Part II Introduction to Wireless Networking CS 490WN/ECE 401WN Winter 2007 Lecture 4: Wireless LANs and IEEE 802.11 Part II This lecture continues the study of wireless LANs by looking at IEEE 802.11. I. 802.11

More information

Local Area Networks. Lecture 17 Fall Token Ring and FDDI

Local Area Networks. Lecture 17 Fall Token Ring and FDDI Local Area Networks Lecture 17 Fall 2010 Token Ring and FDDI IEEE 802.5 Ring LAN Unidirectional ring network 4 Mbps and 16 Mbps on twisted pair Differential Manchester line coding Token passing protocol

More information

Fairness and Transmission Opportunity Limit in IEEE802.11e Enhanced Distributed Channel Access

Fairness and Transmission Opportunity Limit in IEEE802.11e Enhanced Distributed Channel Access Fairness and Transmission Opportunity Limit in IEEE802.11e Enhanced Distributed Channel Access by Anni Matinlauri Instructor: Jouni Karvo Supervisor: Professor Raimo Kantola Agenda Background Research

More information

WiFi Networks: IEEE b Wireless LANs. Carey Williamson Department of Computer Science University of Calgary Winter 2018

WiFi Networks: IEEE b Wireless LANs. Carey Williamson Department of Computer Science University of Calgary Winter 2018 WiFi Networks: IEEE 802.11b Wireless LANs Carey Williamson Department of Computer Science University of Calgary Winter 2018 Background (1 of 2) In many respects, the IEEE 802.11b wireless LAN (WLAN) standard

More information

Introduction to IEEE Yu-Chee Tseng CS.NCTU. ieee802.11:1 WirelessNet Tseng

Introduction to IEEE Yu-Chee Tseng CS.NCTU. ieee802.11:1 WirelessNet Tseng Introduction to IEEE 802.11 Yu-Chee CS.NCTU ieee802.11:1 Why do we need MAC? Contention and Collision Avoidance!!! ieee802.11:2 Why Do We Need MAC? Fairness!!! ieee802.11:3 Disconeinuity that We Have Seen

More information

EVALUATION OF EDCF MECHANISM FOR QoS IN IEEE WIRELESS NETWORKS

EVALUATION OF EDCF MECHANISM FOR QoS IN IEEE WIRELESS NETWORKS MERL A MITSUBISHI ELECTRIC RESEARCH LABORATORY http://www.merl.com EVALUATION OF EDCF MECHANISM FOR QoS IN IEEE802.11 WIRELESS NETWORKS Daqing Gu and Jinyun Zhang TR-2003-51 May 2003 Abstract In this paper,

More information

CHAPTER 4 CALL ADMISSION CONTROL BASED ON BANDWIDTH ALLOCATION (CACBA)

CHAPTER 4 CALL ADMISSION CONTROL BASED ON BANDWIDTH ALLOCATION (CACBA) 92 CHAPTER 4 CALL ADMISSION CONTROL BASED ON BANDWIDTH ALLOCATION (CACBA) 4.1 INTRODUCTION In our previous work, we have presented a cross-layer based routing protocol with a power saving technique (CBRP-PS)

More information

CHAPTER 8: LAN Standards

CHAPTER 8: LAN Standards CHAPTER 8: LAN Standards DR. BHARGAVI GOSWAMI, ASSOCIATE PROFESSOR HEAD, DEPARTMENT OF COMPUTER SCIENCE, GARDEN CITY COLLEGE BANGALORE. LAN STRUCTURE NETWORK INTERFACE CARD MEDIUM ACCESS CONTROL SUB LAYER

More information

Overview. Wireless networks basics IEEE (Wi-Fi) a/b/g/n ad Hoc MAC protocols ad Hoc routing DSR AODV

Overview. Wireless networks basics IEEE (Wi-Fi) a/b/g/n ad Hoc MAC protocols ad Hoc routing DSR AODV Wireless networks 1 Overview Wireless networks basics IEEE 802.11 (Wi-Fi) a/b/g/n ad Hoc MAC protocols ad Hoc routing DSR AODV 2 Wireless Networks Autonomous systems of mobile hosts connected by wireless

