EETS 8316 Wireless Networks Fall 2013

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "EETS 8316 Wireless Networks Fall 2013"

Transcription

1 EETS 8316 Wireless Networks Fall 2013 Lecture: WiFi Discovery, Powersave, and Beaconing Shantanu Kangude

2 Discovery and Beaconing

3 Discovery? Who else is there? Any pre-existing network? Common sense methods for Discovery Hear an advertisement Hear beacons, Broadcast channels, in networks Ask someone, may be a store or a friend Probe Requests and Responses in networks Found a few options, how to decide on one Do we have common parameters we can agree with? E.g. capabilities Am I allowed? E.g. Authentication

4 Beaconing for Advertisement Network owner / AP broadcasts beacons every beacon interval with network info Name of the network (SSID) Network operation parameters PHY and MAC protocol parameters like rates supported, EDCA parameters etc. Powersave related info (more later) & more Before connecting, potential participant STAs, listen for beacons, and copy name & parameters of all networks heard

5 Probe Requests & Responses Potential participant STAs may Be impatient, & don t wait for a beacon Need to take initiative if certain beacon info suppressed (why suppressed out of scope) Probe Request Broadcast from a STA Requesting network info from APs / designated owners Probe Response Unicast from various APs to the STA With info to the STA sending request

6 Probes and Backoff After a Probe Request, all APs hearing the request are looking to respond How are collisions avoided on Probe Responses? Backoff like for all other packets Usual CSMA/CA helps Correspondence in Bluetooth Probe Request Inquiry? Probe Response Inquiry Response?

7 High Level Network Join Process Image Source:

8 Scanning in infrastructure Wifi (1/2) Look for networks in the neighborhood They can be on various different channels 2.4 Ghz => ~80 MHz available 3 non-overlapping networks possible 5 Ghz => more than 150Mhz available Many more possible Where to scan? Depends on STA s capability 11b or 11g station may scan only in the 2.4Ghz band

9 Scanning in infrastructure Wifi (2/2) Scan in different center frequencies 1 by 1 Stay in 1 frequency for certain time Collect beacon information from those heard Potentially send probe requests & collect information from responses 2 types of scanning Active scanning = Probe Requests sent Passive scanning = only wait for beacons Scan results are presented to the user as available networks Reading Assigned:

10 IEEE GHz Channels Channels 1,6,& 11 are non-overlapping 5 MHz 22 MHz 2.4 GHz GHz 1: : : : : : : : : : : Slide Source: Ivan Marsic s publicly available slides at:

11 Wifi Powersave Mainly on the Infrastructure based BSSs Remember: All methods require time synchronization, as they involve rendezvous

12 Shut Circuits (Sleep) to Powersave TX and RX RF-chains (circuits) burn significant power (TX > RX) Shut down circuits to save power, but No reception possible while shut down Others may send packets to you expecting you to receive and ACK Not responding properly to protocol activities can Cause mis-interpretation & excessive retransmissions & capacity wastage Cause eventual loss of association, authentication etc. => redo those

13 Shutting Circuits, But Responsibly When to shut circuits? No uplink or downlink traffic or flows But don t shutdown for too long Wake and do basic activities regularly to maintain connection & synch Wake up regularly to check if any downlink traffic And tell the AP, your Sleep-Wake schedule Generally wake up for specific beacons E.g. every Nth beacon Stay awake to make sure no data transfer needed in both directions

14 Another Perspective on Sleep & Wake Periods One of the nodes, typically AP, is always awake Other STA alternates between 2 states Doze /Sleep Awake Both stations should agree on When the AP should expect the STA to be awake When, after being awake, can a STA go back to sleep

15 Basic Infrastructure Powersave Method

16 Basic Concepts AP buffers packets for power-saving stations until they are awake Traffic Indication Map (TIM): A bitmap transmitted in beacons Tells which STAs have pending DL traffic Once a STA sees its TIM bit set It stays awake and gets its DL traffic Goes back to sleep after somehow informing AP For UL traffic arrival STA can wake up ANYTIME (even in scheduled sleep times) and transmit (since AP always awake) STA can change mode to active (always awake mode) for an extended period when it has traffic

17 Different TIM Beacons & Sleep Intervals TIM bitmap can be there in every beacon Delivery TIM (DTIM) beacon is a beacon that indicates any broadcast/multicast traffic pending in DL ALL STAs must be awake for DTIM beacons If broadcast/multicast DL traffic is indicated Stay awake to receive it Since all STAs wake up on DTIM Typical sleep intervals (called LISTEN INTERVAL) = Submultiples of DTIM period E.g. if DTIM period is 16 Beacon Intervals, STA A, B, & C can have Listen Intervals of 1,2,4,8, or 16 beacon intervals

18 PS-Poll Frames to Retrieve DL Buffered Traffic Once TIM/DTIM indicates traffic That STA keeps awake and retrieves packets using PS-Poll frames STAs send PS-Poll frames to AP AP responds with data packets STA keeps awake generally until More Data bit in header is RESET to 0, or TIM bitmap indicates no more traffic During data transfer More Data bit in Frame- Control field in header tells about more buffered packets or not before TIM bit can in a beacon

19 Basic Powersave Operation

20 Picture Source in the next few slides snet06-02/ieee power-savingmode.ppt

21 Example: Unicast With TIM STA 1 has a listen interval of 2, and STA 2 of 3

22 Example: Broad/Multicast with DTIM

23 IBSS Powersave Method Quite Inefficient, and not used much in practice Wifi Direct Powersave much more efficient

24 Basics of IBSS Powersave No AP, so no one is always awake Traffic goes to any neighbor, plus may have Broadcast/Multicast Ensure RENDEZVOUS times when ALL are awake => ATIM Window Time Announce in ATIM Window Who all shall stay awake to receive packets Multiple announcements from multiple senders possible Random backoff, and large enough window time

