CN102638820B - Ad Hoc network link stability prediction method - Google Patents

Abstract

Do you the invention discloses a kind of Ad? Hoc network link stability prediction method.The steps include: the first step, the direct stability assessment of link; Second step, link indirect stabilization is assessed; 3rd step, link comprehensive stability is assessed; 4th step, based on the multicast routing protocol of stability.The multicast routing protocol solved using existing link stability as route standard can not adapt to the problem of the unstable environment such as high mobility, high interference well.The present invention calculates simply, and assessment link stability process operand is low, and the overall performance of network is stable, strong adaptability, and not high to hardware requirement, energy consumption is little.<pb pnum="1" />

Description

Ad Hoc network link stability prediction method

Technical field

The invention belongs to Ad Hoc network (MANET) field, be specifically related to the AdHoc link in network stability prediction method to link stability.

Background technology

Ad Hoc network is a kind of wireless network of dynamic reconfigurable, and each node serves as main frame and router simultaneously.As main frame, node needs the application running himself; As router, node is responsible for forwarding data according to ad hoc routing protocol.AdHoc network is widely used in the occasions such as disaster assistance (as earthquake, fire) and distributed collaboration computing.

In actual applications, because a node often needs to send identical data to multiple node, therefore multicast routing protocol is arisen at the historic moment.But have the features such as the random movement of such as node, limited resource, insecure channel due to mobile ad hoc network, traditional multicast protocol can not be adapted to MSNET network environment well.

The random movement of node causes the dynamic change of network topology structure, adds the frequency of rerouting, and then have impact on network performance.Therefore, need a kind of appraisal procedure to link stability, and as evaluation index, when route selection, avoid unstable link, this greatly can improve the overall performance of network undoubtedly.

Also few to the research of link stability in adhoc field at present, major part research hypothetical network environment is constant, only the mobility of node is studied, predict the mobile behavior etc. of node subsequent time as quantized, utilizing statistical method to the position of node and velocity vector by GPS to node motion behavior modeling.But, in actual applications, be not that each node has GPS module, and GPS module has very large error in indoor environment, and statistical method carry out modeling based on probability theory to node, has certain limitation and accuracy to remain to be discussed.In addition, in existing research, without exception, all the angles standing in detection node, link between detection node and tested node is assessed, the angle not standing in tested node carries out stability assessment to the chain environment residing for it, and therefore existing link stability Forecasting Methodology has significant limitation, and effect is unsatisfactory.Accordingly, the unstable environment such as high mobility, high interference can not be adapted to well using link stability as the multicast routing protocol of route standard, therefore, more reasonably link stability appraisal procedure and corresponding multicast routing protocol solve above problem to need one.

Summary of the invention

The object of this invention is to provide a kind of AdHoc link in network stability prediction method, to solve the problem of the frequent open circuit of the link caused because of node motion in adhoc network, route instability, improve network performance (as increase bag delivery ratio, reduce end-to-end time delay etc.) to adapt to high mobility environment.

For this reason, the technical solution used in the present invention is:

A kind of AdHoc link in network stability prediction method, it is by sampling the signal strength signal intensity received continuously, with the true environment of Approximation Network realistically, for detection node and tested node, assess the stability of each bar link of environment residing for it respectively, consider detection node and tested node pair, calculate comprehensive stability value, and in this, as the routing standard of stability multicast routing protocol, concrete steps are:

The first step, to the direct stability assessment of link

Node maintains neighborhood by timed sending hello message, and when detection node receives the hello message of its neighbor node transmission, detection node maintains a received signal strength and received power list for each neighbor node and tested node;

Second step, link indirect stabilization is assessed

Tested node adopts the method stability to its neighbor node same with the first step to assess; Because this stability is intended to assess environment residing for tested node, after therefore rejecting the extra high node of mobility, get average to other node stabilitys, average is lower, then the environment residing for tested node is more stable, otherwise environment is more unstable;

3rd step, link comprehensive stability is assessed, and adopts the method COMPREHENSIVE CALCULATING of weighted sum by the direct of link and indirect stabilization assessed value;

4th step, based on the multicast routing protocol of stability, based on the multicast routing protocol of stability using stability as routing standard.

