1.5 Compare and contrast transmission media and transceivers
Wireless Media
📘CompTIA Network+ (N10-009)
Introduction to 802.11 Wireless Standards
The IEEE 802.11 standards define how wireless local area networks (WLANs) operate.
These standards are created by the Institute of Electrical and Electronics Engineers (IEEE) and determine how wireless devices communicate, the speed of data transfer, frequency bands, and range.
All Wi-Fi technologies we use in networking—such as laptops, smartphones, and wireless access points—follow some version of the 802.11 standard.
Key Concepts Before the Standards
| Term | Meaning |
|---|---|
| SSID (Service Set Identifier) | The name of a wireless network. All devices must use the same SSID to connect. |
| Access Point (AP) | The device that allows wireless devices to connect to a wired network. |
| Frequency Band | The radio spectrum used for wireless signals, mainly 2.4 GHz and 5 GHz, and newer 6 GHz bands. |
| Channel | A smaller section within a frequency band that separates signals to avoid interference. |
| MIMO (Multiple Input Multiple Output) | A technology that uses multiple antennas to increase speed and reliability. |
| MU-MIMO (Multi-User MIMO) | Allows multiple devices to receive data simultaneously, improving performance. |
| OFDMA (Orthogonal Frequency Division Multiple Access) | Efficiently divides channels among multiple users—used in modern Wi-Fi standards. |
802.11 Standards Comparison Table
| Standard | Frequency Band | Maximum Data Rate | Typical Range | Channel Width | Modulation/Technology | Notes |
|---|---|---|---|---|---|---|
| 802.11a | 5 GHz | Up to 54 Mbps | ~35 m indoors | 20 MHz | OFDM | Less interference but shorter range. |
| 802.11b | 2.4 GHz | Up to 11 Mbps | ~35 m indoors | 22 MHz | DSSS | Older, prone to interference from other 2.4 GHz devices. |
| 802.11g | 2.4 GHz | Up to 54 Mbps | ~35 m indoors | 20 MHz | OFDM | Backward compatible with 802.11b. |
| 802.11n (Wi-Fi 4) | 2.4 GHz & 5 GHz | Up to 600 Mbps | ~70 m indoors | 20/40 MHz | MIMO | Introduced MIMO and channel bonding. |
| 802.11ac (Wi-Fi 5) | 5 GHz | Up to 6.9 Gbps | ~35 m indoors | 20/40/80/160 MHz | MU-MIMO, Beamforming | Major speed boost using wider channels and more antennas. |
| 802.11ax (Wi-Fi 6) | 2.4 GHz & 5 GHz | Up to 9.6 Gbps | ~70 m indoors | 20/40/80/160 MHz | OFDMA, MU-MIMO | Improves performance in crowded environments. |
| 802.11be (Wi-Fi 7) | 2.4 GHz, 5 GHz & 6 GHz | Up to 46 Gbps (theoretical) | ~70 m indoors | 20–320 MHz | Multi-Link Operation (MLO), 4096-QAM | Future Wi-Fi standard for ultra-high speed and low latency. |
Detailed Explanation of Each Standard
1. IEEE 802.11a
- Operates in the 5 GHz band.
- Uses Orthogonal Frequency Division Multiplexing (OFDM) for efficient data transfer.
- Maximum speed: 54 Mbps.
- Shorter range than 2.4 GHz networks due to higher frequency.
- Less interference because fewer devices use the 5 GHz band.
2. IEEE 802.11b
- Operates in the 2.4 GHz band.
- Uses Direct Sequence Spread Spectrum (DSSS).
- Maximum speed: 11 Mbps.
- Good range, but easily interfered by Bluetooth, microwaves, and other 2.4 GHz devices.
3. IEEE 802.11g
- Also operates in the 2.4 GHz band.
- Uses OFDM (like 802.11a) for better performance.
- Maximum speed: 54 Mbps.
- Backward compatible with 802.11b devices.
- Still suffers from interference because it uses 2.4 GHz.
4. IEEE 802.11n (Wi-Fi 4)
- Works on both 2.4 GHz and 5 GHz bands (dual-band).
- Introduced MIMO (Multiple Input Multiple Output) — uses multiple antennas for sending/receiving data simultaneously.
- Maximum speed: up to 600 Mbps with 4 antennas.
