Why are cells in real-world deployments not perfect hexagons, and what is a tri-sectorized cell?

Real cells are irregular shapes determined by terrain, buildings, and antenna placement — hexagons are just a theoretical model.

In textbooks, cells are drawn as neat hexagons because they tile a plane efficiently. In practice, the actual coverage footprint depends on:

• Terrain — hills, valleys, water bodies
• Buildings — urban canyons reflect and block signals
• Antenna height and type — directional vs. omnidirectional
• Transmit power and the mobile standard used

A tri-sectorized cell uses a single tower with three directional antennas, each covering a 120-degree sector. This is the most common configuration in urban deployments because it:

• Triples the capacity per tower site compared to a single omnidirectional antenna
• Allows better frequency reuse planning
• Reduces interference by focusing energy in specific directions

Go deeper:

• Sector antenna (Wikipedia) — the 120-degree directional antennas mounted in threes on a tower, exactly the tri-sectorized cell described.
• Cellular network (Wikipedia) — why real footprints are irregular and how three 120-degree sectors triple per-site capacity.