More information

AN ENHANCED DISTRIBUTED CHANNEL ACCESS DEFICIT ROUND-ROBIN (EDRR) SCHEME FOR IEEE 802.HE WIRELESS NETWORKS CASEY POWELL

AN ENHANCED DISTRIBUTED CHANNEL ACCESS DEFICIT ROUND-ROBIN (EDRR) SCHEME FOR IEEE 802.HE WIRELESS NETWORKS CASEY POWELL AN ENHANCED DISTRIBUTED CHANNEL ACCESS DEFICIT ROUND-ROBIN (EDRR) SCHEME FOR IEEE 802.HE WIRELESS NETWORKS by CASEY POWELL B.Sc, The University of Nevada, Reno, 2002 A THESIS SUBMITTED IN PARTIAL FULFILMENT

More information

Institutionen för systemteknik Department of Electrical Engineering

Institutionen för systemteknik Department of Electrical Engineering Institutionen för systemteknik Department of Electrical Engineering Examensarbete An adaptive solution for power efficiency and QoS optimization in WLAN 802.11n Master thesis performed at NEC Laboratories

More information

Mobile Communications I

Mobile Communications I Mobile Communications I Prof. Dr.-Ing. Rolf Kraemer chair owner telefon: 0335 5625 342 fax: 0335 5625 671 e-mail: kraemer [ at ] ihp-microelectronics.com web: Mobile Communications Chapter 4: Wireless

More information

Mobile Communications Chapter 7: Wireless LANs

Mobile Communications Chapter 7: Wireless LANs Characteristics IEEE 802.11 PHY MAC Roaming IEEE 802.11a, b, g, e HIPERLAN Bluetooth Comparisons Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02 7.1 Comparison: infrastructure vs.

More information

IEEE Wireless LANs Part I: Basics

IEEE Wireless LANs Part I: Basics IEEE 802.11 Wireless LANs Part I: Basics Raj Jain Professor of Computer Science and Engineering Washington University in Saint Louis Saint Louis, MO 63130 Jain@cse.wustl.edu Audio/Video recordings of this

More information

Wireless Local Area Network (IEEE )

Wireless Local Area Network (IEEE ) Wireless Local Area Network (IEEE 802.11) -IEEE 802.11 Specifies a single Medium Access Control (MAC) sublayer and 3 Physical Layer Specifications. Stations can operate in two configurations : Ad-hoc mode

More information

IEEE Technical Tutorial. Introduction. IEEE Architecture

IEEE Technical Tutorial. Introduction. IEEE Architecture IEEE 802.11 Technical Tutorial Introduction The purpose of this document is to give technical readers a basic overview of the new 802.11 Standard, enabling them to understand the basic concepts, principle

More information

Guide to Wireless Communications, Third Edition. Objectives

Guide to Wireless Communications, Third Edition. Objectives Guide to Wireless Communications, Third Edition Chapter 7 Low-Speed Wireless Local Area Networks Objectives Describe how WLANs are used List the components and modes of a WLAN Describe how an RF WLAN works

More information

Advanced Wireless. Networks

Advanced Wireless. Networks TC IST Semester Networks - Part 2 - Advanced Wireless Networks Département Télécommunications Services & Usages Advanced Wireless Networks Speakers Razvan Stanica razvan.stanica@insa-lyon.fr Alexandre

More information

IEEE WLANs (WiFi) Part II/III System Overview and MAC Layer

IEEE WLANs (WiFi) Part II/III System Overview and MAC Layer IEEE 802.11 WLANs (WiFi) Part II/III System Overview and MAC Layer Design goals for wireless LANs (WLANs) Global, seamless operation Low power for battery use No special permissions or licenses needed

