CN103095382B - Node layout method for improving fairness in underwater sound three-dimensional (3D) sensor network - Google Patents

Abstract

The invention belongs to the technical field of sensor network communication, and relates to a layout method for nodes in an underwater sound 3D sensor network. A receiving node is set to be underwater where the depth of water is D, and a reference node is underwater where the depth of water is the same. According to the relationship between underwater sound speed and water depth, the time delay required when a data packet transmitted from the reference node reaches the receiving node is obtained through calculation. According to the same time delay required when the data packet reaches the receiving node, the trajectory of a transmitting node is obtained. During node layout, reference needs to be given to the trajectory. Relative to the reference node, the proper positions of other transmitting nodes are outside the upper half ellipsoid and within the lower half ellipsoid. According to the node layout method, full consideration is given to the changes of wave velocity along with depth, and possible unfairness in transmission can be avoided because consideration is given to node positions during node layout. In an underwater sound sensor network with a 3D structure, fairness in transmission can be improved by using the method.

Description

In a kind of underwater sound 3D sensor network, improve the node method for arranging of fairness

Technical field

The present invention relates to underwater sound sensor network communication technical field, is a kind of node method for arranging that relatively transmits fairness under 3D tactic pattern in order to improve node concretely.

Background technology

Underwater sound sensor network is that sensor technology, radio network technique combine with subsurface communication technology and the recent studies on field that produces.Channel is a kind of and the distinct transmission medium of atmospheric environment under water, is one of the most complicated transmission environment that researcher faces so far.Land radio communication generally adopts frequency electromagnetic waves as the carrier wave of communication, but under water in environment, electromagnetic transmission decay is very large, cannot realize telecommunication, so electromagnetic wave is not suitable as the carrier wave of subsurface communication.Comparatively speaking, sound wave is propagated in the mode of compressional wave under water, and the rate of decay is much slower than electromagnetic wave, is the comparatively desirable carrier wave of subsurface communication.So underwater sound sensor network is to using the cordless communication network of sound wave as carrier wave.

The development of underwater sound sensor network faces a lot of challenges, is mainly that Underwater Acoustic Environment factor causes, as long and serious and complex environment causes the variation etc. of the velocity of sound with propagation delay, Bandwidth-Constrained, the Multipath Transmission of change in time and space.

Node cloth at underwater sound sensing network is set up, and in order to improve coverage of communication, we select 3D node arrangement mode, in the different degree of depth, arranges node Information Monitoring and transmits.Such layout just must be considered a problem, that be exactly in underwater environment acoustic velocity be not a definite value, it is affected by temperature, pressure etc., with change in depth changes, this point needs to consider when we design underwater sound sensor network.

In aqueous medium, longer propagation delay and the velocity of sound make us must consider the position of receiving node and potential competition node with the characteristic of depth of water gradual change, and under 3D node arrangement mode, the position relationship between competition node and receiving node is complicated various especially.In addition, in underwater sound sensor network, also there is the uncertain problem of space-time, the uncertainty that it refers to time of reception depends on the transmission time (time is uncertain) and from sending to the relative propagation delay (uncertainty in space) of reception, this is just for hidden danger has been buried in the fairness transmission of underwater sensing network.

The problem of so-called fairness transmission, refer to that node or data flow exist unjust phenomenon when access channel, be no longer that data under fair state " are first sent out first and received ", " after rear sending out, receiving ", may there is a lot of node datas " first send out rear receipts ", " rear sending out first received ", when situation is serious, even may occur that individual node or data flow are monopolized channel width resource and other nodes or the data flow state in " hunger " completely.We want the fairness realizing to refer to that each node of shared medium utilizes the ability of resource equably.

Fairness is a very important factor in the performance measurement of radio communication, and it often means the mean allocation of Internet resources.In underwater sound medium, the node close to receiving node often more easily accesses channel, and apart from far away likely the catching less than channel of receiving node always.But simultaneously due to the variation of acoustic velocity with the depth of water, also likely there will be from the node close to receiving node " first send out rear receipts ", and from the phenomenon of the node away from receiving node " rear sending out first received ", this is a kind of special and serious unjust phenomenon, so we need to detect also and then carry out according to this more reasonably to arrange node the fairness of underwater sound sensing network, to realize higher transmission fairness.

