CN100574223C - The distributed collaborative network coordinate that a kind of position-based merges is determined method - Google Patents

The distributed collaborative network coordinate that a kind of position-based merges is determined method Download PDF

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CN100574223C
CN100574223C CNB2007100355653A CN200710035565A CN100574223C CN 100574223 C CN100574223 C CN 100574223C CN B2007100355653 A CNB2007100355653 A CN B2007100355653A CN 200710035565 A CN200710035565 A CN 200710035565A CN 100574223 C CN100574223 C CN 100574223C
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coordinate
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service station
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CN101106484A (en
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王意洁
符永铨
郑重
杨永滔
孙伟东
李小勇
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National University of Defense Technology
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Abstract

The distributed collaborative network coordinate that the invention discloses a kind of position-based fusion is determined method, and purpose is to solve the existing network coordinate to determine deficiencies such as method terrestrial reference bottleneck effect, low precision and poor stability.Technical scheme is first system initialization, utilizes the multiple spot coordinate to determine that method Coordinate_M is provided with the initial network coordinate of all service stations; Then determine the initial network coordinate of initiate user's node and service station; Extent of deviation between current network coordinate distance d and real network delay l satisfies | (l-d)/l| 〉=β, β is taken as at 0.2 o'clock, carries out network coordinate and upgrades.Adopt the present invention can effectively avoid the generation of terrestrial reference bottleneck effect, can effectively guarantee the precision that coordinate is determined, can effectively improve stability and fault-tolerance that coordinate is determined.

Description

The distributed collaborative network coordinate that a kind of position-based merges is determined method
Technical field:
The network coordinate that the present invention relates in the wan environment is determined method, especially definite method of distributed network coordinate in the wan environment.
Background technology:
Network coordinate is determined one of key problem that field of network computing needs to be resolved hurrily.It is one of network distance method of measurement that extensively adopts at present that coordinate Network Based carries out the network distance measurement, and it utilizes the coordinate distance between node to be similar to network delay by giving a coordinate position in the preferred coordinates space to node.The implementation strategy of network application system is based on the network distance between the node mostly, and precision, stability and the efficient that network coordinate is determined will directly have influence on the effect that network distance is measured, thereby influences the operational efficiency of network application system.
The typical method of existing definite network coordinate has: 1) GNP (Global Networking Positioning) method, it utilizes the concentrated sensing point of one group of terrestrial reference node as static state, employing lacks autgmentability based on the network coordinate of the nonlinear method centralized calculation node of iteration; Do not consider the deployment issue of terrestrial reference node, limited terrestrial reference node is easy to become the performance bottleneck of system, thereby directly influences the efficient that network coordinate is determined; Its network coordinate invariant feature is difficult to continuous variation according to the network state network coordinate that upgrades in time, thereby directly has influence on the levels of precision that network coordinate is determined.2) PIC (Practical Internet coordinates) method, it adopts hybrid-type terrestrial reference system of selection, compare with the GNP method, its autgmentability increases, but its convergence rate is low, be difficult to continuous variation according to the network state network coordinate that upgrades in time, thereby directly have influence on the levels of precision that network coordinate is determined, the deviation of the network coordinate of the node that network distance is far away is bigger.3) Vivaldi method, it utilizes the network coordinate that constantly upgrades in time alternately between the node, and its autgmentability is better; But it does not consider the concussion problem of the caused coordinate Calculation of false coordinate that the malice node provides in the network, and the break rules error issues of caused coordinate Calculation of the triangle inequality that exists in the network, these all can have influence on the stability that network coordinate is determined.
