Why do they decide that the coverage area (cell in GSM network) has a hexagon shape? Why hexagon not circle or Pentagon or square?

The original shape of any cell is circle, but these circles when arranged in a way the coverage boundaries between them form a certain shape.

Actually some other arrangements and shapes are used, for example, square cells in New York. However, the hexagon arrangement of the base stations provides best and most efficient use of the base stations.

I dont know exactly, it may be because the hexagonal shape gives the minimum overlap area of the adjacent cells and the frequency planning is also simplfied if the shape is hexagonal.
Circle on the other hand will give overlaps and blind aread too, where the frewuency of neither tower will reach.
And hexagonal shape is certainly advantageous over pentagon as it has more adjacent cells and therefore provides for more frequencies.
All this may have been decided intially at the time the technology was being developed.

Der Sir:

Thank you for your question

The hexagon shape in cellular communication planning and design of mobile networks is the most suitable shape for many reasons, most important of them the following:

- The hexagon is used because it best represent and simulates the seven tower over lapping of circle. Circle being the way radio frequency are depicted.

- The hexagon was chosen as it comes the closest to the circle, and the hexagon layout requires fewer cells (when compared to triangles rectangles)

- The radius of a hexagon is defined to be the radius of the circle that circumscribes it.

- Provide equidistant antenna.

 

Best regard

in the engineering language  earth is divided   into cell every  cell have own bts the shape of cell is because that are covered all the area that is main reason of hexagon shape

well its so sample , it just provide us with the minimum interferance 

Because,1)It has the most sides that can fit together without gaps.

2)The frequecncy reuse become possible using this shape.

3) The radiation pattern of the antennas used is60 degree which means6 are required for the full360 degrees coverage which is the same no. of sides the hexagon consists.

4) Frequency are emitted in circular way which makes the square, rectangle or a triangle unsuitable shapes for the cell while if we use a circular shape for the cell there will be gaps between cells.

Planning simplification purpose

In7 cell resuse the frequency band is divided into7 segments and each cell uses one segment. Geographically, each cell is surrounded by6 cells using a different frequency band. This is called a cluster. The simplest option is to have a hexagonal cell shape so that the cells do not overlap each other and there are no zones without coverage. Hexagonal cells fit perfectly.

 

In reality the a cell's coverage area is neither hexagonal nor circular. It is determined by the construction in that area as well as foliage. If you look at the coverage area of a cell as determined by a Network Planning tool you would see that its amoeba like. There would be areas where two cells having the same frequency might be interfering with each other as well as some dead zones.