The direct stability assessment value of described first step link:

According to Friis free space propagation model, received power P _rXwith the ratio P of transmitted power _tXwith square being inversely proportional to of transmission range R, namely $\frac{P_{\mathrm{RX}}}{P_{\mathrm{TX}}}\&Proportional;\frac{1}{R^2}$ Or $R\&Proportional;\sqrt{\frac{P_{\mathrm{TX}}}{P_{\mathrm{RX}}}};$

Assuming that the lower limit of received power is P _min, namely when received power is lower than this value, can produce the higher error rate, cause the re-transmission of packet, correspondingly, transmission range is now R _max; The P of all nodes _minbe initialized as a fixed value, when certain neighbor node shifts out its communication range, think that the received power be carved into upper a period of time when merit receives is approximately equal to P now _min, that therefore uses a moment accepts the P that power upgrades this node _min;

Assuming that the n-th sub-sampling value of detection node i to tested node j received power is P _n ^ij, then according to Friis free space propagation model, have again due to wherein P _tXfor the transmitted power of node, R _n ^ijdistance when being n-th power sampling between sending node and receiving node, P _min ⁱfor the minimal detectable power of detection node i, R _maxfor received power is P _min ⁱtime corresponding maximum transmission distance, therefore, have

If node keeps relative distance change slowly, then think that link stability is therebetween good, therefore the direct stability assessment value of variance as link between detection node i and tested node j is got to above formula, that is:

${d\_S}_{\mathrm{ij}}=\sqrt{P_{\min }^i}\mathrm{var}\{\frac{1}{\sqrt{P_1^{\mathrm{ij}}}},\frac{1}{\sqrt{P_2^{\mathrm{ij}}}},...,\frac{1}{\sqrt{P_n^{\mathrm{ij}}}}\}$

Resulting in the computing formula of the direct stability assessment value of link, assessed value is less, and link stability is better.

Described second step link indirect stabilization assessed value:

Suppose that tested nodes X has n neighbours (Y ₁, Y ₂y _n), nodes X is to its neighbor node Y _kstability assessment value calculates identical with the first step, that is:

$S_X\left(Y_K\right)=\sqrt{P_{\min }^X}\mathrm{var}\{\frac{1}{\sqrt{P_1^{{\mathrm{XY}}_k}}},\frac{1}{\sqrt{P_2^{{\mathrm{XY}}_K}}},...,\frac{1}{\sqrt{P_n^{{\mathrm{XY}}_k}}}\}$

Because tested nodes X has n neighbours, and indirect link stability is the assessment to environment residing for tested nodes X, and therefore, X node needs the stability assessment value calculating its n neighbour, i.e. S _x(Y ₁), S _x(Y ₂) ... S _x(Y _n); In order to eliminate the impact of least stable node, this n stability being sorted and gets its minimum 0.5n value, being assumed to be S _x(Y _t1), S _x(Y _t2) ... S _x(Y _t0.5n), then the assessed value of average as environment residing for tested nodes X is got to this 0.5n value, i.e. the indirect stabilization assessed value of link:

in_S _X＝avg(S _X(Y _T1)，S _X(Y _T2)，…S _X(Y _T0.5n))

Resulting in the computing formula of link indirect stabilization assessed value, assessed value is less, and the network environment residing for tested node is more stable.

The comprehensive stability of link between detection node i and tested node j is assessed in described 3rd step:

S _ij＝w ₁*d_S _ij+w ₂*in_S _j(w ₁+w ₂＝1)

Tested node j not only serves as sender but also serve as recipient.

In described 4th step based on the multicast routing protocol of stability using stability as routing standard, when node produces route request information, in route request information, an additional specific territory is to characterize the stability assessment value in the path of process; The stability assessment value of one paths equal the stability assessment maximum of all links of process, namely the stability of a paths depends on one section of least stable link; When node receives routing reply message, the path that selection stability assessment value is minimum from all paths is activated.

