scholarly journals Analysis of iteration control for turbo decoders in turbo synchronization applications

2009 ◽  
Vol 7 ◽  
pp. 139-144
Author(s):  
T. Lehnigk-Emden ◽  
U. Wasenmüller ◽  
C. Gimmler ◽  
N. Wehn
Keyword(s):  
Turbo Codes ◽  
Channel Coding ◽  
Communication Systems ◽  
Wireless Data ◽  
Turbo Decoder ◽  
Wireless Data Transmission ◽  
Turbo Decoders ◽  
Xilinx Fpga ◽  
Digital Communication Systems ◽  
Turbo Synchronization

Abstract. Wireless data transmission results in frequency and phase offsets of the signal in the receiver. In addition, the received symbols are corrupted by noise. Therefore, synchronization and channel coding are vital parts of each receiver in digital communication systems. By combining the phase and frequency synchronization with an advanced iterative channel decoder (inner loop) e.g. turbo codes in an iterative way (outer loop), the communications performance can be further increased. This principle is referred to as turbo synchronization. The energy consumption and the peak throughput of the system depend on the number of iterations for both loops. An advanced iteration control can decrease the mean number of needed iterations by detecting correctly decoded blocks. This leads to a dramatic energy saving or to an increase of throughput. In this paper we present a new stopping criterion for decodable blocks for turbo decoding in interrelation with turbo synchronization. Furthermore the implementation complexity of the turbo decoder is shown on a Xilinx FPGA.

scholarly journals Low complexity Turbo synchronization without initial carrier synchronization

2010 ◽  
Vol 8 ◽  
pp. 123-128 ◽  
Author(s):  
U. Wasenmüller ◽  
C. Gimmler ◽  
N. Wehn
Keyword(s):  
Turbo Codes ◽  
Channel Coding ◽  
Communication Systems ◽  
Low Complexity ◽  
Wireless Data ◽  
Carrier Synchronization ◽  
Wireless Data Transmission ◽  
Xilinx Fpga ◽  
Digital Communication Systems ◽  
Turbo Synchronization

Abstract. Wireless data transmission results in frequency and phase offsets of the signal in the receiver. In addition the received symbols are corrupted by noise. Therefore synchronization and channel coding are vital parts of each receiver in digital communication systems. By combining the phase and frequency synchronization with an advanced iterative channel decoder (inner loop) like turbo codes in an iterative way (outer loop), the communications performance can be increased. This principal is referred to as turbo synchronization. For turbo synchronization an initial estimate of phase and frequency offset is required. In this paper we study the case, where the initial carrier synchronization is omitted and an approach with trial frequencies is chosen. We present novel techniques to minimize the number of trial frequencies to be processed. The communications performance and effort of our method is demonstrated. Furthermore the implementation complexity of the whole system is shown on a Xilinx FPGA.

scholarly journals Técnicas para la implementación de turbo decodificadores con baja latencia

2019 ◽  
pp. 29-41
Author(s):  
Lennin Conrado Yllescas-Calderon ◽  
Ramón Parra-Michel ◽  
Luis F Gonzalez-Pérez
Keyword(s):  
Channel Coding ◽  
Iterative Decoding ◽  
Turbo Coding ◽  
Processing Capacity ◽  
Turbo Decoding ◽  
Turbo Decoder ◽  
Transmission Rates ◽  
Communications Systems ◽  
Lte Advanced ◽  
Turbo Decoders

Turbo coding is a channel coding technique that increases the capacity of communications systems, especially wireless and mobile. Due to its high correction capability, this technique is used in modern wireless communication standards such as 3GPP and LTE/LTE-Advanced. One of the features of these systems is the increase in data processing capacity, where transmission rates of up to 1 Gbps are specified. However, the turbo coding technique inherently presents a limited performance as a consequence of the turbo decoding process at the reception stage. The turbo decoder presents a high operation latency mainly caused by the iterative decoding process, the interleaver and deinterleaver stage and the estimation process of the information bits. In this work, we show the techniques used to implement modern low-latency turbo decoders suitable for 3G and 4G standards.

scholarly journals Efficient MAP-algorithm implementation on programmable architectures

2003 ◽  
Vol 1 ◽  
pp. 259-263 ◽  
Author(s):  
F. Kienle ◽  
H. Michel ◽  
F. Gilbert ◽  
N. Wehn
Keyword(s):  
Turbo Codes ◽  
Communication Systems ◽  
Building Blocks ◽  
Communication Performance ◽  
Channel Decoding ◽  
Turbo Decoder ◽  
Decoding Algorithms ◽  
Map Algorithm ◽  
Algorithm Implementation ◽  
Log Map