25 ATIM Announcement TIM Like DTIM in infrastructure mode, all IBSS STAs should be awake for a periodic ATIM beacon ATIM window of time after every ATIM Beacon All STAs are awake during this time period All senders send announcements about receivers who should stay awake to receive packets A potential receiver who sees its name in announcement has to ACK to the potential sender All those who have successful Announcement-ACKs stay awake during beacon interval and go through transfers Others not in announcements, go to sleep No actual data in ATIM window No announcements outside ATIM window Those who stay awake, do so until next ATIM window end

26 Example: ATIM Window

27 Example IBSS Powersave Operation

28 E QoS Powersave Enhancements Scheduled and Unscheduled Automatic Power Save Delivery (APSD) Remember: 11e has 4 access categories in EDCA, and in general traffic classes

29 What Basic Powersave Lacks Quantum of time over which sleep/wake done = Beacon Intervals or Multiples Not fine grained enough For VOIP traffic, may have to be awake all the time if Beacon Interval >= 100ms PS-Poll method is a slow and uncontrolled method in delivering packets in the DL All we need to know is if the STA is awake, and any UL transmission can indicate that Synchronizing UL and DL transmissions can help save time to be awake

30 Service Period (SP) in APSD One contiguous burst of time for which a STA is awake for data transfers in APSD Service Periods end with End Of Service Period (EOSP) bit set to 1 typically by AP Like More Data bit Or Maximum SP duration is up (in Scheduled APSD)

31 Unscheduled APSD 2 Types of APSD Service Period begins with Trigger and ends with a packet with EOSP bit set Triggers frame is a QoS+Data or QoS+Null frame Scheduled APSD No triggers needed to start Service Periods Pre-negotiated PERIODIC schedules set for Doze- Wake cycles Scheduled periods are shorter than beacon intervals typically => fine grained Powersave cycles

32 Scheduled APSD Parameters APSD periodicity Beginning time Maximum Service Period duration Service Period may be ended earlier by the AP Used for periodic traffic like VOIP, Video conferencing etc.

33 Unscheduled APSD No pre-set schedules of when to wake up No inherent pre-set periodicities Service Periods (SPs) start with an UL frame SP started is of the same Access Category (AC) as the UL frame transmitted Access Categories are U-APSD enabled or disabled as per needs SPs end when a EOSP bit set DL packet received => AP says no more data

34 Regular PS vs U-APSD (More Efficient) Baseline PS U-APSD Src:http://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/emob41dg/ch5_QoS.html# wp

35 What Next in WiFi Powersave? Powersave in n Spatial Multiplexing Powersave Powersave Multi Poll (PSMP) Powersave in Wifi Direct (when one p2p STA becomes soft AP) In p2p, both nodes may sleep, so the assumptions of the OTHER NODE ALWAYS AWAKE is not valid All mechanisms are modified to fit the scenario TWO great project topics First come first serve

CS6956: Wireless and Mobile Networks Lecture Notes: 2/11/2015. IEEE 802.11 Wireless Local Area Networks (WLANs)

CS6956: Wireless and Mobile Networks Lecture Notes: 2/11/2015. IEEE 802.11 Wireless Local Area Networks (WLANs) CS6956: Wireless and Mobile Networks Lecture Notes: //05 IEEE 80. Wireless Local Area Networks (WLANs) CSMA/CD Carrier Sense Multi Access/Collision Detection detects collision and retransmits, no acknowledgement,

More information

A Short Look on Power Saving Mechanisms in the Wireless LAN Standard Draft IEEE 802.11

A Short Look on Power Saving Mechanisms in the Wireless LAN Standard Draft IEEE 802.11 A Short Look on Power Saving Mechanisms in the Wireless LAN Standard Draft IEEE 802.11 Christian Röhl, Hagen Woesner, Adam Wolisz * Technical University Berlin Telecommunication Networks Group {roehl,

More information

Voice-over-Wi-Fi Implementation with Single Stream 802.11n

Voice-over-Wi-Fi Implementation with Single Stream 802.11n Voice-over-Wi-Fi Implementation with Single Stream 802.11n The 802.11n standard provides for increased throughput and greater range in VoWiFi devices. This article looks in detail at the benefits as well

More information

Philippe Klein. avb-phkl-802-11-qos-overview-0811-1

Philippe Klein. avb-phkl-802-11-qos-overview-0811-1 802.11 QoS Overview Philippe Klein IEEE Plenary Meeting Nov 08 Dallas, TX avb-phkl-802-11-qos-overview-0811-1 Disclaimer This presentation is not a highly detailed technical presentation but a crash course

More information

Attenuation (amplitude of the wave loses strength thereby the signal power) Refraction Reflection Shadowing Scattering Diffraction

Attenuation (amplitude of the wave loses strength thereby the signal power) Refraction Reflection Shadowing Scattering Diffraction Wireless Physical Layer Q1. Is it possible to transmit a digital signal, e.g., coded as square wave as used inside a computer, using radio transmission without any loss? Why? It is not possible to transmit

More information

Workshop Presentation Chapter4. Yosuke TANAKA

Workshop Presentation Chapter4. Yosuke TANAKA Workshop Presentation Chapter4 Yosuke TANAKA Agenda(Framing in Detail) Data Frames Control Frames type RTS Duration CTS Addressing (!!important!!) Variation on Data Frame Theme Applied Data Framing ACK

More information

Enhanced Power Saving for IEEE 802.11 WLAN with Dynamic Slot Allocation

Enhanced Power Saving for IEEE 802.11 WLAN with Dynamic Slot Allocation Enhanced Power Saving for IEEE 802.11 WLAN with Dynamic Slot Allocation Changsu Suh, Young-Bae Ko, and Jai-Hoon Kim Graduate School of Information and Communication, Ajou University, Republic of Korea

More information

CSE331: Introduction to Networks and Security. Lecture 6 Fall 2006

CSE331: Introduction to Networks and Security. Lecture 6 Fall 2006 CSE331: Introduction to Networks and Security Lecture 6 Fall 2006 Open Systems Interconnection (OSI) End Host Application Reference model not actual implementation. Transmits messages (e.g. FTP or HTTP)

More information

Wiereless LAN 802.11

Wiereless LAN 802.11 Tomasz Kurzawa Wiereless LAN 802.11 Introduction The 802.11 Architecture Channels and Associations The 802.11 MAC Protocol The 802.11 Frame Introduction Wireless LANs are most important access networks

More information

IEEE 802.11e WLANs / WMM. S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd.