More information

Master thesis 60 credits

Master thesis 60 credits UNIVERSITY OF OSLO Department of informatics Capacity and performance study of IEEE 802.11e in WLANs and ad hoc networks Master thesis 60 credits Frank Roar Mjøberg 2. May 2007 Abstract Today, WLANs allow

More information

. 14 Byte for Acks. Due to this fact, the overhead is more relevant if the data contained in packets is sent to high rates:

. 14 Byte for Acks. Due to this fact, the overhead is more relevant if the data contained in packets is sent to high rates: QoS in IEEE 802.11 Issues Some issues are important for quality of service: the first one mentioned is the difference of performances expired by nodes based on their position in the network. Indeed, considering

More information

MSIT 413: Wireless Technologies Week 8

MSIT 413: Wireless Technologies Week 8 MSIT 413: Wireless Technologies Week 8 Michael L. Honig Department of EECS Northwestern University November 2017 The Multiple Access Problem How can multiple mobiles access (communicate with) the same

More information

Advanced Computer Networks WLAN

Advanced Computer Networks WLAN Advanced Computer Networks 263 3501 00 WLAN Patrick Stuedi Spring Semester 2014 1 Oriana Riva, Department of Computer Science ETH Zürich Last week Outlook Medium Access COPE Short Range Wireless Networks:

More information

Wireless LANs. Outline. Outline II. Benefits Applications Technologies Issues Configurations Overview of Standard

Wireless LANs. Outline. Outline II. Benefits Applications Technologies Issues Configurations Overview of Standard Wireless LANs Outline Benefits Applications Technologies Issues Configurations Overview of 802.11 Standard Dr. Michael S. Boykin Spring 02-2 Local Area Networks 2 Outline II MAC layer protocols PHY layer

More information

Wireless Local Area Networks. Networks: Wireless LANs 1

Wireless Local Area Networks. Networks: Wireless LANs 1 Wireless Local Area Networks Networks: Wireless LANs 1 Wireless Local Area Networks The proliferation of laptop computers and other mobile devices (PDAs and cell phones) created an obvious application

More information

Wireless and Mobile Networks

Wireless and Mobile Networks Wireless and Mobile Networks Raj Jain Washington University in Saint Louis Saint Louis, MO 63130 Jain@wustl.edu Audio/Video recordings of this lecture are available on-line at: http://www.cse.wustl.edu/~jain/cse473-11/

More information

Wireless Networks (MAC)

Wireless Networks (MAC) 802.11 Wireless Networks (MAC) Kate Ching-Ju Lin ( 林靖茹 ) Academia Sinica 2016.03.18 CSIE, NTU Reference 1. A Technical Tutorial on the IEEE 802.11 Protocol By Pablo Brenner online: http://www.sss-mag.com/pdf/802_11tut.pdf

More information

original standard a transmission at 5 GHz bit rate 54 Mbit/s b support for 5.5 and 11 Mbit/s e QoS

original standard a transmission at 5 GHz bit rate 54 Mbit/s b support for 5.5 and 11 Mbit/s e QoS IEEE 802.11 The standard defines a wireless physical interface and the MAC layer while LLC layer is defined in 802.2. The standardization process, started in 1990, is still going on; some versions are:

More information

Logical Link Control (LLC) Medium Access Control (MAC)

Logical Link Control (LLC) Medium Access Control (MAC) Overview of IEEE 802.11 Data Link layer Application Presentation Session Transport LLC: On transmission, assemble data into a frame with address and CRC fields. On reception, disassemble frame, perform

More information

Announcements : Wireless Networks Lecture 11: * Outline. Power Management. Page 1

Announcements : Wireless Networks Lecture 11: * Outline. Power Management. Page 1 Announcements 18-759: Wireless Networks Lecture 11: 802.11* Please mail survey team information» Can include topic preferences now if you have them Submit project designs through blackboard Homework 2

More information

WLAN 1 IEEE Basic Connectivity. Manuel Ricardo. Faculdade de Engenharia da Universidade do Porto

