WiFi Engineer Guidline
Complete Wireless Engineering Guide
In-depth guide on RF principles, connection standards, testing tools, and troubleshooting procedures for Network Engineers.
# 1. Overview & Frequency Bands
WiFi is a wireless networking technology using 2.4GHz, 5GHz, and 6GHz radio waves.
Band Comparison & Recommended Devices
| Criteria | 2.4GHz | 5GHz | 6GHz |
|---|---|---|---|
| Characteristics | Good penetration, low speed, high interference. | High speed, stable, moderate coverage. | Ultra-fast, low latency, no penetration. |
| Priority Devices |
|
|
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# 2. RF Physics & Antennas
TX / RX & Real-World Speed
Client → AP. Usually weaker because phones have small antennas.
RX (Download)
AP → Client. Faster because AP has stronger transmit power.
- WiFi 5: ~350–500 Mbps
- WiFi 6: ~500–700 Mbps
RF Behaviors
Antenna Theory
# 3. Bandwidth & Interference
Interference Types
Same-channel sharing
Overlapping channels
Microwave, Bluetooth…
# 4. Common WiFi Standards
Speed: 600 Mbps
Works on both 2.4GHz & 5GHz. Legacy standard.
Speed: 3.5 Gbps
Only 5GHz. Introduced MU-MIMO.
Speed: 9.6 Gbps
OFDMA, BSS Coloring, improved upload efficiency & lower latency.
Speed: 46 Gbps
- MLO (Multi-Link Operation)
- 4K-QAM modulation
- 320 MHz ultra-wide channels
# 5. Authentication & Security
Home (WPA-Personal)
Simple, uses a shared WiFi password.
- WPA2-AES — current default
- WPA3-SAE — protection against brute-force
Enterprise (802.1X)
Uses RADIUS server for authentication.
- PEAP-MSCHAPv2 — login with domain credentials
- EAP-TLS — certificate-based, most secure
- Dynamic VLAN — assign VLAN per user
# 6. Roaming
Roaming Standards
# 7. Deployment Models & Case Studies
- Mesh WiFi system
- Prefer wired backhaul
- Single SSID
- High-density APs
- Client isolation
- Short DHCP lease time
- Controller-based WiFi
- VLAN segmentation
- Enterprise authentication
Ubiquiti UniFi
SME / ProsumerBeautiful UI, no license fees.
- Controller: UDM Pro / Cloud Key
- APs: U6-Pro, U6-Lite
Aruba Instant On
Retail / StableExtremely stable. Free Cloud management.
- Switch: Aruba 1930
- AP: AP22 / AP11
# 8. Tools & Assessment
Signal Quality Assessment Table
| RSSI (dBm) | Quality | Usage |
|---|---|---|
| -30 to -50 | Excellent | 4K Video, Gaming |
| -51 to -60 | Good | Meetings, HD video |
| -61 to -70 | Fair | Web, Email |
| -71 to -80 | Weak | Messaging only |
| < -80 | Very Weak | Unstable |
Calculate Wavelength
Shorter wavelength → easier to block.
// Where:
c = 300,000,000 m/s
f = Frequency
2.4GHz ≈ 12.5 cm
5GHz ≈ 6 cm
Free mobile scanning app.
Channel graphs, signal meter.
Detect non-WiFi interference.
# 9. OSI Troubleshooting Guide
Scientific troubleshooting from lowest → highest layer.
L1 Physical Layer
AP offline / link 100Mbps.
Fix: Re-crimp cable, check PoE, check spectrum.
L2 Data Link Layer
SSID visible but cannot connect.
Fix: Check password, RADIUS logs, channel overlap.
L3 Network Layer
Connected but no internet.
Fix: DHCP, VLAN tagging, ping gateway.
L7 Application Layer
Web slow, captive portal missing.
Fix: Change DNS, check firewall filter.
