EN FA11 Network Embedded Systems/Sensor Networks Week 1: Introduction and Applications

Transcription

1 EN FA11 Network Embedded Systems/Sensor Networks Week 1: Introduction and Applications Marcus CS JHU with help from Andreas Terzis and Prabal Dutta 1

2 Administrivia Tuesday, Thursday 1:30-2:45 Shaffer 202 Instructor: Marcus Chang (mchang AT cs.jhu.edu) Teaching Assistant: Zainan Victor Zhou (zzn AT jhu.edu) General course consulting and help with programming assignments Class website: Class material will also be on: Office Hours: By appointment (Shaffer 200) 2

3 Embedded System An embedded system is a computer system designed to do one or a few dedicated and/or specific functions It is embedded as part of a complete device often including hardware and mechanical parts By contrast, a general-purpose computer, such as a personal computer (PC), is designed to be flexible and to meet a wide range of end-user needs - Wikipedia 3

4 Wireless Sensor Networks E.g. Environmental Monitoring: Sample sensors Store measurements Process data Forward results 4

5 Course Outcomes Learn about embedded systems and wireless networks Program microcontrollers Program Android cell phones Learn about low-power system design Cross-platform optimization Learn how to (start to) do research Critically review the literature Learn how to discover and formulate problems Learn about experiment design, interpreting and presenting results 5

6 Prerequisites CS344 or other networking course, Operating Systems, systems programming Must feel comfortable programming in C Grad student attitude (self-directed, deal with open ended problems/assignments, highly motivated, critical, dedicated) 6

7 What will this class be like? This is partly a seminar course We will be reading and discussing papers (10%) Class attendance and participation mandatory Approximately 2-3 papers per week Tuesdays, topic overview (lecture) Thursdays, 1-2 students present a paper and lead discussion (10%) All students hand in a review 2 programming assignments (25%) Introduction to programming embedded systems Big project (30%) Work in teams of 2 people Midterm, but no final! 7

8 Readings and Reviews You are responsible for completing assigned readings before lecture Submit the review through BlackBoard Review is due before beginning of lecture and should include At least two thought-provoking questions on the assigned paper Discussion of any strengths and weaknesses Two possible directions for extensions on the ideas / topic presented in the paper. Your questions should critically evaluate the paper (e.g., questioning the assumptions, questioning whether the experiments are lacking (and why), flaws in the analysis, etc). You are allowed to miss two reviews but send to let me know 8

9 Assignments and Project Implement body sensor network Transmit data from wireless sensors to Android phone Store measurements in the cloud Visualize measurements on Android phone and the web Assignments Android programming (JAVA) Wireless sensor programming (TinyOS, nesc) Project Cross-platform optimization Implement your own device driver (memory mapped IO, C) Progress reports, give presentation, write final report 9

10 Moore s Law: IC transistor count doubles every two years 10 Photo Credit: Intel

11 Flash memory cost 11

12 Hendy s Law : Pixels per dollar doubles annually 12 Credit: Barry Hendy/Wikipedia

13 Bell s Law, revised: Corollary to the Laws of Scale Photo credits: Intel, U. Michigan 13 UMich Phoenix Processor Introduced 2008 Initial clock speed V Vdd Number of transistors 92,499 Manufacturing technology 0.18 µ

14 MEMS Accelerometers: Rapidly falling price and power O(mA) Hz ADXL345 [Analog Devices, 2009] bits [ST Microelectronics, annc. 2009]

15 Energy harvesting and storage Thin-film batteries RF Energy harvesting [Powercast] Shock Energy Harvesting CEDRAT Technologies Piezoelectric [Holst/IMEC] 15 Electrostatic Energy Harvester [ICL] Thermoelectric Ambient Energy Harvester [PNNL]

16 Current Generation Mote: Epic Core Microcontroller CPU: 8 MHz RAM: 10K RAM Program: 48K ROM Energy consumption: Radio 6 mw (active) 60 uw (sleep mode) 250 kbps Energy consumption: 60 mw 16

17 Why Wireless Sensor Networks? Sensors, computation, and communication feasible at small packages and large numbers Ability to monitor phenomena at fine spatial AND temporal granularities Vision: Embedded Networked Sensing will reveal previously unobservable phenomena A new type of scientific instrument: macroscope 17

18 Example Arctic lake monitoring Remote and harsh environment Manual water sampling expensive and time consuming 18

19 Wireless sensor network In-situ sensing Wireless data collection 19

20 The System Challenge Monitoring & Managing Spaces and Things applications data mgmt service network system architecture MEMS sensing Comm. Store Proc technology urobots actuate Power 20 Miniature, low-power connections to the physical world

21 A decade of sensor network applications [Werner-Allen06] ACTIVE [Jiang09] [Abdelzaher07] ACTIVE [Liu04] High [Aoki09] [Hull06] [Lifton07] Power [Wark07] [Lorincz08] SOLVED EMERGING [Ganti06] Low 21 [Szewczyk04] Low [Tolle05] [Malinowski07] [Thiele08] Mobility High

22 Mobility makes energy and communication challenges fundamentally harder in low-power systems 22 Energy Must carry it along Or harvest it from the ambient environment And deal with inherent uncertainty of harvesting Implies dynamic duty cycles How to measure usage? Link Topological turmoil Link. What link? Never before seen link What radio channel? When, where to look? Can t just probe during deployment History is a poor/no guide Network Stability of routing peers? Routers, hosts, both? Transport Disruption-tolerant Store-and-forward Weather + mobility = uncertain energy budget - Jacob Sorber, Sensys 2007 J. Sorber et al., Eon: A Language and Runtime for Perpetual Systems, Sensys 07, Sydney, Australia

23 The fight goes on 23

24 Summary of Technical Challenges Energy consumption Low-power wireless Resource constraints Dealing with the physical world Unattended operation Coordination 24

25 Schedule Week 1: Introduction and Applications Week 2: Mote Hardware Week 3: Embedded Programming Week 4: Medium Access Control Week 5: Link Estimation and Tree Routing Week 6: IP Networking Week 7: Time Synchronization Week 8: Energy Management Week 9: Review and Midterm Week 10: Operating Systems and Programming Languages Week 11: Advanced Networking Topics Week 12: Localization Week 13: Energy Harvesting Week 14: TBD 25