Core Networking · Study deck
Wi-Fi Access: Standards and Link Budget
This first route develops Wi-Fi standards, band choices, link margins, and device power constraints.
Packet Pete is your guide for this deck.
After studying this chapter
Learning objectives
You will be able to:
- Summarize the evolution of IEEE 802.11 Wi-Fi protocols from 802.11b to Wi-Fi 7
- Compare Wi-Fi standards (802.11 a/b/g/n/ac/ax) for IoT applications across speed, range, and power trade-offs
- Evaluate IoT-specific Wi-Fi standards: Wi-Fi HaLow (802.11ah) and Wi-Fi 6 (802.11ax)
- Explain how OFDMA and Target Wake Time (TWT) optimize Wi-Fi for IoT device density and battery life
Major section
Start With a Device Joining Shared Air
Shared air, walls, other users, and sleep timing can change the link without changing the device code.
- An access point means the local radio station that Wi-Fi devices join.
- Modulation means changing a radio signal over time to carry information.
- This runway does not prove coverage, security, or battery life for every site.
Major section
Start With a Device Joining Shared Air (continued)
Received signal strength is a device's estimate of received radio power; RSSI means received signal strength indicator.
- A working bench connection is only the first proof.
- “Good signal strength is not the same claim as room on the channel — prove both before you call it delivered.”.
- Here Pete follows the shared air itself: what it costs to join, what it costs to stay heard, and what the record needs to show.
Major section
For Beginners: What is Wi-Fi?
Wi-Fi is how devices connect to the internet wirelessly - like invisible cables made of radio waves!
- When your phone connects to your home router without a cable, that's Wi-Fi.
- Wi-Fi uses radio frequencies (like a radio station) to send data through the air.
- The 2.4 GHz frequency travels farther through walls but is slower and more crowded.
- The 5 GHz frequency is faster but doesn't travel as far.
Major section
Wi-Fi Speed, Power Saving, and Frequency Bands
"Wi-Fi keeps getting faster and smarter!" said the microcontroller. "The original 802.11b from 1999 was only 11 Mbps.
- "But speed is not the only improvement for IoT," noted Temperature Terry. "Wi-Fi 6 has two features I love.
- With hundreds of IoT devices in a smart building, that is essential.".
- TWT makes Wi-Fi actually practical for battery-powered sensors!".
Major section
IEEE 802.11 Wi-Fi Overview
IEEE 802.11, commonly known as Wi-Fi, is a protocol replacing wired Ethernet for wireless communications.
- It uses the unlicensed radio band for data transmission.
Major section
IoT-Specific Wi-Fi Standards
That labelled check bounds wi-fi halow features and iot applications.
- The same record must verify the labelled one-kilometre range and 8,191-device ceiling against the deployment's actual link and capacity budgets.
- That sequence keeps 802.11ax (wi-fi 6) tied to what is visibly labelled.
Major section
Compare Wi-Fi Modulation
This provides 4 dB margin above minimum SNR in worst-case interference, ensures sub-2 ms burst transmission to minimize collision window, and far exceeds the 2.73 kbps requirement.
- The gateway sends 10 kB data bursts to the cloud every 30 seconds.
- Building has 8 competing Wi-Fi networks causing channel congestion.
- Key Insight: For IoT gateways in congested Wi-Fi environments, do NOT select the highest modulation scheme your SNR supports.
Deck summary
Key takeaways
Shared air, walls, other users, and sleep timing can change the link without changing the device code.
- Received signal strength is a device's estimate of received radio power; RSSI means received signal strength indicator.
- Wi-Fi is how devices connect to the internet wirelessly - like invisible cables made of radio waves!
- "Wi-Fi keeps getting faster and smarter!" said the microcontroller. "The original 802.11b from 1999 was only 11 Mbps.
- IEEE 802.11, commonly known as Wi-Fi, is a protocol replacing wired Ethernet for wireless communications.
Retrieval practice
Recall check
Packet Pete says: answer from memory, then check your reasoning.
Q1A hospital deploys 300 patient monitors across 5 floors (100m x 80m each). Devices transmit vitals every 2 seconds with <100ms latency requirement. Which protocol meets requirements?
Show answer
Answer: B
Print reference
Answers
Answer key.
- B