We need more spectrum for 5G. But the traditional bands are crowded.
Solution: Go higher! Use millimeter waves.
What is mmWave?
Frequencies between 24 GHz and 100 GHz.
The wavelength at these frequencies is only 1-10 millimeters. Hence the name.
The Spectrum Comparison
| Band | Frequency | Wavelength |
|---|---|---|
| LTE | 700 MHz - 2.6 GHz | 11 - 43 cm |
| Sub-6 GHz 5G | 3.5 - 6 GHz | 5 - 8 cm |
| mmWave 5G | 24 - 100 GHz | 1 - 10 mm |
Higher frequency = shorter wavelength = more bandwidth available.
Advantages of mmWave
1. Massive Bandwidth
Traditional bands give you 20 MHz chunks. That’s it.
mmWave has hundreds of MHz available. Wide open spectrum.
More bandwidth = faster speeds. Simple math.
2. Very High Data Rates
With all that bandwidth, you can achieve multi-gigabit speeds.
| Band | Typical Speed |
|---|---|
| LTE | 100 Mbps |
| Sub-6 GHz 5G | 500 Mbps - 1 Gbps |
| mmWave 5G | 1 - 10 Gbps |
Perfect for eMBB applications.
3. Less Crowded
Nobody was using these frequencies before. Fresh, open spectrum.
- No interference from existing users
- Easier to get licenses
- Room to grow
Challenges of mmWave
Here’s the catch: high frequency = problems.
1. Limited Range
mmWave signals don’t travel far.
| Band | Typical Range |
|---|---|
| LTE | Several kilometers |
| Sub-6 GHz 5G | 1-2 km |
| mmWave 5G | 200-300 meters |
You need many small cells to cover an area.
2. Blocked by Everything
mmWave can’t penetrate obstacles.
What blocks mmWave:
- Walls (can’t go indoors)
- Buildings
- Trees and foliage
- Rain (yes, rain)
- Even your hand
mmWave needs line-of-sight. If something’s in the way, signal dies.
3. Expensive Deployment
Because of limited range, you need lots of small cells.
- More base stations = more cost
- More backhaul connections needed
- More maintenance
Great for dense urban areas. Not practical for rural.
mmWave Trade-off
| Advantage | Disadvantage |
|---|---|
| Huge bandwidth | Short range |
| Multi-gigabit speeds | Blocked by obstacles |
| Uncrowded spectrum | Expensive to deploy |
| Low latency | Needs line-of-sight |
mmWave = blazing fast, but only if you’re close and nothing’s in the way.
Where mmWave Makes Sense
mmWave works best in specific scenarios:
- Stadiums - dense crowds, limited area
- Airports - high traffic, controlled environment
- Shopping malls - indoor, can place many cells
- Urban hotspots - city centers, high demand
- Fixed wireless - home internet, stationary receiver
Don’t expect mmWave everywhere. It’s a tool for specific situations.
The 5G Spectrum Strategy
5G uses all bands together:
| Layer | Band | Purpose |
|---|---|---|
| Coverage | Low band (600-900 MHz) | Wide area, indoors |
| Capacity | Mid band (2.5-6 GHz) | Balance of speed/range |
| Speed | mmWave (24-100 GHz) | Extreme speed in hotspots |
5G isn’t just mmWave. It’s a layered approach using the right band for each situation.