IEEE 802.11e WLANs / WMM. S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd. IEEE 802.11e WLANs / WMM S.Rajesh (rajeshsweb@gmail.com) AU-KBC Research Centre, BroVis Wireless Networks, smartbridges Pte Ltd. Outline A short review of 802.11 MAC Drawbacks of 802.11 MAC Application

More information

Continuous network discovery using Opportunistic Scanning

Continuous network discovery using Opportunistic Scanning Continuous network discovery using Opportunistic Scanning Authors: Date: 2009-11-17 Slide 1 Abstract This presentation is in response to WNG requesting more information on the capability of 802.11 to support

More information

EETS 8316 Wireless Networks Fall 2013

EETS 8316 Wireless Networks Fall 2013 EETS 8316 Wireless Networks Fall 2013 Lecture: LTE Scheduling and DRX http://lyle.smu.edu/~skangude/eets8316.html Shantanu Kangude skangude@lyle.smu.edu Scheduling & Rate Control Scheduler operation Signalling

More information

Performance Analysis and Comparison between Legacy-PSM and U-APSD

Performance Analysis and Comparison between Legacy-PSM and U-APSD Performance Analysis and Comparison between Legacy-PSM and U-APSD Adriano Vinhas, Vitor Bernardo, Marilia Curado, Torsten Braun Center for Informatics and Systems, University of Coimbra, Coimbra, Portugal

More information

Performance Analysis and Comparison between Legacy-PSM and U-APSD

Performance Analysis and Comparison between Legacy-PSM and U-APSD Performance Analysis and Comparison between Legacy-PSM and U-APSD Adriano Vinhas, Vitor Bernardo, Marilia Curado, Torsten Braun Center for Informatics and Systems, University of Coimbra, Coimbra, Portugal

More information

The Wireless Network Road Trip

The Wireless Network Road Trip The Wireless Network Road Trip The Association Process To begin, you need a network. This lecture uses the common logical topology seen in Figure 9-1. As you can see, multiple wireless clients are in

More information

CSMA/CA. Information Networks p. 1

CSMA/CA. Information Networks p. 1 Information Networks p. 1 CSMA/CA IEEE 802.11 standard for WLAN defines a distributed coordination function (DCF) for sharing access to the medium based on the CSMA/CA protocol Collision detection is not

More information

Advanced Wireless LAN VoIP Technology

Advanced Wireless LAN VoIP Technology Wireless LAN VoIP QoS Advanced Wireless LAN VoIP Technology A technical overview is given of an optimal access point selection method and an autonomous distributed scheduling MAC method that take QoS into

More information

Lecture 17: 802.11 Wireless Networking"

Lecture 17: 802.11 Wireless Networking Lecture 17: 802.11 Wireless Networking" CSE 222A: Computer Communication Networks Alex C. Snoeren Thanks: Lili Qiu, Nitin Vaidya Lecture 17 Overview" Project discussion Intro to 802.11 WiFi Jigsaw discussion

More information

Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh

Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh Express Forwarding : A Distributed QoS MAC Protocol for Wireless Mesh, Ph.D. benveniste@ieee.org Mesh 2008, Cap Esterel, France 1 Abstract Abundant hidden node collisions and correlated channel access

More information

Multiple Access Techniques PROF. MICHAEL TSAI 2011/12/8

Multiple Access Techniques PROF. MICHAEL TSAI 2011/12/8 Multiple Access Techniques PROF. MICHAEL TSAI 2011/12/8 Multiple Access Scheme Allow many users to share simultaneously a finite amount of radio spectrum Need to be done without severe degradation of the

More information

802.11. Markku Renfors. Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak

802.11. Markku Renfors. Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak 802.11 Markku Renfors Partly based on student presentation by: Lukasz Kondrad Tomasz Augustynowicz Jaroslaw Lacki Jakub Jakubiak Contents 802.11 Overview & Architecture 802.11 MAC 802.11 Overview and Architecture

More information

TECHNICAL NOTE. GoFree WIFI-1 web interface settings. Revision Comment Author Date 0.0a First release James Zhang 10/09/2012

TECHNICAL NOTE. GoFree WIFI-1 web interface settings. Revision Comment Author Date 0.0a First release James Zhang 10/09/2012 TECHNICAL NOTE GoFree WIFI-1 web interface settings Revision Comment Author Date 0.0a First release James Zhang 10/09/2012 1/14 Web interface settings under admin mode Figure 1: web interface admin log

More information

Lab Exercise 802.11. Objective. Requirements. Step 1: Fetch a Trace

Lab Exercise 802.11. Objective. Requirements. Step 1: Fetch a Trace Lab Exercise 802.11 Objective To explore the physical layer, link layer, and management functions of 802.11. It is widely used to wireless connect mobile devices to the Internet, and covered in 4.4 of

More information

Chapter 7 Low-Speed Wireless Local Area Networks

Chapter 7 Low-Speed Wireless Local Area Networks Wireless# Guide to Wireless Communications 7-1 Chapter 7 Low-Speed Wireless Local Area Networks At a Glance Instructor s Manual Table of Contents Overview Objectives s Quick Quizzes Class Discussion Topics

