scholarly journals Simplified Log-MAP Algorithm for Very Low-Complexity Turbo Decoder Hardware Architectures

2014 ◽  
Vol 63 (3) ◽  
pp. 531-537 ◽  
Author(s):  
Maurizio Martina ◽  
Stylianos Papaharalabos ◽  
P. Takis Mathiopoulos ◽  
Guido Masera
Keyword(s):  
Low Complexity ◽  
Turbo Decoder ◽  
Map Algorithm ◽  
Hardware Architectures ◽  
Log Map

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.

A Low Complexity Implementation in Hardware on Simplified Log-MAP Algorithm for T-TCM Decoding

2013 ◽  
Vol 433-435 ◽  
pp. 1539-1544
Author(s):  
Jian Wang ◽  
Jian Ping Li
Keyword(s):  
Computational Complexity ◽  
Low Complexity ◽  
Coded Modulation ◽  
Maclaurin Series ◽  
Logarithmic Term ◽  
Map Algorithm ◽  
Trellis Coded ◽  
Low Complexity Implementation ◽  
Simulation Results ◽  
Log Map

A simplified decoding algorithm for turbo trellis-coded modulation (T-TCM) is proposed, which is easy to implement in hardware. The algorithm exploits a new piece-wise function to replace the logarithmic term of the Jacobian logarithm based on the MacLaurin Series. Simulation results show that the proposed algorithm can archive log-MAP-similar decoding performance with a much lower computational complexity. It can reduce about 40% of calculation in contrast to the improved MAX-Log-MAP.

scholarly journals Turbo Decoder Design based on an LUT-Normalized Log-MAP Algorithm

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 814
Author(s):  
Jun Li ◽  
Xiumin Wang ◽  
Jinlong He ◽  
Chen Su ◽  
Liang Shan
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Lookup Table ◽  
Clock Frequency ◽  
High Complexity ◽  
Decoding Algorithm ◽  
Turbo Decoder ◽  
Map Algorithm ◽  
Map Decoding ◽  
Log Map

Turbo codes have been widely used in wireless communication systems due to their good error correction performance. Under time division long term evolution (TD-LTE) of the 3rd generation partnership project (3GPP) wireless communication standard, a Log maximum a posteriori (Log-MAP) decoding algorithm with high complexity is usually approximated as a lookup-table Log-MAP (LUT-Log-MAP) algorithm and Max-Log-MAP algorithm, but these two algorithms have high complexity and high bit error rate, respectively. In this paper, we propose a normalized Log-MAP (Nor-Log-MAP) decoding algorithm in which the function max* is approximated by using a fixed normalized factor multiplied by the max function. Combining a Nor-Log-MAP algorithm with a LUT-Log-MAP algorithm creates a new kind of LUT-Nor-Log-MAP algorithm. Compared with the LUT-Log-MAP algorithm, the decoding performance of the LUT-Nor-Log-MAP algorithm is close to that of the LUT-Log-MAP algorithm. Based on the decoding method of the Nor-Log-MAP algorithm, we also put forward a normalization functional unit (NFU) for a soft-input soft-output (SISO) decoder computing unit. The simulation results show that the LUT-Nor-Log-MAP algorithm can save about 2.1% of logic resources compared with the LUT-Log-MAP algorithm. Compared with the Max-Log-MAP algorithm, the LUT-Nor-Log-MAP algorithm shows a gain of 0.25~0.5 dB in decoding performance. Using the Cyclone IV platform, the designed Turbo decoder can achieve a throughput of 36 Mbit/s under a maximum clock frequency of 44 MHz.

Performance Analysis and Implementation of SISO Iterative Receiver for SCCC

2014 ◽  
Vol 644-650 ◽  
pp. 3763-3766
Author(s):  
Lin Tao Li ◽  
Peng Zheng ◽  
Jin Hao
Keyword(s):  
Performance Analysis ◽  
High Throughput ◽  
Convolutional Codes ◽  
Low Complexity ◽  
Error Floor ◽  
Iterative Receiver ◽  
Map Algorithm ◽  
Improved Methods ◽  
Log Map ◽  
Ber Performance

Serial concatenated convolutional codes (SCCC) have gained a great interest in recent years for outperforming PCCC at high SNR and lower error floor. In this paper, the BER performance of SCCC based on different decoding algorithm such as Log-MAP algorithm, Max-Log-MAP algorithm and improved Max-Log-MAP algorithm are investigated. In order to achieve a flexible high throughput, low complexity and multi-rate decoding process, some improved methods are proposed.

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