Key Laboratory of Underwater Acoustic Communication and Marine Information Technology

Xiamen, China

Key Laboratory of Underwater Acoustic Communication and Marine Information Technology

Xiamen, China
SEARCH FILTERS
Time filter
Source Type

Tu X.,Xiamen University | Tu X.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Xu X.,Xiamen University | Xu X.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | And 6 more authors.
Journal of Systems Engineering and Electronics | Year: 2017

To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acoustic communications. An FrFD frequency-hopped communication method based on chirp modulation, namely multiple chirp shift keying-FrFD hopping (MCSK-FrFDH), is proposed for underwater acoustic channels. Validated by both simulations and experimental results, this method can reach a bandwidth efficiency twice more than conventional frequency-hopped methods with the same data rate and anti-multipath capability, suggesting that the proposed method achieves a better performance than the traditional frequency-hopped communication in underwater acoustic communication channels. Results also show that in practical scenarios, the MCSK-FrFDH system with longer symbol length performs better at the low signal-to-noise ratio (SNR), while the system with larger frequency sweeping range performs better at a high SNR. © 2017 Beijing Institute of Aerospace Information.


Wang D.,Xiamen University | Wang D.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Xu R.,Xiamen University | Xu R.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | And 4 more authors.
International Journal of Distributed Sensor Networks | Year: 2016

Energy-efficient data aggregation is important for underwater acoustic sensor networks due to its energy constrained character. In this paper, we propose a kind of energy-efficient data aggregation scheme to reduce communication cost and to prolong network lifetime based on distributed compressed sensing theory. First, we introduce a distributed compressed sensing model for a cluster-based underwater acoustic sensor network in which spatial and temporal correlations are both considered. Second, two schemes, namely, BUTM-DCS (block upper triangular matrix DCS) and BDM-DCS (block diagonal matrix DCS), are proposed based on the design of observation matrix with strictly restricted isometric property. Both schemes take multihop underwater acoustic communication cost into account. Finally, a distributed compressed sensing reconstruction algorithm, DCS-SOMP (Simultaneous Orthogonal Matching Pursuit for DCS), is adopted to recover raw sensor readings at the fusion center. We performed simulation experiments on both the synthesized and real sensor readings. The results demonstrate that the new data aggregation schemes can reduce energy cost by more than 95 percent compared with conventional data aggregation schemes when the cluster number is 20. © 2016 Deqing Wang et al.


Guo Y.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Sun H.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Cheng E.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Shen W.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology
Journal of Convergence Information Technology | Year: 2012

OFDM is a high date rate underwater acoustic transmission scheme even for underwater acoustic communication. OFDM modulation scheme has many obvious advantages. It have been widely studied to overcome the complexity of underwater acoustic channels. Impulsive noise is one of the major impairments for communication over underwater acoustic channels. When it occurs, it is very destructive and results in dropping the affected symbols at the receiver. Generally speaking, OFDM modulation method is less sensitive to impulsive noise than single-carrier systems. Nevertheless, it was recently recognized that this advantage turns into a disadvantage if the impulsive noise energy exceeds a certain threshold. In this paper, the nonlinear clipping methods for impulsive noise suppression in underwater acoustic OFDM system is considered and soft compensation is employed for signal clipping effect mitigation. The experimental results are provided to verify the proposal. It is shown that with the proposed method, a good trade-off between impulsive noise suppression and signal clipping distortion mitigation can be achieved.


Fu X.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Fu X.,Xiamen University | Zeng D.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Zeng D.,Xiamen University | And 7 more authors.
2013 IEEE Global Conference on Signal and Information Processing, GlobalSIP 2013 - Proceedings | Year: 2013

Low light image enhancement is prerequisite in many fields, such as surveillance systems, road safety and waterway transport. In this paper, a new variational framework using bright channel prior is proposed to address the low light image enhancement problem within a single image. An alternating direction optimization method is employed to solve the variational problem. Experiment results show that the new method can better eliminate the black halo and suppressing the issues of over-enhancement and color distortion when compared with other existing methods. © 2013 IEEE.


Chen K.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Cheng E.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Yuan F.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Su W.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Wang D.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology
Program Book - OCEANS 2012 MTS/IEEE Yeosu: The Living Ocean and Coast - Diversity of Resources and Sustainable Activities | Year: 2012

An Underwater acoustic channel is characterized as time-varying, multipath environment. In order to get a better location result, we firstly analysised the environment in the water tank and modeled it in this paper. Using long time observation, the successive time-variant impulse response and the statistical parameters changing is obtained. All these parameters can effectively avoid multipath (indirect) signals which can be mistaken for the direct signal that would affect the positioning system for a relative positioning system. Compared with the absolute positioning systems, the relative positioning systems don't need an external infrastructure. Only the distances between the buoys are used to obtain their position. The results showed that using LFM signal can get the stable location result. Meanwhile the positioning system is easy on the equipments which has great application future for the specific environment, such as the animal breeding and dolphin protection. © 2012 IEEE.


