Wireless & Mobile Networks

01Overview

In 1971 the University of Hawaii’s ALOHAnet linked the islands by radio and designed the first random-access protocol. Cellular phones went commercial in the 1980s, and GSM opened its first digital network in Finland in 1991. In 1997 IEEE 802.11 standardised wireless LANs, and Wi-Fi moved into homes and cafés.

Mobile networks change generation roughly every decade: 2G texting, 3G data, 4G video, 5G low latency and massive connection counts. Each generation reallocates spectrum, modulation and architecture. Wireless is harder than wire: attenuation, interference and handover all have to be solved in the protocol.

02History

1971
ALOHAnet
A pioneer of random access over radio.
1991
GSM goes commercial
The digital cellular standard.
1997
IEEE 802.11
Wi-Fi is born.
2009
4G LTE
Mobile broadband.
2019
5G goes commercial
Low latency and massive IoT.

03Core concepts

Cellular

Divide coverage into cells so frequencies can be reused.

Random access

Terminals contend for a shared channel and retry after collisions.

Handover

Move a connection smoothly from one base station to another as you move.

04Hands-on

Do it once — it beats reading it ten times

Measure Wi-Fi signal strength across a room, then explain the drop where the door is

Tick this once you have built it and written down what you learned; the topic is then marked as built.

05Self-check

Say it in your own words first, then open the answer. Whatever you cannot explain is what to review next.

Can you explain "Cellular"?

Divide coverage into cells so frequencies can be reused.

Can you explain "Random access"?

Terminals contend for a shared channel and retry after collisions.

Can you explain "Handover"?

Move a connection smoothly from one base station to another as you move.

What problem did it solve, and why was there nothing better at the time?

Go back to the history section: how was this done before, and what did it cost?

If you had to build it today, how would you break it down?

Use the hands-on task above: write a plan of at most three steps before you start.

06Key people

Norman Abramson

1932 – 2020

Led ALOHAnet.

Martin Cooper

1928 –

Made the first handheld mobile phone call.

07Further reading

Wireless CommunicationsAndreas Molisch · 2010
Mobile Edge ComputingTaleb et al. · 2017