EPL 657 Wireless Networks

Size: px
Start display at page:

Download "EPL 657 Wireless Networks"

Transcription

1 EPL 657 Wireless Networks Some fundamentals: Multiplexing / Multiple Access / Duplex Infrastructure vs Infrastructureless Panayiotis Kolios

2 Recall: The big picture... Modulations: some basics 2

3 Multiplexing / multiple access / duplexing (1) Multiplexing / multiple access Signals to/from different users share a common channel using time division methods (TDM/TDMA, CSMA), frequency division methods (FDM/FDMA), code division methods (CDMA), or space division (SDMA). A combination of above is also often used

4 Multiplexing / multiple access / duplexing (2) Duplexing: The signals moving between two elements in opposite directions can be separated using time division duplexing (TDD) frequency division duplexing (FDD) Code Division Duplexing (CDD)

5 Multiplexing Goal: multiple use of a shared medium Multiplexing in 4 dimensions: space (si) time (t) frequency (f) code (c) or even a combination Important: guard spaces needed! Selective receivers/filters required to obtain/extract signal intended for user

6 Time multiplex A channel gets the whole spectrum for a certain amount of time Advantages: only one carrier in the medium at any time throughput high even for many users Disadvantages: Precise Synchronization necessary Can be complex Can be inefficient TDM (Time Division Multiplexing): channel divided into N time slots, one per user; inefficient with low duty cycle users and at light load.

7 Example Channel Partitioning MAC protocols: TDMA TDMA: time division multiple access access to channel in "rounds" each station gets fixed length slot (length = packet transmision time) in each round unused slots go idle example: 6-station LAN, 1,3,4 have packet, slots 2,5,6 idle

8 Frequency multiplex Separation of the whole spectrum into smaller frequency bands A channel gets a certain band of the spectrum for the whole time Advantages: no dynamic coordination necessary works also for analog signals Disadvantages: waste of bandwidth if the traffic is distributed unevenly inflexible guard spaces Selective filters required Can be complex FDM (Frequency Division Multiplexing): frequency subdivided among N users, each user takes one; inefficient with low duty cycle users and at light load.

9 frequency bands Example Channel Partitioning MAC protocols: FDMA FDMA: frequency division multiple access channel spectrum divided into frequency bands each station assigned fixed frequency band unused transmission time in frequency bands go idle example: 6-station LAN, 1,3,4 have pkt, frequency bands 2,5,6 idle e.g. Assigned channel frequency Mhz Needs of each user: 1Mhz f1= 800 Mhz, f2=801, Mhz... f1-f2 f11-f12

10 Time and frequency multiplex Combination of both methods A channel gets a certain frequency band for a certain amount of time Example: GSM Advantages: better protection against tapping protection against frequency selective interference higher data rates compared to code multiplex but: precise coordination required increased complexity, and inefficiency

11 Code multiplex Each channel has a unique code All channels use the same spectrum at the same time (spread the spectrum- each bit is expanded to many bits-a code, e.g logical bit 1' is expanded to ) Advantages: bandwidth efficient no coordination and synchronization necessary good protection against interference and tapping Disadvantages: lower user data rates more complex signal regeneration Implemented using spread spectrum technology

12 Example: Channel Partitioning (CDMA) CDMA (Code Division Multiple Access) unique code assigned to each user; i.e., code set partitioning used mostly in wireless broadcast channels (cellular, satellite, etc) all users share same frequency, but each user has own chipping sequence (i.e., code, language ) to encode data encoded signal = (original data) X (chipping sequence) decoding: inner-product of encoded signal and chipping sequence allows multiple users to coexist and transmit simultaneously with minimal interference (if codes are orthogonal ) Note each user appears as interference to others!!!

13 Example: CDMA Encode/Decode

14 Example: CDMA two-sender interference

15 space division multiplex Cell structure Implements space division multiplex: base station covers a certain transmission area (cell) Mobile stations communicate only via the base station Advantages of cell structures: higher capacity, higher number of users less transmission power needed more robust, decentralized base station deals with interference, transmission area etc. locally Problems: fixed network needed for the base stations handover (changing from one cell to another) necessary interference with other cells Cell sizes from some 100 m in cities to, e.g., 35 km on the country side (GSM) - less for higher frequencies (e.g. UMTS)

16 Example: cell What is a Cell? Cell is the Basic Union in The Mobile Telecommunications System defined as the area where radio coverage is given by one base station. A cell has one or several frequencies, depending on traffic load. Fundamental idea: Frequencies are reused, but not in neighboring cells due to interference.