More information

TCP in Wireless Networks

TCP in Wireless Networks Outline Lecture 10 TCP Performance and QoS in Wireless s TCP Performance in wireless networks TCP performance in asymmetric networks WAP Kurose-Ross: Chapter 3, 6.8 On-line: TCP over Wireless Systems Problems

More information

FOMA (R) /Wireless LAN Dual Terminals, Wireless LAN Technology

FOMA (R) /Wireless LAN Dual Terminals, Wireless LAN Technology FOMA (R) /Wireless LAN Dual Terminals, Wireless LAN Technology SHINOHARA Masahito, ITOH Masashi, IWATA Shinichiro, NISHIMURA Yasunori, ZAITSU Makoto Abstract FOMA (R) /wireless LAN dual terminals are dual-phone

More information

IEEE 802.11 Technical Tutorial. Introduction. IEEE 802.11 Architecture

IEEE 802.11 Technical Tutorial. Introduction. IEEE 802.11 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

Wireless LAN Services for Hot-Spot

Wireless LAN Services for Hot-Spot Wireless LAN Services for Hot-Spot Woo-Yong Choi Electronics and Telecommunications Research Institute wychoi53@etri.re.kr ETRI Contents Overview Wireless LAN Services Current IEEE 802.11 MAC Protocol

More information

Enabling Wi-Fi Internet of Things with ah Technology

Enabling Wi-Fi Internet of Things with ah Technology Enabling Wi-Fi Internet of Things with 802.11ah Technology July 8, 2015 Dr. Eldad Perahia Internet of Things Group eldad.perahia@intel.com 1 Introduction The 802.11ah amendment provides new modes and mechanisms

More information

CS263: Wireless Communications and Sensor Networks

CS263: Wireless Communications and Sensor Networks CS263: Wireless Communications and Sensor Networks Matt Welsh Lecture 4: Medium Access Control October 5, 2004 2004 Matt Welsh Harvard University 1 Today's Lecture Medium Access Control Schemes: FDMA TDMA

More information

WLAN QoS : 802.11e. Merle Frédéric

WLAN QoS : 802.11e. Merle Frédéric WLAN QoS : 802.11e Merle Frédéric Summary Introduction What is QoS? Why do we need QoS in wireless LAN nowadays? 802.11e MAC Protocol Enhanced Distributed Channel Access (EDCA) Presentation How does it

More information

WUA-0605 300Mbps Wireless USB Network Adapter

WUA-0605 300Mbps Wireless USB Network Adapter WUA-0605 300Mbps Wireless USB Network Adapter User Manual V1.0 Certification FCC CE FCC Statement This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant

More information

IEEE802.11 Wireless LAN

IEEE802.11 Wireless LAN IEEE802.11 The broadband wireless Internet Maximilian Riegel wlan-tutorial.ppt-1 (28.11.2000) WLAN Dream Finally Seems to Happen... Recently lots of serious WLAN activities have been announced Big players

More information

Video Transmission over Wireless LAN. Hang Liu Hang.liu@thomson.net

Video Transmission over Wireless LAN. Hang Liu Hang.liu@thomson.net Video Transmission over Wireless LAN Hang Liu Hang.liu@thomson.net Page 1 Introduction! Introduction! Wi-Fi Multimedia and IEEE 802.11e for QoS Enhancement! Error Control Techniques Page 2 Introduction!

More information

Bluetooth voice and data performance in 802.11 DS WLAN environment

Bluetooth voice and data performance in 802.11 DS WLAN environment 1 (1) Bluetooth voice and data performance in 802.11 DS WLAN environment Abstract In this document, the impact of a 20dBm 802.11 Direct-Sequence WLAN system on a 0dBm Bluetooth link is studied. A typical

More information

Lecture 7 Multiple Access Protocols and Wireless

Lecture 7 Multiple Access Protocols and Wireless Lecture 7 Multiple Access Protocols and Wireless Networks and Security Jacob Aae Mikkelsen IMADA November 11, 2013 November 11, 2013 1 / 57 Lecture 6 Review What is the responsibility of the link layer?

More information

A Technical Tutorial on the IEEE 802.11 Protocol

A Technical Tutorial on the IEEE 802.11 Protocol A Technical Tutorial on the IEEE 802.11 Protocol By Pablo Brenner Director of Engineering copyright BreezeCOM 1997 Introduction The purpose of this document is to give technical readers a basic overview

More information

802.11 Wireless LAN Protocol CS 571 Fall 2006. 2006 Kenneth L. Calvert All rights reserved

802.11 Wireless LAN Protocol CS 571 Fall 2006. 2006 Kenneth L. Calvert All rights reserved 802.11 Wireless LAN Protocol CS 571 Fall 2006 2006 Kenneth L. Calvert All rights reserved Wireless Channel Considerations Stations may move Changing propagation delays, signal strengths, etc. "Non-transitive"

More information

- Cognitive Radio (CR) technology is a promising emerging technology that enables a more efficient usage of

- Cognitive Radio (CR) technology is a promising emerging technology that enables a more efficient usage of An Asynchronous Neighbor Discovery Algorithm for Cognitive Radio Networks Short Paper Chanaka J. Liyana Arachchige, S. Venkatesan and Neeraj Mittal Erik Jonsson School of Engineering and Computer Science

More information

10. Wireless Networks

10. Wireless Networks Computernetzwerke und Sicherheit (CS221) 10. Wireless Networks 1. April 2011 omas Meyer Departement Mathematik und Informatik, Universität Basel Chapter 6 Wireless and Mobile Networks (with changes CS221

More information

An Overview of ZigBee Networks

An Overview of ZigBee Networks An Overview of ZigBee Networks A guide for implementers and security testers Matt Hillman Contents 1. What is ZigBee?... 3 1.1 ZigBee Versions... 3 2. How Does ZigBee Operate?... 3 2.1 The ZigBee Stack...