Detailed process is:

A. group membership adds

Node adds multicast group to be needed through three phases: route request stage, routing reply stage and route activation stage work as a node and will add multicast group or have message to send to multicast group, but its be not group membership and also the route of not leading to multicast tree time, it sends a RREQ message; The destination address territory dest_addr of message is the address of multicast group, and source address source_addr is the address of this node oneself; RREQ message increase an extra Path_Stable territory with record node the stability assessment value in path of process;

After a node receives RREQ message, first check whether processed identical RREQ, if then abandon, otherwise calculate the comprehensive stability value of upper hop link according to link stability appraisal procedure set forth above; Then the stationary value calculated being compared in territory with Path_Stable in RREQ, is the higher value in the two by Path_Stable area update, then continues to forward this RREQ message;

If a node is multicast member or has the route of leading to multicast tree, after receiving RREQ, by this RREQ buffer memory a period of time, due to same RREQ message may be had in the meantime to arrive this node from different paths, the RREQ message that therefore this sensor selection problem Path_Stable territory is minimum sends routing reply message RREP;

When an intermediate node receives RREP message, creating a QoS routing table clause with this entry state of tense marker based on this RREP is un-activation and the non-set of Activated_Flag, upgrade its Path_Stable territory, the reverse path then continued along RREQ message establishing forwards RREP message simultaneously;

A node may receive multiple RREP message, but it only processes the less RREP message in Path_Stable territory that namely RREP sequence number is larger or more stable upgraded, and other RREP message abandons simply;

When namely RREP message arrival source node asks the node adding multicast group, source node buffer memory a period of time, what from the multiple RREP message received, selection Path_Stable territory was minimum carries out route activation and MACT message, that is: be activation and Activated_Flag set by the route entry status indication created in the routing reply stage, other unactivated route entrys are deleted by respective nodes due to time-out;

B. group membership leaves

When a group membership wishes to leave multicast tree, if it is the routing node of other nodes, do not take any measure.If it is a leaf node, then to its upper hop clean culture prune message Prune, the route entry corresponding by its this descendant node of upper hop knot removal, if cause upper hop node also to become leaf node after deleting, then continue to send prune message to its upper hop and perform cut operator;

C. link open circuit

When multicast tree occurs in open circuit, the branch that open circuit occurs can become invalid; Now, upstream node deletes invalid node from its route entry, and then downstream node is responsible for link repair; Downstream node sends RREQ and additional multicast group reconstruction message carries out open circuit reparation; Rebuild in message in multicast group and comprise multicast group jumping figure territory Group_Hop_Cnt to record the jumping figure of open circuit nodal distance root vertex, the node only having hop count to be not more than this counting could respond RREQ message, this avoid the generation of route loop; After receiving RREP message, it is described identical that route activation and group membership add part;

D. multicast tree is safeguarded

Each node timed sending hello message is with maintenance of neighbor relation and upgrade the received power list of neighbor node; In addition, the root vertex timed sending GroupHello message of each multicast tree, root vertex sequence number increases 1 simultaneously; When multicast tree member receives GroupHello message, send MACT message and carry out route activation, ensure that each node can obtain the up-to-date routing iinformation of multicast tree thus;

E. multicast tree merges

In a mobile environment, due to the mobility of node, adhoc network may be divided into several mutual disconnected region, the multicast tree of each regional maintenance its oneself; Due to the mobility of node, two or more disconnected regions may be communicated with again, in order to clear away confusion, the root vertex having maximum sequence number becomes the root vertex of new multicast tree, and other root vertexes stop sending GroupHello message and the reconstruction waiting for multicast tree.

The method that the present invention adopts compared with prior art has the following advantages:

(1) signal strength signal intensity that the present invention is based on continuous receipt message calculates, fashionable when there being new node to add, only have when new node and detection node keep the neighborhood of a period of time, this node just can be included in the computer capacity of link stability, decrease the unstable situation of the calculating caused because new node adds, there is higher adaptability and stability.

(2) compared with the simple method assessed node motion speed, the present invention is not by other third party's modules (as GPS), and accuracy is higher.

(3) from only to carry out the method for stability assessment to detection node different, the present invention carries out link stability assessment from detection node and tested node two angles, and assessment result is comprehensive, credible and adaptability is good.

(4) the present invention calculates simply, and assessment link stability process operand is low, and not high to hardware requirement, energy consumption is little.

(5) link stability appraisal procedure is applied in the multicast routing protocol based on stability, the present invention can be widely used in actual demand, improve the stability of network, and then increase work efficiency.

Accompanying drawing explanation

Fig. 1 is embodiment of the present invention link stable calculation schematic diagram.

Fig. 2 is group membership's adition process flow chart in the multicast routing protocol based on stability.