WLAN 1 IEEE Basic Connectivity. Manuel Ricardo. Faculdade de Engenharia da Universidade do Porto WLAN 1 IEEE 802.11 Basic Connectivity Manuel Ricardo Faculdade de Engenharia da Universidade do Porto WLAN 2 Acknowledgements Based on Jochen Schiller slides Supporting text» Jochen Schiller, Mobile Comunications,

More information

Wireless Communications

Wireless Communications 4. Medium Access Control Sublayer DIN/CTC/UEM 2018 Why do we need MAC for? Medium Access Control (MAC) Shared medium instead of point-to-point link MAC sublayer controls access to shared medium Examples:

More information

Rahman 1. Application

Rahman 1. Application Data Link layer Overview of IEEE 802.11 Application Presentation Session Transport LLC: On transmission, assemble data into a frame with address and CRC fields. On reception, disassemble frame, perform

More information

Wireless# Guide to Wireless Communications. Objectives

Wireless# Guide to Wireless Communications. Objectives Wireless# Guide to Wireless Communications Chapter 7 Low-Speed Wireless Local Area Networks Objectives Describe how WLANs are used List the components and modes of a WLAN Describe how an RF WLAN works

More information

Introduction to Wireless LAN

Introduction to Wireless LAN Introduction to Wireless LAN Po-Ning Chen, Professor Depart. Of Communications Engineering National Chiao-Tung University 1 Topologies of Wireless o Infrastructure versus ad hoc Infrastructure Portable-to-fixed

More information

3.1. Introduction to WLAN IEEE

3.1. Introduction to WLAN IEEE 3.1. Introduction to WLAN IEEE 802.11 WCOM, WLAN, 1 References [1] J. Schiller, Mobile Communications, 2nd Ed., Pearson, 2003. [2] Martin Sauter, "From GSM to LTE", chapter 6, Wiley, 2011. [3] wiki to

More information

The MAC layer in wireless networks

The MAC layer in wireless networks The MAC layer in wireless networks The wireless MAC layer roles Access control to shared channel(s) Natural broadcast of wireless transmission Collision of signal: a /space problem Who transmits when?

More information

A new Traffic Separation Mechanism (TSm) in Wireless e Networks: A simulation study

A new Traffic Separation Mechanism (TSm) in Wireless e Networks: A simulation study A new Traffic Separation Mechanism (TSm) in Wireless 802.11e Networks: A simulation study Ricardo Moraes 1, Francisco Vasques 1, Paulo Portugal 1, José Alberto Fonseca 2 1 Faculdade de Engenharia Universidade

More information

802.11MAC Fundamentals

802.11MAC Fundamentals Wireless Mesh and Vehicular Networks 802.11MAC Fundamentals Renato Lo Cigno ANS Group locigno@disi.unitn.it http://disi.unitn.it/locigno/teaching-duties/wmvn Copyright Quest opera è protetta dalla licenza:

More information

Hands-On Exercises: IEEE Standard

Hands-On Exercises: IEEE Standard Hands-On Exercises: IEEE 802.11 Standard Mohammad Hossein Manshaei and Jean-Pierre Hubaux {hossein.manshaei,jean-pierre.hubaux}@epfl.ch Laboratory for Computer Communications and Applications (LCA) March

More information

WLAN (802.11) Nomadic Communications. Renato Lo Cigno - Tel: Dipartimento di Ingegneria e Scienza dell Informazione

WLAN (802.11) Nomadic Communications. Renato Lo Cigno - Tel: Dipartimento di Ingegneria e Scienza dell Informazione Nomadic Communications WLAN (802.11) Renato Lo Cigno LoCigno@disi.unitn.it - Tel: 2026 Dipartimento di Ingegneria e Scienza dell Informazione Home Page: http://isi.unitn.it/locigno/index.php/teaching-duties/nomadic-communications

