Turbo Codes―A New PCCC Design

Abstract

Coding techniques have always been a major area of scientific interest. Due to this interest, many coding schemes were invented. Eventually, their implementation in various systems contributed in the evolvement of Wireless Communications. A breakthrough was definitely Turbo coding. Particularly, the concept of joining two or more convolutional encoders in parallel (PCCC) or in serial (SCCC), along with the iterative decoding technique, literally raised the expectations of the anticipated BER performance. In fact, Concatenated Convolutional Codes clearly outperform convolutional codes. Moreover, various systems, either under development or either for future use, will have high standards. The previous systems should present exceptional tolerance of noise effects and consequently a low overall number of received errors. For this purpose a new PCCC design was developed. The system's performance analysis, using an AWGN channel, showed better results for various iterations compared to other schemes such as typical PCCC, SCCC and finally a Convolutional encoder with a Viterbi decoder.

Performance of Turbo Coded OFDM Under the Presence of Various Noise Types

“…The simulated platform of noise AWGN, Rice, Rayleigh and phase noise consisted of an OFDM system (IFFT output = 2048 carriers) with a Turbo coding technique [9,11]. The selected coding scheme contained convolutional encoders, each one with a code rate of 1/2.…”

“…Equation (14) for the particular case of our PCCC system [9,11] Table 1 [14, 23,36]. Furthermore, the maximum utilized Doppler spread was equal to 5.55 Hz [29] which means that the channel was changing 5.55 times per second.…”

“…If the code's concatenation is performed in a parallel way then PCCC codes [20][21] are produced and if it happens serially then SCCC codes are constructed. Our previous studies included the development of new PCCC codes [9] which they were compared with existing and high-performance typical systems of PCCC and SCCC codes. Specifically, the new Turbo codes in the encoder's part consisted of three convolutional encoders joined in parallel.…”

Fast Converging Generalized Turbo Decoding Scheme with Enhanced Throughput for Mobile Radio

“…As shown in Figure 1, the UMTS turbo encoder is composed of two constraint length 4 Recursive Systematic Convolutional (RSC) encoders concatenated in parallel [5,6]. Feedback of shift register output to input of encoder effect the behavior of error pattern.…”

Adaptive deactivation and zero-forcing scheme for low-complexity LDPC decoders

“…Therefore, reducing the complexity of the decoding algorithm makes LDPC codes more applicable, especially to the energy limited applications, such as Internet of Things (IoT) and deep space communication. Since this paper is the research for LDPC codes, only schemes for LDPC codes are briefly introduced in this section, but there were various researches for practical usage of turbo codes [4][5][6][7]. The complexity of the LDPC decoding process is determined by three major factors: the computational complexity, the number of iterations, and the number of activated nodes.…”