1 Introduction
References | Year | classification | Main goal | advantages |
---|---|---|---|---|
[26] | 2017 | Vector-based, depth based, clustered based, AUV based, | Routing protocols based on node mobility | Considering node mobility Analytical and numerical simulation method |
[27] | 2017 | Localization-based protocols Localization-free protocols | Detailed description of the classified protocols with a focus on their energy efficiency | Exhaustive comparison of the described protocols according to many performance aspects |
[28] | 2018 | Localization-based protocols Localization-free protocols | Exhaustive literature review along with the merits and demerits of each described protocol | Personalized sub-classification of every class according to its particularity |
[29] | 2020 | Localization-based protocols Localization-free protocols Cooperative routing protocols | Detailed description of the protocols related to the provided description as well as their advantages and disadvantages | Newly introduced classification paradigm related to “cooperative routing” Detailed description of UASN background |
[30] | 2021 | Energy-based protocols Data-based protocols Geographic information-based protocols | Comparative study with learned lessons and future research directions | Unique classification of recent routing protocols, Detailed performance comparison: end-to-end delay, energy consumption and packet delivery ratio |
2 Challenges in underwater communications
2.1 High energy consumption in UASN
2.2 UASN are highly prone to error
2.3 UASN are highly dynamic
2.4 UASN have limited bandwidth
Convergence | Range (km) | Bandwidth (kHz) |
---|---|---|
Very long | 100 | Less than 1 |
Long | 10–100 | 2–5 |
Medium | 1–10 | Almost 10 |
Short | 0.1–1 | 20–50 |
Very short | Less than 0.1 | Greater than 100 |
2.5 Connectivity void
3 Underwater routing protocols
3.1 Reliable data forwarding protocols
3.1.1 Location-based data forwarding protocols
3.1.1.1 Vector-based forwarding protocol (VBF)
3.1.1.2 Hop-by-hop vector-based forwarding protocol (HH-VBF)
3.1.1.3 Focused beam routing protocol (FBR)
3.1.2 Depth-based data forwarding protocols
3.1.2.1 Depth-based routing protocol (DBR).
3.1.2.2 Hydraulic pressure-based anycast routing protocol (HydroCast)
3.1.2.3 Void-aware pressure routing protocol (VAPR)
3.2 Prediction-based data forwarding protocols
3.2.1 Mobility model-based data forwarding protocols
3.2.1.1 Movement predicted data forwarding protocol (MPDF).
3.2.1.2 Sidewinder protocol
3.2.1.3 Space–time–energy-based forwarding protocol (STE)
3.2.1.4 Hop-by-Hop dynamic addressing-based routing protocol (H2-DAB)
3.2.1.5 Mobility prediction optimal data forwarding for freely floating underwater acoustic sensor networks (MPODF)
3.2.2 Filter-based data forwarding protocols
3.2.2.1 Q-learning-based delay tolerant routing protocol (QDTR)
3.2.2.2 Opportunistic forwarding algorithm based on irregular mobility protocol (OFAIM)
4 Comparing between data forwarding protocols for underwater wireless sensor networks (UWSNs)
Protocols | Years | Complexity | Assumptions | Routing Strategy | Results |
---|---|---|---|---|---|
VBF | 2006 | Low Complexity data forwarding protocol | Node in the network knows its location • The packet carries the locations of the source, the sink, and the sender • Sensor nodes can measure the distance and the angle of arrival (AOA) of the signal • All the nodes are deployed in layers For one layer if one node receives a packet, all the normal nodes will receive the packet | Selects only the forwarding nodes within the virtual pipe from the source node to the sink node | VBF is robust against both packet loss and node failure. When the packet loss is as high as 50%, the success rate can still reach 80% The VBF protocol success rate is above 95% |
HH-VBF | 2007 | Low Complexity data forwarding protocol | Node in the network knows its location The packet carries the locations of the source, the sink, and the sender Adjustable distance threshold | Different from VBF that is defining a single routing pipe from the source to the sink node, in HH-VBF every forwarder node defines a separate pipe | HH-VBF has a much better performance in terms of success rate and energy tax than VBF in sparse networks In the case of a sparse network, the energy cost of HH-VBF is greatly lower than that of VBF |