Embodiment

Provide one embodiment of the present of invention below and by reference to the accompanying drawings the present invention be described further.

In Fig. 1, Fig. 2

(1) the direct stability assessment of link

According to Friis free space propagation model, received power (P _rX) with the ratio (P of transmitted power _tX) with square being inversely proportional to of transmission range (R), namely $\frac{P_{\mathrm{RX}}}{P_{\mathrm{TX}}}\&Proportional;\frac{1}{R^2}$ Or $R\&Proportional;\sqrt{\frac{P_{\mathrm{TX}}}{P_{\mathrm{RX}}}}.$

In the present invention, assuming that the lower limit of received power is P _min, namely when received power is lower than this value, can produce the higher error rate, cause the re-transmission of packet, correspondingly, transmission range is now R _max.Environment residing for different node is different, therefore P _minvalue different, in the present invention, the P of all nodes _minbe initialized as a fixed value, when certain neighbor node shifts out its communication range, can think that the received power be carved into upper a period of time when merit receives is approximately equal to P now _min, that therefore uses a moment accepts the P that power upgrades this node _min.

As shown in accompanying drawing 1 (a), assuming that the n-th sub-sampling value of detection node i to tested node j received power is P _n ^ij, then according to Friis free space propagation model, have again due to wherein P _tXfor the transmitted power of node, R _n ^ijdistance when being n-th power sampling between sending node and receiving node, P _min ⁱfor the minimal detectable power of detection node i, R _maxfor received power is P _min ⁱtime corresponding maximum transmission distance, therefore, have

If node keeps relative distance change slowly, then can think that link stability is therebetween good, therefore the direct stability assessment value of variance as link between detection node i and tested node j can be got to above formula.That is:

${d\_S}_{\mathrm{ij}}=\sqrt{P_{\min }^i}\mathrm{var}\{\frac{1}{\sqrt{P_1^{\mathrm{ij}}}},\frac{1}{\sqrt{P_2^{\mathrm{ij}}}},...,\frac{1}{\sqrt{P_n^{\mathrm{ij}}}}\}$

Resulting in the computing formula of the direct stability assessment value of link.Assessed value is less, and link stability is better.

(2) link indirect stabilization assessment

As shown in accompanying drawing 1 (b), tested nodes X has n neighbours (Y ₁, Y ₂y _n).Nodes X is to its neighbor node Y _kstability assessment value calculates identical with (1), that is:

$S_X\left(Y_K\right)=\sqrt{P_{\min }^X}\mathrm{var}\{\frac{1}{\sqrt{P_1^{{\mathrm{XY}}_k}}},\frac{1}{\sqrt{P_2^{{\mathrm{XY}}_K}}},...,\frac{1}{\sqrt{P_n^{{\mathrm{XY}}_k}}}\}$

Because tested nodes X has n neighbours, and indirect link stability is the assessment to environment residing for tested nodes X, and therefore, X node needs the stability assessment value calculating its n neighbour, i.e. S _x(Y ₁), S _x(Y ₂) ... S _x(Y _n).In order to eliminate the impact of least stable node (link), the present invention sorts to this n stability and gets its minimum 0.5n value, is assumed to be S _x(Y _t1), S _x(Y _t2) ... S _x(Y _t0.5n), then the assessed value of average as environment residing for tested nodes X is got to this 0.5n value, i.e. the indirect stabilization assessed value of link:

in_S _X＝avg(S _X(Y _T1)，S _X(Y _T2)，…S _X(Y _T0.5n))

Resulting in the computing formula of link indirect stabilization assessed value.Assessed value is less, and the network environment residing for tested node is more stable.

(3) link comprehensive stability assessment

Direct, the indirect stabilization value of integrated link, the present invention adopts the comprehensive stability assessing link between detection node i and tested node j with the following method:

S _ij＝w ₁*d_S _ij+w ₂*in_S _j(w ₁+w ₂＝1)

Can find out, the present invention is when computational stability assessed value, and tested node j not only serves as sender but also serve as recipient.

(4) based on the multicast routing protocol of stability

A. group membership adds

As can be seen from accompanying drawing 2, node adds multicast group to be needed through three phases: route request stage, routing reply stage and route activate the stage.