In a word, existing network coordinate determines that the main weak point of method is: 1) terrestrial reference bottleneck effect, the static network coordinate determines that method is the basic calculation network coordinate with centralized terrestrial reference node, limited terrestrial reference node is easy to become the performance bottleneck of system, thereby directly influences the efficient that network coordinate is determined; 2) low precision, the static network coordinate is determined the low continuous variation that all will be difficult to according to network state of the network coordinate invariant feature of method and convergence rate that the dynamic network coordinate the is determined method network coordinate that upgrades in time, thereby directly has influence on the levels of precision that network coordinate is determined; 3) poor stability, the false coordinate that the malice node provides in the network will cause the concussion problem of coordinate Calculation, the triangle inequality that exists in the network breaks rules and will cause the error issues of coordinate Calculation, all can have influence on the stability that network coordinate is determined.Therefore, how to improve the hot research problem that network coordinate definite precision, stability and efficient have become field of network computing.
Summary of the invention:
The technical problem to be solved in the present invention is to determine deficiency such as terrestrial reference bottleneck effect, low precision and poor stability that method exists at existing network coordinate and the distributed collaborative network coordinate of the position-based fusion that proposes is determined method.
The technical scheme that solution the technology of the present invention problem is adopted is: the existing node of Dynamic Selection is used for determining the coordinate of new node, thereby effectively avoids the generation of terrestrial reference bottleneck effect; Utilize multiple coordinate to determine that method determines new node coordinate, improve the convergence rate that coordinate is determined, in time adapt to the continuous variation of network state, effectively guarantee the precision that coordinate is determined; The position concussion influence that the false coordinate that utilizing the position to merge to weaken the malice node provides brings, utilize and to broadcast chosen distance node far away arbitrarily and carry out coordinate and determine to weaken the influence that breaks rules of triangle inequality that the nearer node of chosen distance causes, effectively improve stability and fault-tolerance that coordinate is determined.
Concrete technical scheme is:
The first step, system initialization.
1. according to node function node is divided into service station and user's node.User's node only can be inquired about the coordinate of oneself; Service station also is responsible for the coordinate of other node of response and is determined request except that the function with user's node.
2. utilize distributed hashtable DHT (Distributed Hash Table) organization service node and user's node.Each node has a unique identifier ID, and node ID is the binary string (being that ID is the integer between 0 to 2m) of a m (m=160) position, and it obtains by hash function (SHA-1 algorithm) according to the IP address of node.
3. the dimension D of setting network coordinate, the dimension D of knot-net coordinate is many more, and the precision of network coordinate is high more, and the complexity that coordinate is determined is high more, and usually, the dimension D of network coordinate is decided to be 7.
4. at system initial state, all nodes all are set to service station, select a service station as root node arbitrarily, and root node utilizes the multiple spot coordinate to determine that method Coordinate_M is provided with the initial network coordinate of all service stations.
The multiple spot coordinate determines that the idiographic flow of method Coordinate_M is:
1) total N service station in the assumed initial state system, N is a positive integer;
2) utilize the network detection method, obtain N the real network between the service station and postpone, and constitute the network delay matrix M,
M = 0 l 1,2 . . . l 1 , N l 2,1 0 . . . l 2 , N l 3,1 l 3 , 2 . . . l 3 , N . . . . . . . . . . . . l N , 1 l N , 2 . . . 0
l I, jReal network between expression service station i and the j postpones, i=1, and 2 ..., N, j=1,2 ..., N.
3) for N service station be provided with at random W group network coordinate (N<W<2N),, select to make objective function F to reach the initial network coordinate of that group network coordinate of minimum as N service station based on the value of each group network coordinate Calculation objective function F:
F = Σ i = 1 N Σ j = 1 N ( l i , j - d i , j l i , j ) 2
d i , j = Σ k = 1 D ( s i k - s j k ) 2
s iThe coordinate of expression service station i, s jThe coordinate of expression service station j, s i kThe k dimension coordinate of expression service station i, s j kThe k dimension coordinate of expression service station j.l I, jReal network between expression service station i and the j postpones, d I, jBe the coordinate distance between service station i and the j.
4) utilize the network detection method obtain service station i and arbitrarily service station j (real network between the j ≠ i) postpones latency.According to the coordinate distance d between service station i and the service station j I, jPostpone the coordinate mistake diff that latency is provided with service station i with real network i, the coordinate mistake refers to the deviation between knot-net coordinate and the node actual physical location,
diff i = | d i , j - latency | min ( d i , j , latency )
5) by initial network coordinate and the coordinate mistake of root node after N service station transmission determined.
