Environmental interference and physical defects in the communication medium can cause random bit errors during data transmission. Channel coding also known as Error coding is a method of detecting and correcting these errors to ensure that information is transferred from its source to its destination reliably.
The idea behind channel coding is, to make the data more secure and error free. Channel Coding is done to ensure that the signal transmitted is recovered with very low probability of error at the destination. You can think channel coding as a “Security guard” for data .
What happens If Channel coding is not used?
If data is transmitted without channel coding ,and an error occurs in data , the receiver will inform the transmitter that an error has occurred in data, therefore transmit it again.Transmitter will have to retransmit the whole data ! A question may arise in your mind that, incase of error, data will be retransmitted so, what’s the need of using channel coding?
The reason is, if transmitter retransmits the whole data definitely there will be wasteage of power,and delay in communication. Therefore to avoid these factors it is necessary to implement channel coding.
In channel coding extra bits are added along with actual data bits. These extra bits are termed as “Redundant bits” because they actually cause redundancy in data. They ensure minimal or no error.
Error coding uses mathematical formulas to encode data bits at the transmitter or source into longer bits for transmission. The "coded data " is then decoded at the destination to retrieve the information. These bits help the the destination or receiver to determine if the communication medium introduced errors, if yes correct them so that the data need not be retransmitted.
Error coding is used in satellite and deep space communications, network communications, cellular telephone networks, magnetic and optical data storage media, and almost any other form of digital data communication.