Convolutional Coding

Summary: The convolutional code (CC) is a very fast way to encode messages. Since most codes send messages and multiple parity bits, these are different from the other code described in the class. These codes include, but are not limited to, Hamming code, parity code, and Reed-Solomon code, as well as many other codes. Convolutional codes transmit only parity bits instead of sending messages and parity bits. This makes it easier to detect errors occurring during transmission and allows more accurately received messages since there is less chance of occurrence.

There are some differences in the operation of the turbo code and convolutional code. It is known that the performance of convolutional code improves as the length of the constraint increases (code complexity). This does not apply to turbo codes that have a small code constraint length optimal for turbo codes. The simulation result of turbo code is obtained at a rate of R = 1/2. The length of the data block here is 400 bits (hypothesis), and the MAP decoder is used in the simulation. As you can see from the results, for any value, the greatest improvement in BER can be seen with the first few iterations.

In telecommunications, a convolutional code is an error correction code that generates a parity symbol by applying a slip of Boolean polynomial function to the data stream. A sliding application represents the "convolution" of the data by the encoder and is the term "convolution coding". The sliding nature of the convolutional code facilitates grid decoding using time-invariant lattices. Time-invariant trellis decoding allows convolutional codes to perform maximum likelihood soft-decision decoding with reasonable complexity

One of the methods developed in recent years is to combine OFDM and convolutional coding (CC) and trellis coded modulation (TCM) for Rice fading channels according to the specification given by the system. Here we consider the 8 - PSK and 16 - QAM modulation techniques and the error rate (BER) performance of OFDM using two different coding schemes for the LEO satellite channel. Trellis coded OFDM provides the best performance compared to convolutional coded OFDM. Using partial transmission sequence technology (PTS), you can reduce peak-to-average power ratio (PAPR) by approximately 5 dB. Later, the results of more research and simulation demonstrate that turbo coding (TC) OFDM is better than CC or TCM using OFDM.