Summary of the invention

The object of the invention is, a kind of node method for arranging that can improve underwater sound 3D sensor network transmission fairness is provided.Technical scheme of the present invention is as follows:

A node method for arranging that improves fairness in underwater sound 3D sensor network, comprises the following steps:

Step 1: establish by receiving node be arranged in the depth of water be 500 meters near under water, reference node in identical with its depth of water under water, take receiving node as the center of circle, the distance of take between reference node and receiving node makes ball as radius, on ball, each sending node is to the same distance of receiving node, but the required time delay of transfer of data is different;

Step 2: according to the functional relation of underwater sound speed C and depth of water D

$C=\left\{\begin{array}{c}1449.2+{4.6}^{*}(25-\frac{D}{15})-{0.055}^{*}{(25-\frac{D}{15})}^2+{0.00029}^{*}{(25-\frac{D}{15})}^3+(1.09+\frac{D}{1500})(\frac{D}{250}-2)-0.017D,0<D\&le;150\\ 1449.2+{4.6}^{*}(\frac{162}{7}-\frac{6D}{175}){-0.055}^{*}{(\frac{162}{7}-\frac{6D}{175})}^2+{0.00029}^{*}{(\frac{162}{7}-\frac{6D}{175})}^3+(\frac{194}{175}+\frac{6D}{17500})(\frac{D}{250}-2)-0.017D,150<D\&le;500\\ 1449.2+{4.6}^{*}(8-\frac{D}{250})-{0.055}^{*}{(8-\frac{D}{250})}^2+{0.00029}^{*}{(8-\frac{D}{250})}^3+(1.26+\frac{D}{25000})(\frac{D}{250}-2)-0.017D,500<D\&le;1000\\ 1469.33856-0.017D,1000<D\end{array}\right.$

Calculate the packet sending from reference node and arrive the required time delay of receiving node, according to packet, arrive the required time delay of receiving node identical, find a series of sending nodes, obtain the track of sending node, it is identical with the required time delay of reference node packet arrival receiving node that the packet of these nodes arrives the required time delay of receiving node;

Step 3: need be with reference to this track when node is arranged, with respect to reference node, the position of other sending nodes is suitable to be taken at outside semielliptical and within lower semielliptical, to guarantee the fairness of transmission relatively.

As preferred implementation, the acquisition methods of sending node track is as follows: according to acoustic velocity, with the depth of water, increase the relation reducing, set up Mathematical Modeling, consider that the equal node of the packet arrival required time delay of receiving node is positioned at upside of ellipse and two approximate half elliptic tracks of lower semiellipse rotate a circle on upper and lower two half ellipsoidal surfaces that form, set the receiving node degree of depth, the distance l of sending node degree of depth available range receiving node represents, obtain underwater sound speed about the formula C=f (l) of relative distance, then according to time delay and utilize interpolation type quadrature formula Simpson formula to solve, obtain major axis and the lower semielliptical minor axis of upside of ellipse, and then draw the hemielliptic formula that transmits data to the two-dimensional projection that reaches the identical sending node track of the required time delay of receiving node.

The present invention, by setting up model, can calculate the arrangement that can improve node fairness.So just can carry out subregion judgement and detection to the transmission fairness of underwater sound sensor network, for the layout of node provides reference.

Accompanying drawing explanation

Fig. 1 is that acoustic velocity of the present invention is with depth of water change curve;

Fig. 2 is circle of reference of the present invention (with reference to the two-dimensional projection of sphere);

Fig. 3 is upper and lower two the approximate half elliptic tracks of the present invention.

Embodiment

To enforcement of the present invention, provide detailed reference now.For explaining that the present invention will be described with reference to the drawings following embodiment.

The present invention is based on the consideration that acoustic velocity changes with the depth of water, proposed a kind of node method for arranging that improves node transmission fairness.In the method, suppose that node all fixes, temporal evolution not, and seawater is vertical demixing, the propagation velocity of sound in seawater do not change with horizontal direction, is only the function of the degree of depth.Select one and receiving node with the sending node of the degree of depth as with reference to node, the distance of receiving node and selected reference node of take is made ball as radius, the same distance of node and receiving node on sphere, but the data that send arrive the required time delay difference of receiving node.By acoustic velocity with the variation empirical equation of the depth of water and the temperature of seawater, salinity common model, derivation draws two approximate half elliptic tracks---upside of ellipse and lower semiellipse, two semiellipses are rotated and obtain two semiellipticals, node and the distance between receiving node on half ellipsoidal surface are not equal to the distance between reference node and receiving node, but the required time delay of the data that send arrival receiving node is identical with the required time delay of reference node data arrival receiving node.Node outside node within upper ellipsoid and lower ellipsoid is compared the phenomenon that all can occur unfair transmission with reference node, wherein, upper ellipsoid and with reference between sphere, lower ellipsoid and with reference to the node between the shadow region between sphere, compare with reference node, there will be especially special and serious unjust phenomenon.So just can carry out subregion judgement and detection to the transmission fairness of underwater sound sensor network, for the layout of node provides reference.The concrete performing step of the present invention is:

