# US 2025/0097684 A1 · High-reliability and high-robustness routing method for maritime search and rescue wireless sensor networks

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- Number: US 2025/0097684 A1
- Document ID: US20250097684A1
- Status: Published application
- Kind: A1
- Application number: 18/971,586
- Filed: 2024-12-06
- Published: 2025-03-20
- Earliest claimed: 2023-09-19
- Assignees: Shanghai Maritime University
- Applicants: Shanghai Maritime University
- Inventors: Jiangfeng XIAN; Junling MA; Huafeng WU; Xiaojun MEI; Weijun WANG; Yuanyuan ZHANG; Xinqiang CHEN; Yongsheng YANG; Chaofeng LI
- Web page: https://patentgrep.com/patent/US20250097684A1

## CPC

- H04W 4/90: Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
- H04W 40/20: based on geographic position or location
- H04W 40/22: using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
- H04W 40/30: for proactive routing
- H04W 40/32: for defining a routing cluster membership
- H04W 84/18: Self-organising networks, e.g. ad-hoc networks or sensor networks
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A high-reliability and high-robustness routing method for MSR-WSNs is provided, including: S1: generating an initial dynamic topological structure of MSR-WSNs; S2: determining a cluster head node for any maritime search and rescue node, and joining a corresponding cluster to obtain a set of clusters; S3: calculating a predicted forward distance of a maritime search and rescue data packet of a target node; S4: calculating the correct reception rate among nodes under the communication link of the maritime search and rescue environment; S5: calculating and sorting the priority of each relay node from high to low according to the priority; S6: when carrying out the task of forwarding maritime search and rescue data packets, the target nodes select the candidate relay nodes in turn and combined with the reliable response mechanism to forward until the maritime search and rescue data packets are successfully received by search and rescue ship.

## Claims

### Claim 1

A high-reliability and high-robustness routing method for MSR-WSNs, comprising following steps:
S1, generating an initial dynamic topological structure of MSR-WSNs, wherein the topological structure comprises a plurality of maritime search and rescue nodes and target nodes, wherein the maritime search and rescue nodes are evenly distributed;
S2, generating a random number for any maritime search and rescue node and comparing the random number with a threshold value, and determining whether the maritime search and rescue node is a cluster head node according to a comparison result, wherein the maritime search and rescue node being not the cluster head node selects a maritime search and rescue cluster corresponding to a cluster head node with a smallest indication value of a maritime search and rescue cluster, and joins the maritime search and rescue cluster to obtain a set of maritime search and rescue clusters;
S3, calculating predicted values of advance distances of maritime search and rescue data packets of the target nodes by using an adaptive filtering method;
S4, predicting a connectivity of communication links in maritime search and rescue environment and calculating a correct reception rate among nodes;
S5, according to the set in the S2, determining a relay node of any maritime search and rescue node in each cluster, calculating a priority of each relay node according to the predicted values of the advance distances of the maritime search and rescue data packets in the S3, the correct reception rate between the nodes in the S4 and residual energy of the nodes, and ranking the priorities from high to low according to priority values; and
S6, taking any maritime search and rescue node receiving the maritime search and rescue data packet of the target node as a current node, introducing a reliable response mechanism, selecting a relay node corresponding to the current node to forward the data packet according to the priority, taking the relay node selected as a current node, and repeatedly selecting the relay node of the current node to forward until the maritime search and rescue data packet is successfully received by a search and rescue ship.

### Claim 2 (depends on 1)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 1, wherein an indication value of the maritime search and rescue cluster is:
MSR
Instruction
(
n
i
,
n
j
)
=
ω
1
×
NRS
⁡
(
n
i
,
n
j
)
+
ω
2
×
NGLS
⁡
(
n
i
,
n
j
)
wherein ni and nj represent i-th and j-th maritime search and rescue nodes respectively, ω1 and ω2 represent weight coefficients of a received signal strength value similarity and a geographical location information similarity respectively, NRS represents a regularized received signal strength value similarity, and NGLS represents a regularized geographical location information similarity.