17 Example: cell planning (capacity, power, etc...) Cell splitting Decrease transmission power in base and mobile Results in more and smaller cells Reuse frequencies in noncontiguous cell groups Example: ½ cell radius leads 4 fold capacity increase (BUT higher infrastructure costs) Cell sectoring Directional antennas subdivide cell into 3 or 6 sectors Might also increase cell capacity by factor of 3 or 6

18 Example: Different Types of Cells

19 Duplex Frequency Division Duplex (FDD): Uplink and downlink transmissions use two separated radio frequencies in different frequency bands. A pair of frequency bands with specified separation is assigned for the system. Time Division Duplex (TDD): Uplink and downlink transmissions are carried over same radio frequency by using synchronized time slots that divide the physical channel into transmission and reception part. Information on uplink and downlink are transmitted reciprocally. Code Division Duplex (CDD): Uplink and downlink transmissions are carried over the same radio frequency and time using orthogonal signal sequences (different codes).

20 Example Radio Access FDMA/FDD (as in 1st Generation Wireless) Access is FDMA: Frequency Division Multiple Access The 1st generation mobile system uses FDMA only. Example: AMP in USA Uplink Downlink Frequency Duplex is FDD: Frequency Division Duplex The FM channels are paired with an uplink and a downlink channel for each user.

21 Example Radio Access TDMA (as in 2nd Generation wireless) GSM, a 2nd generation mobile system, uses 8 time slots in TDMA mode for each 200 khz carrier. Carriers are derived from frequency division over the licensed frequency band (FDMA) Frequency Time Note: Capacity in GSM is doubled by using alternate time slots to support 16 channels

22 Example Radio Access TDMA (as in 2nd Generation wireless) IS-136 TDMA or DAMP (Digital AMP) is the American TDMA system with 3 time slots over a 30kHz carrier TDMA6 provides 6 channels by alternating the 3 time slots

23 Example Radio Access TDMA/FDD (as in 2nd Generation wireless) GSM and IS-136 TDMA are TDMA/FDD Frequency Time

24 Example Radio Access CDMA (as in 2nd Generation wireless) IS-95, a 2nd generation mobile system, uses CDMA User E User D User C Code Sequences Frequency User B User A Time

25 Example Radio Access CDMA/FDD (as in 2nd Generation wireless) IS-95 is CDMA/FDD Frequency Code Sequences Time

26 Example Radio Access 2nd Generation Going from analog to digital and to CDMA makes more efficient use of the scarce radio resources (and expensive frequency spectrum license), and hence helps to lower the price.

27 Example Radio Access Wideband CDMA (3G) WCDMA allocates 10 ms (38,400 chips) frames to users. The data rate for a user may change from frame to frame (using variable length CDMA codes). Frequency 10ms, 38,400 chips per frame User E User D User C User B User A Variable data rate Time

28 Example Radio Access Wideband CDMA UTRA/FDD Frequency Separate carriers for Uplink downlink Time

29 Examples Multiplexing / multiple access / duplexing Network IEEE WPAN (Bluetooth) IEEE LR- WPAN (ZigBee) IEEE WLAN (WiFi) IEEE WMAN (WiMAX) Multiplexing / MA / duplexing TDMA / TDD CSMA/CA CSMA/CA TDM/TDMA (down/uplink) / TDD or (semi-duplex) FDD

30 Multiple Access protocols (MAC) Share access (time) on the common channel single shared broadcast channel two or more simultaneous transmissions by nodes cause interference only one node can send successfully at a time, therefore need multiple access protocols distributed algorithm that determines how nodes share channel, i.e., determine when node can transmit communication about channel sharing must use channel itself!

31 Ideal Multiple Access Protocol Broadcast channel of rate R bps 1. When one node wants to transmit, it can send at rate R. 2. When M nodes want to transmit, each can send at average rate R/M 3. When more than one send at the same time, then collision 4. Fully decentralized: no special node to coordinate transmissions no synchronization of clocks, slots 5. Simple

32 MAC Protocols: a taxonomy Three broad classes: Channel Partitioning divide channel into smaller pieces (time slots, frequency, code, space) allocate piece to node for exclusive use Random Access (e.g. Ethernet) access when data available to send (random) channel not divided, allow collisions recover from collisions Taking turns (e.g. Token ring) tightly coordinate shared access to avoid collisions

33 A popular wireless MAC: CSMA/CA (Collision Avoidance) Recall in wired Ethernet: CSMA/CD: carrier sensing, deferral if busy collisions detected within short time colliding transmissions aborted, reducing channel wastage collision detection: easy in wired LANs: measure signal strengths, compare transmitted, received signals difficult in wireless LANs: receiver shut off while transmitting in wireless CSMA/CA (Collision Avoidance) more later

34 Infrastructure / Infrastructureless networks

35

36 Sensor networks and VANETs are another form of infrastructureless network, with many similarities to ad-hock

37 infrastructure vs. ad-hoc networks (WLAN) infrastructure network AP AP wired network AP: Access Point AP ad-hoc network

38 Infrastructure-based networks (WLAN) Infrastructure networks provide access to other networks. Communication typically takes place only between the wireless nodes and the access point, but not directly between the wireless nodes. The access point does not just control medium access, but also acts as a bridge to other wireless or wired networks. Several wireless networks may form one logical wireless network: The access points together with the fixed network in between can connect several wireless networks to form a larger network beyond actual radio coverage.

