Electronics Project:Channel Coding

  Implementation of Channel coding :Forward error correction codes and Convolution codes:

Channel coding is referred to the processes done in both transmitter and receiver of a digital communications system. The mentioned processes require allocating extra bits, parity bits, and consuming extra bandwidth. Using this amount of communications resources results in more reliable connection between transmitter and its receiver. There are two policies to deal with channel coding:

1. forward error correction (FEC)

2. automatic repeat-request (ARQ)

FEC tries to discover the errors and correct them if it can. However, ARQ just discovers the error and sends a resend request to the transmitter.

Back to channel coding theory. There are two types of channel codes:

1. block codes

2. convolution codes

Convolution codes are coding algorithms with memory. Since, their coding rate (R) is higher than its counterpart in block codes; they are more frequently used coding method in practice.

 The channel code is used to protect data sent over it for storage or retrieval even in the presence of noise (errors). In telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels. The central idea is the sender encodes their message in a redundant way by using an error-correcting code (ECC).  . FEC gives the receiver the ability to correct errors without needing a reverse channel to request retransmission of data, but at the cost of a fixed, higher forward channel bandwidth. FEC is therefore applied in situations where retransmissions are costly or impossible, such as one-way communication links and when transmitting to multiple receivers in multicast. FEC information is usually added to mass storage devices to enable recovery of corrupted data, and is widely used in modems.