More information

Department of Computer Science Columbia University

Department of Computer Science Columbia University Towards the Quality of Service for VoIP traffic in IEEE 82.11 Wireless Networks Sangho Shin Henning Schulzrinne Email: sangho, hgs@cs.columbia.edu Department of Computer Science Columbia University 28

More information

VoIP-Kapazität im Relay erweiterten IEEE 802.16 System

VoIP-Kapazität im Relay erweiterten IEEE 802.16 System VoIP-Kapazität im Relay erweiterten IEEE 802.16 System 21. ComNets-Workshop Mobil- und Telekommunikation Dipl.-Ing. Karsten Klagges ComNets Research Group RWTH Aachen University 16. März 2012 Karsten Klagges

More information

ADV-MAC: Advertisement-based MAC Protocol for Wireless Sensor Networks

ADV-MAC: Advertisement-based MAC Protocol for Wireless Sensor Networks ADV-MAC: Advertisement-based MAC Protocol for Wireless Sensor Networks Surjya Ray, Ilker Demirkol and Wendi Heinzelman Department of Electrical and Computer Engineering University of Rochester, Rochester,

More information

TCOM 370 NOTES 99-12 LOCAL AREA NETWORKS AND THE ALOHA PROTOCOL

TCOM 370 NOTES 99-12 LOCAL AREA NETWORKS AND THE ALOHA PROTOCOL 1. Local Area Networks TCOM 370 NOTES 99-12 LOCAL AREA NETWORKS AND THE ALOHA PROTOCOL These are networks spanning relatively short distances (e.g. within one building) for local point-to-point and point-to-multipoint

More information

EPL 657 Wireless Networks

EPL 657 Wireless Networks EPL 657 Wireless Networks Some fundamentals: Multiplexing / Multiple Access / Duplex Infrastructure vs Infrastructureless Panayiotis Kolios Recall: The big picture... Modulations: some basics 2 Multiplexing

More information

802.11 standard. Acknowledgement: Slides borrowed from Richard Y. Yang @ Yale

802.11 standard. Acknowledgement: Slides borrowed from Richard Y. Yang @ 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

Basic processes in IEEE802.11 networks

Basic processes in IEEE802.11 networks Module contents IEEE 802.11 Terminology IEEE 802.11 MAC Frames Basic processes in IEEE802.11 networks Configuration parameters.11 Architect. 1 IEEE 802.11 Terminology Station (STA) Architecture: Device

More information

... neither PCF nor CA used in practice

... neither PCF nor CA used in practice IEEE 802.11 MAC CSMA/CA with exponential backoff almost like CSMA/CD drop CD CSMA with explicit ACK frame added optional feature: CA (collision avoidance) Two modes for MAC operation: Distributed coordination

More information

II. IEEE802.11e EDCA OVERVIEW

II. IEEE802.11e EDCA OVERVIEW The 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'7) CACITY IMPROVEMENT OF WIRELESS LAN VOIP USING DISTRIBUTED TRANSMISSION SCHEDULING Kei Igarashi,

More information

ECE/CS 372 introduction to computer networks. Lecture 13

ECE/CS 372 introduction to computer networks. Lecture 13 ECE/CS 372 introduction to computer networks Lecture 13 Announcements: HW #4 hard copy due today Lab #5 posted is due Tuesday June 4 th HW #5 posted is due Thursday June 6 th Pickup midterms Acknowledgement:

More information

IEEE 802.11 WLAN (802.11) ...Copyright. Renato Lo Cigno www.disi.unitn.it/locigno/didattica/nc/

IEEE 802.11 WLAN (802.11) ...Copyright. Renato Lo Cigno www.disi.unitn.it/locigno/didattica/nc/ WLAN (802.11) Renato Lo Cigno www.disi.unitn.it/locigno/didattica/nc/...copyright Quest opera è protetta dalla licenza Creative Commons NoDerivs-NonCommercial. Per vedere una copia di questa licenza, consultare:

More information

COMP 3331/9331: Computer Networks and Applications

COMP 3331/9331: Computer Networks and Applications COMP 3331/9331: Computer Networks and Applications Week 10 Wireless Networks Reading Guide: Chapter 6: 6.1 6.3 Wireless Networks + Security 1 Wireless and Mobile Networks Background: # wireless (mobile)

More information

Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks

Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks Adaptive DCF of MAC for VoIP services using IEEE 802.11 networks 1 Mr. Praveen S Patil, 2 Mr. Rabinarayan Panda, 3 Mr. Sunil Kumar R D 1,2,3 Asst. Professor, Department of MCA, The Oxford College of Engineering,

More information

Wireless LAN Pen-Testing. Part I

Wireless LAN Pen-Testing. Part I Wireless LAN Pen-Testing Part I To know your Enemy, you must become your Enemy (Sun Tzu, 600 BC) Georg Penn 23.03.2012 Motivation Read manuals, documentation, standards Check sources for their reliability,

More information

Random Access Protocols

Random Access Protocols Lecture Today slotted vs unslotted ALOHA Carrier sensing multiple access Ethernet DataLink Layer 1 Random Access Protocols When node has packet to send transmit at full channel data rate R. no a priori

More information

DISCUSSION. Sophia-Antipolis, France August 16-20, 1999. Agenda item: 14.4 Golden Bridge Technology CPCH Delay Measurements for TS25.