Step 1: a selected depth of water scope is at the receiving node of 500 meters of left and right, near this receiving node, the selected a certain sending node in the same depth of water is as with reference to node, take receiving node as the center of circle, approximately 300 meters of the distances of take between reference node and receiving node make ball as radius, each sending node on sphere is compared with reference node, distance to receiving node equates, but because acoustic velocity increases and reduces with the depth of water, so the required time delay of the packet sending arrival receiving node is unequal.Step 2: according to experiential sound speed formula in national standard hydrographic survey

C＝1449.2+4.6T-0.055T ²+0.00029T ³+(1.34-0.01T)(S-35)-0.017D

(note: C is the velocity of sound (m/s), and T is temperature (° C), and S is salinity (1 ‰), and D is the degree of depth (m)) and ocean temperature, salinity, with the variation model of the depth of water, are derived and are drawn the functional relation of acoustic velocity and the depth of water:

$C=\left\{\begin{array}{c}1449.2+{4.6}^{*}(25-\frac{D}{15})-{0.055}^{*}{(25-\frac{D}{15})}^2+{0.00029}^{*}{(25-\frac{D}{15})}^3+(1.09+\frac{D}{1500})(\frac{D}{250}-2)-0.017D,0<D\&le;150\\ 1449.2+{4.6}^{*}(\frac{162}{7}-\frac{6D}{175}){-0.055}^{*}{(\frac{162}{7}-\frac{6D}{175})}^2+{0.00029}^{*}{(\frac{162}{7}-\frac{6D}{175})}^3+(\frac{194}{175}+\frac{6D}{17500})(\frac{D}{250}-2)-0.017D,150<D\&le;500\\ 1449.2+{4.6}^{*}(8-\frac{D}{250})-{0.055}^{*}{(8-\frac{D}{250})}^2+{0.00029}^{*}{(8-\frac{D}{250})}^3+(1.26+\frac{D}{25000})(\frac{D}{250}-2)-0.017D,500<D\&le;1000\\ 1469.33856-0.017D,1000<D\end{array}\right.$

Calculate the packet sending from reference node and arrive the required time delay of receiving node, according to packet, arrive the required time delay of receiving node identical, can obtain the track of a series of sending nodes, method is as follows: according to acoustic velocity, with the depth of water, increase the relation reducing, set up Mathematical Modeling, the equal node of time delay that consider to receive packet is positioned at upper that upside of ellipse and two approximate half elliptic tracks of lower semiellipse rotate a circle and form, on lower two half ellipsoidal surfaces, set the receiving node degree of depth, the distance of sending node degree of depth available range receiving node represents, obtain underwater sound speed about the formula C=f (l) of relative distance, then pass through and utilize interpolation type quadrature formula Simpson formula to solve, can obtain major axis and the lower semielliptical minor axis of upside of ellipse, and then draw the hemielliptic formula that transmits data to the two-dimensional projection that reaches the identical sending node track of the required time delay of receiving node.

Step 3: the fairness of carrying out decision node transmission according near the position of sending node receiving node.It is cautious as detecting to using other sending nodes, contrasts with reference node, according to the position of detection node, it is carried out to subregion detection:

1) at upper half ellipsoidal surface with between with reference to sphere, may there is a kind of special serious unjust phenomenon in detection node, to the sending node data of receiving node distance, " sends out and arrive first afterwards ".

2) detection node is positioned at reference to sphere and above receiving node, may occur a kind of common unjust phenomenon, to the sending node data of receiving node near distance, " sends out and arrives first afterwards ".

3) at lower half ellipsoidal surface with between with reference to sphere, may there is a kind of special serious unjust phenomenon in detection node, to the sending node data of receiving node near distance, " first sends out afterwards and arrive ".

4) detection node is positioned at reference to outside sphere and below receiving node, may occur a kind of common unjust phenomenon, to the sending node data of receiving node distance, " first sends out afterwards and arrives ".

Step 4: need consider this track when node is arranged, with respect to reference node, the position of other sending nodes is suitable to be taken at outside half ellipsoidal surface and within lower half ellipsoidal surface, can improve so to a certain extent the fairness of relative transmission.

The underwater sound sensor network 3D node placement model that the present invention sets up, in 3D UWASN, by regulating the degree of depth of underwater sensor, monitor or monitor oceanographic phenomena etc., its node is anchored at seabed by anchor chain, by adjusting the degree of anchor chain, forms the three-dimensional network that is distributed in seabed.

