Cell Splitting And Cell Sectoring

With the growing number of mobile users, it is important for the cellular capacity to also keep growing to meet the needs of the users. In this article, we will look at some of the capacity-increasing methods in cellular networks.

 Figuratively speaking there are broadly two ways to increase the channel capacity:

1. The new addition of channels
2. Borrowing of frequency

Both of the above two methods will also lead to an increase in cost along with capacity. Two distinct approaches we use in the modern day to increase channel capacity are Cell Splitting and Cell Sectoring. We will discuss them in detail below.

Cell Splitting 

Cell Splitting is the process of subdividing a cell into smaller cells each with its own Base Station. On splitting, new cells with smaller radius are added called microcells. Each new cell created is independent and has reduced antenna height and transmitter power. The creation of new smaller cells increases the capacity of the system as a whole. Cell Splitting increases the frequency reuse factor. A higher frequency reuse factor increases the capacity of the cellular system in Cell Splitting. 

Advantages

• Increases the capacity of the channel considerably.
• Enhances dependability of cellular networks.
• Increases the frequency reuse factor.
• Increases signal-to-noise (SNR) ratio.
• Reduces interference.

Disadvantages

• For each individual cell, an individual base station is required so a huge number of base stations are needed in this process.
• Handoff occurs frequently.
• Assigning channels is difficult

Cell Sectoring

Cells are divided into a number of wedge-shaped sectors, each with its own set of channels. By wedge-shaped we mean that the cells are divided at an angle of 120° or 60°. These sectored cells are called microcells. Like Cell Splitting, it also helps in increasing channel capacity and decreases channel interference. 3 or 6 sectors are created from a given cell. But unlike Cell Splitting, here the cell radius does not change after sectoring the cells although the co-channel reuse ratio has decreased. It increases system performance by using a directional antenna. 

Advantages

• Sectoring increases the signal-to-interference ratio which means the cluster size gets reduced.
• Reduces interference without altering the system performance.
• Increases channel capacity without necessarily changing the cell radius.
• Increases frequency reuse by reducing the number of cells in the cluster.
• Assigning a channel is easier.

Disadvantages

• Increases the number of antennas per base station.
• It decreases efficiency as sectoring reduces the channel groups.
• Excessive interference leads to traffic loss.
• The number of handoffs increases as the working area of the cell decreases in Cell Sectoring.