39 Infrastructure-based networks (WLAN) Network functionality lies within the access point (controls network flow), whereas the wireless clients can remain quite simple. Use different access schemes with or without collision. Collisions may occur if medium access of the wireless nodes and the access point is not coordinated (e.g. DCF: CSMA/CA). If only the access point controls medium access, no collisions are possible (e.g. PCF). Useful for quality of service guarantees (e.g., minimum bandwidth for certain nodes) The access point may poll the single wireless nodes to ensure the data rate. Infrastructure-based wireless networks lose some of the flexibility wireless networks can offer in general: E.g. they cannot be used for disaster relief in cases where no infrastructure is left.

40 Infrastructureless No need of any infrastructure to work greatest possible flexibility Each node communicate with other nodes, so no access point controlling medium access is necessary (autonomous operation). The complexity of each node is higher implement medium access mechanisms, forwarding data Nodes within an ad-hoc network can only communicate if they can reach each other physically if they are within each other s radio range if other nodes can forward the message

41 Infrastructureless (Ad Hoc Networks) Some Features (typically) Lack of a centralized entity Network self-organization All the communication is carried over the wireless medium Rapid mobile host movements possible Multi-hop routing Power and computing power may be constrained

42 Infrastructureless (Sensor Networks) Some Features Many similarities to ad-hock networks power and computing power constrained Large number of sensors (application dependant) Limited wireless bandwidth Limited battery power Low energy use Efficient use of the small memory Data aggregation Network self-organization Collaborative signal processing Querying ability

43 VANET Networks: VANETS: Vehicle Ad-hock Networks Some Features Many similarities to ad-hock networks power and computing power not necessarily as constrained as in sensor or ad-hoc networks Large number of mobile nodes (cars) Network self-organization Topology dictated by road system

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

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

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

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

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

Wireless Information Transmission System Lab. Introduction to Wireless Communications

Wireless Information Transmission System Lab. Introduction to Wireless Communications Wireless Information Transmission System Lab. Introduction to Wireless Communications Wireless Communication Systems Network Radio wave wire wire LAN Network Base station transceiver LAN 2 Wireless Technologies

More information

Revision of Lecture Eighteen

Revision of Lecture Eighteen Revision of Lecture Eighteen Previous lecture has discussed equalisation using Viterbi algorithm: Note similarity with channel decoding using maximum likelihood sequence estimation principle It also discusses

More information

Wireless Personal Area Networks (WPANs)

Wireless Personal Area Networks (WPANs) Wireless Personal Area Networks (WPANs) Bluetooth, ZigBee Contents Introduction to the IEEE 802 specification family Concept of ISM frequency band Comparison between different wireless technologies ( and

More information

GSM Network and Services

GSM Network and Services GSM Network and Services Cellular networks GSM Network and Services 2G1723 Johan Montelius 1 The name of the game The number one priority for mobile/cellular networks is to implement full-duplex voice

More information

Module 5. Broadcast Communication Networks. Version 2 CSE IIT, Kharagpur

Module 5. Broadcast Communication Networks. Version 2 CSE IIT, Kharagpur Module 5 Broadcast Communication Networks Lesson 9 Cellular Telephone Networks Specific Instructional Objectives At the end of this lesson, the student will be able to: Explain the operation of Cellular

More information

Lecture 1. Introduction to Wireless Communications 1

Lecture 1. Introduction to Wireless Communications 1 896960 Introduction to Algorithmic Wireless Communications Lecture 1. Introduction to Wireless Communications 1 David Amzallag 2 May 25, 2008 Introduction to cellular telephone systems. How a cellular

More information

CS 8803 - Cellular and Mobile Network Security: CDMA/UMTS Air Interface

CS 8803 - Cellular and Mobile Network Security: CDMA/UMTS Air Interface CS 8803 - Cellular and Mobile Network Security: CDMA/UMTS Air Interface Hank Carter Professor Patrick Traynor 10/4/2012 UMTS and CDMA 3G technology - major change from GSM (TDMA) Based on techniques originally

More information

Multiple Access Techniques

Multiple Access Techniques Chapter 8 Multiple Access Techniques Multiple access techniques are used to allow a large number of mobile users to share the allocated spectrum in the most efficient manner. As the spectrum is limited,

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

3GPP Wireless Standard

3GPP Wireless Standard 3GPP Wireless Standard Shishir Pandey School of Technology and Computer Science TIFR, Mumbai April 10, 2009 Shishir Pandey (TIFR) 3GPP Wireless Standard April 10, 2009 1 / 23 3GPP Overview 3GPP : 3rd Generation

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

Chapter 2 Mobile Communication

Chapter 2 Mobile Communication Page 77 Chapter 2 Mobile Communication 2.1 Characteristics of Mobile Computing 2.2 Wireless Communication Basics 2.3 Wireless Communication Technologies PANs (Bluetooth, ZigBee) Wireless LAN (IEEE 802.11)