FBR | 2008 | Low Complexity data forwarding protocol | Nodes know their own locations The node knows exactly the location of all other nodes The source node knows the location of final destination The transmitting node decides which power level to use Only the nodes that are within this radius are receiving the signal The receiving node will not escape before the packet is reached | Selects the next forwarder node based on power level within a virtual cone formed from the source to the destination | FBR with an aperture of 30◦ cones reduce the end-to-end delay but increases the energy consumption FBR in a lower network density, on average, reduce the energy per bit consumption |
DBR | 2008 | Low Complexity data forwarding protocol | Nodes know their own depth information Sinks located at the water surface Nodes have a packet history buffer | Selects the forwarder node with the shallower depth from bottom to top to forward packets in a flooding manner | DBR can achieve high packet delivery ratios of 95% for dense networks, with reasonable energy consumption DBR has a packet delivery ratio of around 70%, which is more than four times larger than 15%, the delivery ratio of VBF |
Sidewinder | 2009 | High Complexity data forwarding protocol | Nodes know their own locations All nodes that overhear the forwarded data | The data packets are forwarded to neighbors who lie in the specified 60◦ forwarding zone in the direction to the sink node with growing precision as the data packet approaches the sink node | Sidewinder achieves a 92% packet delivery ratio in 20 m/s node speed, which is 52% higher than Beaconless GF and 42% higher than that of GF Sidewinder achieves an 82% packet delivery ratio in random mobility, which is 20% higher than that of Beaconless GF and 72% than that of GF |
STE | 2010 | High Complexity data forwarding protocol | Nodes know their own locations Nodes know the residual energy of all nodes in the network | Selects the forwarders with dominance in both spatial and time dimensions then select the best forwarder node based on the highest residual energy | The STE has the highest success rate of sending packets than PEBF, EERT and PVBF The STE is a high energy-efficient protocol that outperforms PEBF, EERT and PVBF in terms of the residual energy of the various nodes STE have higher calculation load than that in EERT |
VAPR | 2013 | High Complexity data forwarding protocol | Nodes know their own depth information Sinks located at the water surface Local maximum node has a node with lower depth than itself The sinks (sonobuoys) on the surface are equipped with GPS All the nodes move in the same velocity field All the nodes measure the pairwise distance | Selects the next forwarder node that matches the next-hop data forwarding direction of the previous forwarder node | The packet delivery ratio of VAPR outperforms the HydroCast and DBR The performance of VAPR is far better than that of HBR due to VAPR’s localized opportunistic forwarding VAPR save more energy per packet than does HydroCast VAPR outperform HydroCast with route recovery |
QDTR | 2013 | High Complexity data forwarding protocol | All nodes follow the kinematic model for water currents No underlying node mobility model | Selects to forward to the encountered node with the higher reward function | The performance of QDTR is within 10% difference from that of Ideal, which always has accurate and infinite future information The performance of QDTR is more than 10% better than Second and Average, which do not have accurate next contact time prediction QDTR achieves more than 90% of delivery rate, with all the PROPHET, PASR and Binary Spray and Wait protocols less than 80% QDTR performs better than PROPHET and PASR in terms of average delay |
MPDF | 2014 | Medium Complexity data forwarding protocol | Node in the network knows its initial anchor position and the cable length The Reply packet carries the locations of the forwarder, its uplink transmission reliability and reachability to sink Network knows the four forces values: gravity, buoyancy, water current, and tension of the string to calculate the node displacement from the original position | Selects the forwarder node with the highest coverage probability, the best uplink transmission reliability, and the best link reachability | MPDF has a higher Packet Delivery Ratio than that of the OMFP, especially at a faster data generation rate MPDF requires less routing overhead than OMFP MPDF consumes less energy per successfully received packet than OMFP MPDF is more scalable than OMFP in terms of data delivery, routing overhead and energy consumption MPDF performs better than OMPF by considering node movement during forwarder selection process |
H2-DAB | 2014 | Medium Complexity data forwarding protocol | Nodes know their own depth information Multi-sink architecture Sinks located at the water surface The sinks (sonobuoys) on the surface are equipped with GPS | Selects the forwarders with the least Hop Count to the sink | H2-DAB achieve high delivery ratio of more than 90% in both, dense and spars networks, with the small delays and energy consumptions |
