FH-FSK Underwater Acoustic Control and Communication System Based on LDPC Code

2014 ◽  
Vol 511-512 ◽  
pp. 375-380
Author(s):  
Ji Gang Dong ◽  
Da Jun Sun ◽  
You Wen Zhang ◽  
Wei Wei Fan
Keyword(s):  
Communication System ◽  
Convolutional Code ◽  
Gaussian White Noise ◽  
Ldpc Code ◽  
Parity Check ◽  
Underwater Acoustic ◽  
Low Density Parity Check ◽  
Acoustic Control ◽  
Shift Keying ◽  
Parity Check Codes

In this paper, a frequency-hopping frequency-shift keying (FH-FSK) underwater acoustic control and communication system based on Low Density Parity Check Codes (LDPC) is proposed by combining with FH-FSK system and LDPC. The anti-jamming performance of the system in the condition of Gaussian white noise and coherent multi-path channel is simulated respectively. The simulation result shows that FH-FSK system based on LDPC has a better performance than that of convolutional code. Therefore, it is more applicable for the system to have a stable anti-jamming performance and better robustness.

Reduced decoding time of LDPC code using convolutional code with Vitrebi decoding in Underwater Communication

2018 ◽  
Vol 7 (2.25) ◽  
pp. 167
Author(s):  
Krishnamoorthy N.R ◽  
Ramadevi R ◽  
Marshiana M ◽  
Sujatha Kumaran
Keyword(s):  
No Value ◽  
Convolutional Code ◽  
Ldpc Code ◽  
Code Rate ◽  
Underwater Communication ◽  
Parity Check ◽  
Minimal Error ◽  
Ldpc Decoding ◽  
Low Density Parity Check ◽  
High Code Rate

Low Density Parity Check code is the more efficient technique to attain the minimal error rate in the underwater channel. To reduce the processing delay in the LDPC decoding, convolutional code with high code rate is used. The result showed that the BER of 10-4 can be obtained with Eb/No value of 20 for code rate of ½ and 12 for code rate of 1/8. It is also showed in result that the decoding time is reduced one-third for data size of 500 and one-tenth for the data size of 1500 bits.  

scholarly journals The Analytical Description of Regular LDPC Codes Correcting Ability

2014 ◽  
Vol 15 (3) ◽  
pp. 177-184 ◽  
Author(s):  
Leonid Uryvsky ◽  
Serhii Osypchuk
Keyword(s):  
Analytical Formula ◽  
Analytical Description ◽  
Ldpc Code ◽  
Code Word ◽  
Parity Check ◽  
Low Density Parity Check ◽  
Minimum Divergence ◽  
Parity Check Codes ◽  
Analytical Expressions ◽  
Theoretical Results

Abstract The analytical description of regular LDPC (Low-Density Parity Check) codes correcting ability has been investigated. The statistical dependencies for the maximum number of corrected bits per the code word as a function of LDPC code word length and code rate are given based on multiple experimental analyses of LDPC check matrices. The analytical expressions are proposed for the cases of linear, exponential and polynomial approximations of given results. The most exact analytical formula is proved by criterion of the minimum divergence between the experimental and theoretical results.

The Study and Implementation of the Anti-Doppler Technology of AUV Communication System

2014 ◽  
Vol 536-537 ◽  
pp. 999-1004
Author(s):  
Ji Gang Dong ◽  
Da Jun Sun ◽  
Wei Wei Fan
Keyword(s):  
Frequency Shift ◽  
Communication System ◽  
Doppler Frequency ◽  
Doppler Frequency Shift ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Acoustic Control ◽  
Shift Keying ◽  
Pair Method ◽  
On Chip

Due to the complexity of the underwater acoustic channel, a reliable mobile underwater acoustic communication system must have high resistance to Doppler and multi-path extension. In this paper, an AUV underwater acoustic control and communication system based on frequency-hopping frequency-shift keying (FH-FSK) is proposed. The system uses pulse pair method to estimate Doppler frequency shift, and analyzes the performance of the algorithm via simulation. The system has been developed based on chip OMAP-L138, with lake test conducted. Result of the tests shows that the system can estimate and compensate the Doppler frequency shift generated by the platform's movement precisely, and has strong resistance to interference to transmit AUV control messages effectively.

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