Co-Channel and Adjacent Channel Interference in Mobile Computing
Co-channel interference is not actually an interference but more a sort of congestion when more than one device is operating on the same frequency channel. It hinders performance by increasing the wait time as the same channel is used by different devices. Sources of interference are as follows:
- Another mobile in the same cell.
- Ongoing call in neighbor’s cell
- When a different Base Station operates on the same frequency.
Types of channels on which interference is present are-
- On Voice Channel: leads to crosstalk which is an interference or background noise while we are talking to another person on mobile. Crosstalk is unwanted interference that should be minimized.
- On Control Channel: It can lead to problems in creating a connection between the sender and receiver during a call which leads to missed calls. Calls may terminate abruptly known as blocked calls.
Interference causes the above two problems because it reduces the channel capacity and thus, affects the performance.
Types of Interference in Mobile Communication
- Co-Channel Interference
- Adjacent Cell Interference
Co-channel cells are those cells that use the same frequency in a given coverage area. Interference from these cells is called co-channel interference. In co-channel interference, the cells are clustered as close together as possible to reduce the co-channel interface and provide sufficient isolation. Increasing the co-channel reuse ratio improves the transmission quality because of the smaller level of co-channel interference. An example of co-channel interference is when a radio transmitter is operating on the same frequency.
The reasons behind Co-channel interference are:
- Bad weather condition
- Poor frequency planning
Ways we can reduce co-channel interference in cellular communication are:
- Proper planning and implementation.
- The frequency reuse technique increases overall system capacity.
Adjacent Channel Interference
It is the interference caused to the signal which is adjacent in frequency to the desired signal. Imperfect receiver side filters allow the neighboring signal to mix with the actual pass band. if adjacent channel signal strength becomes strong, it will be difficult for Base Station to differentiate the actual mobile signal from the strong mobile signal.
The reasons behind adjacent channel interference are as follows:
- Due to multiple channels close to each other communicating using similar frequencies.
- Irrelevant power emission from an adjacent channel.
Factors for reducing Adjacent Channel Interference are as follows:
- Proper filtering
- Careful Channel Assignments
- By managing the space between two adjacent cells which should remain constant.
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