Wireless Networking�We will start ~14:05 today, but promptly at 14:00 in the future

Pat Pannuto, UC San Diego

ppannuto@ucsd.edu

CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Introduction Goals

• Overview of the course

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• Introduction to the Internet of Things

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• Introduction to wireless communication

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Welcome to CSE 122 / CSE 222C / WES 269�Wireless Networking

• ~65 students (25 undergrad; 25 graduate; 15 professional masters)
• Many different backgrounds and interests
• Wait, how is this both one class and three different classes?
• The core material is the same
• With adaptations to lecture format, lab material, [grad] research content, and final
• We wrote a paper about how to do this well if you’re interested
• Experiences Teaching a Wireless for the Internet of Things Course Cooperatively at Multiple Universities
• This is an experience- and design-oriented course
• Experience comes from labs
• Design comes from written assignments (Homework, Final Design Report)
• Lectures give foundation to understand what you are doing and how to make design decisions
• Minute-Quizzes keep you honest on lecture material

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Quick Logistics

• Everything is on the course website
• https://cseweb.ucsd.edu/classes/wi25/{cse122-a,cse222C-a,wes269-a}/
• ^This is also the homepage in Canvas
• This is an advanced course
• Target is senior-level undergraduate, or early-career graduate students
• This is still a newer / semi-experimental course
• Please bear with us, we’re scaling up this quarter and trying new things
• We will use Gradescope to submit stuff
• We will use Matrix (think free slack) for a message board

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Hi, I’m Professor Pannuto

• Originally from Michigan
• BSE CE, MSE CS from U of M
• PhD in EECS from UC Berkeley
• I work in “embedded systems”

🡪

• I thrive when abstractions break
• Resource constrained computing

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• Interstitial / highly collaborative
• 40 co-authors
• 9 institutions
• 4 continents

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Outline

• Internet of Things

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• Course Overview

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• Overview of wireless networks

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Perspective of this course

• This class is about wireless protocols
• Largely motived by a specific domain: “the Internet of Things”
• Aka, “resource-constrained systems”
• Aka, “embedded”, aka “the far edge”, aka …

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• So we’ll spend some amount of time discussing the Internet of Things and embedded systems

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

What is the IoT anyway?

• Seriously: let’s define “Internet of Things”

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Discussion: what is the Internet of Things?

1. Name a few Internet of Things devices

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• What are the qualities that designate those devices at “IoT”?

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Discussion: what is the Internet of Things?

1. Name a few Internet of Things devices

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• What are the qualities that designate those devices at “IoT”?

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Thought experiment on capabilities

• What if the Nest thermostat was powered by…
• a desktop: 8-core x86-64 processor, 32 GB RAM, 1 TB SSD
• a laptop?
• an iPad?

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• Would that still count as IoT?

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• Why don’t we see “desktop IoT” in practice?

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Thought experiment on energy

• IoT devices include a mix of batteries, wall power, (and energy-harvesting)

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• Why do we put so much focus on systems with batteries?
• Why do they need batteries?

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

The two hardest things in embedded systems / IoT are�power and communication

• This class is about wireless technologies
• For resource-constrained systems, such as the IoT
• We will focus on the tradeoffs between technologies
• How they balance differing constraints
• Power, spectrum, complexity, etc.
• And the technical foundations of these designs and differences

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Energy is the defining constraint of emerging technologies

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Mini Computer

Laptop

Workstation

Personal Computer

Mainframe

Smartphone

IoT/Wearable

Computer

Battery

By volume, the emerging computing classes are mostly energy storage

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Volume is shrinking cubically

CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Pat’s Take on the Internet of Things

• Pretty literal
• My early grad school essays described the “last inch” problem
• Now I often say “expanding the reach of digital world”
• For me, it is about ‘networked’ ‘things’
• Which implicitly adds some computational capacity

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Branden’s take on the Internet of Things

• Key features
• Computation
• Local to the device
• With some capability for arbitrary compute and storage
• Connectivity
• Almost certainly wireless
• Likely Internet, possibly local
• Interaction
• Sensing or Actuation
• Secondary features
• Low energy
• (Relatively) Low cost

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Brad’s take on the Internet of Things

• “Expanding the reach of digital world”
• Key features
• Computation
• Local to the device
• With some capability for arbitrary compute and storage
• Connectivity
• Almost certainly wireless
• Likely Internet, possibly local
• Interaction
• Sensing or Actuation
• Secondary features
• Low energy
• (Relatively) Low cost