DISCUSSION. Sophia-Antipolis, France August 16-20, 1999. Agenda item: 14.4 Golden Bridge Technology CPCH Delay Measurements for TS25. TSG RAN WG 2#6 Sophia-Antipolis, France August 16-20, 1999 TSGR2#6(99)802 Agenda item: 14.4 Source: Golden Bridge Technology Title: CPCH Delay Measurements for TS25.331, RRC Protocol Document for: Discussion

More information

Reducing MAC Layer Handoff Latency in IEEE 802.11 Wireless LANs

Reducing MAC Layer Handoff Latency in IEEE 802.11 Wireless LANs Reducing MAC Layer Handoff Latency in IEEE 80211 Wireless LANs Sangho Shin Andrea G Forte Columbia University {ss2020,andreaf}@cscolumbiaedu Anshuman Singh Rawat New York University asr245@nyuedu Henning

More information

Embedded Systems. 8. Communication

Embedded Systems. 8. Communication Embedded Systems 8. Communication Lothar Thiele 8-1 Contents of Course 1. Embedded Systems Introduction 2. Software Introduction 7. System Components 10. Models 3. Real-Time Models 4. Periodic/Aperiodic

More information

WLAN (802.11) Nomadic Communications. Renato Lo Cigno - Tel: 2026. Dipartimento di Ingegneria e Scienza dell Informazione

WLAN (802.11) Nomadic Communications. Renato Lo Cigno - Tel: 2026. 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

Virtual Access Points

Virtual Access Points Virtual Access Points Performance Impacts in an 802.11 environment and Alternative Solutions to overcome the problems By Thenu Kittappa Engineer Author: Thenu Kittappa Page 1 Virtual Access Points... 1

More information

Wireless Networks. Reading: Sec5on 2.8. COS 461: Computer Networks Spring 2011. Mike Freedman

Wireless Networks. Reading: Sec5on 2.8. COS 461: Computer Networks Spring 2011. Mike Freedman 1 Wireless Networks Reading: Sec5on 2.8 COS 461: Computer Networks Spring 2011 Mike Freedman hep://www.cs.princeton.edu/courses/archive/spring11/cos461/ 2 Widespread Deployment Worldwide cellular subscribers

More information

IEEE 802.11 Wireless LAN Standard. Updated: 5/10/2011

IEEE 802.11 Wireless LAN Standard. Updated: 5/10/2011 IEEE 802.11 Wireless LAN Standard Updated: 5/10/2011 IEEE 802.11 History and Enhancements o 802.11 is dedicated to WLAN o The group started in 1990 o First standard that received industry support was 802.11b

More information

Link Layer Standards and Protocols

Link Layer Standards and Protocols Link Layer Standards and Protocols Link Layer Standards IP Layer (Network Layer) LLC IEEE 802.2 MAC IEEE 802.X Physical Layer Medium Access Control Layer Services Concerned with the following Channel allocation

More information

Mobile Computing/ Mobile Networks

Mobile Computing/ Mobile Networks Mobile Computing/ Mobile Networks TCP in Mobile Networks Prof. Chansu Yu Contents Physical layer issues Communication frequency Signal propagation Modulation and Demodulation Channel access issues Multiple

More information

Tutorial 7 : Link layer part I

Tutorial 7 : Link layer part I Lund University ETSN01 Advanced Telecommunication Tutorial 7 : Link layer part I Author: Antonio Franco Course Teacher: Emma Fitzgerald February 12, 2015 Contents I Before you start 3 II Exercises 3 1

More information

Troubleshooting Guide Ascom i62 VoWiFi Handset

Troubleshooting Guide Ascom i62 VoWiFi Handset Troubleshooting Guide About this document This guide describes how to investigate and remedy Quality of Service problems experienced by handset users when accessing a WLAN and making calls using the Voice

More information

Research In Motion D. Stanley, Ed. Aruba Networks March 2009

Research In Motion D. Stanley, Ed. Aruba Networks March 2009 Network Working Group Request for Comments: 5416 Category: Standards Track P. Calhoun, Ed. Cisco Systems, Inc. M. Montemurro, Ed. Research In Motion D. Stanley, Ed. Aruba Networks March 2009 Control and

More information

Wireless and Mobile Networks

Wireless and Mobile Networks Wireless and Mobile Networks Reading: Sec7ons 2.8 and 4.2.5 COS 461: Computer Networks Spring 2009 (MW 1:30 2:50 in COS 105) Mike Freedman Teaching Assistants: WyaO Lloyd and Jeff Terrace hop://www.cs.princeton.edu/courses/archive/spring09/cos461/

More information

Optimization of VoIP over 802.11e EDCA based on synchronized time

Optimization of VoIP over 802.11e EDCA based on synchronized time Optimization of VoIP over 802.11e EDCA based on synchronized time Padraig O Flaithearta, Dr. Hugh Melvin Discipline of Information Technology, College of Engineering and Informatics, National University

More information

ISSN: 2319-5967 ISO 9001:2008 Certified International Journal of Engineering Science and Innovative Technology (IJESIT) Volume 2, Issue 5, September

ISSN: 2319-5967 ISO 9001:2008 Certified International Journal of Engineering Science and Innovative Technology (IJESIT) Volume 2, Issue 5, September Analysis and Implementation of IEEE 802.11 MAC Protocol for Wireless Sensor Networks Urmila A. Patil, Smita V. Modi, Suma B.J. Associate Professor, Student, Student Abstract: Energy Consumption in Wireless

More information

SELECTIVE ACTIVE SCANNING FOR FAST HANDOFF IN WLAN USING SENSOR NETWORKS

SELECTIVE ACTIVE SCANNING FOR FAST HANDOFF IN WLAN USING SENSOR NETWORKS SELECTIVE ACTIVE SCANNING FOR FAST HANDOFF IN WLAN USING SENSOR NETWORKS Sonia Waharte, Kevin Ritzenthaler and Raouf Boutaba University of Waterloo, School of Computer Science 00, University Avenue West,