More information

WPAN, WLAN, WMAN. Bluetooth, ZigBee, WiFi, WiMAX

WPAN, WLAN, WMAN. Bluetooth, ZigBee, WiFi, WiMAX WPAN, WLAN, WMAN Bluetooth, ZigBee, WiFi, WiMAX Contents Introduction to the IEEE 802 specification family Concept of ISM frequency band Comparison between different wireless technologies (PHY and MAC

More information

communication over wireless link handling mobile user who changes point of attachment to network

communication over wireless link handling mobile user who changes point of attachment to network Wireless Networks Background: # wireless (mobile) phone subscribers now exceeds # wired phone subscribers! computer nets: laptops, palmtops, PDAs, Internet-enabled phone promise anytime untethered Internet

More information

Chapter 6 Wireless and Mobile Networks

Chapter 6 Wireless and Mobile Networks Chapter 6 Wireless and Mobile Networks A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you see the animations;

More information

Mobile Communications TCS 455

Mobile Communications TCS 455 Mobile Communications TCS 455 Dr. Prapun Suksompong prapun@siit.tu.ac.th Lecture 26 1 Office Hours: BKD 3601-7 Tuesday 14:00-16:00 Thursday 9:30-11:30 Announcements Read the following from the SIIT online

More information

Hello viewers, welcome to today s lecture on cellular telephone systems.

Hello viewers, welcome to today s lecture on cellular telephone systems. Data Communications Prof. A. Pal Department of Computer Science & Engineering Indian Institute of Technology, Kharagpur Lecture minus 31 Cellular Telephone Systems Hello viewers, welcome to today s lecture

More information

Wireless LAN advantages. Wireless LAN. Wireless LAN disadvantages. Wireless LAN disadvantages WLAN:

Wireless LAN advantages. Wireless LAN. Wireless LAN disadvantages. Wireless LAN disadvantages WLAN: WLAN: Wireless LAN Make use of a wireless transmission medium Tipically restricted in their diameter: buildings, campus, single room etc.. The global goal is to replace office cabling and to introduce

More information

CHAPTER - 4 CHANNEL ALLOCATION BASED WIMAX TOPOLOGY

CHAPTER - 4 CHANNEL ALLOCATION BASED WIMAX TOPOLOGY CHAPTER - 4 CHANNEL ALLOCATION BASED WIMAX TOPOLOGY 4.1. INTRODUCTION In recent years, the rapid growth of wireless communication technology has improved the transmission data rate and communication distance.

More information

CDMA Network Planning

CDMA Network Planning CDMA Network Planning by AWE Communications GmbH www.awe-com.com Contents Motivation Overview Network Planning Module Air Interface Cell Load Interference Network Simulation Simulation Results by AWE Communications

More information

About Me" List of Lectures" In This Course" Mobile and Sensor Systems. Lecture 1: Introduction to Wireless Systems" " Dr. Cecilia Mascolo" "

About Me List of Lectures In This Course Mobile and Sensor Systems. Lecture 1: Introduction to Wireless Systems  Dr. Cecilia Mascolo About Me Reader in Mobile Systems NetOS Research Group Research on Mobile, Social and Sensor Systems More specifically, Human Mobility and Social Network modelling Opportunistic Mobile Networks Mobile

More information

GSM and Similar Architectures Lesson 07 GSM Radio Interface, Data bursts and Interleaving

GSM and Similar Architectures Lesson 07 GSM Radio Interface, Data bursts and Interleaving GSM and Similar Architectures Lesson 07 GSM Radio Interface, Data bursts and Interleaving 1 Space Division Multiple Access of the signals from the MSs A BTS with n directed antennae covers mobile stations

More information

EECS 122: Introduction to Computer Networks Multiaccess Protocols. ISO OSI Reference Model for Layers

EECS 122: Introduction to Computer Networks Multiaccess Protocols. ISO OSI Reference Model for Layers EECS 122: Introduction to Computer Networks Multiaccess Protocols Computer Science Division Department of Electrical Engineering and Computer Sciences University of California, Berkeley Berkeley, CA 94720-1776

More information

MAC Algorithms in Wireless Networks

MAC Algorithms in Wireless Networks Department of Computing Science Master Thesis MAC Algorithms in Wireless Networks Applications, Issues and Comparisons Shoaib Tariq Supervisor: Dr. Jerry Eriksson Examiner: Dr. Per Lindström Dedicated

More information

Multiple Access Techniques

Multiple Access Techniques Multiple Access Techniques Dr. Francis LAU Dr. Francis CM Lau, Associate Professor, EIE, PolyU Content Introduction Frequency Division Multiple Access Time Division Multiple Access Code Division Multiple

More information

Communication Networks. MAP-TELE 2011/12 José Ruela

Communication Networks. MAP-TELE 2011/12 José Ruela Communication Networks MAP-TELE 2011/12 José Ruela Network basic mechanisms Multiple Access Multiple Access In early data communication systems, one solution to provide access of remote terminals to a

More information

Data Center Networks, Link Layer Wireless (802.11)

Data Center Networks, Link Layer Wireless (802.11) Internet-Technologien (CS262) Data Center Networks, Link Layer Wireless (802.11) 1.4.2015 Christian Tschudin Departement Mathematik und Informatik, Universität Basel 6 Wiederholung Warum «multiple access»?

