Wireless Notes
One-page wireless communication cheatsheet with all important formulas, constants, conversion tables, modulation comparison, generation comparison, dB dBm conversion, and quick reference for exam revision.
Hindi: Exam, interview, ya quick revision ke liye one-page cheatsheet. Saari important formulas, constants, comparisons, aur key facts ek jagah.
📊 Quick Comparison Tables
Modulation Performance (BER = 10⁻⁶):
| Scheme | Eb/N₀ | bps/Hz |
|---|---|---|
| BPSK/QPSK | 10.5 dB | 1/2 |
| 16-QAM | 14.5 dB | 4 |
| 64-QAM | 18.5 dB | 6 |
| 256-QAM | 24 dB | 8 |
Mobile Generations:
| Gen | Access | Speed | Year |
|---|---|---|---|
| 1G | FDMA | Analog | 1983 |
| 2G | TDMA | 9.6-236 kbps | 1991 |
| 3G | CDMA | 2-42 Mbps | 2001 |
| 4G | OFDMA | 100M-1G | 2009 |
| 5G | OFDMA+mMIMO | 1-10 Gbps | 2019 |
WiFi Generations:
| Gen | Standard | Speed | Band |
|---|---|---|---|
| WiFi 4 | 802.11n | 600 Mbps | 2.4/5 |
| WiFi 5 | 802.11ac | 3.5 Gbps | 5 |
| WiFi 6 | 802.11ax | 9.6 Gbps | 2.4/5/6 |
| WiFi 7 | 802.11be | 46 Gbps | 2.4/5/6 |
Wireless Security:
| Protocol | Status | Key Feature |
|---|---|---|
| WEP | BROKEN ❌ | Never use |
| WPA2 | OK ✅ | AES-CCMP |
| WPA3 | BEST ✅ | SAE, forward secrecy |
🔑 Key Constants
| Constant | Value |
|---|---|
| Speed of light (c) | 3 × 10⁸ m/s |
| Boltzmann (k) | 1.38 × 10⁻²³ J/K |
| Noise floor (290K) | -174 dBm/Hz |
| Earth radius | 6,371 km |
| GEO altitude | 35,786 km |
| Free space impedance | 377 Ω |
💡 Conversion Quick Reference
| dB | Linear | Power Ratio |
|---|---|---|
| 0 dB | 1× | Same |
| 3 dB | 2× | Double |
| 6 dB | 4× | Quadruple |
| 10 dB | 10× | Ten times |
| 20 dB | 100× | Hundred times |
| 30 dB | 1000× | Thousand times |
| dBm | Power |
|---|---|
| 0 dBm | 1 mW |
| 10 dBm | 10 mW |
| 20 dBm | 100 mW |
| 23 dBm | 200 mW (typical phone) |
| 30 dBm | 1 W |
| 43 dBm | 20 W (typical small cell) |
| 46 dBm | 40 W (typical macro BS) |
Exam Focus
Revise definitions, diagrams, examples, and short-answer points for Wireless Communication Cheatsheet All Formulas Quick Reference.
Interview Use
Prepare one clear explanation, one practical example, and one common mistake for this Wireless Communications topic.
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