CN103442435A

CN103442435A - Method for expanding positioning coverage area in underwater sound 3D sensor network

Info

Publication number: CN103442435A
Application number: CN2013103684516A
Authority: CN
Inventors: 金志刚; 姚贵丹; 张俊亮
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2013-08-21
Filing date: 2013-08-21
Publication date: 2013-12-11
Anticipated expiration: 2033-08-21
Also published as: CN103442435B

Abstract

The invention belongs to the technical field of underwater sound sensor network communication, and relates to a method for expanding a positioning coverage area in an underwater sound 3D sensor network. The method includes the steps that four anchor nodes are selected and send signals to cooperation points and unknown nodes respectively at the same time; after the cooperation points receive the signals from the anchor nodes, the signal are decoded and then recoded and sent to the unknown nodes; when the unknown nodes receive the signal from the anchor nodes, the time when the signal reach to is recoded; the signals from the anchor nodes and the signals of the cooperation points corresponding to the anchor nodes are combined to obtain information sent by the anchor nodes; ID numbers of the anchor nodes, the time when the signals are sent and positions of the anchor nodes are obtained; the distances from the anchor nodes to the unknown nodes are obtained; the distances from the four anchor nodes to the unknown nodes and corresponding coordinates of the anchor nodes are obtained to carry out positioning. According to the method, multipath fading underwater sound channel characteristics and limited node power are sufficiently considered, and the node positioning coverage area can be expanded.

Description

A kind of method that improves the location coverage in underwater sound 3D sensor network

Technical field

The present invention relates to the water sound sensor network communication technical field, is a kind of method that can improve the location coverage under the 3D tactic pattern concretely.

Background technology

Water sound sensor network (UASNs, Underwater Acoustic Sensor Networks) be to take the underwater sound as communication media, take marine monitoring as purpose, and the wireless sensor network be comprised of various underwater sensor nodes, be a kind of necessary means of marine monitoring.Node in network utilizes the various monitoring informations in transducer Real-Time Monitoring, collection network distributed areas, after the information processings such as data fusion, by the node under water with long-distance transmissions ability, Real-Time Monitoring information is delivered to water surface base station, then by offshore base station or satellite, real time information is passed to the user.But, in overwhelming majority's application of water sound sensor network, to only have when the sensor node location aware, the information of acquisition just has meaning.Therefore, the research of water sound sensor network node locating technique is emphasis and the focus of water sound sensor network technical research.

Different from atmospheric environment, underwater environment is extremely complicated and changeable, has brought very large challenge to the development of water sound sensor network.The underwater acoustic channel propagation delay is long; Bandwidth-Constrained; The channel characteristics such as concussion with multipath fading, motion Doppler drift and phase place and amplitude.

The fading characteristic of wireless channel is to hinder the one of the main reasons that channel capacity increases and serve quality improvement.Diversity technique is exactly for to anti-fading, improves transmission performance and an important technology growing up.Its basic ideas are: if the signal in radio propagation path has experienced the deep fading, may comprise stronger signal in another relatively independent path so.If select two or more signals in multipath signal, be expected to guarantee to have at least an intensity enough large signal copy can offer receiver.If they are got up by certain compatible rule merging, can obtain diversity gain.MIMO(multiple-input multiple-output) technology is a kind of of space diversity reception to communicate.It forms the mimo channel structure, thereby takes full advantage of the spatial domain resource by receiving terminal and transmitting terminal, settle a plurality of antennas simultaneously, has increased substantially channel capacity.But the application of MIMO technology has been subject to obstruction.

In water sound sensor network, node each several part integrated level is very high, and the volume less limited the capacity of battery, and underwater environment complicated and changeable makes and can't change continually power supply for it.Yet the MIMO Technology Need is equipped with a plurality of antennas at transmitting terminal and receiving terminal, this is little for volume, the water sound sensor network node of energy constraint is unpractiaca.

Summary of the invention

The objective of the invention is, overcome the above-mentioned deficiency of prior art, the consideration of sensor node power limited from water sound sensor network, propose a kind of method that can improve the location coverage.Technical scheme of the present invention is as follows:

A kind of method that improves the location coverage in underwater sound 3D sensor network, adopt anchor node that 4 coordinates the are known node to a coordinate the unknown, and unknown node positions, and step is as follows:

1) 4 anchor nodes are chosen neighbors separately as via node separately, i.e. cooperation point;

2) each anchor node is simultaneously to oneself cooperation point and unknown node transmitted signal, the time of No. ID of comprising anchor node self of signal, positional information and transmission, the front two of this signal is marked as to 00;

3) after cooperation point receives the signal from anchor node, signal is decoded, then change mark 00 into 11, other content is constant, and after recompile, cooperation point sends to unknown node by signal;

When 4) unknown node is received the signal of 00 mark, the time that under immediate record, signal arrives;

5) unknown node will be merged from the signal of anchor node and its corresponding cooperation point, before merging, removes 00 or 11 mark; During merging, two signals are simply superposeed, the signal be combined is decoded, and obtains the information that anchor node is sent: No. ID of anchor node, the time that signal sends and the position of anchor node;

6) with 4) in time of arriving of the signal that obtains deduct 5) in time of sending of the signal that obtains, obtain signal time used from the anchor node to the unknown node, be multiplied by the velocity of sound with this time, just can obtain the distance that anchor node arrives unknown node;

7), by top process, can obtain four anchor nodes to the distance of unknown node and the coordinate of corresponding anchor node, and then position.

