---
title: "Sectoring versus cell splitting for capacity"
subject: "Wireless Communication"
chapter: 2
key: "semester_7/wireless_communication:sectoring-vs-cell-splitting"
source: https://www.bctengineer.com/q/semester_7/wireless_communication/sectoring-vs-cell-splitting
site: BCT Engineering
---

# Sectoring versus cell splitting for capacity

Wireless Communication · Chapter 2: Cellular Mobile Communication Concepts

- Asked in: 2081 Bhadra, 4 marks; 2075 Bhadra, 5 marks (asked 2 times)
- Video: [Cell Sectoring and Cell Splitting | Improving Coverage and Capacity In Cellular System](https://www.youtube.com/watch?v=7rjmKgMrDpM) — ECIT Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/wireless_communication/sectoring-vs-cell-splitting
- Whole chapter: https://www.bctengineer.com/md/semester_7/wireless_communication/chapter-2

## Question

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?

## 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.

## Answer

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.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. How does 120-degree sectoring increase capacity?
   A. It reduces co-channel interferers from 6 to 2, raising S/I so a smaller cluster size N can be used
   B. It builds new sites
   C. It increases trunking efficiency
   D. It removes handoffs
   Answer: A. Capacity rises only through smaller N. (Key point: Sectoring effect)

2. Halving the cell radius gives approximately what capacity gain in the area?
   A. 2 times
   B. 4 times
   C. 8 times
   D. No change
   Answer: B. Capacity is proportional to (R_old/R_new)^2 = 4. (Key point: Splitting capacity)

3. Which technique reduces trunking efficiency?
   A. Cell splitting
   B. Sectoring, since channels are divided among sectors
   C. Neither
   D. Both equally
   Answer: B. Dividing channels into sector groups lowers trunking efficiency. (Key point: Trunking)

4. What does the answer recommend?
   A. Sectoring alone forever
   B. Cell splitting as the long-term choice, with sectoring first for quick gain
   C. Neither technique
   D. Reducing the number of channels
   Answer: B. Sectoring is quick and cheap; splitting is for hot spots and growth. (Key point: Recommendation)

## Related in Wireless Communication

- [Numerical: trunking capacity loss with sectoring](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Atrunking-loss-sectoring) — Wireless Communication, chapter 2
- [Numerical: 12-cell system capacity at 2% GOS](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Acellular-capacity-12-cell-system) — Wireless Communication, chapter 2
- [Numerical: maximum cell radius using Hata model](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Ahata-max-cell-radius) — Wireless Communication, chapter 3
- [Techniques to enhance capacity and coverage](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Acapacity-coverage-enhancement) — Wireless Communication, chapter 2

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