More information

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

INTRODUCTION TO COMMUNICATION SYSTEMS AND TRANSMISSION MEDIA

INTRODUCTION TO COMMUNICATION SYSTEMS AND TRANSMISSION MEDIA COMM.ENG INTRODUCTION TO COMMUNICATION SYSTEMS AND TRANSMISSION MEDIA 9/6/2014 LECTURES 1 Objectives To give a background on Communication system components and channels (media) A distinction between analogue

More information

Controlled Random Access Methods

Controlled Random Access Methods Helsinki University of Technology S-72.333 Postgraduate Seminar on Radio Communications Controlled Random Access Methods Er Liu liuer@cc.hut.fi Communications Laboratory 09.03.2004 Content of Presentation

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

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

CHAPTER 1 1 INTRODUCTION

CHAPTER 1 1 INTRODUCTION CHAPTER 1 1 INTRODUCTION 1.1 Wireless Networks Background 1.1.1 Evolution of Wireless Networks Figure 1.1 shows a general view of the evolution of wireless networks. It is well known that the first successful

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

Frequency Hopping Spread Spectrum (FHSS) vs. Direct Sequence Spread Spectrum (DSSS) in Broadband Wireless Access (BWA) and Wireless LAN (WLAN)

Frequency Hopping Spread Spectrum (FHSS) vs. Direct Sequence Spread Spectrum (DSSS) in Broadband Wireless Access (BWA) and Wireless LAN (WLAN) FHSS vs. DSSS page 1 of 16 Frequency Hopping Spread Spectrum (FHSS) vs. Direct Sequence Spread Spectrum (DSSS) in Broadband Wireless Access (BWA) and Wireless LAN (WLAN) by Sorin M. SCHWARTZ Scope In 1997

More information

CSE 123A Computer Networks

CSE 123A Computer Networks CSE 123A Computer Networks Winter 2005 Lecture 5: Data-Link II: Media Access Some portions courtesy Srini Seshan or David Wetherall Last Time Framing: How to translate a bitstream into separate packets

More information

Cellular Network Organization. Cellular Wireless Networks. Approaches to Cope with Increasing Capacity. Frequency Reuse

Cellular Network Organization. Cellular Wireless Networks. Approaches to Cope with Increasing Capacity. Frequency Reuse Cellular Network Organization Cellular Wireless Networks Use multiple low-power transmitters (100 W or less) Areas divided into cells Each served by its own antenna Served by base station consisting of

More information

1 Lecture Notes 1 Interference Limited System, Cellular. Systems Introduction, Power and Path Loss

1 Lecture Notes 1 Interference Limited System, Cellular. Systems Introduction, Power and Path Loss ECE 5325/6325: Wireless Communication Systems Lecture Notes, Spring 2015 1 Lecture Notes 1 Interference Limited System, Cellular Systems Introduction, Power and Path Loss Reading: Mol 1, 2, 3.3, Patwari

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

TABLE OF CONTENTS. Dedication. Table of Contents. Preface. Overview of Wireless Networks. vii 1.1 1.2 1.3 1.4 1.5 1.6 1.7. xvii

TABLE OF CONTENTS. Dedication. Table of Contents. Preface. Overview of Wireless Networks. vii 1.1 1.2 1.3 1.4 1.5 1.6 1.7. xvii TABLE OF CONTENTS Dedication Table of Contents Preface v vii xvii Chapter 1 Overview of Wireless Networks 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Signal Coverage Propagation Mechanisms 1.2.1 Multipath 1.2.2 Delay

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

Local Area Networks transmission system private speedy and secure kilometres shared transmission medium hardware & software

Local Area Networks transmission system private speedy and secure kilometres shared transmission medium hardware & software Local Area What s a LAN? A transmission system, usually private owned, very speedy and secure, covering a geographical area in the range of kilometres, comprising a shared transmission medium and a set

More information

Introduction to Ad hoc Networks

Introduction to Ad hoc Networks Introduction to Ad hoc Networks CS-647: Advanced Topics in Wireless Networks Drs. Baruch Awerbuch & Amitabh Mishra Department of Computer Science Johns Hopkins University Amitabh Mishra & Baruch Awerbuch

More information

Introduction to Wireless Communications and Networks

Introduction to Wireless Communications and Networks Introduction to Wireless Communications and Networks Tongtong Li Dept. Electrical and Computer Engineering East Lansing, MI 48824 tongli@egr.msu.edu 1 Outline Overview of a Communication System Digital