Multicast group to be added when a node or have message to send to multicast group, but its be not group membership and also the route of not leading to multicast tree time, it sends a RREQ message.The destination address territory dest_addr of message is the address of multicast group, and source address source_addr is the address of this node oneself.In the present invention, RREQ message add an extra Path_Stable territory with record node the stability assessment value in path of process.

After a node receives RREQ message, first check whether processed identical RREQ, if then abandon, otherwise calculate the comprehensive stability value of upper hop link according to link stability appraisal procedure set forth above.Then the stationary value calculated being compared in territory with Path_Stable in RREQ, is the higher value in the two by Path_Stable area update, then continues to forward this RREQ message.

If a node is multicast member or has the route of leading to multicast tree, after receiving RREQ, by this RREQ buffer memory a period of time, due to same RREQ message may be had in the meantime to arrive this node from different paths, the RREQ message that therefore this sensor selection problem Path_Stable territory is minimum sends routing reply message RREP.

When an intermediate node receives RREP message, creating a QoS routing table clause with this entry state of tense marker based on this RREP is un-activation (the non-set of Activated_Flag), upgrade its Path_Stable territory, the reverse path then continued along RREQ message establishing forwards RREP message simultaneously.

A node may receive multiple RREP message, but it only processes (RREP sequence number is larger) that upgrade or more stable (Path_Stable territory is less) RREP message, and other RREP message abandons simply.

When RREP message arrives source node (request adds the node of multicast group), source node buffer memory a period of time, what from the multiple RREP message received, selection Path_Stable territory was minimum carries out route activation (MACT message), that is: by the route entry status indication that creates in the routing reply stage for activating (Activated_Flag set), other unactivated route entrys are deleted by respective nodes due to time-out.

B. group membership leaves

When a group membership wishes to leave multicast tree, if it is the routing node of other nodes, do not take any measure.If it is a leaf node, then to its upper hop clean culture prune message Prune, the route entry corresponding by its this descendant node of upper hop knot removal, if cause upper hop node also to become leaf node after deleting, then continue to send prune message to its upper hop and perform cut operator.

C. link open circuit

When multicast tree occurs in open circuit, the branch that open circuit occurs can become invalid.Now, upstream node deletes invalid node from its route entry, and then downstream node is responsible for link repair.Downstream node sends RREQ and additional multicast group reconstruction message carries out open circuit reparation.Rebuild in message in multicast group and comprise multicast group jumping figure territory (Group_Hop_Cnt) to record the jumping figure of open circuit nodal distance root vertex, the node only having hop count to be not more than this counting could respond RREQ message, this avoid the generation of route loop.After receiving RREP message, it is described identical that route activation and group membership add part.

D. multicast tree is safeguarded

In this agreement, each node timed sending hello message is with maintenance of neighbor relation and upgrade the received power list of neighbor node.In addition, the root vertex timed sending GroupHello message of each multicast tree, root vertex sequence number increases 1 simultaneously.When multicast tree member receives GroupHello message, send MACT message and carry out route activation, ensure that each node can obtain the up-to-date routing iinformation of multicast tree thus.

E. multicast tree merges

In a mobile environment, due to the mobility of node, adhoc network may be divided into several mutual disconnected region, the multicast tree of each regional maintenance its oneself.Due to the mobility of node, two or more disconnected regions may be communicated with again, in order to clear away confusion, the root vertex having maximum sequence number becomes the root vertex of new multicast tree, and other root vertexes stop sending GroupHello message and the reconstruction waiting for multicast tree.

Thus, network node completes foundation and the maintenance of Multicast Routing tree according to link stability appraisal procedure of the present invention, embodiments of the invention simulation result shows, adopt method of the present invention, compared with existing other technologies, network has the highest packet delivery fraction, low end-to-end time delay and higher network throughput in a mobile environment, and the overall performance of network is stable, strong adaptability.