More information

An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e

An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e An Overview of Wireless LAN Standards IEEE 802.11 and IEEE 802.11e Jahanzeb Farooq, Bilal Rauf Department of Computing Science Umeå University Sweden Jahanzeb Farooq, 2006 (tipputhegreat@hotmail.com) Chapter

More information

Mustafa Ergen June 2002 ergen@eecs.berkeley.edu. Department of Electrical Engineering and Computer Science University of California Berkeley

Mustafa Ergen June 2002 ergen@eecs.berkeley.edu. Department of Electrical Engineering and Computer Science University of California Berkeley Mustafa Ergen June 2002 ergen@eecs.berkeley.edu Department of Electrical Engineering and Computer Science University of California Berkeley 2 Abstract This document describes IEEE 802.11 Wireless Local

More information

Cooperative Handoff in Wireless Networks

Cooperative Handoff in Wireless Networks Cooperative Handoff in Wireless Networks George Athanasiou, Thanasis Korakis and Leandros Tassiulas Dept. of Computer and Communications Engineering, University of Thessaly, Greece Email: gathanas@uth.gr

More information

LAN Switching. 15-441 Computer Networking. Switched Network Advantages. Hubs (more) Hubs. Bridges/Switches, 802.11, PPP. Interconnecting LANs

LAN Switching. 15-441 Computer Networking. Switched Network Advantages. Hubs (more) Hubs. Bridges/Switches, 802.11, PPP. Interconnecting LANs LAN Switching 15-441 Computer Networking Bridges/Switches, 802.11, PPP Extend reach of a single shared medium Connect two or more segments by copying data frames between them Switches only copy data when

More information

VoIP Session Capacity Expansion with Packet Transmission Suppression Control in Wireless LAN

VoIP Session Capacity Expansion with Packet Transmission Suppression Control in Wireless LAN 1144 PAPER Special Section on Internet Technology and its Architecture for Ambient Information Systems VoIP Session Capacity Expansion with Packet Transmission Suppression Control in Wireless LAN Yasufumi

More information

Saturday, August 25, 2012 1. MUM Home INDIA Assignment 2012 Soumil Gupta Bhaya PROPRIETARY WIRELESS PROTOCOLS. N-Streme and Nv2

Saturday, August 25, 2012 1. MUM Home INDIA Assignment 2012 Soumil Gupta Bhaya PROPRIETARY WIRELESS PROTOCOLS. N-Streme and Nv2 1 MUM Home INDIA Assignment 2012 Soumil Gupta Bhaya PROPRIETARY WIRELESS PROTOCOLS N-Streme and Nv2 2 3 Nstreme and NV2 are Wireless Protocols created by Mikrotik to improve Point to Point and Point to

More information

LTE VoIP Capacity with Soft Frequency Reuse. Dipl.-Ing. Maciej Mühleisen ComNets TUHH FFV Workshop 15.3.2013

LTE VoIP Capacity with Soft Frequency Reuse. Dipl.-Ing. Maciej Mühleisen ComNets TUHH FFV Workshop 15.3.2013 LTE VoIP Capacity with Soft Frequency Reuse Dipl.-Ing. Maciej Mühleisen ComNets TUHH FFV Workshop 15.3.2013 1 Outline Motivation VoIP Scheduling Soft Frequency Reuse Scheduler Concept Scenario & Results

More information

Investigating Power Consumption in 802.11 WLANs: Measurement, Visualization, and Improvement

Investigating Power Consumption in 802.11 WLANs: Measurement, Visualization, and Improvement Investigating Power Consumption in 802.11 WLANs: Measurement, Visualization, and Improvement By Meng Li Thesis submitted in Partial Fulfillment of the Requirements for the Degree Master of Technology in

More information

WiLink 8 Solutions. Coexistence Solution Highlights. Oct 2013

WiLink 8 Solutions. Coexistence Solution Highlights. Oct 2013 WiLink 8 Solutions Coexistence Solution Highlights Oct 2013 1 Products on market with TI connectivity 2004 2007 2009-11 2013 Use cases: BT voice, WLAN data Features: TDM based operation Strict protection

More information

CS 5480/6480: Computer Networks Spring 2012 Homework 4 Solutions Due by 1:25 PM on April 11 th 2012

CS 5480/6480: Computer Networks Spring 2012 Homework 4 Solutions Due by 1:25 PM on April 11 th 2012 CS 5480/6480: Computer Networks Spring 2012 Homework 4 Solutions Due by 1:25 PM on April 11 th 2012 Important: The solutions to the homework problems from the course book have been provided by the authors.

More information

CS698T Wireless Networks: Principles and Practice

CS698T Wireless Networks: Principles and Practice CS698T Wireless Networks: Principles and Practice Topic 10 IEEE 802.15.4 Bhaskaran Raman, Department of CSE, IIT Kanpur http://www.cse.iitk.ac.in/users/braman/courses/wless-spring2007/ Personal Area Networks

More information

Adjacent Overlapping Channel / Adjacent Non-overlapping Channel - The IEEE 802.11-2007 standard defines the following terms:

Adjacent Overlapping Channel / Adjacent Non-overlapping Channel - The IEEE 802.11-2007 standard defines the following terms: CWNP Exam Terms Active Mode - Power management of a non-ap station (STA) operates in either active mode or powersave mode. A STA in active mode is always in an awake state. Vendors have called this, Continually

More information

ECE 428 Computer Networks and Security

ECE 428 Computer Networks and Security ECE 428 Computer Networks and Security 1 Instructor: Sagar Naik About the Instructor Office: EIT 4174, ECE Dept. Other courses that I teach ECE 355: Software Engineering ECE 453/CS 447/ SE 465: Software