More information

Mobile Network Evolution Part 1. GSM and UMTS

Mobile Network Evolution Part 1. GSM and UMTS Mobile Network Evolution Part 1 GSM and UMTS GSM Cell layout Architecture Call setup Mobility management Security GPRS Architecture Protocols QoS EDGE UMTS Architecture Integrated Communication Systems

More information

Multiplexing on Wireline Telephone Systems

Multiplexing on Wireline Telephone Systems Multiplexing on Wireline Telephone Systems Isha Batra, Divya Raheja Information Technology, Dronacharya College of Engineering Farrukh Nagar, Gurgaon, India ABSTRACT- This Paper Outlines a research multiplexing

More information

CDMA Technology : Pr. S. Flament www.greyc.fr/user/99. Pr. Dr. W. Skupin www.htwg-konstanz.de. On line Course on CDMA Technology

CDMA Technology : Pr. S. Flament www.greyc.fr/user/99. Pr. Dr. W. Skupin www.htwg-konstanz.de. On line Course on CDMA Technology CDMA Technology : Pr. Dr. W. Skupin www.htwg-konstanz.de Pr. S. Flament www.greyc.fr/user/99 On line Course on CDMA Technology CDMA Technology : Introduction to Spread Spectrum Technology CDMA / DS : Principle

More information

What is it all about? Some simple solutions. Multiple Access. Contexts for the multiple access problem. Outline. Contexts

What is it all about? Some simple solutions. Multiple Access. Contexts for the multiple access problem. Outline. Contexts Multiple Access An Engineering Approach to Computer Networking What is it all about? ider an audioconference where if one person speaks, all can hear if more than one person speaks at the same time, both

More information

Questions for Mobile Communications 2 nd ed.

Questions for Mobile Communications 2 nd ed. Questions for Mobile Communications 2 nd ed. Jochen H. Schiller, Freie Universität Berlin, Germany schiller@computer.org, www.jochenschiller.de 1. Introduction 1.1 Discover the current numbers of subscribers

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

Lecture 18: CDMA. What is Multiple Access? ECE 598 Fall 2006

Lecture 18: CDMA. What is Multiple Access? ECE 598 Fall 2006 ECE 598 Fall 2006 Lecture 18: CDMA What is Multiple Access? Multiple users want to communicate in a common geographic area Cellular Example: Many people want to talk on their cell phones. Each phone must

More information

Objectives. Lecture 4. How do computers communicate? How do computers communicate? Local asynchronous communication. How do computers communicate?

Objectives. Lecture 4. How do computers communicate? How do computers communicate? Local asynchronous communication. How do computers communicate? Lecture 4 Continuation of transmission basics Chapter 3, pages 75-96 Dave Novak School of Business University of Vermont Objectives Line coding Modulation AM, FM, Phase Shift Multiplexing FDM, TDM, WDM

More information

802.16 - Usage. Wireless Broadband Networks. Need for Speed WMAN

802.16 - Usage. Wireless Broadband Networks. Need for Speed WMAN Wireless Broadband Networks - Usage WLAN: Support of mobile devices, but low data rate for higher number of users What to do for a high number of users or even needed QoS support? Problem of the last mile

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

Collision of wireless signals. The MAC layer in wireless networks. Wireless MAC protocols classification. Evolutionary perspective of distributed MAC

Collision of wireless signals. The MAC layer in wireless networks. Wireless MAC protocols classification. Evolutionary perspective of distributed MAC 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

Wireless LAN Concepts

Wireless LAN Concepts Wireless LAN Concepts Wireless LAN technology is becoming increasingly popular for a wide variety of applications. After evaluating the technology, most users are convinced of its reliability, satisfied

More information

Chapter 1 Introduction to Wireless Communication Systems. School of Information Science and Engineering, SDU

Chapter 1 Introduction to Wireless Communication Systems. School of Information Science and Engineering, SDU Chapter 1 Introduction to Wireless Communication Systems School of Information Science and Engineering, SDU Outline Wireless History The Wireless Vision Technical Challenges Wireless definitions Classification

More information

Wireless Cellular Networks: 1G and 2G

Wireless Cellular Networks: 1G and 2G Wireless Cellular Networks: 1G and 2G Raj Jain Professor of Computer Science and Engineering Washington University in Saint Louis Saint Louis, MO 63130 Audio/Video recordings of this lecture are available

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

Local Area Network By Bhupendra Ratha, Lecturer School of Library and Information Science Devi Ahilya University, Indore Email: bhu261@gmail.com Local Area Network LANs connect computers and peripheral

More information

Mobile Communications Chapter 2: Wireless Transmission

Mobile Communications Chapter 2: Wireless Transmission Mobile Communications Chapter 2: Wireless Transmission Frequencies Signals Antennas Signal propagation Multiplexing Spread spectrum Modulation Cellular systems Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/

More information

Lecture 1: Introduction

Lecture 1: Introduction Mobile Data Networks Lecturer: Victor O.K. Li EEE Department Room: CYC601D Tel.: 857 845 Email: vli@eee.hku.hk Course home page: http://www.eee.hku.hk/courses.msc/ 1 Lecture 1: Introduction Mobile data