In second step, determine the new initial network coordinate that adds node.
1. new node is P adding the fashionable probability that becomes service station, and P is a system parameters, and P is big more, and the autgmentability of system is high more, and the system maintenance expense is big more.Usually, the value of P is 50%, and P should dynamically adjust according to the autgmentability and the maintenance costs of system.
2. determine the initial network coordinate of initiate user's node.
1) suppose that A is initiate user's node, node A adopts the mode of broadcasting arbitrarily to send the definite request of network coordinate.
2) each node in the forward-path all carries out following processing to the definite request of network coordinate that node A sends:
A) each node is all preserved a service station set, is used to write down the contact details (comprising node IP, node ID and node coordinate) of related service node, and wherein, the service station far away apart from this node is called the remote service node.
B) each node from the set of the service station of its buffer memory at random selection percentage be the remote service node of Q (Q gets 50% usually).
C), then continue to transmit this network coordinate and determine request if the service station number of selecting is less than the service station number K (the K value is the dimension D of knot-net coordinate) that coordinate is determined needs.
D), then the contact details of the service station selected are issued the node A that submits request to, and notify these service stations to determine the network coordinate of request node A if the service station number of selecting is determined the service station number K that needs more than or equal to coordinate.
3) service station that has notice (being made as S) utilizes two point coordinates to determine that method Coordinate_T determines the network coordinate of request node A, and the network coordinate that obtains is returned request node A.
Two point coordinates determine that the idiographic flow of method Coordinate_T is as follows:
A) obtain the current coordinate and the current coordinate mistake of asking node A,, then current coordinate (a is set at random for request node A if do not have 1, a 2..., a D), current coordinate mistake diff is set A=1.
B) coordinate of establishing the service station S that has notice is (s 1, s 2..., s D), obtain this node S and the coordinate distance CoordinateDis that asks node A,
CoordinateDis = Σ i = 1 D ( a i - s i ) 2 .
C) on each dimension, obtain the relative movement distance x of request node A with respect to S i(i=1,2 ..., D)
x i=s i-a i,i=1,2,......,D。
D) real network of utilizing the network detection method to obtain between S and the request node A postpones latency.
E) the new coordinate (n of definite request node A 1, n 2..., n D)
n i=a i+δ×x i×(CoordinateDis-latency),i=1,2,......,D
Wherein, δ = diff A diff S + diff A , Diff AThe current coordinate mistake of expression request node, diff SThe current coordinate mistake of expression S.
F) postpone the coordinate mistake diff that latency adjusts request node A according to new coordinate distance NewCoordinateDis between request node A and the S and real network A,
NewCoordinateDis = Σ i = 1 D ( n i - s i ) 2 dif f A = | NewcoordinateDis - latency | min ( NewCoordinateDis , latency )
4) request node A utilizes position fusion method Coordinate_Fuse to determine final network coordinate after receiving the definite network coordinate of all remote service nodes.
Position fusion method Coordinate_Fuse has three kinds, can select a kind of determining of final network coordinate that carry out arbitrarily:
A) minimum deflection degree position fusion method: each service station not only returns the network coordinate of request node A, and return the coordinate mistake corresponding with network coordinate, the network coordinate of choosing coordinate mistake minimum in the all-network coordinate is as the network coordinate of finally choosing, promptly
FCoord = Coord i = ( Coord i 1 , . . . , Coord i j , . . . , Coord i N ) ,
diff i=min(diff 1,diff 2,......,diff SNum)
FCoord represents the network coordinate finally chosen.
Suppose to receive altogether SNum service station and return network coordinate,
Coord iAnd diff iRepresent network coordinate and corresponding coordinate mistake thereof that i service station returns, i=1,2 ..., SNum.
Coord i jThe j dimension of representing the network coordinate that i service station returns, j=1,2 ..., D.