Claims (5)

1. an AdHoc link in network stability prediction method, it is by sampling the signal strength signal intensity received continuously, with the true environment of Approximation Network realistically, for detection node and tested node, assess the stability of each bar link of environment residing for it respectively, consider detection node and tested node pair, calculate comprehensive stability value, and in this, as the routing standard of stability multicast routing protocol, it is characterized in that, concrete steps are:

The first step, by timed sending hello message, neighborhood is maintained to the direct stability assessment node of link, when detection node receives the hello message of its neighbor node transmission, detection node maintains a received signal strength and received power list for each neighbor node and tested node;

Second step, link indirect stabilization is assessed tested node and is adopted the method stability to its neighbor node same with the first step to assess; Because this stability is intended to assess environment residing for tested node, after therefore rejecting the extra high node of mobility, get average to other node stabilitys, average is lower, then the environment residing for tested node is more stable, otherwise environment is more unstable;

3rd step, link comprehensive stability is assessed, and adopts the method COMPREHENSIVE CALCULATING of weighted sum by the direct of link and indirect stabilization assessed value;

4th step, based on the multicast routing protocol of stability using stability as routing standard;

The direct stability assessment value of described first step link:

According to Friis free space propagation model, received power (P _rX) with the ratio (P of transmitted power _tX) with square being inversely proportional to of transmission range (R), namely or

Assuming that the lower limit of received power is P _min, namely when received power is lower than this value, can produce the higher error rate, cause the re-transmission of packet, correspondingly, transmission range is now R _max; Environment residing for different node is different, therefore P _minvalue different, the P of all nodes _minbe initialized as a fixed value, when certain neighbor node shifts out its communication range, can think that the received power be carved into upper a period of time when merit receives is approximately equal to P now _min, the received power of therefore using a moment upgrades the P of this node _min;

Assuming that the n-th sub-sampling value of detection node i to tested node j received power is then according to Friis free space propagation model, have again due to wherein P _tXfor the transmitted power of node, R _ndistance when being n-th power sampling between sending node and receiving node, P _min ⁱfor the minimal detectable power of detection node i, R _maxfor received power is P _min ⁱtime corresponding maximum transmission distance, therefore, have $\frac{R_n}{R_{\max }}=\sqrt{\frac{P_{\min }^i}{P_n^{\mathrm{ij}}}}$

If node keeps relative distance change slowly, then think that link stability is therebetween good, therefore the direct stability assessment value of variance as link between detection node i and tested node j is got to above formula, that is:

$d\_S_{\mathrm{ij}}=\sqrt{P_{\min }^i}\mathrm{var}\{\frac{1}{\sqrt{P_1^{\mathrm{ij}}}},\frac{1}{\sqrt{P_2^{\mathrm{ij}}}},...,\frac{1}{\sqrt{P_n^{\mathrm{ij}}}}\}$

Resulting in the computing formula of the direct stability assessment value of link, assessed value is less, and link stability is better.

2. AdHoc link in network stability prediction method as claimed in claim 1, is characterized in that, described second step link indirect stabilization assessed value:

Suppose that tested nodes X has n neighbours (Y ₁, Y ₂y _n), nodes X is to its neighbor node Y _kstability assessment value calculates identical with the first step, that is:

$S_X\left(Y_K\right)=\sqrt{P_{\min }^X}\mathrm{var}\{\frac{1}{\sqrt{P_1^{{\mathrm{XY}}_K}}},\frac{1}{\sqrt{P_2^{{\mathrm{XY}}_K}}},...,\frac{1}{\sqrt{P_n^{{\mathrm{XY}}_K}}}\}$

for the minimal detectable power of detection node X, because tested nodes X has n neighbours, and indirect link stability is the assessment to environment residing for tested nodes X, and therefore, X node needs the stability assessment value calculating its n neighbour, i.e. S _x(Y ₁), S _x(Y ₂) ... S _x(Y _n); In order to eliminate the impact of least stable node, this n stability being sorted and gets its minimum 0.5n value, being assumed to be S _x(Y _t1), S _x(Y _t2) ... S _x(Y _t0.5n), then the assessed value of average as environment residing for tested nodes X is got to this 0.5n value, i.e. the indirect stabilization assessed value of link:

in_S _X＝avg(S _X(Y _T1),S _X(Y _T2),…S _X(Y _T0.5n))

Resulting in the computing formula of link indirect stabilization assessed value; Assessed value is less, and the network environment residing for tested node is more stable.

3. AdHoc link in network stability prediction method as claimed in claim 1, is characterized in that, assess the comprehensive stability of link between detection node i and tested node j in described 3rd step:

S _ij＝w ₁*d_S _ij+w ₂*in_S _j(w ₁+w ₂＝1)

Tested node j not only serves as sender but also serve as recipient, in_S _jfor the indirect stabilization assessed value of the link of node j.