OFAIM | 2015 | High Complexity data forwarding protocol | Nodes know their own locations Sensor nodes are generally heterogeneous | Selects the forwarders with the highest contacting probabilities with the sink node | OFAIM achieves a delivery ratio larger than 67% compared to epidemic forwarding, motion vector forwarding and predict and spread forwarding |
HydroCast | 2016 | Medium Complexity data forwarding protocol | Nodes know their own depth information Sinks located at the water surface Local minimum node has a node with lower depth than itself Node measures the pairwise distance Node computes the NADV of each neighbor nodes | Selects a subset of forwarder nodes with the highest Expected Packet Advance (EPA) that is closer to the water surface to forward packets. In case of the void area situation the local maximum node has a less shallow node as a recovery route | The HydroCast had a lower end-to-end delay than DBR due to its adaptive timer setting at each hop The HydroCast with forwarding set selection and recovery significantly improved its reliability and surpassed the delivery ratio of DBR The HydroCast without recovery exhibited the minimum energy consumption where the DBR consumed significantly more energy for each packet delivery |
MPODF | 2021 | High Complexity data forwarding protocol | Node in the network knows its initial position and the sink position Node in the network knows the four forces values: the node weight, the gravitational force, the buoyant force, and the water resistance to calculate and determine the location and velocity of any sensor at any time The transmitting node decides the path to the sink Nodes know the residual energy of all nodes in the network | Select the path with the highest residual energy to the sink with all nodes that will remain moving within the communication range of a sender node during data transmission | MPODF is achieving 70% higher throughput when the water current velocity equals 5 m/s MPODF protocol is at least 99% more energy efficient than the flooding protocol which is the commonly used protocol for highly mobile networks |
Protocols | Advantages | Disadvantages |
---|---|---|
VBF | VBF is Energy efficient, Scalable and robust protocol High Success data delivery rate due to multiple path selection to the sink nodes Self-adaption algorithm that reduces the number of nodes in the forwarding process. [4] Reduce the multiple copies of the data packet in the network that achieves energy efficiency | Energy holes due to nodes dying quickly in the vertical pipe which is caused by high data load (dead nodes). [5] Performance sensitivity to the number of nodes in the vertical pipe Performance sensitivity to the radius of the vertical pipe VBF lacks communication void algorithm. [52] |
HH-VBF | Minimal energy hole compared to VBF thanks to controlling the data forwarding load on the nodes. [5] Significantly high packet delivery ratio due to multiple vertical pipe paths from each forwarder node toward the sink node, especially in low network density compared to VBF protocol | High computational delay due to the necessity to recompute the virtual pipe for each forwarder node. [5] High energy cost in the dense network due to multiple paths for the source to the destination. [40] No mechanism to handle the communication holes. (not void aware) [40] The data forwarding performance can be influenced and affected by the Radius of the virtual pipe. [4] A hop-by-hop approach in the H-VBF protocol increases the exchange of messages which will create a signaling overhead and will impact the throughput of the overall network. [4] |
FBR | FBR has a high energy efficiency and low end-to-end delay FBR reduces the number of nodes in the forwarding process. [55] | FBR faces Low throughput when the network density is low, (nodes are far apart). [5] It utilizes a transmitting cone that covers only a portion of the underwater sensor node The necessity to rebroadcast and send every time RTS message when it cannot find a next forwarding node in its transmitting cone CTS message may easily collide in high dense networks because it lacks a collision handling mechanism Communication overhead due to the frequent use of RTS message that will affect the data packet delivery ratio in low network density. [73] |
