1. How is Information Transferred? Developing an Intuition for Network Communication Protocols a 6.UAT concept talk by Olga Stroilova

2. 2 Information transfer networks are everywhere Internet connection: Ethernet Laptop WiFi: Wireless LAN Cell phones: Mobile network How do these systems work? Read the lengthy (and complicated) 802 IEEE standard Build up an intuition by trying to design them yourself!

3. 3 What is Information and how do I Transfer It? Real life: Sounds, letters, signs, pictures, movies Digital world: 0’s and 1’s, voltage high and lows, radio waves Methods of Information Transfer Speech, Morse code, wire and radio communication Rules of transfer are called Communication Protocols

4. 4 Ethernet Idea Cut down costs by connecting all computers with a single wire Communication Protocol Listen to the wire and transmit if it is free Monitor wire during transmission If interference is detected, stop, wait and try again “Play Nice”: Randomized Backoff + Collision Detection

5. 5 Wireless Local Area Network Idea Use radio waves as transfer medium for increased portability Communication Protocol Divide 2.4 GHz radio wave band into channels Assign several transmissions to each channel Cannot detect collisions, so acknowledge each message “Play First, Check Later”: Randomized Backoff + Collision Avoidance

6. 6 Mobile Phone Network Idea Ensure quality of data stream by reducing probability of collision Communication Protocol Put up towers to divide area into cells Divide company frequency bandwidth into channels Allot one transmission per channel per cell “Play By Yourself”: No Collisions, No Backoff

7. 7 In Conclusion … Protocols are designed based on the product goals, limitations, and tradeoffs. To understand how they work, Think like an Engineer! Ethernet Cellular Wireless