Wireless Communications Systems Design

6Error Correction Codes

In Part II, we design key wireless communication blocks such as error correction codes, OFDM, MIMO, channel estimation, equalization, and synchronization. The floating point design step is to check the reliability of each block in wireless communication system design flows. In this step, we select suitable algorithms and evaluate their performances. The floating point design is getting more important because the modern wireless communication system design flow is automated and many parts of the back-end design flow are already optimized. Thus, we focus on the floating point design in this book. In Part III, we will deal with the wireless communication system design flow and system integration in detail. An error correction code is an essential part of wireless communication systems. In this chapter, we design the turbo encoder/decoder, turbo product encoder/decoder, and Low-Density Parity Check (LDPC) encoder/decoder. These codes opened a new era of coding theory because their performance is close to the Shannon limit. We look into design criteria, describe the algorithms, and discuss hardware implementation issues.

6.1 Turbo Codes

6.1.1 Turbo Encoding and Decoding Algorithm

The turbo codes [Ref. 4 in Chapter 5] achieved very low error probability which is close to the Shannon limit. They became an essential part of many broadband wireless communication systems. The idea of the revolutionary error correction codes originates from concatenated encoding ...