The method that the present invention proposes, taken into full account underwater acoustic channel characteristics and the limited problem of node power of multipath fading, when positioning distance measuring, utilizes the thought of virtual MIMO, adds cooperation point, forms trunk channel and transmit locating information.In water sound sensor network, the method can improve the node locating coverage.

The accompanying drawing explanation

Fig. 1 is water sound sensor network schematic diagram of the present invention.

Fig. 2 is network model of the present invention.

Fig. 3 is trunk channel mode of the present invention.

Embodiment

The present invention, by add cooperation point in location, forms virtual MIMO, to improve the localization method of location coverage.In the method, suppose that node is all static, temporal evolution not, the velocity of sound is not with the degree of depth, and the variations such as ocean temperature, salinity, do not consider time synchronization problem.At least have four anchor node location awares, and every three anchor nodes are on the same straight line, every four anchor nodes are not at grade.If wherein the anchor node of four location awares is A, B, C, D, the node of another one coordinate the unknown is S.Choose respectively anchor node A, B, C, the neighbors of D, as cooperation point separately, in order to narrate conveniently, be take A here as example, chooses a cooperation point R _a.This cooperation point and A form two transmit ports, have formed the virtual MIMO array together with receiving port S, form the trunk channel model.A is to R _a, S sends and to comprise self ID, the signal of transmitting time and positional information.A is to R _a, the S transmitted signal.R _asignal from A is decoded, and recompile, change and be labeled as the cooperation point mark, then sends to unknown node S.S records time of reception while receiving the signal of A, what then will receive is merged from the signal of A and RA respectively, extracts wherein information.With the location algorithm of these information and Range-based, position.The concrete performing step of the present invention is:

Step 1: anchor node A, B, C, D chooses respectively neighbors R separately _a, R _b, R _c, R _das via node separately, i.e. cooperation point.A is to R _asend with S the signal t that comprises self ID, positional information and transmitting time _at, the signal front two is labeled as 00, means that this signal is that anchor node by the location aware that participates in location sends.

Step 2: work as R _aafter receiving the signal from A, signal is decoded, changed marking signal into 11, as the cooperation point mark, shown that this message is that cooperative node sends.Then signal is sent to unknown node S.The nonlinear transformation that the decoding now adopted and recoding processing receive signal often.

Step 3: unknown node S receives A and cooperation point R _athe signal of sending.Unknown node S records the time of arrival (toa) t of mark 00 _ar.By receive from A and R _asignal merged, extract wherein information, A No. ID, positional information and t _at.Remove marking signal before merging, because the disposal ability of individual node is limited, merge and adopt equal gain combining.Equal gain combining is very simple, and it carries out direct addition by each decentralized signal with identical branch gain, need not be to signal weighting respectively, and the signal after addition is as receiving signal.Can obtain thus time difference Δ t _a=t _ar-t _at.

Step 4: B, C, D repeating step one is to the step of step 3.Unknown node obtains B, C, No. ID of D, positional information and time difference Δ t _b, Δ t _c, Δ t _d.According to r=v * t, be not multiplied by velocity of sound 1500m/s by the time difference, obtain the distance of each anchor node to S.

Step 5: process with Maximum Likelihood Estimation Method, the equidistant relevant location algorithm of four limit mensurations the data that obtain, comprise the distance of anchor node to S, the coordinate position of each anchor node, position.Position again correction after location estimation.

Below in conjunction with drawings and Examples, the present invention will be described.

In Fig. 1, showed that one by the mobile anchor node based on naval vessel, water surface float anchor node (Buoy), from sedimentation buoy (DNR, Dive'N'Rise), groove node, Intelligent Underwater Robot (AUV, Autonomous Underwater Vehicle), floating sensor node and the fixation of sensor node forms under water water sound sensor network.To be exactly the anchor node that utilizes location aware position the position of unknown node location technology in water sound sensor network.

In Fig. 2, provided the network model adopted in the present invention.Suppose that node is all static, temporal evolution not, the velocity of sound is not with the degree of depth, and the variations such as ocean temperature, salinity, do not consider time synchronization problem.At least have four anchor node location awares, and every three anchor nodes are on the same straight line, every four anchor nodes are not at grade.If wherein the anchor node of four location awares is A, B, C, D, the node of another one coordinate the unknown is S.

In Fig. 3, A is the anchor node of location aware, R _abe the neighbors of A, be selected as the cooperative node of A, S is unknown node.Source node A, via node R _athe network formed with destination node S has formed the relay transmission channel.All nodes all are operated in same frequency, and from the angle of source node, system is equivalent to a broadcast channel; From the angle of destination node, system is equivalent to a multiple access access channel.Source node to the communication of destination node in two steps.At first, source node A arrives destination node S and via node R by communication _a; Second step, via node R _athe information that will receive from A is sent to destination node S, finally at node S, signal is merged to processing.Utilize this collaboration mode, can effectively obtain diversity gain, thereby improve the communication performance between source node and destination node, for location, can enlarge orientation range.

Claims

1. a kind of method that improves the location coverage in underwater sound 3D sensor network, adopt anchor node that 4 coordinates the are known node to a coordinate the unknown, and unknown node positions, and step is as follows: