# US 12,120,627 B2 · Data processing method for node localization in wireless sensor networks

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- Number: US 12,120,627 B2
- Document ID: US12120627B2
- Status: Granted
- Kind: B2
- Application number: 18/530,247
- Filed: 2023-12-06
- Published: 2024-08-29
- Granted: 2024-10-15
- Earliest claimed: 2022-04-07
- Assignees: Sun Yat-Sen University
- Applicants: Sun Yat-sen University
- Inventors: Yitong Liu; Hao Lin; Xingcheng Liu; Qiang Tu; Yi Xie
- Web page: https://patentgrep.com/patent/US12120627B2

## CPC

- H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management
- 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

In a data processing method for node localization in wireless sensor networks, a plurality of potential coordinate calculation values for a to-be-located node are calculated based on RSSI data received by the to-be-located node from a plurality of anchor nodes. A centroid C1 of these coordinate calculation values is calculated. Then coordinate calculation values with distances to the centroid C1 less than a threshold are screened out, and a centroid C2 of the screened-out coordinate calculation values is calculated. A coordinate position of the centroid C2 is used as the position of the to-be-located node. In other words, a plurality of potential positions for the to-be-located node are calculated using multiple groups of RSSI data and these potential positions are then screened through calculation. Instead of directly processing the received RSSI data, the present disclosure processes the coordinate calculation values obtained based on the received RSSI data.

## Claims

### Claim 1

A data processing method for node localization in wireless sensor networks, comprising the following steps:
S1: obtaining received signal strength indicator (RSSI) data received by a to-be-located node from n anchor nodes, wherein m groups of RSSI data are collected for each anchor node, and n≥3;
S2: calculating distances between the to-be-located node and the anchor nodes based on the RSSI data;
S3: calculating coordinates of the to-be-located node based on coordinates of the anchor nodes and the distances between the to-be-located node and the anchor nodes;
and obtaining a plurality of coordinate calculation values for the to-be-located node through permutations and combinations of the m groups of RSSI data of each of the n anchor nodes;
S4: calculating a centroid C1 of the plurality of coordinate calculation values for the to-be-located node obtained in step S3;
S5: screening out coordinate calculation values with distances to the centroid C1 less than a threshold from the plurality of coordinate calculation values for the to-be-located node obtained in step S3, wherein the threshold is less than half of a distance between two furthest apart coordinate calculation values among the plurality of coordinate calculation values for the to-be-located node obtained in step S3, wherein the threshold is denoted by r:
r
=
1
4
⁢
max
⁢
{
(
x
s
-
x
j
)
2
+
(
y
s
-
y
j
)
2
}
,
s
,
j
∈
[
1
,
k
]
;
and
S6: calculating a centroid C2 of the coordinate calculation values screened out in step S5, and using a coordinate position of the centroid C2 as a position of the to-be-located node.

### Claim 2 (depends on 1)

The data processing method according to claim 1, wherein the coordinates of the to-be-located node are calculated using a ranging localization method in step S3.

### Claim 3 (depends on 2)

The data processing method according to claim 2, wherein the coordinates of the to-be-located node are calculated based on trilateration in step S3, to obtain Cn3Am1Am1Am1 coordinate calculation values for the to-be-located node.

### Claim 4 (depends on 3)

The data processing method according to claim 3, wherein n=3, and m=10.

### Claim 5 (depends on 1)

The data processing method according to claim 1, wherein in step S3, when a number of the coordinate calculation values for the to-be-located node is k, the coordinate calculation values for the to-be-located node are Oi=(xi,yi), wherein i=1, 2, 3, . . . , k; and
in step S4, when the centroid C1=(xC1, yC1), then:
x
C
⁢
1
=
1
k
⁢
∑
1
k
⁢
x
i
;
y
C
⁢
1
=
1
k
⁢
∑
1
k
⁢
y
i
.

### Claim 6 (depends on 1)

The data processing method according to claim 1, wherein in step S5, t coordinate calculation values for the to-be-located node are screened out, and the coordinate calculation values for the to-be-located node are Oi=(xi,yi), wherein i=1, 2, 3, . . . , t; and
in step S7, when the centroid C2=(xC2, yC2), then:
x
C
⁢
2
=
1
t
⁢
∑
1
t
⁢
x
i
;
y
C
⁢
2
=
1
t
⁢
∑
1
t
⁢
y
i
.

### Claim 7 (depends on 1)

The data processing method according to claim 1, wherein in step S1, a time interval between adjacent RSSI data collections for each of the anchor nodes is 10 seconds or more.

### Claim 8 (depends on 1)

The data processing method according to claim 1, wherein the anchor nodes are wireless beacon nodes.