Wang D.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Hu X.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Xu F.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Chen H.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Wu Y.,Xiamen University
Program Book - OCEANS 2012 MTS/IEEE Yeosu: The Living Ocean and Coast - Diversity of Resources and Sustainable Activities | Year: 2012

In this paper, we investigate the performance of carrier sensing multiple access (CSMA)-based medium access control (MAC) protocol in fully connected underwater acoustic sensor networks (UWASNs). CSMA-based MAC protocols run inefficiently because of a new hidden terminal problem (we refer to it as long-delay hidden terminal problem). Based on our findings, this paper presents novel performance analysis model of physical CSMA (P-CSMA) for UWASNs. Compared with other analytical methods, the analysis model in this paper is closer to the actual network, in which the number of nodes is finite and propagation delays among certain nodes are variable. The close form expressions for throughput and packet loss ratio indicate that CSMA-based MAC protocols are influenced greatly by long-delay hidden terminal problem. Simulation results show the correctness of the analysis model. © 2012 IEEE.


Hai-Yan L.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Fei Y.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | En C.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology
Proceedings of the 2013 IEEE 8th Conference on Industrial Electronics and Applications, ICIEA 2013 | Year: 2013

Underwater acoustic communication technology is an effective mean of development and study of the sea. It is widely used in marine environment three-dimensional monitoring, underwater multimedia communication, underwater mobile carrier navigation and positioning, marine resources detection, remote control of submarine topography mapping and offshore oil industry, data acquisition, etc. The sea buoy is an important part of underwater acoustic communication system. It is of great significance to track and locate it. This paper describes the application of the monitoring service of GPRS / GPS module at sea buoy. It can achieve real-time location of underwater acoustic communication devices and route tracking to avoid the loss of the device, as well as assist to retrieve the lost device. © 2013 IEEE.


Chun-Xian G.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Bin-Yi Z.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Wei S.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Fei Y.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology
Proceedings of the 2013 IEEE 8th Conference on Industrial Electronics and Applications, ICIEA 2013 | Year: 2013

This paper introduce the architecture and design principals of a new trial platform. The platform use the GPRS network to connect sea trial system and website system. Researchers can operate monitoring software after log on the website, control remote equipment to finish the underwater acoustic communication experiment, realize the goal that researchers don't go to the sea but also can do underwater acoustic experiment. © 2013 IEEE.


Shang S.L.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Shang S.L.,Xiamen University | Dong Q.,Xiamen University | Hu C.M.,University of South Florida | And 4 more authors.
Biogeosciences | Year: 2014

Chlorophyll a (Chl) concentrations derived from satellite measurements have been used in oceanographic research, for example to interpret eco-responses to environmental changes on global and regional scales. However, it is unclear how existing Chl products compare with each other in terms of accuracy and consistency in revealing temporal and spatial patterns, especially in the optically complex marginal seas. In this study, we examined three MODIS (Moderate Resolution Imaging Spectroradiometer) Chl data products that have been made available to the community by the US National Aeronautics and Space Administration (NASA) using community-accepted algorithms and default parameterization. These included the products derived from the OC3M (ocean chlorophyll three-band algorithm for MODIS), GSM (Garver-Siegel-Maritorena model) and GIOP (generalized inherent optical properties) algorithms. We compared their temporal variations and spatial distributions in the northern South China Sea. We found that the three products appeared to capture general features such as unique winter peaks at the Southeast Asian Time-series Study station (SEATS, 18 N, 116 E) and the Pearl River plume associated blooms in summer. Their absolute magnitudes, however, may be questionable in the coastal zones. Additional error statistics using field measured Chl as the truth demonstrated that the three MODIS Chl products may contain high degree of uncertainties in the study region. Root mean square error (RMSE) of the products from OC3M and GSM (on a log scale) was about 0.4 and average percentage error (ε) was ∼ 115% (Chl between 0.05-10.41 mg m-3, n Combining double low line 114). GIOP with default parameterization led to higher errors (ε Combining double low line 329%). An attempt to tune the algorithms based on a local coastal-water bio-optical data set led to reduced errors for Chl retrievals, indicating the importance of local tuning of globally-optimized algorithms. Overall, this study points to the need of continuous improvements for algorithm development and parameterization for the coastal zones of the study region, where quantitative interpretation of the current Chl products requires extra caution. ©Author(s) 2014.


Cheng E.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Xu X.-N.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology | Wu S.-L.,Key Laboratory of Underwater Acoustic Communication and Marine Information Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Bluetooth is one of the wireless communication technology, which is developing rapidly in recent years. As a result of low cost and short distance, Bluetooth can set up a special connection for portable electronic devices and stationary electronic equipment communication environment. The paper studies a data acquisition system based on Bluetooth. The system can collect the angle of motor rotation and send it to the Receiver through the Bluetooth. The results show that the system can be run normal.[1]. © 2013 SPIE.

Loading Key Laboratory of Underwater Acoustic Communication and Marine Information Technology collaborators
Loading Key Laboratory of Underwater Acoustic Communication and Marine Information Technology collaborators