Frequency Reuse Density

lReuse density is the number of cells in a basic reuse cluster.

pFor the n x m frequency reuse pattern,

n

nn: The number of BTSs in the reuse clusters

nm: The number of the cells under each BTS.

Usually, 12 is the boundary. That is, the reuse density smaller than 12 is called tight reuse, reuse density larger than 12 is called loose reuse, and 12 is the regular reuse. In specific frequency planning, we usually use the average reuse density to measure the objective interference in networks. If total frequency resource is 1~n, the reuse density of carrier i is re-use(i), then the average reuse density will be:

  re-use(ave.)=[re-use(1)+...re-use(i)+..re-use(n)]/n

4×3 Frequency Reuse

The basic frequency reuse mode of GSM is 4×3 frequency reuse. It is the basic of other frequency reuse modes, we also call it regular frequency reuse model. "4" represents 4 sites, "3" represents 3 cells in each site. Totally 12 cells become a basic frequency reuse cluster. Different cells in the same cluster have different frequencies. The above figure shows a cell cluster of 4×3 frequency reuse mode, while those inside the bold black line is a basic cell cluster model, including 4 BTS which have 3 frequency reuse group, there are 12 cells totally. In a specific allocation, all frequencies are allocated to each cell according to certain principle and same as other cell clusters. In this way, each frequency carrier is “reused” in different cell cluster time and time again.

Certainly, other reuse model n×m means that each basic reuse cell cluster contains n BTS, and each BTS includes m frequency reuse group. All frequency carriers in this cell cluster are allocated to respective cells according to certain principle, and by analogy for other surrounding cells.