Traditional networks use only big towers spread far apart. This creates problems: coverage holes and capacity limits.
HetNet = Heterogeneous Network = mixing different cell sizes together.
Instead of “one size fits all,” use the right size cell for each situation.
Cell Types
| Cell Type | Coverage | Where it’s used |
|---|---|---|
| Macro cell | Kilometers | Wide area coverage |
| Micro cell | Hundreds of meters | Urban streets |
| Pico cell | Tens of meters | Offices, malls |
| Femto cell | One room | Homes, small offices |
Smaller cells = more capacity in that area.
Why Mix Cell Sizes?
Big cells alone can’t handle crowded areas. Everyone shares the same tower.
Small cells alone would need thousands of towers for coverage.
Solution: Big cells for coverage, small cells for capacity where needed.
The macro cell is your safety net. Small cells are speed boosters in busy spots.
Two Types of HetNets
Intra-technology HetNets
All cells use the same technology, just different sizes.
Example: LTE macro tower + LTE picocells
- Seamless handoff between cells
- Same network, same technology
- Easier to manage
Inter-technology HetNets
Cells use different technologies mixed together.
Example: LTE macro cell + WiFi hotspots
- Different networks working together
- Requires switching between technologies
- More complex, but flexible
Relay Nodes
What if you can’t run fiber to a new small cell? Relay nodes solve this.
A relay node:
- Receives signal from the macro cell wirelessly
- Retransmits to users nearby
- No fiber needed!
Think of it like a signal repeater. It grabs the signal and passes it along.
Types of Relay Nodes
| Type | Backhaul | User link | Complexity |
|---|---|---|---|
| Out-band | Different frequency | Different frequency | Simpler |
| In-band | Same frequency | Same frequency | Trickier |
Out-band is easier because backhaul and user traffic don’t interfere with each other.
In-band saves spectrum but requires careful timing to avoid interference.
Why Use Relay Nodes?
| Advantage | Why it matters |
|---|---|
| Cheap | No fiber installation costs |
| Fast to deploy | Just mount and power on |
| Flexible | Can be moved easily |
| Fills gaps | Reaches hard-to-wire areas |
Perfect for: Temporary events, rural areas, coverage holes, construction zones.
Summary
| Concept | Key Point |
|---|---|
| HetNet | Mix of different cell sizes |
| Macro cells | Wide coverage |
| Small cells | High capacity in busy areas |
| Intra-technology | Same tech, different sizes |
| Inter-technology | Different techs working together |
| Relay nodes | Extend coverage without fiber |
HetNets are about using the right tool for the job. Big towers for coverage, small cells for capacity, relays to fill the gaps.