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Warning: Internet of Crap

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Internet of Insecure Crap

• Mirai botnet (2016)
• Takes control of up to 600,000 insecure connected devices
• IP-attached cameras, DVRs, routers, printers
• Used to DoS websites

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Break + xkcd

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https://xkcd.com/1966/

CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Outline

• Internet of Things

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• Course Overview

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• Overview of wireless networks

​

21

CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

CSE 122 / 222C ; WES 269�Wireless Networking

• You will learn the most influential wireless protocols (used by IoT devices)
• Ex: BLE, Zigbee, LoRa, WiFi, Thread, Matter
• Things we won’t cover
• Digital wireless communication and the physical layer
• Transceiver hardware design
• Internet networking and TCP/IP
• This is an experience- and design-oriented course
• Experience comes from labs and assignments
• Design comes from final project
• Lectures give you the foundation to understand what you are doing and how to make design decisions
• Minute-Quizzes keep you honest on lecture material

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

What to expect

• “Late-stage education career” class
• Goal is to help prepare you to engineer projects in the real world

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Computing course structure and guidance

Very curated and structured

(e.g. CS1)

Real world project at a job

autograder

detailed programming assignments

course-specific libraries

full provided documentation

defining requirements and milestones

online documentation

multiple solutions

real-world software stacks

CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

What we want you to learn

1. Fundamentals of IoT wireless networks
• You are no doubt VERY well prepared to learn this
• Lecture, homework, labs
2. How to design a wireless system
• Domain expertise and intuition to assess needs and balance tradeoffs
• Labs, final project
3. How to build and hack on real systems
• Experience learning and using existing software stack
• Labs, post labs

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Collaboration?�Experiential bits – Yes, please!

• This is an experience- and design-oriented course
• Experience comes from labs
• This part is highly collaborative
• You cannot talk to each other too much, help each other out in the labs
• One Rule: Hands on your own keyboards
• Don’t copy/paste stuff
• Don’t do things for someone else, explain how to do it
• (As a team) write up your pre-labs, post-lab reports with all your own work

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Collaboration?�Design pieces – That’s all just you

• This is an experience- and design-oriented course
• Design comes from written assignments
• These you must do on your own
• You can talk to others, but don’t write anything down or look at anything they have written down
• Guiding rule: Start from a blank piece of paper to prepare your final submission

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Labs

• Semi-guided efforts of getting wireless communication working on real hardware
• Wireshark
• Bluetooth
• 802.15.4
• WiFi
• LoRa

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Pre-Labs

• Absolutely essential to success in lab
• Lab time is limited
• Must have pre-lab complete before lab to make lab successful
• Pre-labs are due by the start of lab, no exceptions, no make-ups

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

In-Lab

• Semi-directed activities
• Some parts you will be expected to figure out
• Help each other!
• Be sure to save your work as you go along
• The lab guide will try to remind you

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Post-Lab / Lab Writeup

• Each lab has a post-lab assignment, two parts inside
• Report on your lab activities
• Some extra questions related to lab activities
• Generally, due one week after the final in-class lab session

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Access to the lab?

• You can come into the lab if it is not currently in use when convenient
• We will host our office hours in the lab
• The door code is in Canvas

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• We are sharing the lab with Prof. Schulman’s CSE 190B
• Like us, they have a mixture of lecture days and lab days
• It meets MWF, 11–12 and generally has office hours MW, 3–4

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• During non-class hours, will be a mix of students – be nice! ☺

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Mastery Grading�aka: no, there is not a curve

• My goal is to teach you the material and for everyone to learn it
• I am most successful if everyone in class earns an A

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• You earn in four [or five] categories:
• Labs
• Design Assignment (Final Exam)
• Homework
• Minute-Quizzes
• [Grad students only]: Paper responses
• Your final grade is the minimum across the categories

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

What’s a Design Final?

• More on that later in the term
• Homework will give you some preparation and experience

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• There is no final exam for this course

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Hey, what about that mini-quiz thing you snuck in there?

• Lecture will begin with a "minute-quiz”
• These will be (very) short and will cover material from the prior lecture, or possibly pre-lab, lab, post-lab, homework or other assignment
• You should not need to study or worry about these – if you were there and paying attention, you'll be prepared

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• Correct quizzes earn 10pt/ea, incorrect quizzes earn 5pt/ea
• Not counting today, there are 19 more lecture sessions
• And you only need to get to 100 points

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Questions, Concerns, Confused?