More information

frequency experienced by mobile is not f but distorted version of f: call it f

frequency experienced by mobile is not f but distorted version of f: call it f Impact of mobility: Doppler frequency shift and fading First, Doppler frequency shift Set-up: mobile (e.g., car, train, pedestrian) travels in straight line at speed v mph sender transmits data on carrier

More information

Computer Networks. Wireless and Mobile Networks. László Böszörményi Computer Networks Mobile - 1

Computer Networks. Wireless and Mobile Networks. László Böszörményi Computer Networks Mobile - 1 Computer Networks Wireless and Mobile Networks László Böszörményi Computer Networks Mobile - 1 Background Number of wireless (mobile) phone subscribers now exceeds number of wired phone subscribers! Computer

More information

From reconfigurable transceivers to reconfigurable networks, part II: Cognitive radio networks. Loreto Pescosolido

From reconfigurable transceivers to reconfigurable networks, part II: Cognitive radio networks. Loreto Pescosolido From reconfigurable transceivers to reconfigurable networks, part II: Cognitive radio networks Loreto Pescosolido Spectrum occupancy with current technologies Current wireless networks, operating in either

More information

Chapters 1-21 Introduction to Wireless Communication Systems

Chapters 1-21 Introduction to Wireless Communication Systems Chapters 1-21 Introduction to Wireless Communication Systems Yimin Zhang, Ph.D. Department of Electrical & Computer Engineering Villanova University http://yiminzhang.com/ece8708 Yimin Zhang, Villanova

More information

RTT 60.5 msec receiver window size: 32 KB

RTT 60.5 msec receiver window size: 32 KB Real-World ARQ Performance: TCP Ex.: Purdue UCSD Purdue (NSL): web server UCSD: web client traceroute to planetlab3.ucsd.edu (132.239.17.226), 30 hops max, 40 byte packets 1 switch-lwsn2133-z1r11 (128.10.27.250)

More information

CS 8803 - Cellular and Mobile Network Security: Cellular Networking

CS 8803 - Cellular and Mobile Network Security: Cellular Networking CS 8803 - Cellular and Mobile Network Security: Cellular Networking Professor Patrick Traynor 9/13/2012 The Big Picture Details create the big picture. -Sanford I. Weill 2 Overview Evolution Architecture

More information

LoRaWAN. What is it? A technical overview of LoRa and LoRaWAN. Technical Marketing Workgroup 1.0

LoRaWAN. What is it? A technical overview of LoRa and LoRaWAN. Technical Marketing Workgroup 1.0 LoRaWAN What is it? A technical overview of LoRa and LoRaWAN Technical Marketing Workgroup 1.0 November 2015 TABLE OF CONTENTS 1. INTRODUCTION... 3 What is LoRa?... 3 Long Range (LoRa )... 3 2. Where does

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

CHAPTER 8 MULTIPLEXING

CHAPTER 8 MULTIPLEXING CHAPTER MULTIPLEXING 3 ANSWERS TO QUESTIONS.1 Multiplexing is cost-effective because the higher the data rate, the more cost-effective the transmission facility.. Interference is avoided under frequency

More information

Modern Wireless Communication Systems

Modern Wireless Communication Systems Chapter 2 Modern Wireless Communication Systems At the initial phase, mobile communication was restricted to certain official users and the cellular concept was never even dreamt of being made commercially

More information

Appendix A: Basic network architecture

Appendix A: Basic network architecture Appendix A: Basic network architecture TELECOMMUNICATIONS LOCAL ACCESS NETWORKS Traditionally, telecommunications networks are classified as either fixed or mobile, based on the degree of mobility afforded

More information

Ethernet, VLAN, Ethernet Carrier Grade

Ethernet, VLAN, Ethernet Carrier Grade Ethernet, VLAN, Ethernet Carrier Grade Dr. Rami Langar LIP6/PHARE UPMC - University of Paris 6 Rami.langar@lip6.fr www-phare.lip6.fr/~langar RTEL 1 Point-to-Point vs. Broadcast Media Point-to-point PPP

More information

Performance Issues of TCP and MPEG-4 4 over UMTS

Performance Issues of TCP and MPEG-4 4 over UMTS Performance Issues of TCP and MPEG-4 4 over UMTS Anthony Lo A.Lo@ewi.tudelft.nl 1 Wiskunde end Informatica Outline UMTS Overview TCP and MPEG-4 Performance Summary 2 1 Universal Mobile Telecommunications

More information

Physical Layer. Communication Satellites. ECE 453 Introduction to Computer Networks. Lecture 3 Physical Layer II

Physical Layer. Communication Satellites. ECE 453 Introduction to Computer Networks. Lecture 3 Physical Layer II ECE 453 Introduction to Computer Networks Lecture 3 Physical Layer II 1 Physical Layer Services transmit bits from sender to receiver. Transmission media Guided: twisted pair, coax, fiber Unguided (wireless):

