BTC (Block Turbo Code)

BTC, or Block Turbo Code, is a type of forward error correction (FEC) code that is widely used in digital communications. It is a powerful coding scheme that is capable of correcting errors in digital data transmission over noisy channels. In this article, we will explain BTC in detail, including its history, principles, and applications.

History

The development of BTC began in the early 1990s, when researchers at the University of California, Berkeley, started exploring the use of iterative decoding techniques for error correction. The idea was to use a combination of hard-decision and soft-decision decoding to improve the performance of error correction codes.

In 1993, Claude Berrou, Alain Glavieux, and Punya Thitimajshima proposed a new type of FEC code called Turbo Code, which was based on the idea of iterative decoding. The Turbo Code was able to achieve near-Shannon limit performance in terms of error correction, and it quickly gained popularity in the telecommunications industry.

In 1996, Berrou and Glavieux proposed a modification to the Turbo Code called Block Turbo Code (BTC). BTC was designed to overcome the limitations of the original Turbo Code, which had difficulty handling long frames of data.

Principles

BTC is a type of FEC code that is based on the principle of turbo decoding. It is a block code, meaning that it operates on fixed-length blocks of data. BTC uses two parallel encoders, each of which generates a set of parity bits that are added to the original data to create a codeword. These two sets of parity bits are generated independently, and they are used to form two separate trellis structures for decoding.

The trellis structure is a graphical representation of the decoding process, and it consists of a series of interconnected states that represent the possible values of the code symbols. The decoder traverses this trellis structure to find the most likely sequence of code symbols that could have generated the received data.

The key to BTC's performance is its use of iterative decoding. The decoder makes a first pass through the trellis structure to generate a preliminary estimate of the transmitted data. This estimate is then used to refine the decoder's estimate in subsequent passes through the trellis structure. This iterative process continues until the decoder reaches a stable estimate of the transmitted data.

Applications

BTC is used in a wide range of applications that require reliable digital data transmission over noisy channels. It is commonly used in satellite communications, mobile telecommunications, and digital broadcasting. BTC is also used in optical communication systems, where it can help to compensate for optical fiber impairments such as dispersion and attenuation.

BTC is a versatile coding scheme that can be adapted to suit different applications. For example, the code rate can be adjusted to trade off between error correction performance and data rate. The block size can also be adjusted to suit the characteristics of the communication channel.

Conclusion

BTC is a powerful FEC code that is widely used in digital communications. It is based on the principle of iterative decoding, which allows it to achieve near-Shannon limit performance in terms of error correction. BTC is used in a wide range of applications that require reliable digital data transmission over noisy channels. It is a versatile coding scheme that can be adapted to suit different applications, making it an important technology for the digital age.