DBR | Loosen the need for the 3D geographical location information of the sensor nodes. [5] High scalability and High throughput. [5] Algorithm used by this protocol is much simpler. [41] | Increasing the depth threshold result in decreasing the packet delivery ratio. [41] Low performance in low density network. [41] High end-to-end delay. [41] Significant energy consumption due to the transmission of multiple data packets. [5] High packets collision There is no mechanism for handling the void region (communication holes) |
HydroCast | High Energy Efficiency. [42] Provide a mechanism to handle void communication holes in the underwater network. [42] HydroCast uses a multiple sink system, thereby improves performance. [42] | Performance sensitivity to sparse areas. [42] High data forwarding load of shallower nodes (nodes closer to the water surface) due to opportunistic routing. [42] Shallower nodes (low depth nodes) rapidly die due to the high data forwarding load on them. [42] Energy metrics are not considered in forwarding nodes’ selection. [42] High communication overhead because of the needs of localization information in the two‐hop clustering technique. [42] High network overhead and High energy consumption due to repetitive use of the void‐handling algorithm used in this protocol. [52] High network load due to redundant copies of the same data packet being forwarded to the sink node. [4] |
HydroCast | High Energy Efficiency. [42] Provide a mechanism to handle void communication holes in the underwater network. [42] HydroCast uses a multiple sink system, thereby improves performance. [42] | Performance sensitivity to sparse areas. [42] High data forwarding load of shallower nodes (nodes closer to the water surface) due to opportunistic routing. [42] Shallower nodes (low depth nodes) rapidly die due to the high data forwarding load on them. [42] Energy metrics are not considered in forwarding nodes’ selection. [42] High communication overhead because of the needs of localization information in the two‐hop clustering technique. [42] High network overhead and High energy consumption due to repetitive use of the void‐handling algorithm used in this protocol. [52] High network load due to redundant copies of the same data packet being forwarded to the sink node. [4] |
VAPR | Provide a mechanism to avoid void communication holes in the network. [59] VAPR is a simple and robust soft-state protocol. [59] VAPR does not forward redundant copies of the same data packets | The VAPR protocol uses a much complex algorithm High network overhead and energy consumption due to sending periodical beacon messages in a dynamic topology in the UWSNs. [59] The VAPR protocol does not consider link quality in finding a new path. [52] Performance sensitivity to the network density. [59] Performance sensitivity to the number of buoys (sinks). [59] Significant end to end delay. [59] |
MPDF | High chance of reliable data delivery since MPDF has better coverage (communication range). [41] High Energy efficiency. [41] MPDF is scalable. [41] | Low Packet Delivery Ratio (PDR), due to collision which increases the packet loss rate. [41] Low Packet Delivery Ratio (PDR), with an increased number of source nodes, which results in an increased collision and hence a high packet loss rate. [41] High routing overhead with increased packet generation interval. [41] High routing overhead with an increased number of source nodes. [41] • Significant end-to-end delay due to the need for each forwarder to send and receive a control packet before selecting the next forwarder limited performance due to the lack of consideration of node movement. [41] |
Sidewinder | High packet delivery ratio and low latency. [68] Sidewinder utilizes geographic-based routing, that uses shorter path length. [68] | Relatively high energy consumption during prediction. [68] Significant overhead due to the calculation of the next hop forwarder and retransmission. [68] Performance sensitivity to the speed of mobile sink nodes that cause the increases in the number of hops, which causes a higher chance of packet collisions Sidewinder achieves a high delivery ratio due to long path length, a high number of retransmissions, and routing overhead Sidewinder does not suppose multiple mobile sink nodes Performance may change depending on the beaconing frequency in Sidewinder. [68] |
STE | High Energy efficiency High packet delivery ratio | High end-to-end delay Significant overhead due to the calculation of the next hop forwarder in space, time and energy Not suitable for real-time networks |
H2-DAB | High packet delivery ratio H2-DAB is robust and scalable | High end-to-end delay End-to-end delay is sensitive to sparseness Significant overhead due to the calculation of the next hop forwarder Communication overhead due to the frequent use of Request and Reply messages |