4. AdHoc link in network stability prediction method as claimed in claim 1, it is characterized in that, in described 4th step based on the multicast routing protocol of stability using stability as routing standard, when node produces route request information, in route request information, an additional specific territory is to characterize the stability assessment value in the path of process; The stability assessment value of one paths equal the stability assessment maximum of all links of process, namely the stability of a paths depends on one section of least stable link; When node receives routing reply message, the path that selection stability assessment value is minimum from all paths is activated.

5. AdHoc link in network stability prediction method as claimed in claim 4, it is characterized in that, detailed process is:

A. group membership adds

Node adds multicast group to be needed through three phases: route request stage, routing reply stage and route activate the stage;

Multicast group to be added when a node or have message to send to multicast group, but its be not group membership and also the route of not leading to multicast tree time, it sends a RREQ message; The destination address territory dest_addr of message is the address of multicast group, and source address source_addr is the address of this node oneself; RREQ message increase an extra Path_Stable territory with record node the stability assessment value in path of process;

After a node receives RREQ message, first check whether processed identical RREQ, if then abandon, otherwise calculate the comprehensive stability value of upper hop link according to link stability appraisal procedure set forth above; Then the stationary value calculated being compared in territory with Path_Stable in RREQ, is the higher value in the two by Path_Stable area update, then continues to forward this RREQ message;

If a node is multicast member or has the route of leading to multicast tree, after receiving RREQ, by this RREQ buffer memory a period of time, due to same RREQ message may be had in the meantime to arrive this node from different paths, the RREQ message that therefore this sensor selection problem Path_Stable territory is minimum sends routing reply message RREP;

When an intermediate node receives RREP message, creating a QoS routing table clause with this entry state of tense marker based on this RREP is un-activation and the non-set of Activated_Flag, upgrade its Path_Stable territory, the reverse path then continued along RREQ message establishing forwards RREP message simultaneously; A node may receive multiple RREP message, but it only processes comparatively large or that Path_Stable territory the is less RREP message of RREP sequence number, and other RREP message abandons simply;

When namely RREP message arrival source node asks the node adding multicast group, source node buffer memory a period of time, what from the multiple RREP message received, selection Path_Stable territory was minimum carries out route activation and MACT message, that is: be activation and Activated_Flag set by the route entry status indication created in the routing reply stage, other unactivated route entrys are deleted by respective nodes due to time-out;

B. group membership leaves

When a group membership wishes to leave multicast tree, if it is the routing node of other nodes, do not take any measure; If it is a leaf node, then to its upper hop clean culture prune message Prune, the route entry corresponding by its this descendant node of upper hop knot removal, if cause upper hop node also to become leaf node after deleting, then continue to send prune message to its upper hop and perform cut operator;

C. link open circuit

When multicast tree occurs in open circuit, the branch that open circuit occurs can become invalid; Now, upstream node deletes invalid node from its route entry, and then downstream node is responsible for link repair; Downstream node sends RREQ and additional multicast group reconstruction message carries out open circuit reparation; Rebuild in message in multicast group and comprise multicast group jumping figure territory Group_Hop_Cnt to record the jumping figure of open circuit nodal distance root vertex, the node only having hop count to be not more than this jumping figure could respond RREQ message, this avoid the generation of route loop; After receiving RREP message, it is described identical that route activation and group membership add part;

D. multicast tree is safeguarded

Each node timed sending hello message is with maintenance of neighbor relation and upgrade the received power list of neighbor node; In addition, the root vertex timed sending GroupHello message of each multicast tree, root vertex sequence number increases 1 simultaneously; When multicast tree member receives GroupHello message, send MACT message and carry out route activation, ensure that each node can obtain the up-to-date routing iinformation of multicast tree thus;

E. multicast tree merges

In a mobile environment, due to the mobility of node, adhoc network may be divided into several mutual disconnected region, the multicast tree of each regional maintenance its oneself; Due to the mobility of node, two or more disconnected regions may be communicated with again, in order to clear away confusion, the root vertex having maximum sequence number becomes the root vertex of new multicast tree, and other root vertexes stop sending GroupHello message and the reconstruction waiting for multicast tree.