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15-441 Computer Networking

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15-441 Computer Networking

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    Slide 1:15-441 Computer Networking

    Lecture 1 Introduction

    Slide 2:Course Goals

    Learn about the unique challenges in wireless networking What forces us to reconsider many traditional designs? Starting point is regular wired networks Understand state-of-the-art in wireless/ubiquitous systems Get a broad view of the ongoing research in the wireless domain. Focus on the protocol level Understand where wireless research is going Learn tools for doing wireless research Gain hands on experience in working with wireless networks. Implementing protocols, algorithms Measurements of wireless networks

    Slide 3:Todays Lecture

    Why Wireless? Course Overview Administrivia

    Slide 4:Wireless is THE Key Driver for the Future Internet

    Historic shift from PCs to mobile computing and embedded devices >2B cell phones vs. 500M Internet-connected PCs in 2005 >400M cell phones with Internet capability, rising rapidly Sensor deployment just starting, but some estimates ~5-10B units by 2015 INTERNET Wireless Edge Network INTERNET ~500M server/PCs, ~100M laptops/PDAs ~750M servers/PCs, >1B laptops, PDAs, cell phones, sensors 2005 2010 Wireless Edge Network

    Slide 5:Market Size

    Wireless as the common case vs. the exception Laptop (54%) vs. desktop sales (46%) >2B cell phones vs. 500M Internet-connected PCs Estimates of ~5-10B wireless sensors by 2015 Rapid deployment of new technology Highly dynamic environment Must accommodate new/unexpected technologies 9 million hotspot users in 2003 (30 million in 2004) Approx 4.5 million WiFi access points sold in 3Q04 Sales will triple by 2009 Many more non-802.11 devices Staggering Market Statistics 7/2004 wardrive (802.11g standardized in 6/2003) According to IDC, some 8 million Wi-Fi access points were shipped in 2001, with that number expected to rise to 36 million units sold in 2006. Of that number, 802.11a product sales are projected to increase from 1 percent to 7 percent during the five-year period. In 3Q04, Wi-Fi unit shipments increased 12% from 2Q04. 10.99 million units shipped in 3Q04 compared to 9.82 million units in 2Q04. Strong growth segments included 802.11g NICs and APs. NIC unit shipments for 802.11g increased 14% from 5.07 million units in 2Q04 to 5.80 million units in 3Q04. AP unit shipments for 802.11g increased 30% to 3.55 million in 3Q04 from 2.74 million in 2Q04. The multimode NIC market saw healthy growth as well. Multimode NICs are capable of operating at 2.4GHz or 5GHz. Unit shipments for multimode NICs increased 21% from 2Q04. Revenue for multimode NICs increased 16%. Wi-Fi unit shipments are expected to decline slightly in 4Q04, due to the historically slower first quarter. However, in 2004, total Wi-Fi unit shipments are projected to show a healthy 24% gain from 2003. 214% increase in WiFi equipment in 2003According to IDC, some 8 million Wi-Fi access points were shipped in 2001, with that number expected to rise to 36 million units sold in 2006. Of that number, 802.11a product sales are projected to increase from 1 percent to 7 percent during the five-year period. In 3Q04, Wi-Fi unit shipments increased 12% from 2Q04. 10.99 million units shipped in 3Q04 compared to 9.82 million units in 2Q04. Strong growth segments included 802.11g NICs and APs. NIC unit shipments for 802.11g increased 14% from 5.07 million units in 2Q04 to 5.80 million units in 3Q04. AP unit shipments for 802.11g increased 30% to 3.55 million in 3Q04 from 2.74 million in 2Q04. The multimode NIC market saw healthy growth as well. Multimode NICs are capable of operating at 2.4GHz or 5GHz. Unit shipments for multimode NICs increased 21% from 2Q04. Revenue for multimode NICs increased 16%.Wi-Fi unit shipments are expected to decline slightly in 4Q04, due to the historically slower first quarter. However, in 2004, total Wi-Fi unit shipments are projected to show a healthy 24% gain from 2003. 214% increase in WiFi equipment in 2003

    Slide 6:Why is it so popular?

    Flexible Low cost Easy to deploy Support mobility

    Slide 7:Implication: Market Size

    Past efforts ? emphasis on adapting wireless nodes to support existing architecture Wireless TCP, Mobile IP, etc. Adoption of these evolutionary changes has lagged expectations Market size justifies more dramatic changes Broader architectural changes to support range of issues created by wireless systems Consider changes to Internet that may simplify future wireless system design

    Slide 8:Growing Deployment Diversity

    Devices Laptops, PDAs, audio/video equipment, appliances, sensors and Constellations of devices Scale Billions of sensors & RFID tags expected by 2015 Deployment styles Homes, hot-spots, airports and infrastructure/municipal networks Past: largely 802.11 campus networks with laptops FUTURE Radio technology Sensor radios, 3+G cellular, Bluetooth, UWB, WiMax, software radios, and RFID

    Slide 9:Wireless Technologies

    UWB Bluetooth WiFi 3G range BW WiMax RFID

    Slide 10:Growing Application Diversity

    Relay Node Access Point Sensor Wired Internet Ad-Hoc/Sensor Networks Collision Avoidance: Car Networks Wireless Home Multimedia Mesh Networks