### Claim 3 (depends on 1)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 1, wherein the predicted values of the advance distances of the maritime search and rescue data packets are:
d
ˆ
i
j
t
=
ω
1
′
⁢
d
ˆ
i
j
t
-
1
+
ω
2
′
⁢
d
ˆ
i
j
t
-
2
+
…
+
ω
q
′
⁢
d
ˆ
i
j
t
-
q
wherein {circumflex over (d)}ijt-1, {circumflex over (d)}ijt-2, . . . {circumflex over (d)}ijt-q represent predicted values of advance distances of q maritime search and rescue data packets towards the search and rescue ship when the maritime search and rescue data packets sent to the node i are forwarded by a neighbor node i, of the node i, {circumflex over (d)}ijt represents a predicted value of the advance distance of the maritime search and rescue data packets at a timing t, wherein ω′ represents weight, and an update of ω′ is:
ω
i
′
⁢
t
=
ω
i
′
⁢
t
-
1
+
2
⁢
υ
⁢
e
i
⁢
d
ˆ
i
j
t
-
i
wherein v represents a learning constant, and ei represents a learning error of {circumflex over (d)}ijt.

### Claim 4 (depends on 3)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 3, wherein the advance distance represents a difference between a Euclidean distance between node i and the search and rescue ship and a Euclidean distance between node i; and the search and rescue ship.

### Claim 5 (depends on 1)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 1, wherein the correct reception rate between the nodes is:
P
⁡
(
P
R
(
d
)
≥
Th
)
=
=
Q
⁢
(
Th
-
E
P
R
(
d
)
σ
)
wherein represents a correct reception rate, PR(d) represents a signal strength received by the nodes, d represents a distance between the node sending information and the node receiving information, Th represents an information strength threshold; if the signal strength received by nodes is greater than or equal to the information strength threshold, a correct reception among nodes is realized,
wherein
Q
⁡
(
Z
)
=
1
2
⁢
π
⁢
∫
Z
∞
exp
⁢
(
-
χ
2
2
)
⁢
dx
the signal strength of the node i receiving information sent by a node with a distance d is:
[
P
R
(
d
)
]
dBm
=
[
P
T
]
dBm
-
[
PL
⁡
(
d
0
)
]
dBm
-
10
⁢
α
⁢
log
10
⁢
(
d
d
0
)
-
[
X
σ
]
dBm
wherein PT represents transmitting power of the nodes, PL(d0) represents a signal strength loss value when a reference distance d0=1 m, α represents a path loss attenuation index, and Xσ represents a wave shielding factor obeying Gaussian distribution with an expected value of 0 and a variance of σ2.

### Claim 6 (depends on 5)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 5, wherein when the correct reception is realized among the nodes, the transmitting power of the nodes satisfies:
P
T
≥
PL
⁡
(
d
0
)
+
10
⁢
α
⁢
log
10
⁢
(
d
d
0
)
+
Th
+
X
σ
wherein PL(d0) represents the signal strength loss value when the reference distance d0=1 m, αrepresents the path loss attenuation index, and X, represents the wave shielding factor obeying the Gaussian distribution with the expected value of 0 and the variance of σ2.

### Claim 7 (depends on 1)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 1, wherein specific steps of determining the relay node of the node i are as follows:
for the node i, calculating an intersection unit of a node set in a cluster where the node i is located and a neighbor node set of the node i, and taking all nodes in the intersection set as relay nodes of the node i.

### Claim 8 (depends on 1)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 1, wherein the priority of the relay nodes of the node i is:
P
i
j
(
t
)
=
ln
⁢
(
1
+
d
ˆ
i
j
t
·
·
e
i
j
-
residual
t
)
wherein {circumflex over (d)}ijt represents a predicted value of the advance distance of the maritime search and rescue data packet at a timing t, represents the correct reception rate, and eij-residualt represents the residual energy of the node at the timing t.

### Claim 9 (depends on 8)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 8, wherein specific steps of selecting the relay node corresponding to the current node for data packet forwarding according to the priority are as follows:
the current node first selects a corresponding relay node with a highest priority to forward the maritime search and rescue data packet, and if the relay node with the highest priority successfully receives the data packet, a reply packet is broadcast, and other relay nodes with lower priority discard the reply packet after receiving a successfully sent reply packet, and then the relay node with the highest priority is used as a new current node, and above steps are repeated;
if other relay nodes do not receive the reply packet, the current node selects the relay node with a second highest priority to forward the data packet, and so on until other relay nodes receive the reply packet and discard the reply packet.

### Claim 10 (depends on 9)

The high-reliability and high-robustness routing method for MSR-WSNs according to claim 9, wherein after introducing the reliable response mechanism CACK (Credible, ACK), a number of ACK transmissions among the nodes is:
γ
=
[
1
/
f
ACK
]
+
1
wherein fACK represents a delivery rate of the ACK;
a delivery rate of the reliable response mechanism CACK is:
P
CACK
=
1
-
(
1
-
f
ACK
)
γ
wherein fACK represents the delivery rate of the ACK and y represents the number of ACK transmissions among nodes.