Actually Cell have random shape ( shape of Cell depends on geographical conditions such as Hills, Buildings, water bodies etc)

Ideal shape of cell is Circle

Hexagon is close to Circle so it is considered for Drawing as well as calculation.

The Hexagon cell represent Theoretical concept .

As the coverage area has random shape. If you need to cover it with circle, all the areas will be covered but the circles will be overlapped at boundaries, causing interference. But if it is covered in hexagons, the overlapping would either be reduced or not observed at all. Draw a rough sketch on paper and try to break it in circles and then hexagons, you would find the logic.

Three reasons (just providing keywords here)

- Omni-directional transmissions

- Frequency re-use analysis

- For hexagons of equal sides, every cell fits tight with every other cell.

There is more.

Sectored sites traditionally have 3 sectors, and hexagons lend themselves nicely to the cause, since one site is easily represented with 3 hexagons, and a site in a middle. So a hexagon works for both circular and sectored coverage.

In reality, however, things are very different. Area covered primarily with a single sector is called a "best server", but the interfering neighbours make things a bit more fun. In that sense you may observe the book definitions with hexagons merely a learning tool.

It is just a geometric reason. Hexagons are the polygons that naturally tessellate the plane. Bees make cells circular then they become hexagons due to the pressure, when they are compacted: http://www.nature.com/news/how-honeycombs-can-build-themselves-1.13398

In case you were wondering, if you want to cover a volume, instead of an area, a truncated octahedron would be used: http://www.matematicasvisuales.com/english/html/geometry/space/truncatedoctahedrontessela.html

Hexagonal cell shape is perfect in cellular architecture because it cover an entire area without overlapping.

Satellite radios are most commonly used by consumers in automobiles as it offers better sound quality and more station programming choices over traditional AM and FM radio.Consumers typically pay for Satellite radio programming on a monthly subscription basis.

In reality, as it has been already been said, cells do not have regular shapes, they are irregular and overlapping regions. There are several regular shapes that can be used, i.e. square, circular, hexagonal, etc.

However, there are few reasons that explain this approach:

• This shape approximates a circle quite well, which means that we can almost ensure equidistance between antennas (drawback of the square shape). This point is important in order to determine when to switch a user to an adjacent antenna
• An hexagonal cell-layout uniformly covers any surface (without overlapping, which solves the drawback of the circular shape)
• It is  justified when three sectors are used (as Mr. Virkes explained)
• The hexagon has the largest area coverage among the candidates

Nevertheless, it shall be noted that the hexagonal shape is something that cannot be implemented in reality.

The Mobile Terminals use the frequency which is very costly. In communication there is a concept of Frequency Reuse Through Spatial Diversity which means that the same frequency can be used in two areas which are a distant apart. The Hexagonal structure of a cell is a theoretical approximation and a easier visualization of the overall network cell structure. The hexagon having 6 sides makes the Frequency reuse capabilities more easier to be implemented.

In practical terms there is no perfect circle cell coverage for a variety of reasons such as problems associated with antenna dimensions, propagation environment, etc. As such it wouldn't be technically correct to represent cell coverage as a circle on the very least.