More information

Chapter 5: Wireless Design Models, Topologies, and Infrastructure

Chapter 5: Wireless Design Models, Topologies, and Infrastructure Chapter 5: Wireless Design Models, Topologies, and Infrastructure Overview Define, describe, and apply the following concepts associated with WLAN service sets Stations and BSSs Starting and Joining a

More information

A Software Architecture for Simulating IEEE 802.11e HCCA

A Software Architecture for Simulating IEEE 802.11e HCCA A Software Architecture for Simulating IEEE 802.11e HCCA Claudio Cicconetti, Luciano Lenzini, Enzo Mingozzi, Giovanni Stea Dipartimento di Ingegneria dell'informazione University of Pisa, Italy IPS-MoMe

More information

HO Policies for Combined WLAN/UMTS Networks

HO Policies for Combined WLAN/UMTS Networks HO Policies for Combined WLAN/UMTS Networks Sven Wiethölter Telecommunication Networks Group TU Berlin Telecommunication Networks Group Technische Universität Berlin Project Overview Project partners Goal:

More information

GTER 26 tudo o que você. quer saber sobre 802.11n

GTER 26 tudo o que você. quer saber sobre 802.11n GTER 26 tudo o que você (não) quer saber sobre 802.11n Luiz Eduardo Dos Santos CISSP CWNE CEH GISP GCIH Sr. Systems & Security Engineer Americas hello agenda evolution of wi-fi what makes 11n what actually

More information

IEEE 802 Protocol Layers. IEEE 802.11 Wireless LAN Standard. Protocol Architecture. Protocol Architecture. Separation of LLC and MAC.

IEEE 802 Protocol Layers. IEEE 802.11 Wireless LAN Standard. Protocol Architecture. Protocol Architecture. Separation of LLC and MAC. IEEE 802.11 Wireless LAN Standard IEEE 802 Protocol Layers Chapter 14 Protocol Architecture Functions of physical layer: Encoding/decoding of signals Preamble generation/removal (for synchronization) Bit

More information

WiFi. Is for Wireless Fidelity Or IEEE 802.11 Standard By Greg Goldman. WiFi 1

WiFi. Is for Wireless Fidelity Or IEEE 802.11 Standard By Greg Goldman. WiFi 1 WiFi Is for Wireless Fidelity Or IEEE 802.11 Standard By Greg Goldman WiFi 1 What is the goal of 802.11 standard? To develop a Medium Access Control (MAC) and Physical Layer (PHY) specification for wireless

More information

ProSafe 16 AP Wireless Management System WMS5316

ProSafe 16 AP Wireless Management System WMS5316 ProSafe 16 AP Wireless Management System WMS5316 Reference Manual 350 East Plumeria Drive San Jose, CA 95134 USA July 2010 202-10601-02 v1.0 2010 NETGEAR, Inc. All rights reserved. No part of this publication

More information

ECE 333: Introduction to Communication Networks Fall 2002

ECE 333: Introduction to Communication Networks Fall 2002 ECE 333: Introduction to Communication Networks Fall 2002 Lecture 14: Medium Access Control II Dynamic Channel Allocation Pure Aloha In the last lecture we began discussing medium access control protocols

More information

PREVENTING WIRELESS LAN DENIAL OF SERVICE ATTACKS

PREVENTING WIRELESS LAN DENIAL OF SERVICE ATTACKS PREVENTING WIRELESS LAN DENIAL OF SERVICE ATTACKS A Guide to combating WLAN DoS Vulnerabilities Executive Summary Wireless communications that use a shared Radio Frequency (RF) medium are often vulnerable

More information

Mac Protocols for Wireless Sensor Networks

Mac Protocols for Wireless Sensor Networks Mac Protocols for Wireless Sensor Networks Hans-Christian Halfbrodt Advisor: Pardeep Kumar Institute of Computer Science Freie Universität Berlin, Germany halfbrodt@inf.fu-berlin.de January 2010 Contents

More information

Fast Retransmission Mechanism for VoIP in IEEE 802.11e wireless LANs

Fast Retransmission Mechanism for VoIP in IEEE 802.11e wireless LANs Fast Mechanism for VoIP in IEEE 802.11e wireless LANs Gyung-Ho Hwang and Dong-Ho Cho Division of Electrical Engineering, Department of Electrical Engineering and Computer Science, KAIST, 373-1 Guseong-dong

More information

Wireless LAN Consortium

Wireless LAN Consortium Wireless LAN Consortium 802.11abgn Infrastructure Interoperability Test Suite Version 4.5 Technical Document Last Updated: May 27, 2014 Wireless LAN Consortium 121 Technology Drive, Suite 2 InterOperability

More information

Adaptive Coding and Energy Efficient Packet Rate Transmission over Wireless LAN Friendly VOIP

Adaptive Coding and Energy Efficient Packet Rate Transmission over Wireless LAN Friendly VOIP Adaptive Coding and Energy Efficient Packet Rate Transmission over Wireless LAN Friendly VOIP Shruti Chaurasia Department of computer science Amity University sector -125, Noida (U.P.) Kamal Kant Department

More information

Protection Ripple in ERP 802.11 WLANs White Paper

Protection Ripple in ERP 802.11 WLANs White Paper Protection Ripple in ERP 802.11 WLANs White Paper June 2004 Planet3 Wireless, Inc. Devin Akin, CTO Devin@cwnp.com Copyright 2004 The CWNP Program www.cwnp.com Page 1 Understanding Use of 802.11g Protection

More information

Chapter 6: Medium Access Control Layer

Chapter 6: Medium Access Control Layer Chapter 6: Medium Access Control Layer Chapter 6: Roadmap Overview! Wireless MAC protocols! Carrier Sense Multiple Access! Multiple Access with Collision Avoidance (MACA) and MACAW! MACA By Invitation!

More information