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

1 Which network type is a specifically designed configuration of computers and other devices located within a confined area? A Peer-to-peer network

1 Which network type is a specifically designed configuration of computers and other devices located within a confined area? A Peer-to-peer network Review questions 1 Which network type is a specifically designed configuration of computers and other devices located within a confined area? A Peer-to-peer network B Local area network C Client/server

More information

Efficient Preemption Method on CDMA Systems

Efficient Preemption Method on CDMA Systems Efficient Preemption Method on CDMA Systems Naoki KANADA, Kakuichi SHIOMI kanada@enri.go.jp, shiomi@enri.go.jp Traffic Management Systems Division, Electronic Navigation Research Institute Efficient Preemption

More information

Modern Wireless Communication

Modern Wireless Communication Modern Wireless Communication Simon Haykin, Michael Moher CH01-1 Chapter 1 Introduction CH01-2 1 Contents 1.1 Background 1.2 Communication Systems 1.3 Physical Layer 1.4 The Data-Link Layer 1.4.1 FDMA

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

Wireless Cellular Networks: 3G

Wireless Cellular Networks: 3G Wireless Cellular Networks: 3G Raj Jain Washington University Saint Louis, MO 63131 Jain@cse.wustl.edu These slides are available on-line at: http://www.cse.wustl.edu/~jain/cse574-06/ 7-1 Overview Wireless

More information

Performance Evaluation of Wired and Wireless Local Area Networks

Performance Evaluation of Wired and Wireless Local Area Networks International Journal of Engineering Research and Development ISSN: 2278-067X, Volume 1, Issue 11 (July 2012), PP.43-48 www.ijerd.com Performance Evaluation of Wired and Wireless Local Area Networks Prof.

More information

A Novel Decentralized Time Slot Allocation Algorithm in Dynamic TDD System

A Novel Decentralized Time Slot Allocation Algorithm in Dynamic TDD System A Novel Decentralized Time Slot Allocation Algorithm in Dynamic TDD System Young Sil Choi Email: choiys@mobile.snu.ac.kr Illsoo Sohn Email: sohnis@mobile.snu.ac.kr Kwang Bok Lee Email: klee@snu.ac.kr Abstract

More information

Chapter 6 Bandwidth Utilization: Multiplexing and Spreading 6.1

Chapter 6 Bandwidth Utilization: Multiplexing and Spreading 6.1 Chapter 6 Bandwidth Utilization: Multiplexing and Spreading 6.1 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Note Bandwidth utilization is the wise use of

More information

Appendix C GSM System and Modulation Description

Appendix C GSM System and Modulation Description C1 Appendix C GSM System and Modulation Description C1. Parameters included in the modelling In the modelling the number of mobiles and their positioning with respect to the wired device needs to be taken

More information

Communications COMMS (CE700038-2)

Communications COMMS (CE700038-2) Faculty of Computing, Engineering & Technology Multiplexing, (FDM, TDM, CDM) & Communications COMMS (CE700038-2) Alison L Carrington C203 A.L.Carrington@staffs.ac.uk www.fcet.staffs.ac.uk/alg1 2008/9 2

More information

The GSM and GPRS network T-110.300/301

The GSM and GPRS network T-110.300/301 The GSM and GPRS network T-110.300/301 History The successful analog 1:st generation mobile telephone systems proved that there is a market for mobile telephones ARP (AutoRadioPuhelin) in Finland NMT (Nordic

More information

Yu.M. Tulyakov, D.Ye. Shakarov, A.A. Kalashnikov. Keywords: Data broadcasting, cellular mobile systems, WCDMA, GSM.

Yu.M. Tulyakov, D.Ye. Shakarov, A.A. Kalashnikov. Keywords: Data broadcasting, cellular mobile systems, WCDMA, GSM. Аnalysis of data broadcasting in modern cellular mobile systems of ground radio communications Yu.M. Tulyakov, D.Ye. Shakarov, A.A. Kalashnikov At the analysis of channel formation in WCDMA networks the

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

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

LTE, WLAN, BLUETOOTHB

LTE, WLAN, BLUETOOTHB LTE, WLAN, BLUETOOTHB AND Aditya K. Jagannatham FUTURE Indian Institute of Technology Kanpur Commonwealth of Learning Vancouver 4G LTE LTE (Long Term Evolution) is the 4G wireless cellular standard developed

More information

Wireless Local Area Network

Wireless Local Area Network Wireless Local Area Network ดร. อน นต ผลเพ ม Anan Phonphoem, Ph.D. anan@cpe.ku.ac.th http://www.cpe.ku.ac.th/~anan Computer Engineering Department Kasetsart University, Bangkok, Thailand iwing Lab CPE

More information

Basic Goals of Networking

Basic Goals of Networking Cellular Network Basic Goals of Networking Call management Call setup Call termination Different Service: voice over IP, call forwarding, 2 Basic Goals of Networking User Information Transport Modulation

More information