Accurate Doppler estimation for underwater acoustic communications

2014

JEEE

Abstract:In this paper, image transmission in underwater channels is considered. The images are encoded with forward error correction using an unequal error protection technique together with the Reed-Solomon codes and dynamic bit-rate allocation before transmitted. This paper proposes a novel rate allocation scheme for efficient image bit stream transmission in underwater acoustic channels with optimum bit rates. The optimality is achieved in the sense that the comprehensive peak signal-to-noise ratio of the image transmission is maximized under channel bit rate and bit error rate constraints. Based on a modified set partitioning in hierarchical trees (M-SPIHT) image coder, four different flocks of bit-streams based on their significance levels are generated. According to their significance levels, the blocks of the significant bits, the sign bits, the set bits and the refinement bits are transmitted with different protection levels, so as to reduce the total distortion of received image. In addition to the careful selection of each component and intuitive justification in the detailed system design, simulation results have also been included. It is demonstrated that the proposed scheme outperforms the equal error protection for image transmission in underwater channels, significantly improves the peak signals-to-noise ratio (PSNR) performance in comparison to existing coding schemes.

Section: Doppler Shift In Uwa Channel Multipathmentioning

confidence: 99%

Optimum Bit Rate for Image Transmission over Underwater Acoustic Channel

2014

JEEE

“…It is required to estimate the Doppler shift and compensate it for all UWAC applications. Different from the case of terrestrial communication where the Doppler effect is modeled by a frequency shift, due to the slow sound speed in water, the effect of transceiver motion on the duration of the symbol cannot be neglected [11] [12] caused in the received signal as:…”

Section: Doppler Shift and Uwac Multipathmentioning

confidence: 99%

“…In underwater acoustic transmissions, Doppler effects can be caused by propagation medium movements or by the relative velocity between the transmitter and the receiver [12]. It often causes additional difficulties for the processing of received signals.…”

Section: Doppler Shift Estimation For Underwater Acoustic Communicationsmentioning

confidence: 99%

Review Article: Multicarrier Communication for Underwater Acoustic Channel

2013

IJCNS

In past decades, there has been a growing interest in the discussion and study of using underwater acoustic channel as the physical layer for communication systems, ranging from point-to-point communications to underwater multicarrier modulation networks. A series of review papers were already available to provide a history of the development of the field until the end of the last decade. In this paper, we attempt to provide an overview of the key developments, both theoretical and applied, in the particular topics regarding multicarrier communication for underwater acoustic communication such as the channel and Doppler shift estimation, video and image transmission throw multicarrier techniques, etc. This paper also includes acoustic propagation properties in seawater and underwater acoustic channel representation.

“…The proposed scheme for image transmission over underwater acoustic channel (UWAC) has been done using channel model implement, where we assume the distance between transmitter and receiver about 5 Km, in 40m water depth and the relative velocity set to be 8m/s and use (8) to detect the Doppler shift effect [20], attenuation-noise (AN) factor [23] produce 8.6 KHz as optimal frequency for our suggested underwater channel physical parameter. Table I. shows the calculation results for channel relative delays and magnitudes for each path.…”

Section: Simulation Setupmentioning

confidence: 99%

“…Doppler phase d ϕ depends on the relative velocity v and the ratio between the carrier frequency c f and the symbol rate 20] will appear at received signal as given below:…”

mentioning

confidence: 99%

Image transmission over underwater acoustic environment using OFDM technique with HQAM mapper

2013 IEEE Third International Conference on Information Science and Technology (ICIST)

2013

Performanceof underwater acoustic communication system is influenced on channel characteristic. Especially, an important feature of the underwater acoustic communication is multipath propagation and Doppler spread cause by the surface and bottom reflections. In this paper, we study the application of high speed image transmission using multi-carrier modulation, where this capability can enable the next generation of undersea expeditions. We use Hierarchical Quadrature Amplitude Modulation (HQAM) as Zero-padded (ZP) orthogonal frequency division multiplexing (OFDM) mapper to be unequal error protection for the transmitted bit stream. We proved capability of ZP-OFDM multi-carrier modulation based on HQAM mapper with Reed Solomon channel coder in sensitive bit error reduction without receiver equalizer. Proposed scheme evaluated using different types of images for different values of the modulation parameter and underwater channel physical parameters.