Wireless Networking

1. Wireless Networking Sachin Katti 1/3/2011

2. Goal of the class • To become familiar with the field of wireless networking research: Architecture, protocols and systems. • To get some practice in the art of reading research papers. • To get started on doing wireless research It’s a big field, so we will focus on just a few topics. 2

3. Basics Lecture • Each class we will discuss ~2 papers. • You must read the papers before classPapers should be read in depth (see later) • Most of the time will be spent on discussion • 30% of your grade comes from in-class participation • 10% from scribing 3

4. Grade In-class Participation: 30% Taking part in discussions Scribing 5 lectures: 10% Project: 60% 4

5. In-class participation • Come prepared to summarize the paper and discuss the main ideas • We will all learn from each other • Attendance is a necessary but not sufficient condition for “participation” Let’s vote for no laptops in class (unless you are the “scribe”) 5

6. Logistics Lecturers • Sachin Katti skatti@stanford.edu • Philip Levis pal@cs.stanford.edu Teaching Assistant Manu Bansal manub@stanford.edu Administrative Assistant Shaolan Min smin@stanford.edu 6

7. Contact Class webpage: www.stanford.edu/class/ee384e If private: ee384e-win1011-staff@lists.stanford.edu Announcements:ee384e-win1011-students@lists.stanford.edu Office hours and discussion sessions posted on web page 7

8. Hints on reading a paper[Keshav] Three stage approach • Read quickly in 5-10minutes • Read with greater care; ignore proofs • Deconstruct paper; question all assumptions 8

9. Stage 1: 5-10 minute read Read title, abstract, introduction, section headings, conclusion, reference list. Look for “5 C’s” Category: What type of paper is it? Context: Where does it fit in? Correctness: Do assumptions make sense? Contributions: What are the main ones? Clarity: Is it well-written? 9

10. Stage 2: Read with care • Spend an hour re-reading paper in detail • Try to understand the “story” • Summarize the main thrust • Identify main supporting evidence 10

11. Stage 3: Deconstruct the paper • This can take one or more hours • Understand every proof • Question every assumption • Identify missing references • Why was the paper written this way? • How else could the paper have been written? 11

12. First papers: For Wednesday Read thoroughly • Link-level Measurements from an 802.11b Mesh Network, 2003 • Measurement-based models of delivery and interference in static wireless networks, 2008 12

13. Logistics Scribe Each student will do a total of 3 scribes 200 words summary of each “Read deep” paper, 200-400 words summary of in-class discussion 1 paragraph critique/opinion of each paper Posted on class webpage Scribe assignments: Please send your preferred 3 dates to Manu 13

14. Logistics Project Research project (accounts for 60% of grade) Individual projects preferred, teams maybe allowed if scope is very big We will post a set of suggested topics, but you are encouraged to come up with your own 13

15. Logistics Project Milestones 1 page abstract: January 24 Define the problem, why it is relevant 3 page Interim Report: Feb 16 Clarify the original problem statement, exact statement of the deliverables 10 minute class presentation: March 9 Short talk on your project 10 page project paper: March 11 Conference style paper 13

16. Logistics Wireless Research Class in Spring Focused on experimental wireless networking research Co-taught by Philip Levis and me Quarter long project class Goal: To do research that produces a publication worthy paper at a top conference You can pick a project that spans both classes assuming its scope is large enough 13

17. Last Year’s Projects: Full Duplex Radios(ACM MOBICOM 2010, Best Demo Award) • Transmit and receive at the same time • Basic Idea: Cancel self interference • Naïve approaches (Digital/analog cancellation) are not sufficient • Key Idea: Antenna Cancellation

18. Last Year’s Projects: Automatic Rate Adaptation(ACM HotNets 2010) • Fluctuating wireless channels, picking the right code and modulation is hard • Basic Idea: Rateless technique that automatically achieves the optimal rate adaptation • No need to worry about picking the right channel code and modulation • Designed and implemented on software radios

19. Last Year’s Projects: Angle of Arrival Estimation via Compressive Sensing(ACM Cognitive Radio Conference 2010) • Determining angle of arrival of wireless signals • Basic Idea: Angles of arrival are sparse in the spatial domain, apply compressive sensing to estimate • Advantages: Fewer antennas required compared to traditional techniques CR2 Rx CR1 Tx CR2 Tx CR1 Rx

20. Logistics Experimental Wireless Platforms 200 MHz channel sounder Supports up to 8 antennas Precise channel measurements Can be used for profiling wireless environments, used in the compressive sensing project 13

21. Logistics Experimental Wireless Platforms USRP2 software radios Narrowband (~10Mhz) Connects to your PC Open source GNURadio software radios Used in the full duplex and rate adaptation projects 13

22. To summarize • Wireless “networking” is a young field, unlike wireless communications • Explosion of interest in recent years due to the shift to mobile Internet • Many unanswered questions on how to architect these networks: theory, design and systems