Basics of Channel Coding

1- Background of Channel Coding:

Channel coding is used to detect and correct the information bits. There two common types of channel coding that includes automatic repeated request (ARQ) and forward error control coding techniques. Both are used for channel coding. While there are some demerits of automatic repeated request (ARQ) like in this type of channel coding, only transmitter adds parity bits to code word through which it can only detect errors and cannot correct the errors. To correct the error bits as well, we will use forward error control coding technique that is able to detect and correct error bits. We are given with 16- coding word (0000-1111) that is product code for which we consider the block coding as suitable. In block coding, first we will encode the 16-coding word and then new block code will be decoded at the receiver side which will be our last final result of this report.When the information is sent through communication channel, some extra bits are received at receiver communication system. The extra bits are considered as bit errors having no information that only interrupt the information bits. These bits error depends upon the amount of noise and interference in the communication channel. Such problems of communication channel are solved through coding method by introducing redundant bits during transmission of information bits from transmitter communication system as well as in receiver communication system. So, we will use a type of channel coding method to solve the required problem in communication channel.

2- Introduction to channel Coding

Channel coding method is a process through which bit errors are detected and corrected. Channel coding is also called Forward Error Control Coding (FECC). Channel coding is done at both sides of communication systems namely transmitter and receiver. In transmitter part, channel coding is performed as an encoding known as encoder. In encoder, the redundant bits also called parity bits are accumulated with information bits. The parity bits are accumulated before the modulation as shown in Fig. 1. In receiver part, channel coding is performed as an decoding known as decoder which make able the receiver for detection and correction of bit errors that are created in transmission of information due to interference of noise signals and fading as shown in Fig. 1.

Fig. 1 Channel Coding Basic Block

In Fig. 1, the pre-processing steps of channel coding are performed at both sides to enable the correction and detection of bits error. By channel coding, the bandwidth and data rate became very important. By using channel coding methods, the data rate becomes slow and we will need large bandwidth to add redundancy bits. This concept is true for broad band communication. The digital signal processing is performed based on the given bandwidth. As the bandwidth is expensive, so we have to use such type of channel coding method that uses less redundancy bits.

For more detail of channel, read my new post of types of channel coding.