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Underwater Acoustic Networks: Channel Models and Network Coding based Lower Bound to Transmission Power for Multicast
, 809
"... Abstract — The goal of this paper is two-fold. First, to establish a tractable model for the underwater acoustic channel useful for network optimization in terms of convexity. Second, to propose a network coding based lower bound for transmission power in underwater acoustic networks, and compare th ..."
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Abstract — The goal of this paper is two-fold. First, to establish a tractable model for the underwater acoustic channel useful for network optimization in terms of convexity. Second, to propose a network coding based lower bound for transmission power in underwater acoustic networks, and compare this bound to the performance of several network layer schemes. The underwater acoustic channel is characterized by a path loss that depends strongly on transmission distance and signal frequency. The exact relationship among power, transmission band, distance and capacity for the Gaussian noise scenario is a complicated one. We provide a closed-form approximate model for 1) transmission power and 2) optimal frequency band to use, as functions of distance and capacity. The model is obtained through numerical evaluation of analytical results that take into account physical models of acoustic propagation loss and ambient noise. Network coding is applied to determine a lower bound to transmission power for a multicast scenario, for a variety of multicast data rates and transmission distances of interest for practical systems, exploiting physical properties of the underwater acoustic channel. The results quantify the performance gap in transmission power between a variety of routing and network coding schemes and the network coding based lower bound. We illustrate results numerically for different network scenarios.
Recent Advances in Underwater Acoustic Communications & Networking
"... The past three decades have seen a growing interest in underwater acoustic communications. Continued research over the years has resulted in improved performance and robustness as compared to the initial communication systems. Research has expanded from point-to-point communications to include unde ..."
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The past three decades have seen a growing interest in underwater acoustic communications. Continued research over the years has resulted in improved performance and robustness as compared to the initial communication systems. Research has expanded from point-to-point communications to include underwater networks as well. A series of review papers provide an excellent history of the development of the field until the end of the last decade. In this paper, we aim to provide an overview of the key developments, both theoretical and applied, in the field in the past two decades. We also hope to provide an insight into some of the open problems and challenges facing researchers in this field in the near future.
Opportunistic ARQ with bidirectional overhearing for reliable multihop underwater networking
- In Proc. Oceans 2010 Asia. IEEE
, 2010
"... Abstract—As reliable data delivery over a long-range singlehop underwater acoustic link is considerably challenging due to severe channel impairments, multihop data transmission schemes over one or more relay nodes have been proposed. In this paper, we propose a data delivery scheme using a fully-op ..."
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Abstract—As reliable data delivery over a long-range singlehop underwater acoustic link is considerably challenging due to severe channel impairments, multihop data transmission schemes over one or more relay nodes have been proposed. In this paper, we propose a data delivery scheme using a fully-opportunistic ARQ that employs bidirectional overhearing, whereby nodes leverage on the broadcast nature of acoustic channels and their spatial and temporal variance to overhear (i) data packets from all upstream (nearer to source) nodes to speed up data delivery and (ii) data & acknowledgement packets from all downstream (nearer to sink) nodes as implicit acknowledgements. The crosslayer scheme uses implicit acknowledgements to purge duplicates at both data-link and network layer. We demonstrate using simulations that, when implemented on an Interweaved TDMA MAC scheme, the proposed delivery scheme achieves better reliability, energy-efficiency and latency as compared to non-opportunistic or semi-opportunistic schemes in multihop underwater acoustic networks with linear topology. Over a 10-hop network, the proposed scheme outperforms its non-opportunistic counterpart, delivers 88 % more packets, consumes 43 % less energy and achieves an 8 % improvement in latency (per packet delivered). I.
Multi-hop routing is order-optimal in underwater extended networks
- in Proc. IEEE Int. Symp. Inf. Theory (ISIT
, 2010
"... Abstract — Capacity scaling laws are analyzed in an underwater acoustic network with n regularly located nodes. A narrowband model is assumed where the carrier frequency is allowed to scale as a function of n. In the network, we characterize an attenuation parameter that depends on the frequency sca ..."
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Abstract — Capacity scaling laws are analyzed in an underwater acoustic network with n regularly located nodes. A narrowband model is assumed where the carrier frequency is allowed to scale as a function of n. In the network, we characterize an attenuation parameter that depends on the frequency scaling as well as the transmission distance. A cut-set upper bound on the throughput scaling is then derived in extended networks. Our result indicates that the upper bound is inversely proportional to the attenuation parameter, thus resulting in a highly powerlimited network. Furthermore, we describe an achievable scheme based on the simple nearest-neighbor multi-hop (MH) transmission. It is shown under extended networks that the MH scheme is order-optimal as the attenuation parameter scales exponentially with √ n (or faster). Finally, these scaling results are extended to a random network realization. I.
On the Order Optimality of Large-scale Underwater Networks -- Part II: Dense Network Model
"... This is the second in a two-part series of papers on information-theoretic capacity scaling laws for an underwater acoustic network with n regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. Part I showed that in extended networks of u ..."
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This is the second in a two-part series of papers on information-theoretic capacity scaling laws for an underwater acoustic network with n regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. Part I showed that in extended networks of unit node density, using the nearest-neighbor multi-hop (MH) protocol is order-optimal for all operating regimes. Part II shows the analysis for a dense network of unit area. As in Part I, we assume a narrow-band model where the carrier frequency scales as a function of n, and then characterize an attenuation parameter depending on the frequency scaling as well as the transmission distance. In dense networks, by deriving a cut-set upper bound on the throughput scaling, we show that there exists either a bandwidth or power limitation, or both, according to the path-loss attenuation regimes, thus yielding the upper bound that has three fundamentally different operating regimes. As similarly in Part I, an achievability result based on the MH transmission, which is suitable due to the low propagation speed of acoustic channel, is also presented in dense networks. The operating regimes that guarantee the order optimality
Network coding to combat packet loss in underwater networks
- In Proceedings of the Fifth ACM International Workshop on UnderWater Networks (WUWNet), Woods Hole, MA, USA, 30 September–1
, 2010
"... Abstract Channel variability and a high level of ambient noise lead to significant probability of packet loss in many underwater networks. Techniques based on acknowledgements and re-transmissions (such as ARQ) can be used to build robust networks over the unreliable links between underwater nodes. ..."
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Abstract Channel variability and a high level of ambient noise lead to significant probability of packet loss in many underwater networks. Techniques based on acknowledgements and re-transmissions (such as ARQ) can be used to build robust networks over the unreliable links between underwater nodes. An alternative solution based on erasure codes can also be used to combat the packet loss. However, both solutions rely on a node re-transmitting information originating at that node. We propose an alternative solution based on network coding, where nodes transmit packets which are composed partially from information originating at that node, and partially from information received by that node from other nodes. The intuition behind this solution is to effectively route the information over good paths in the network rather than to simply rely on re-transmission of the information by the originating nodes. In this paper, we show that our proposed solution indeed performs better than the acknowledgment and erasure coding based solutions, and has the potential to effectively combat the high packet loss experienced by many underwater networks.