Abstract. Maximum-A-Posteriori (MAP) decoding algorithms are important HW/SW building blocks in advanced communication systems due to their ability to provide soft-output informations which can be efficiently exploited in iterative channel decoding schemes like Turbo-Codes. Multi-standards demand flexible implementations on programmable platforms. In this paper we analyze a quantized turbo-decoder based on a Max-Log-MAP algorithm with Extrinsic Scaling Factor (ESF). Its communication performance approximate to a Turbo-Decoder with a Log-MAP algorithm and is less sensitive to quantization effects. We present Turbo-Decoder implementations on state-of-the-art DSPs and show that only a Max-Log-MAP implementation fulfills a throughput requirement of ~2 Mbit/s. The negligible overhead for the ESF implementation strengthen the use of Max-Log-MAP with ESF implementation on programmable platforms.

scholarly journals Introducing perforation when applying turbo codes

2021 ◽  
Vol 2094 (3) ◽  
pp. 032061
Author(s):  
A A Sidorenko
Keyword(s):  
Data Transmission ◽  
Turbo Codes ◽  
Communication Systems ◽  
Digital Communication ◽  
Turbo Code ◽  
Code Sequence ◽  
Transmission Channel ◽  
Comparison Results ◽  
Decoding Efficiency ◽  
Digital Communication Systems

Abstract The problem of adapting the degree of redundancy introduced in the process of error-correcting coding to the changing characteristics of the data transmission channel is urgent. Turbo codes, used in a variety of digital communication systems, are capable of correcting multiple errors occurring in the data transmission channel. The article compares the decoding efficiency for various options for introducing perforation into the code sequence generated by the turbo code encoder. Based on the comparison results, recommendations were made on the most appropriate option for the introduction of perforation.

scholarly journals Secure image transmission over wireless network

2018 ◽  
Vol 7 (4) ◽  
pp. 2758
Author(s):  
Salah A. Aliesawi ◽  
Dena S. Alani ◽  
Abdullah M. Awad
Keyword(s):  
Turbo Codes ◽  
Channel Coding ◽  
Communication Systems ◽  
Wireless Channels ◽  
Image Transmission ◽  
Signal Propagation ◽  
Data Encryption ◽  
Error Rates ◽  
Delay Spread ◽  
High Level

The advances recently seen in data compression, and communication systems, have made it viable to design wireless image transmission systems. For many applications such as confidential transmission, military and medical applications, data encryption techniques should be also used to protect the confidential data from intruders. For these applications, both encryption and compression need to be performed to transmit a message in a fast and secure way. Further, the wireless channels have fluctuating channel qualities and high bit error rates. In this paper, a new scheme based on encryption and channel coding has been proposed for secure image transmission over wireless channels. In the proposed scheme, the encryption process is based on keys generator and Chaotic Henon map. Turbo codes are utilized as channel coding to deal effectively with the channel errors, multipath signal propagation and delay spread. Simulation results show that the proposed system achieves a high level of robustness against wide different of attacks and channel impairments. Further, it improves image quality with acceptable data rates. 

scholarly journals Improving the performance of BICM-ID and MLC systems with different FEC codes

2013 ◽  
Vol 11 ◽  
pp. 87-93 ◽  
Author(s):  
T. Arafa ◽  
W. Sauer-Greff ◽  
R. Urbansky
Keyword(s):  
Turbo Codes ◽  
Channel Coding ◽  
Communication Systems ◽  
Forward Error Correction ◽  
Convolutional Codes ◽  
Coded Modulation ◽  
Modulation Formats ◽  
Coding Schemes ◽  
Multilevel Modulation ◽  
Exit Charts

Abstract. In bandwidth limited communication systems, the high data rate transmission with performance close to capacity limits is achieved by applying multilevel modulation schemes in association with powerful forward error correction (FEC) coding, i.e. coded modulation systems. The most important practical approaches to coded modulation systems are multilevel coding with multistage decoding (MLC/MSD) and bit interleaved coded modulation with iterative demapping and decoding (BICM-ID). Multilevel modulation formats such as M-QAM, which can be used as a part of coded modulation systems, have the capability of multilevel protection. Based on this fact, we investigate the methods to improve the performance of BICM-ID using multiple interleavers with different binary channel coding schemes such as convolutional codes, turbo codes and low-density parity-check (LDPC) codes. Moreover, an MLC system with parallel decoding on levels (PDL) at the receiver is considered. In our contribution, we propose to design the individual coding schemes using the extrinsic information transfer (EXIT) charts for individual bit levels in the constellation. Our simulation results show that the BICM-ID systems, taking into account different bit-level protections, can provide an improvement of 0.65 dB, 1.2 dB and 1.5 dB for 256-QAM with turbo, LDPC and convolutional codes, respectively. On the other hand, MLC systems with PDL designed using EXIT charts for individual bit levels can slightly improve the performance and eliminate the error floor compared to the systems with MSD.