More information

WIRELESS LANS. By: M. Habibullah Pagarkar Mandar Gori Rajesh Jaiswal

WIRELESS LANS. By: M. Habibullah Pagarkar Mandar Gori Rajesh Jaiswal WIRELESS LANS By: M. Habibullah Pagarkar Mandar Gori Rajesh Jaiswal Introduction Why wireless? World will become fully mobile Increase in wireless devices usage Wireless will succeed; integrates into many

More information

CMPE 257: Wireless and Mobile Networking

CMPE 257: Wireless and Mobile Networking CMPE 257: Wireless and Mobile Networking Katia Obraczka Computer Engineering UCSC Baskin Engineering Lecture 3 CMPE 257 Spring'15 1 Next week Announcements April 14: ICN (Spencer Sevilla) April 16: DTN

More information

IEEE WLAN (802.11) Copyright. Nomadic Communications

IEEE WLAN (802.11) Copyright. Nomadic Communications Nomadic Communications WLAN (802.11) Renato Lo Cigno LoCigno@disi.unitn.it - Tel: 2026 Dipartimento di Ingegneria e Scienza dell Informazione Home Page: http://isi.unitn.it/locigno/index.php/teaching-duties/nomadic-communications

More information

Wireless Protocols. Training materials for wireless trainers

Wireless Protocols. Training materials for wireless trainers Wireless Protocols Training materials for wireless trainers Goals The goal of this lecture is to introduce: IEEE wireless protocols coverage 802.11 radio protocols terminology WiFi modes of operation details

More information

Wireless Communication Session 4 Wi-Fi IEEE standard

Wireless Communication Session 4 Wi-Fi IEEE standard Wireless Communication Session 4 Wi-Fi IEEE802.11 standard M. Daneshvar Farzanegan Soourosh.blogfa.com smdanesh@yahoo.com 1 Reminder on frequencies and wavelenghts twisted pair coax cable optical transmission

More information

The MAC layer in wireless networks

The MAC layer in wireless networks The MAC layer in wireless networks The wireless MAC layer roles Access control to shared channel(s) Natural broadcast of wireless transmission Collision of signal: a time/space problem Who transmits when?

More information

Wireless Local Area Networks (WLANs)) and Wireless Sensor Networks (WSNs) Computer Networks: Wireless Networks 1

Wireless Local Area Networks (WLANs)) and Wireless Sensor Networks (WSNs) Computer Networks: Wireless Networks 1 Wireless Local Area Networks (WLANs)) and Wireless Sensor Networks (WSNs) Computer Networks: Wireless Networks 1 Wireless Local Area Networks The proliferation of laptop computers and other mobile devices

More information

Investigation of WLAN

Investigation of WLAN Investigation of WLAN Table of Contents Table of Contents...1 ABBREVIATIONS...II 1 Introduction...3 2 IEEE 802.11...3 2.1 Architecture...3 2.2 MAC layer...4 2.3 PHY layer...9 2.4 Mobility in IEEE 802.11...12

More information

IEEE e QoS for Wireless LAN:

IEEE e QoS for Wireless LAN: IEEE 802.11e QoS for Wireless LAN: A Research Direction James Yu 12/09/2003 TDC Network Seminar 1 IEEE 802.11 MAC Layer Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) Different from CAMA/CD

More information

Performance anomaly of b

Performance anomaly of b Laboratoire LSR Logiciels Systèmes Réseaux Software, Systems, Networks Performance anomaly of 802.11b Andrzej Duda LSR-IMAG Andrzej.Duda@imag.fr Joint work with Martin Heusse, Franck Rousseau, Gilles Berger-Sabbatel

More information

Outline / Wireless Networks and Applications Lecture 9: Wireless LANs Aloha and 802 Wireless. Regular Ethernet CSMA/CD

Outline / Wireless Networks and Applications Lecture 9: Wireless LANs Aloha and 802 Wireless. Regular Ethernet CSMA/CD Page 1 Outline 18-452/18-750 Wireless Networks and Applications Lecture 9: Wireless LANs Aloha and 802 Wireless Peter Steenkiste Data link fundamentals» And what changes in wireless Aloha Ethernet Wireless-specific

More information