- Supports channel bonding (combining two 20 MHz channels into one 40 MHz channel) for more bandwidth.
- Much faster and more reliable than earlier versions.
5. IEEE 802.11ac (Wi-Fi 5)
- Works only on the 5 GHz band.
- Introduced MU-MIMO (Multi-User MIMO) and Beamforming to improve speed and efficiency.
- Maximum speed: up to 6.9 Gbps (depending on configuration).
- Supports wider channels (up to 160 MHz) for high throughput.
- More suitable for modern enterprise environments with many users.
6. IEEE 802.11ax (Wi-Fi 6)
- Operates on both 2.4 GHz and 5 GHz bands.
- Uses OFDMA to divide channels efficiently among multiple users.
- Introduced Target Wake Time (TWT) to save device battery.
- Supports MU-MIMO (upstream and downstream).
- Maximum speed: up to 9.6 Gbps.
- Designed for high-density environments like offices, universities, or public spaces.
7. IEEE 802.11be (Wi-Fi 7) (Emerging Standard)
- Works across 2.4 GHz, 5 GHz, and 6 GHz bands.
- Supports 320 MHz channels (double that of Wi-Fi 6).
- Introduces Multi-Link Operation (MLO) — devices can use multiple bands at the same time.
- Maximum speed: up to 46 Gbps (theoretical).
- Very low latency, ideal for future high-performance applications.
Frequency Bands Overview
| Band | Pros | Cons |
|---|---|---|
| 2.4 GHz | Longer range, better wall penetration | More interference, fewer non-overlapping channels |
| 5 GHz | Faster speeds, less interference | Shorter range, cannot penetrate walls easily |
| 6 GHz | High speed, less congestion | Limited device support (new technology) |
Modulation and Technologies in 802.11
| Technology | Purpose |
|---|---|
| DSSS | Spreads signal across wide frequencies to reduce interference (used in 802.11b). |
| OFDM | Divides data into multiple subcarriers for efficient transmission (used in 802.11a/g/n/ac/ax). |
| MIMO | Uses multiple antennas to send/receive data, improving performance. |
| Beamforming | Directs wireless signals toward devices to increase speed and reliability. |
| OFDMA | Allows multiple users to share the same channel efficiently (used in Wi-Fi 6 and later). |
Backward Compatibility
Most 802.11 standards are backward compatible:
- 802.11g works with 802.11b devices.
- 802.11n works with a/b/g.
- 802.11ac supports n devices (in 5 GHz band).
- 802.11ax supports ac/n devices.
However, connecting to older devices can reduce the overall network speed.
Security in 802.11 Standards
Different standards work with various Wi-Fi security protocols:
- WEP (Wired Equivalent Privacy): Old and insecure; used in 802.11b/g.
- WPA/WPA2: Stronger encryption; used in 802.11n/ac.
- WPA3: Most secure; recommended for Wi-Fi 6 (802.11ax) and later.
Exam Tip Summary
| Exam Point | Key Detail |
|---|---|
| 802.11a | 5 GHz, 54 Mbps, OFDM |
| 802.11b | 2.4 GHz, 11 Mbps, DSSS |
| 802.11g | 2.4 GHz, 54 Mbps, OFDM |
| 802.11n | 2.4/5 GHz, 600 Mbps, MIMO |
| 802.11ac | 5 GHz, 6.9 Gbps, MU-MIMO, Beamforming |
| 802.11ax | 2.4/5 GHz, 9.6 Gbps, OFDMA, MU-MIMO, TWT |
| 802.11be | 2.4/5/6 GHz, 46 Gbps, MLO, 4096-QAM |
| 2.4 GHz Band | Longer range, more interference |
| 5 GHz Band | Faster, shorter range |
| 6 GHz Band | High speed, less congestion |
| Modern Wi-Fi Names | Wi-Fi 4 = 802.11n, Wi-Fi 5 = 802.11ac, Wi-Fi 6 = 802.11ax, Wi-Fi 7 = 802.11be |
Conclusion
The 802.11 standards define how wireless networks operate—covering speed, frequency, modulation, and technologies used to connect devices.
Understanding these standards is essential for the CompTIA Network+ (N10-009) exam because they appear frequently in network design, troubleshooting, and implementation questions.
Always remember which standard uses which frequency band, data rate, and technology—these are key exam facts.