Vergleich von Hardware- und Software-Implementierungen in der digitalen Kommunikation am Beispiel der Kanalcodierung (Hardware-/Software Trade-Offs in Digital Communication Systems with Special Emphasis on Channel-Coding)

2003 ◽  
Vol 45 (6) ◽  
Author(s):  
Norbert Wehn
Keyword(s):  
Channel Coding ◽  
Communication Systems ◽  
Digital Communication ◽  
Trade Offs ◽  
Digital Communication Systems

ZusammenfassungUnsere heutige Informationsgesellschaft erfordert Datenzugriffe an jedem Ort und zu jeder Zeit. Bandbreite und Energie sind hierbei kritische Ressourcen. Deshalb benötigen drahtlose Kommunikationsstandards effiziente Fehlerkorrekturverfahren. In diesem Beitrag diskutieren wir den Entwurfsraum für fortgeschrittene Kanalcodierungsverfahren und präsentieren verschiedene Hardware- und Softwareimplementierungen.

scholarly journals A Parallel Turbo Decoder Based on Recurrent Neural Network

2021 ◽  
Author(s):  
Li Zhang ◽  
weihong fu ◽  
Fan Shi ◽  
Chunhua Zhou ◽  
Yongyuan Liu
Keyword(s):  
Neural Network ◽  
Turbo Codes ◽  
Communication Systems ◽  
Turbo Code ◽  
Error Rates ◽  
Learning Ability ◽  
Turbo Decoder ◽  
Lstm Network ◽  
T Distribution ◽  
Decoding Delay

Abstract A neural network-based decoder, based on a long short-term memory (LSTM) network, is proposed to solve the problem of high decoding delay caused by the poor parallelism of existing decoding algorithms for turbo codes. The powerful parallel computing and feature learning ability of neural networks can reduce the decoding delay of turbo codes and bit error rates simultaneously. The proposed decoder refers to a unique component coding concept of turbo codes. First, each component decoder is designed based on an LSTM network. Next, each layer of the component decoder is trained, and the trained weights are loaded into the turbo code decoding neural network as initialization parameters. Then, the turbo code decoding network is trained end-to-end. Finally, a complete turbo decoder is realized. Simulation results show that the performance of the proposed decoder is improved by 0.5–1.5 dB compared with the traditional serial decoding algorithm in Gaussian white noise and t-distribution noise. Furthermore, the results demonstrate that the proposed decoder can be used in communication systems with various turbo codes and that it solves the problem of high delay in serial iterative decoding.

scholarly journals Performance analysis of highly improved hybrid turbo codes for 4G wireless networks

2019 ◽  
Vol 8 (4) ◽  
pp. 398
Author(s):  
M. Jose Raj ◽  
Dr. Sharmini Enoch
Keyword(s):  
Wireless Networks ◽  
Turbo Codes ◽  
Communication Systems ◽  
Turbo Code ◽  
Error Correcting Code ◽  
Low Complexity ◽  
Error Correcting Codes ◽  
4G Wireless ◽  
Low Complex ◽  
Digital Communication Systems

Efficient error correcting codes are essential in modern digital communication systems. Highly Improved Hybrid Turbo Code (HIHTC) is a low complex error and efficient error correcting code with excellentBit Error Rate (BER) which is comparable to Low Complexity Hybrid Turbo Codes (LCHTC), Improved Low Complexity Hybrid Turbo Codes (ILCHTC) and other Hybrid Turbo Codes. Rate 1/3 HIHTC shows a BER of 10-5 for E b/No of 1.7 dB which is closer to the E b/No of Improved Low Complexity Hybrid Turbo Codes. In this paper we analyze the performance of HIHTC in comparison with otherLow Complexity Hybrid Turbo Codes, for their performance in 4G and 5G wireless networks  

scholarly journals Index Assignment Optimization for Digital Communication Systems Using M-ary Modulation Schemes

2015 ◽  
pp. 38
Author(s):  
Tran Ngoc Tuan ◽  
Nguyen Quoc Trung
Keyword(s):  
Channel Coding ◽  
Noise Level ◽  
Communication Systems ◽  
Digital Communication ◽  
Error Resilience ◽  
Binary Symmetric Channel ◽  
Symmetric Channel ◽  
Joint Source Channel Coding ◽  
Index Assignment ◽  
Digital Communication Systems

Channel-optimized Index Assignment (IA)  of source  codewords  is a  simple  but  effective  approach  of improving  the  error  resilience  of  the  communication systems. Although IA is a type of Joint Source Channel Coding  (JSCC),  it  does  not  intervene  with  the  source codec design. So, in addition to the fact that this method can  be  used  in  designing  systems  effectively,  it  can  be also applied to the existing system. However, these prior IA  methods  have  usually  been  based  on  assuming  a Binary  Symmetric  Channel  (BSC)  and/or  single-bit error in the codeword. These assumptions are only valid when the  modulation  is binary or the  noise level in  the channel is low. In this paper, we study the IA problem in  a  more  general  case in  which  the  modulation  is  2Dsignalling M-ary  (M-ary  PSK, M-ary  QAM),  proposing the  method  to  optimize  IA  for  this  case.  Some simulations results based on this method are also given

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