B) median location fusion method: on each dimension, choose the network coordinate that the corresponding median conduct of tieing up is finally chosen in all network coordinates that return, that is,
F Coord j = median ( Coord 1 j , . . . , Coord 2 j , . . . , Coord SNum j ) , j=1,2,......,D。
FCoord jThe j dimension of the network coordinate that expression is finally chosen, j=1,2 ..., D.
Coord i jThe j dimension of representing the network coordinate that i service station returns, j=1,2 ..., D, SNum are the service station number.
C) arithmetic average position fusion method: on each dimension, choose the network coordinate that the corresponding arithmetic mean conduct of tieing up is finally chosen in all network coordinates that return, that is,
FCoord j = Σ i = 1 SNum Coor d i j SNum , j=1,2,......,D。
FCoord jThe j dimension of the network coordinate that expression is finally chosen, j=1,2 ..., D.
Coord i jThe j dimension of representing the network coordinate that i service station returns, j=1,2 ..., D, SNum are the service station number.
3. initiate service station B utilizes the minimum errors coordinate to determine that method Coordinate_D is provided with the initial network coordinate.
The minimum errors coordinate determines that the idiographic flow of method Coordinate_D is:
1) initiate service station B sends the definite request of network coordinate to root node.
2) root node is selected D service station (D is the dimension of network coordinate) to form from the service station of existing network coordinate arbitrarily to gather L, and will gather L and send to service station B.
3) utilize the network detection method to obtain the real network delay between each service station among service station B and the set L.
4) for service station B D network coordinate (D is the dimension of coordinate) is set at random,, selects to make objective function F to reach the initial network coordinate of the network coordinate of minimum as service station B based on the value of each network coordinate calculating target function F:
F = Σ i = 1 D ( l i - d i l i ) 2
d i = Σ k = 1 D ( b k - s i k ) 2
s iThe coordinate of i service station among the expression set L, s i kThe k dimension coordinate of i service station among the expression set L, b kThe k dimension coordinate of expression service station B.l iFor the real network delay between i service station among service station B and the set L (i=1,2 ..., D), d iFor the coordinate distance between i service station among service station B and the set L (i=1,2 ..., D).
5) utilize the network detection method to obtain the real network delay latency between any service station i among service station B and the set L.According to the coordinate distance d between service station B and the service station i iPostpone the coordinate mistake diff that latency is provided with service station B with real network B,
diff B = | d i - latency | min ( d i , latency )
6) the initial network coordinate of service station B after the root node transmission is determined.
In the 3rd step, upgrade the node coordinate.
When carrying out information interaction between the node, obtain the other side's current network coordinate, and further obtain the current network coordinate distance between the node; The real network of utilizing the network detection method to obtain between the node postpones; By judging that current network coordinate distance d and real network postpone the extent of deviation between the l, determine whether to carry out network coordinate and upgrade, that is,, then carry out network coordinate and upgrade if meet the following conditions:
| l - d l | ≥ β , Usually, β is taken as 0.2.
The flow process that the network coordinate of user's node and service station upgrades is identical, and the flow process of determining with the initial network coordinate that newly adds the access customer node (i.e. the 2nd point in second step) is identical.
Adopt the present invention can reach following technique effect:
Determine that with existing network coordinate method compares, the present invention is based on distributed service station, and the Dynamic Selection service station is determined the network coordinate of new node, can effectively avoid the generation of terrestrial reference bottleneck effect; The present invention adapts to the variation of network state, according to the extent of deviation between real network delay and the current network coordinate distance between the node, utilize two point coordinates to determine that method, multiple spot coordinate determine that method and minimum errors coordinate determine that several different methods such as method dynamically updates the network coordinate of node, can effectively guarantee the precision that coordinate is determined; The position concussion influence that the false coordinate that the present invention utilizes the position to merge to weaken the malice node to be provided brings, select the remote service node to carry out coordinate and determine to weaken the triangle inequality fault influence that the nearer node of chosen distance causes, can effectively improve stability and fault-tolerance that coordinate is determined.
