Co-Channel Interference and Crosstalk in Mobile Communications

Key Takeaways

• Crosstalk is a phenomenon by which the signal transmitted on one channel of a mobile communication system creates an undesired influence on another channel.

• The poor frequency reuse in cellular networks initiates co-channel interference and causes crosstalk.

• As the distance between the cells utilizing the same frequency range increases, the chances of crosstalk in mobile communication due to frequency reuse decreases. 

Crosstalk in mobile communications can cause all sorts of problems. Crosstalk refers to any interference caused by unwanted signals that interrupt phone conversations. Unfortunately, mobile communication systems are susceptible to crosstalk, which hinders the privacy of mobile phone users. In this article, we will discuss the issue of crosstalk in mobile communications and some mitigation methods that can be used. 

Mobile Communications

Mobile communication technology enables the communication between mobile phones located at different places without any physical connection. In cellular or mobile communication, areas are divided into cells that are served by a base station. The base station consists of a transmitter, receiver, and control unit. A band of frequency is allocated to a cell, and each cell is supported by its own antenna. The cells are arranged such that the antennas are located equidistant from each other.

Communication over cellular networks is constantly improving in speed and accuracy to sustain users. As there are no wires or cables associated with mobile communication, there is less maintenance—and therefore less cost—required for these systems. Mobile communication allows two-way radio telecommunications over a cellular network. Despite these advantages, mobile communication is challenged by several issues including electromagnetic interference, echo, and crosstalk. 

Crosstalk in Mobile Communication

Crosstalk is the phenomenon by which the signal transmitted on one channel of a mobile communication system creates an undesired influence on another channel. Crosstalk can cause mild interference in cellular networks. The most severe effect of crosstalk on mobile communication is hearing unintended conversations while making the intended call.

As mobile communication signals are electromagnetic waves, they are susceptible to interference and cause crosstalk. Inter-cell interference or co-channel interference is the main reason for crosstalk in mobile communication. Channels that reuse the same range of frequencies experience co-channel interference. When the adjacent cells operate on the same range of frequencies, it can lead to interference, which is why no two adjacent cells should be allocated the same range of frequencies. 

Frequency Reuse in Mobile Communication  

The scheme through which the frequency allocation and reuse are done to cover a region is called frequency reuse in mobile or cellular communication. The cells in a mobile communication system cover small geographic areas and each cellular base station is allocated with a frequency band. Through frequency reuse, the frequency bands are used more than once to increase the total capacity of mobile communication without allocating increased bandwidth. There is a requirement of isolation among the cells utilizing the same frequency range to prevent interference below acceptable levels.

However, poor frequency reuse in cellular networks initiates co-channel interference. The bad weather and bleeding from adjacent bands can also overcrowd the radio frequency spectrum and cause co-channel interference and crosstalk. 

Crosstalk Mitigation in Mobile Communications 

Co-channel interference is significant in developing crosstalk in mobile communications. Crosstalk mitigation can be achieved by reducing co-channel interference. Some of the methods employed in mobile communication to reduce co-channel interference and thereby crosstalk are:

1. Better frequency reuse designs. As the distance between the cells utilizing the same frequency range increases, the chances of crosstalk in mobile communication due to frequency reuse decreases. 

2. Reducing the cell size in mobile communication increases the co-channel reuse distance. As the distance between the co-channel increases, the c-channel interference decreases. 

3. Employing co-operating transmitters in mobile communication helps transform the interference channel into the broadcast channel, thereby mitigating co-channel interference and crosstalk. 

4. The interference reconstruction technique (IRT) can be used to reduce co-channel interference. The IRT reconstructs the users’ signals to cross-correlate with the components in the received signals. The cross-correlation process in IRT ensures the desired signals are present in mobile communication. 

5. Power control is a crosstalk mitigation method in mobile communication. Decreasing the base station transmitter-receiver power can reduce co-channel interference. If co-channel interference in mobile communication is reduced, it can mitigate crosstalk as well. 

6. The use of directional antennas at the base station eliminates co-channel interference. Each cell in a cellular network is divided into several sectors with the same number of directional antennas at the base station. The use of a directional antenna assigns a set of frequencies for each sector in the cell, thereby decreasing the co-channel interference. 

Due to the presence of more radiated emissions and more base stations and mobile stations, urban areas experience a comparatively higher amount of crosstalk in mobile communication. Cadence software can help you implement crosstalk mitigation methods in mobile communication systems.

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