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- 2081 Bhadra · 4 marks
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Sectoring versus cell splitting for capacity
Short answer
Cell splitting is the best long-term choice because it multiplies capacity roughly as the square of the radius reduction and can be repeated in hot spots. Sectoring gives a limited one-time gain and reduces trunking efficiency. In practice, apply sectoring first, then split cells where traffic grows.
A telephone network company needs to expand its capacity based on demand on a city. A group of engineers was selected to find the solution. Among the solution sectoring and cell splitting were major technique for expansion purpose. Being a cellular planning engineer, which option do you think is best and why?
Both techniques increase capacity, but in different ways:
- Cell splitting divides a congested cell into smaller cells, each with its own base station and lower power. More cells means more reuse of the same channels, so capacity rises roughly in proportion to the number of new cells (e.g. halving the radius gives about 4 times the capacity in that area).
- Sectoring replaces the omni antenna with directional antennas (3 × 120° or 6 × 60°). It reduces the number of co-channel interferers (6 → 2 for 120°), raising S/I, so a smaller cluster size N can be used. Capacity increases only through the smaller N; channels are also divided among sectors, reducing trunking efficiency.
| Point | Cell splitting | Sectoring |
|---|---|---|
| Method | More, smaller cells | Directional antennas in same cell |
| Capacity gain | Large, ∝ (R_old/R_new)² | Moderate, via smaller N |
| New sites | Needed (cost, land) | Not needed |
| Handoffs | More (smaller cells) | More (between sectors) |
| Trunking efficiency | Unchanged | Reduced |
| Cost/time | High, slower | Low, fast |
Recommendation
For a city where demand keeps growing, cell splitting is the best long-term choice because it multiplies capacity in proportion to the number of new cells and can be repeated (macro → micro → pico) only where traffic is high. Sectoring alone gives a limited, one-time gain and lowers trunking efficiency.
In practice the engineer should first apply sectoring at existing sites (quick, cheap, improves S/I) and then split cells in hot spots (city centre, markets) as traffic grows, using lower power and down-tilted antennas. Combined, they give the maximum capacity at reasonable cost.
✓ Answer checked by Claude Opus 5.5 (high effort)
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