• Please, go read the actual Syllabus

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Break + Mini-Exercise

• I’m going to ask each “column” a question.

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• Everyone at the table needs to answer correctly.

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• Fastest table to have everyone answer wins.

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• If two people talk at the same time that table loses.

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• Take a minute or two to strategize

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Outline

• Internet of Things

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• Course Overview

​

• Overview of wireless networks

​

37

CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Bluetooth Low Energy

• Bluetooth Classic was good for enabling device to device communication
• But not particularly fast or low energy

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• Bluetooth Low Energy was developed to improve this
• Focuses on low-energy interactions
• Much lower throughput that Bluetooth

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• Supported by hardware devices already in smartphones
• Humans can interact directly with nearby devices!!

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

802.15.4 & Thread

• 802.15.4 is a low-energy physical layer
• Radio chips have been widely available for 15-20 years

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• Significant amounts of sensor network research have focused on building layers on top of 802.15.4
• Access control layers
• Network layers

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• Thread is a selection of these possibilities to make a network
• Uses IPv6 networking!!

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

WiFi (802.11)

• Ubiquitous wireless communication
• High energy requirements for high throughput communication

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• Now accessible through relatively low power radios
• ESP32, Electric Imp, and company
• Still significantly more effort than BLE or Thread

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• IoT devices can use the same WiFi that’s already available
• No need for additional infrastructure!!

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

LPWANs (Low-Power Wide-Area Networks)

• How do we collect data from city-scale deployments?
• There’s an unmet need for long-range, but low-throughput networks
• Existing cellular technologies focus on human requirements

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• Still a new space (relatively)
• Unlicensed-band technologies in last decade: Sigfox and LoRaWAN
• Cellular technologies in last half-decade: LTE-M and NB-IoT

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• Focus on long-range, low-energy, low-throughput
• One gateway can cover an entire city!!

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Extras

• Extremely active research areas

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• Backscatter
• Insanely low-energy communication
• Enables energy-harvesting indoor devices

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• Non-RF wireless
• Infrared communication
• Ultrasonic communication

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• Localization
• How do we find all this stuff?
• And how do devices determine where they are relative to each other?

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• Other topics are possible if desired. Tell me what focus you want.

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Why use wireless?

• There are no wires!

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• No need to install and maintain wires
• Reduces cost
• Simplifies deployment – place devices wherever makes sense

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• Supports mobile users
• Move around office, campus, city
• Move devices around home

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

What is hard about wireless?

• There are no wires!

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• Wired networks are constant, reliable, and physically isolated
• Ethernet has the same throughput minute-to-minute
• Bits sent through Ethernet or USB are (usually) received

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• Wireless networks are variable, error-prone, and shared
• WiFi throughput changes based on location and walls
• Signals from nearby devices interfere with your signals
• Individual bits might flip or never be heard at all

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Wireless is a shared medium

• Wired communication has signals confined to a conductor
• Copper or fiber
• Guides energy to destination
• Protects signal from interference

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• Wireless communication is inherently broadcast
• Energy is distributed in space
• Signals must compete with other signals in same frequency band

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Increasing network capacity is challenging

• Wired networks just add more wires
• Buses are many signals in parallel to send more data

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• Wireless networks are harder
• Adding more links just increases interference
• Need to expand to different frequencies

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

RF communication

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IoT focus

CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Wireless spectrum is allocated to specific uses

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Unlicensed bands are where IoT thrives

• 902 MHz – 928 MHz
• LPWANs

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• 2.4 GHz to 2.5 GHz
• WiFi, BLE, Thread

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• 5 GHz
• Faster WiFi

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• Cellular uses licensed bands

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Model of RF communication

• Energy that radiates spherically from an antenna

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• Attenuation with distance
• Density of energy reduces over time, distance
• Signal strength reduced, errors go up

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• Three key features
• Inherently broadcast
• Error rates depend on distance
• Spatial reuse of frequencies

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Up Next: How does the Regular ol’ Internet work?

• Aka Pat tries to speedrun a decent chunk of CSE123

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell

Break+Video

Wireless Network Visualization (Dr. Meghan Clark – UC Berkeley)�https://www.youtube.com/watch?v=KLOdp54_qJ4

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CSE 122/222C, WES 269 [WI25]

CC BY-NC-ND Pat Pannuto – Content developed in coordination with Branden Ghena and Brad Campbell