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- IEEE Transactions on Multimedia
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Video signal transmission enables a wide range of applications in the underwater environment; such as coastal and tactical multimedia surveillance, undersea/offshore exploration, oil pipe/bridge inspection, video monitoring of geologica/biological processes from the seafloor to the air-sea interface-that all require real-time multimedia acquisition and classification. Yet, it is a challenge to achieve an efficient and reliable video transmission, due to the spectrum limitations underwater and also the error prone nature of the acoustic channel. In this paper, we propose a pairwise scheme to manage the video distortion-rate tradeoff for underwater video transmission. The proposed Multi-input Multi-output (MIMO)-based Software-Defined Acoustic Radio (SDAR) system adapts itself to meet the needs of both video compression and underwater channel in a timely manner from one hand, and keeps the overall video distortion-caused by the coder/decoder and channel-under an acceptable threshold from the other hand. The scalability of Universal Software Radio Peripheral (USRP) with high processing capabilities is exploited in the proposed structure along with the temporal, spatial and quality scalability of Scalable Video Coding (SVC) H.264/MPEG-4 AVC compression standard. Experimental results at Sonny Werblin Recreation Center, Rutgers University, as well as simulations are presented, while more experiments are in-progress to evaluate the performance of ourmore »
Scalable Video Coding (SVC) has been widely used in video transmissions. However, inappropriate SVC structures may lead to received video quality lower than user’s requirement or resource waste, especially in underwater time-varying channels. In this work, an adaptive cross-layering solution is proposed and validated for video transmissions in underwater acoustic multicast networks, namely Adaptive Scalable Video Transmission (ASVTuw). In ASVTuw, the transmitter collects over time the information about the channel states and the users’ video quality requirements to adaptively select the SVC video structures and transmission schemes, using Machine Learning (ML). At-sea experiments were conducted to collect the required acoustic data. The collected data were then used in MATLAB simulations to validate the ASVTuw. The results show that the usage of ASVTuw avoids resource wasting from transmitting redundant SVC substreams and satisfies the multicast users’ video quality requirements effectively with higher flexibility compared with the existing noncross-layering designs.
Underwater networks of wireless sensors deployed along the coast or in the deep water are the most promising solution for the development of underwater monitoring, exploration and surveillance applications. A key feature of underwater networks that can significantly enhance current monitoring applications is the ability to accommodate real-time video information on an underwater communication link. In fact, while today monitoring relies on the exchange of simple discrete information, e.g., water temperature, and particle concentration, among others, by introducing real-time streaming capability of non-static images between wireless underwater nodes one can completely revolutionize the whole underwater monitoring scenario. To achieve this goal, underwater links are required to support a sufficiently high data rate, compatible with the streaming rates of the transmitted video sequence. Unfortunately, the intrinsic characteristic of the underwater propagation medium has made this objective extremely challenging. In this paper, we present the first physical layer transmission scheme for short-range and high-data rate ultrasonic underwater communications. The proposed solution, which we will refer to as Underwater UltraSonar (U2S), is based on the idea of transmitting short information-bearing carrierless ultrasonic signals, e.g., pulses, following a pseudo-random adaptive time-hopping pattern with a superimposed rate-adaptive Reed-Solomon forward error correction (FEC) channel coding. Wemore »
Achieving high throughput and reliability in underwater acoustic networks is a challenging task due to the bandwidth-limited and unpredictable nature of the channel. In a multi-node structure, such as in the Internet of Underwater Things (IoUT), the efficiency of links varies dynamically because of the channel variations. When the channel is not in good condition, e.g., when in deep fade, channel-coding techniques fail to deliver the required information even with multiple rounds of retransmissions. An efficient and agile collaborative strategy among the nodes is required to assign appropriate resources to each link based on their status and capability. Hence, a cross-layer collaborative strategy is introduced to increase the throughput of the network by allocating unequal share of system resources to different nodes/links. The proposed solution adjusts the physical- and link-layer parameters in a collaborative manner for a Code Division Multiple Access (CDMA)-based underwater network. An adaptive Hybrid Automatic Repeat Request (HARQ) solution is employed to guarantee reliable communications against errors in poor communication links. Results are being validated using data collected from the LOON underwater testbed, which is hosted by the NATO STO Centre for Maritime Research and Experimentation (CMRE) in La Spezia, Italy.
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