In Fig. 1, the velocity of sound in seawater is controlled by temperature and seawater pressure substantially: temperature is lower, and the velocity of sound is slower; Seawater pressure is larger, and the velocity of sound is faster.Seawater water temperature shines upon and causes, so temperature increases and to reduce with the degree of depth, but just no longer changes to temperature after certain depth, forms deep-sea isothermal layer.And seawater pressure is only relevant with the degree of depth, the degree of depth is larger, and seawater pressure is larger.Therefore, from sea, observe downwards, the velocity of sound reduced and slack-off with degree of depth increase, temperature before this, and when dropping to a minimum, ocean temperature no longer changes, and at this moment, the velocity of sound will increase and accelerate with seawater pressure.In the present invention, suppose that seawater is vertical demixing, the propagation velocity of sound in seawater do not change with horizontal direction, is only the function of the degree of depth.In this example, the node degree of depth is arranged near the 500m depth of water, and nodal pitch is about 300m, and density of sea water is 1.025g/cm3.

In Fig. 2, O point is receiving node, A point is with reference to sending node, radius R is the distance between receiving node and reference node, be about 300m, sending node and reference node are positioned at depth of water 500m place, and now acoustic velocity is about 1466.38264m/s, and the transfer of data that reference node sends is about 0.204585s to the required time delay of receiving node.

In Fig. 3, Node B, C and A coexist with reference on sphere, distance to receiving node O equates, if the data packet transmission speed that sending node B and node C send is respectively,, the data packet transmission speed that reference node sends is, the time delay that the packet that node A, B, C send arrives receiving node is respectively,,, because acoustic velocity increases and reduces with the depth of water, therefore, be variable but certain value, and have, the packet being sent by node A, B, C arrives the required propagation delay of receiving node and meets.

Sending node D, E (for convenience of calculating, get ellipsoid fixed point place node example) respectively on upper half ellipsoidal surface and lower half ellipsoidal surface, establish the data packet transmission speed that D, E send be respectively,, arrive the required time delay of receiving node be respectively,, have, and have

。Circular is as follows:

Suppose that seawater water surface temperature is 25 degree, deep-sea isothermal layer temperature is 4 degree, and temperature with change in depth model is:

$T=\left\{\begin{array}{c}25-\frac{D}{15},0<D\&le;150\\ 18-\frac{6^{*}(D-150)}{175},150<D\&le;500\\ 8-\frac{D}{250},500<D\&le;1000\\ \mathrm{4,1000}<D\end{array}\right.$

Suppose that seawater surface salinity is that 3.3%, 1000 meter of deep-sea salinity is 3.7%, adopts linear salinity variation model:

$S=\left\{\begin{array}{c}33+\frac{D}{250},D<1000\\ 37,D>1000\end{array}\right.$

The known receiving node degree of depth is 500 meters, establishes the distance that sending node D, E order apart from O and is respectively l _oD, l _oE, the degree of depth of sending node D, E is respectively 500+l _oD, 500-l _oE, above formula is brought in velocity of sound formula, can obtain the velocity of sound and with sending node, arrive the functional relation of the change of distance of receiving node:

C _D＝-1.856*10 ^-11*l _OD ³+1.12352*10 ^-6*l _OD ²-0.02776528l _OD+1466.38264

C _E＝1.168793*10 ^-8*l _OE ³+7.216059*10 ^-6l _OE ²+0.1480395457l _OE+1466.38264

Known reference node sends packet to the required time delay of receiving node

τ _A＝300/C _A,C _A＝C _O＝C ₅₀₀≈1466.38264m/s

Known

τ _E＝τ _D＝τ _A≈0.204585s

According to integral formula

$\mathrm{\&tau;}={\&Integral;}_{l_1}^{l_2}\frac{1}{C}\mathrm{dl}={\&Integral;}_{l_1}^{l_2}\frac{1}{f\left(l\right)}\mathrm{dl}$

Utilize interpolation type quadrature formula Simpson formula

${\&Integral;}_a^{b}f\left(x\right)\mathrm{dx}\&ap;\frac{b-a}{6}[f\left(a\right)+4f\left(\frac{a+b}{2}\right)+f\left(b\right)]$

Solving this formula can solve:

l _OD＝299.218m,l _OE＝305.215m

Wherein, 2l _oDthe minor axis of lower ellipse, 2l _oEmajor axis for upper ellipse.