MPODF | MPODF has single copy of the data packet in the network that achieves energy efficiency MPODF has a high energy efficiency, scalable and low end-to-end delay MPODF provide a mechanism to avoid void communication holes in the network | Significant computational delay arises from the need to recompute the virtual pipe for each forwarder node The MPODF protocol employs a considerably intricate algorithm increased propagation delay and increased energy consumption result from the substantial computational overhead of MPODF |
QDTR | QDTR achieves the lowest number of transmissions, due to the accuracy of its prediction. [71] High delivery rate, because QDTR adapts more quickly to mobility changes. [71] Low average delay due to the significantly adaptive prediction mechanism especially in dynamic network. [71] | Restrictive communication pattern, which led to a limited application domain due to layered network structure. [73] QDTR presumes that the sink is always situated on the topmost layer. [73] |
OFAIM | OFAIM is appropriate for heterogeneous networks where sensor nodes have different movement patterns and various communication ranges. [72] OFAIM achieves a favorable data delivery ratio (67% higher than the worst case). [72] The number of redundant data copies forwarded at each time slot is limited to either two or three copies, therefore, the message cost is significantly reduced. [72] | OFAIM algorithm is much complex due to the recalculations of dynamic routes at each slot. [72] High propagation delay and high energy consumption since OFAIM has high computational costs. [72] Performance sensitivity to the number of forwarded copies. [72] |
Classification | Protocols | Selection Parameters | Neighbors Selection Strategy | Forwarder Selection Strategy | |
---|---|---|---|---|---|
Reliable Data Forwarding Protocols | Location based | VBF | Distance information | Neighbor Nodes placed inside the vertical pipe from the source node to the sink node. [52] | Node that have a minimum distance inside the vertical pipe to the sink. [52] |
Reliable Data Forwarding Protocols | Location based | H-VBF | Distance information | Neighbor Nodes placed inside each forwarder pipeline from itself to the sink. [52] | Node that have minimum distance inside vertical pipelines to the sink. [52] |
FBR | Distance information | Neighbor Nodes placed inside the cone from the source node to the sink node. [52] | Node that has minimum distance inside the cone to the sink. [52] | ||
Depth based | DBR | Depth information | Neighbor nodes closer to the water surface. [52] | Neighbor node with the lowest holding time. [52] | |
HydroCast | Depth information and link quality (EPA) | Neighbor Nodes that are shallower with a good link quality. [52] | Neighbor node that is the shallowest neighbor with the best link quality (EPA) and lowest holding time. [52] | ||
VAPR | Depth information, sequence number, hop-count, and the direction of nodes | Neighbor nodes closer to the water surface with hop-count direction. [52] | Neighbor node with the minimum hop-count. [52] | ||
Classification | Protocols | Selection Parameters | Neighbors Selection Strategy | Forwarder Selection Strategy | |
Prediction based Data Forwarding Protocols | Mobility Model based | MPDF | Link reachability, uplink transmission reliability, and coverage probability | Neighbor Nodes that send a “REPLY” message to the source node. [67] | Neighbor node with a minimum selection cost function. [67] |
Sidewinder | Distance information, and angle information | Neighbor Nodes that are placed inside the 60◦ forwarding zone facing the sink. [68] | Neighbor node with a minimum back-off timer. [68] | ||
STE | Distance information and residual energy | Neighbor Nodes selection in terms of both time and space dimensions. [69] | Neighbor node with the highest residual energy [69] | ||
H2-DAB | Address information | Neighbor Nodes that send a “REPLY” message to the source node. [6] | Neighbor nodes that have lower HopID. [6] | ||
MPODF | Distance information and residual energy | Neighbor Nodes that will remain moving within the communication range of a sender node during data transmission | Neighbor node with the highest residual energy | ||
Filter based | QDTR | Contact information | Neighbor Nodes that are placed inside the transmission range of the source node. [71] | Neighbor node with higher reward function. [71] | |
OFAIM | Contact information | Neighbor Nodes that received notification messages including a quintuple value from the source node. [72] | Neighbor node with the largest contacting probability and that received notification messages from the destination. [72] |
Protocol | Needed Location information | Single/ Multi- Sink | Hop-by-hop / end-to-end | Notification Message | Void-Aware | Redundant Copies of data packet | Sender/Receiver-Based |
---|---|---|---|---|---|---|---|
VBF | YES | Single sink | End-to-End | NO | NO | Multiple copies | Receiver-Based |
HH-VBF | YES | Single sink | End-to-End | NO | NO | Multiple copies | Receiver-Based |
FBR | YES | Multiple sinks | Hop-by-Hop | YES | YES | Single copy | Sender-Based |
DBR | YES | Multiple sinks | Hop-by-Hop | NO | NO | Multiple copies | Receiver-Based |
HydroCast | NO | Multiple sinks | Hop-by-Hop | NO | YES | Multiple copies | Receiver-based |
VAPR | YES | Multiple sink | Hop-by-Hop | YES | YES | Single copy | Sender-Based |
MPDF | YES | Multiple sink | Hop-by-Hop | YES | NO | Single copy | Sender-Based |
Sidewinder | YES | Single sink | End-to-End | NO | NO | Multiple copies | Receiver-Based |
STE | YES | Single sink | End-to-End | NO | NO | Single copy | Sender-Based |
H2-DAB | NO | Multiple sink | Hop-by-Hop | YES | YES | Single copy | Sender-Based |
MPODF | NO | Single sink | End-to-End | NO | YES | Single copy | Sender-Based |
QDTR | NO | Single sink | Hop-by-Hop | YES | NO | Single copy | Sender-Based |
OFAIM | YES | NO sink | End-to-End | YES | YES | Multiple copies | Sender-Based |
Protocol | Data Delivery Ratio | Average Delay Efficiency | Energy Efficiency |
---|---|---|---|
VBF | Low | Low | Medium |
HH-VBF | Medium | Medium | Low |
FBR | Low | High | High |
DBR | High | High | Low |
HydroCast | High | High | Medium |
VAPR | Medium | High | Medium |
MPDF | Medium | Low | Low |
Sidewinder | High | High | Medium |
STE | High | Low | High |
H2-DAB | High | Medium | Medium |
MPODF | High | Low | High |
QDTR | High | High | Medium |
OFAIM | High | Low | Low |
4.1 Comparing the advantages and disadvantages of data forwarding protocols in underwater wireless sensor networks
4.2 Selection techniques of the next forwarder
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“End-to-end” means that data forwarding such as the selection of the forwarding nodes and the delivery of the data packet are all handled between the ultimate endpoints, not at intermediate nodes.
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“Hop-by-hop” is the opposite point-of-view, where each intermediate node along the path to the sink should handle the selection of the next forwarding nodes by forwarding to the most suitable adjacent nodes.
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Notification message: this rubric indicates if the protocol exchanges any notification messages.
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Void-aware: the void area is one of the critical problems in data forwarding protocols for UASN due to the dynamic and sparse nature of underwater sensor network topology which may cause a low packet delivery ratio. Void area problem occurs when a data forwarder node finds itself at an impasse to relay the data packet due to the absence of a node in its neighborhood. This rubric points out if a given protocol is overcoming the void area problem.
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Redundant copies of data packet this rubric highlights the number of duplicate copies of the same data packet each protocol forwards at each step.
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Sender/receiver-based forwarding decision The hop-by-hop forwarding decision in a sender-based protocol is exclusively taken by the forwarder node in order to choose the best next hop forwarder among all its candidates. Indeed, when a node receives a data packet, it forwards the packet to the best chosen one among its candidate neighbors. However, in a receiver-based protocol, the forwarding decision is solely taken by the receiver node. In other words, the forwarder node will proceed forwarding the packets to all the next forwarder candidates, and then, it is up to the next hop forwarder to decide to forward the data packet or drop it.
4.3 Comparison of data forwarding protocols based on performance metrics
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Data delivery ratio represents the ratio of data packets that were successfully received by the sink node to the total number of data packets generated by all the source nodes [73].
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Average delay efficiency measures the average end-to-end delay for the successfully received packets from the generation time at the source node until the reception at the sink node [73].
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Energy efficiency measures the total amount of consumed energy per node to forward the packet until the reception by the sink node including all the exchanged notification messages [73].