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Interference Mitigation Techniques in Wireless Communications Systems

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • An unwanted wireless signal injected into the original signal may result in a temporary loss of wireless signals, poor receiver performance, or bad quality of output by the electronic equipment.

  • The channel interferences influencing the performance of wireless communication systems can be co-channel interferences or adjacent channel interferences.

  • Reducing the radio frequency power of wireless signals is an effective method of interference mitigation.

 Wireless signal transmission

Interference is a troubling problem that affects the performance of wireless communication systems. Wireless signal transmission is more susceptible to interference, and it affects the functioning of other consumer and electronic devices nearby.

Wireless communication systems act as a source as well as a victim of interference. There are various interference mitigation techniques in a wireless communication system that make it interference-immune. Let’s discuss the interference in wireless communication systems and some mitigation techniques in this article. 

Interference in Wireless Communication Systems

In wireless communication systems, signal transmission occurs through the medium of air. As transmitters share the common medium of air, devices operating in the same frequencies can be mutually accessible and can disrupt functioning. When the wireless communication signals are disrupted or weakened by the presence of other wireless signals, it is considered to be interference. Any device that emits electromagnetic signals can be subjected to interference.

Unwanted wireless signals injected into the original signal may result in a temporary loss of wireless signals, poor receiver performance, or bad quality of output by electronic equipment. Interference can sometimes cause network slowdown, which is less evident in low capacity data transmission but a serious problem in high capacity data transmission. Most wireless communication systems can generate interference in electronic devices in the nearby vicinity. Similarly, electronic systems such as cordless phones, Bluetooth devices, wireless video cameras, and microwave ovens can interfere with wireless communication systems.

Some other causes of interference in wireless communication systems include:

  • Multiple communication systems that share the bandwidth on one channel
  • Hidden nodes in wireless networks generate numerous cyclic redundancy check code errors 
  • Broad radiofrequency emissions from bad electrical connections
  • Radiofrequency jamming
  • Channel interferences

The channel interferences influencing the performance of wireless communication systems can be co-channel interferences or adjacent channel interferences. The upcoming section introduces these types of interference in wireless communication systems. 

Types of Interference in Wireless Communication Systems 

Based on the spacing between desired and interfering signals, there are two types of interference:

Co-channel interference - Interference in wireless systems that transmit signals at the same frequency is called co-channel interference.

Adjacent channel interference - Interference in wireless systems caused by adjacent frequency signals.

Based on the type of signal interfering, the interference in wireless communications can be classified into:

Electromagnetic interference - The electromagnetic signals emitted by various systems and devices interfere with the desired signals of wireless communication systems.

Sound interference - There can be constructive as well as destructive interference caused by sound waves in speakers and other sound-producing devices.

Light interference - Light waves can interfere with communication systems transmitting signals through other mediums.

Multicarrier systems utilizing orthogonal frequency-division multiplexing (OFDM) techniques experience the following two interference types:

InterCarrier interference - In telecommunications, the OFDM subcarriers lose orthogonality and cause interference called intercarrier interference (ICI).

InterSymbol interference - The time delay in OFDM symbols traveling from the transmitting end to the receiving end results in the spreading out of OFDM symbols and they interfere with consecutive OFDM symbols. 

Interference Mitigation Techniques in Wireless Communication Systems 

There are several techniques and algorithms established in wireless communication systems to mitigate interference.

Reduce the power level: The reduction in radio frequency power of wireless signals is an effective method of interference mitigation.

Filtering and equalizers: In communication channels whose characteristics are known, filters can be incorporated for interference mitigation. If the channel characteristics are unknown, equalizers are an alternative to filters.

Transmission at different frequencies, in different places, and at different times: The wireless communication systems covering the same area can transmit at the same time if they are using different frequencies. Local television stations, radio stations, mobile communication, and other wireless communication systems utilize this technique for mitigating interference. Avoiding the locally used frequencies in wireless communication systems can reduce interference.

The transmission of wireless signals at the same frequency at the same time can be employed without interference problems only when they are separated. If the geographic areas of transmission are far away and the signals are within the allowable power levels, then there can be no interference.

Wireless communication systems can transmit signals over the same area using the same frequency without interference if the transmission times are different. Dividing the radio spectrum into different channels using techniques such as frequency division, time division, and code division is another interference mitigation technique in wireless communication systems.

Cadence software can help you plan interference mitigation techniques that are suitable for the wireless communication system under consideration. Subscribe to our newsletter for the latest updates. If you’re looking to learn more about how Cadence has the solution for you, talk to our team of experts.