Take receiving node as the origin of coordinates, and level, vertical direction are respectively x, y axle, can obtain approximate upper and lower hemielliptic formula to be according to ellipse formula

$\frac{y^2}{{305.215}^2}+\frac{x^2}{{300}^2}=1,y>0$

$\frac{x^2}{{300}^2}+\frac{y^2}{{299.218}^2}=1,y<0$

In order conveniently to check, in schematic diagram, adopt the two-dimensional projection of three-dimensional sphere and two half ellipsoidal surfaces.For any sending node M between upside of ellipse and circle of reference, the data packet transmission speed v that node M sends _mmeet v _m> v _a, the transmission delay τ of arrival receiving node _mmeet τ _m< τ _a, and node M is to the distance d between receiving node O _mObe greater than reference node to the distance d between receiving node _aO, now just likely occur that a kind of special unjust phenomenon---the packet that the node of distance sends " is sent out and arrived first afterwards ".

For the node within upper semi-circle, to compare with reference node, its distance to receiving node is shorter, and message transmission rate is larger, and it is shorter that packet arrives the time delay of receiving node, likely there will be the unjust phenomenon of " rear sending out first received ".

For any sending node N between lower semiellipse and circle of reference, the data packet transmission speed v that node N sends _nmeet v _n< v _a, the transmission delay τ of arrival receiving node _nmeet τ _n> τ _a, and node N is to the distance d between receiving node O _nObe less than reference node to the distance d between receiving node _aO, now just likely occur that a kind of special unjust phenomenon---the packet that the node of near distance sends " is first sent out afterwards and arrived ".

For the node outside lower half circle, to compare with reference node, its distance to receiving node is longer, and message transmission rate is less, and the time delay of packet arrival receiving node is longer, likely there will be the unjust phenomenon of " first send out afterwards and arrive ".

, with respect to the reference node apart from 300 meters of receiving nodes, if think, guarantee fairness as far as possible, sending node should be arranged in outside upper ellipse and within lower ellipse, even if the position coordinates of sending node meets or make to compare with reference node, transfer of data guarantees " first send out and arrive first ", " after rear sending out, arriving " as far as possible, realizes fairness transmission.

Claims (1)

1. in underwater sound 3D sensor network, improve a node method for arranging for fairness, comprise the following steps:

Step 1: establish by receiving node be arranged in the depth of water be 500 meters near under water, reference node in identical with its depth of water under water, take receiving node as the center of circle, the distance of take between reference node and receiving node makes ball as radius, on ball, each sending node is to the same distance of receiving node, but the required time delay of transfer of data is different;

Step 2: according to the functional relation of underwater sound speed C and depth of water D

$C=\left\{\begin{array}{c}1449.2+4.6*(25-\frac{D}{15})-0.055*{(25-\frac{D}{15})}^2+0.00029*{(25-\frac{D}{15})}^3+(1.09+\frac{D}{1500})(\frac{D}{250}-2)-0.017D,0<D\&le;150\\ 1449.2+4.6*(\frac{162}{7}-\frac{6D}{175})-0.055*{(\frac{162}{7}-\frac{6D}{175})}^2+0.00029*{(\frac{162}{7}-\frac{6D}{175})}^3+(\frac{194}{175}+\frac{6D}{17500})(\frac{D}{250}-2)-0.017D,150<D\&le;500\\ 1449.2+4.6*(8-\frac{D}{250})-0.055*{(8-\frac{D}{250})}^2+0.00029*{(8-\frac{D}{250})}^3+(1.26+\frac{D}{25000})(\frac{D}{250}-2)-0.017D,500<D\&le;1000\\ 1469.33856-0.017D,1000<D\end{array}\right.$

Calculate the packet sending from reference node and arrive the required time delay of receiving node, according to packet, arrive the required time delay of receiving node identical, find a series of sending nodes, obtain the track of sending node, it is identical with the required time delay of reference node packet arrival receiving node that the packet of these nodes arrives the required time delay of receiving node;

Step 3: need be with reference to this track when node is arranged, with respect to reference node, the position of other sending nodes is suitable to be taken at outside semielliptical and within lower semielliptical, to guarantee the fairness of transmission relatively, wherein, the acquisition methods of sending node track is as follows: according to acoustic velocity, with the depth of water, increase the relation reducing, set up Mathematical Modeling, consider that packet arrives the equal node of the required time delay of receiving node and is positioned at upper that upside of ellipse and two approximate half elliptic tracks of lower semiellipse rotate a circle and form, on lower two half ellipsoidal surfaces, set the receiving node degree of depth, the distance l of sending node degree of depth available range receiving node represents, obtain underwater sound speed about the formula C=f (l) of relative distance, then according to time delay and utilize interpolation type quadrature formula Simpson formula to solve, obtain major axis and the lower semielliptical minor axis of upside of ellipse, and then draw the hemielliptic formula that transmits data to the two-dimensional projection that reaches the identical sending node track of the required time delay of receiving node.