Interference suppression for code-division multiple-access communications in an underwater acoustic channel

2009 ◽  
Vol 126 (1) ◽  
pp. 220-228 ◽  
Author(s):  
T. C. Yang ◽  
Wen-Bin Yang
Keyword(s):  
Code Division Multiple Access ◽  
Multiple Access ◽  
Interference Suppression ◽  
Underwater Acoustic Channel ◽  
Underwater Acoustic ◽  
Acoustic Channel ◽  
Multiple Access Communications ◽  
Code Division Multiple

scholarly journals Multiuser Chirp Spread Spectrum Transmission in an Underwater Acoustic Channel Applied to an AUV Fleet

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1527
Author(s):  
Christophe Bernard ◽  
Pierre-Jean Bouvet ◽  
Antony Pottier ◽  
Philippe Forjonel
Keyword(s):  
Spread Spectrum ◽  
Multiple Access ◽  
Autonomous Underwater Vehicle ◽  
Matched Filter ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic Channel ◽  
Underwater Acoustic ◽  
Acoustic Channel ◽  
Chirp Spread Spectrum ◽  
Code Division Multiple

The objective of this paper is to provide a multiuser transmission technique for underwater acoustic communication in the framework of an Autonomous Underwater Vehicle (AUV) fleet. By using a variant of a Hyperbolically Frequency-Modulated (HFM) signal, we describe a new family of transmission techniques called MultiUser Chirp Spread Spectrum (MU-CSS), which allows a very simple matched-filter-based decoding. These techniques are expected to provide good resilience against multiuser interference while keeping good robustness to Underwater Acoustic (UWA) channel impairments like Doppler shift. Their implementation for the UWA scenario is described, and the performance results over a simulated shallow-water UWA channel are analyzed and compared against conventional Code-Division Multiple Access (CDMA) and Time-Division Multiple Access (TDMA) transmission. Finally, the feasibility and robustness of the proposed methods are verified over the underWater AcousTic channEl Replay benchMARK (Watermark), fed by several channel responses from sounding experiments performed in a lake.

Photonic code-division multiple-access communications

1997 ◽  
Vol 16 (2) ◽  
pp. 129-157 ◽  
Author(s):  
David D. Sampson ◽  
Graeme J. Pendock ◽  
Robert A. Griffin
Keyword(s):  
Code Division Multiple Access ◽  
Multiple Access ◽  
Multiple Access Communications ◽  
Code Division Multiple

New Constructions of Codebooks Nearly Meeting the Welch Bound

2020 ◽  
Vol 31 (07) ◽  
pp. 875-889
Author(s):  
Zexia Shi ◽  
Lei Sun ◽  
Fang-Wei Fu
Keyword(s):  
Positive Integer ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Bent Functions ◽  
Welch Bound ◽  
Generalized Bent Functions ◽  
Multiple Access Communications ◽  
Generic Construction ◽  
Direct Spread ◽  
Code Division Multiple

Optimal codebooks meeting the Welch bound with equality are desirable in many areas, such as direct spread code division multiple access communications, compressed sensing and so on. However, it is difficult to construct such optimal codebooks. There have been a number of attempts to construct codebooks nearly meeting the Welch bound. In this paper, we introduce a generic construction of codebooks using generalized bent functions from [Formula: see text] to [Formula: see text], where [Formula: see text] is a prime and [Formula: see text] is a positive integer with [Formula: see text]. With this construction, we obtain two new families of codebooks nearly meeting the Welch bound. These codebooks have new parameters and could have a small alphabet size. In particular, a class of regular generalized bent functions from [Formula: see text] to [Formula: see text] is presented.

scholarly journals A fractional Fourier transform–based channel estimation algorithm in single-carrier direct sequence code division multiple access underwater acoustic communication system

2019 ◽  
Vol 15 (1) ◽  
pp. 155014771982600 ◽  
Author(s):  
Lin Zhou ◽  
Qingsheng Zhao ◽  
Shukai Chi ◽  
Yanlong Li ◽  
Lanjun Liu ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Communication System ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Fractional Fourier Transform ◽  
Direct Sequence ◽  
Underwater Acoustic ◽  
Single Carrier ◽  
Sequence Code ◽  
Code Division Multiple

Due to the complexity and variability of the underwater acoustic channel, the communication signal is affected by multi-path, time delay, and Doppler frequency shift. Based on the advantageous characteristics of fractional Fourier transform on chirp signal processing, a fractional Fourier transform–based algorithm using combined linear frequency–modulated signal is proposed, which can estimate parameters of underwater acoustic channel and has a better performance than the existing methods. To distinguish multi-user in underwater acoustic communication system, a single-carrier direct sequence code division multiple access communication system combined with the fractional Fourier transform–based algorithm is proposed. Thus, a preliminary study on underwater multi-target identification is carried out. The simulation and experimental results show that the fractional Fourier transform–based algorithm is simple and effective, and the energy can be focused at the “best” fractional order, which can directly determine the multi-path number and complete the channel estimation. The proposed single-carrier direct sequence code division multiple access communication system has good performance on bit error rate when we use corresponding spreading code to distinguish multi-user.

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