    Slide 11:Challenge: Diversity

    New architectures must accommodate rapidly evolving technology Must accommodate different optimization goals Power, coverage, capacity, price INTERNET Wireless Edge Network INTERNET 2005 2010 Wireless Edge Network

    Slide 12:Spectrum Scarcity

    Densities of unlicensed devices already high Spectrum is scarce ? will get worse Improve spectrum utilization (currently 10%) (Placelab: 28000 APs, MAC, ESSID, GPS) Data in placelab to understand how many APs in each city are in interference range of each other. Specigfically, we construct what we call interference grapsh Figure on the right shows a distribution of the number on interfering neighboring APs in the various cities. More than 4(Placelab: 28000 APs, MAC, ESSID, GPS) Data in placelab to understand how many APs in each city are in interference range of each other. Specigfically, we construct what we call interference grapsh Figure on the right shows a distribution of the number on interfering neighboring APs in the various cities. More than 4

    Slide 13:Spectrum Scarcity

    Interference and unpredictable behavior Need better management/diagnosis tools Lack of isolation between deployments Cross-domain and cross-technology Why is my 802.11 not working?

    Slide 14:Todays Lecture

    Why Wireless Course Overview Administrivia

    Slide 15:Wireless Differences 1

    Physical layer: signals travel in open space Subject to interference From other sources and self (multipath) Creates interference for other wireless devices Noisy ? lots of losses Channel conditions can be very dynamic

    Slide 16:Wireless Differences 2

    Need to share airwaves rather than wire Dont know what hosts are involved Hosts may not be using same link technology Interaction of multiple transmitters at receiver Collisions, capture, interference Use of spectrum: limited resource. Cannot create more capacity very easily More pressure to use spectrum efficiently

    Slide 17:Wireless Differences 3

    Mobility Must update routing protocols to handle frequent changes Requires hand off as mobile host moves in/out range Changes in the channel conditions. Coarse time scale: distance/interference/obstacles change Fine time scale: Doppler effect Other characteristics of wireless Slow

    Slide 18:Wireless Networking

    1980s 1990s 2000s 1G Cellular Telephony Technology Research Goals 2G Digital Cellular First Generation Wireless LANs 3G Data-oriented Cellular 802.11 LANs Invisible computing, sensors Focus on HCI, integration, low power Ubiquitous access to data Challenges: coverage, speed, disconnected operation, devices, ad hoc Applications, hardware, networking (PARC, Infopad, BARWAN, Odyssey, etc.)

    Slide 19:Device Diversity Network Interfaces Design

    1990s 2000s 2010s Single wireless interface per machine Initially developed in mid 90s Require high-bandwidth I/O & lots of processing Couldnt easily handle low-latency interaction required by modern link standards Still power hungry Multiple interfaces per machine Software defined radios? Directional antennas?

    Slide 20:Course Overview

    Physical layer (3 lectures) Textbook-based Signal encoding/modulation Signal propagation basics Spread spectrum concepts Public policy Link layer (3 lectures) 802.11 Emerging technologies (Bluetooth, WiMax, etc.) Wireless MAC protocols Software Radios

    Slide 21:Course Overview

    Multi-hop networks (5 lectures) Ad hoc routing Network capacity Routing metrics Mesh networks Geographic routing

    Slide 22:Course Overview

    Applications layer (4 lectures) Disconnected operation Adaptive applications Delay tolerant networking Localization Miscellaneous (5 lectures) Network simulation/testbeds Multi radio networks Mobile IP connectivity Wireless TCP Security Wireless network management

    Slide 23:Todays Lecture

    Why Wireless? Course Overview Administrivia

    Slide 24:Course Info

    Lectures: MW 10:30-11:50, 4623 Wean Instructor: Srini Seshan Email: srini@cmu.edu Office: Wean Hall 8113 Office Hours: by appointment Course Web page: http://www.cs.cmu.edu/~srini/15-849E/S06/

    Slide 25:Course Format

    3 lectures Cover the basics of physical layer Radio propagation models, modulation, etc. 802.11 basics ~20 lectures on research topics Student led discussion ~ 3 papers per session Mostly conference/journal papers Some white papers, trade magazines, etc. Watch the Web page, still evolving list of topics/readings Recommended textbooks Wireless Communications & Networks by William Stallings

    Slide 26:Discussion Leading

    Present a summary of the papers Prepare discussion questions Cover some of the related work Reading list on Web page has many pointers Signups Will put on my office door next week (for the next ~7 lectures) Glance at syllabus on Web page for topics you want to present

    Slide 27:Grading

    Roughly equal weight in projects and testing 30% discussion leadership Each student is expected to lead 4 discussions 10% class participation 60% class project 1 or 2 person projects Workshop quality result List of project suggestions available by 1/30

    Slide 28:Project

    Proposal (2/15) 1 page proposed research summary Meeting to discuss plans Review (3/20) Meeting with instructor to discuss progress, bottlenecks, etc. Presentation (5/1) 20 minute (ish) conference-style talk about the research Paper (due 5/5) 6-10 page conference-style write up

    Slide 29:Growth of Wireless Users

    Slide 30:The Wi-Fi Space

    It is one of the fastest growing industry sectors 100,000 public hotspots by 2005 Most notebooks will have embedded wi-fi card Go and check the local hotspots online www.ezgoal.com/hotspots/

    Slide 31:Wireless Applications

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