Description of drawings:
Fig. 1 adopts the present invention to carry out the general flow chart that the knot-net coordinate is determined;
Fig. 2 adopts the present invention to determine user's node initial network coordinate and the flow chart that the knot-net coordinate is upgraded.
Embodiment:
Fig. 1 adopts the present invention to carry out the general flow chart that the knot-net coordinate is determined.Idiographic flow is as follows:
The first step, system initialization.
1. according to node function node is divided into service station and user's node.
2. utilize distributed hashtable organization service node and user's node.
3. the dimension D of setting network coordinate is 7.
4. at system initial state, all nodes all are service stations, select a service station as root node arbitrarily, and root node utilizes the multiple spot coordinate to determine that method Coordinate_M is provided with the initial network coordinate of all service stations.
In second step, determine the new initial network coordinate that adds node.
1. new node is P adding the fashionable probability that becomes service station, and usually, the value of P is 50%, and P should dynamically adjust according to the autgmentability and the maintenance costs of system.
2. that determines initiate user's node carries out the initial network coordinate.
3. initiate service station utilizes the minimum errors coordinate to determine that method Coordinate_D is provided with the initial network coordinate.
In the 3rd step, upgrade the node coordinate.
1. when carrying out information interaction between the node, obtain the other side's current network coordinate, and further obtain the current network coordinate distance between the node.
2. the real network of utilizing the network detection method to obtain between the node postpones.
3. if the extent of deviation between current network coordinate distance d and the real network delay 1 satisfies
| l - d l | ≥ β , β is taken as 0.2, then carries out network coordinate and upgrades.
Fig. 2 adopts the present invention to determine user's node initial network coordinate and the flow chart that the knot-net coordinate is upgraded.Idiographic flow is as follows:
1) the request node adopts the mode of broadcasting arbitrarily to send the definite request of network coordinate.
2) each node in the forward-path all carries out following processing to the definite request of network coordinate that the request node sends:
2a) each request handle node from the service station set of its maintenance at random selection percentage be the remote service node of Q (usually, Q gets 50%).
If 2b) the service station number of Xuan Zeing is less than the service station number K (usually, the K value is the dimension D of knot-net coordinate) of the definite needs of coordinate, then continues to transmit this network coordinate and determine to ask.
If 2c) the service station number K that determine to need more than or equal to coordinate of the service station number of Xuan Zeing then issues the node of submitting request to the contact details of the service station selected, and notifies these service stations to determine the network coordinate of request node.
3) service station that has notice utilizes two point coordinates to determine that method Coordinate_T determines the network coordinate of request node, and the network coordinate that obtains is returned the request node.
4) the request node utilizes position fusion method Coordinate_Fuse further to determine final network coordinate after receiving the definite network coordinate of all remote service nodes.

Claims (1)

1. the distributed collaborative network coordinate of a position-based fusion is determined method, it is characterized in that it may further comprise the steps:
The first step, system initialization, method is:
1) according to node function node is divided into service station and user's node, user's node only can be inquired about the coordinate of oneself, and service station is except that the function with user's node, and the coordinate that also responds other node is determined request;
2) utilize distributed hashtable DHT organization service node and user's node, each node has a unique identifier ID, and node ID is the binary string of a m position, and it obtains by hash function according to the IP address of node, wherein m=160;
3) the dimension D of setting network coordinate is 7;
4) at system initial state, all nodes all are set to service station, select a service station as root node arbitrarily, and root node utilizes the multiple spot coordinate to determine that method Coordinate_M is provided with the initial network coordinate of all service stations; Described multiple spot coordinate determines that the idiographic flow of method Coordinate_M is:
1.1) total N service station in the assumed initial state system, N is a positive integer;
1.2) utilize the network detection method, obtain N the real network between the service station and postpone, and constitute the network delay matrix M,
M = 0 l 1,2 . . . l 1 , N l 2,1 0 . . . l 2 , N l 3,1 l 3,2 . . . l 3 , N . . . . . . . . . . . . l N , 1 l N , 2 . . . 0
l I, jReal network between expression service station i and the j postpones, i=1, and 2 ..., N, j=1,2 ..., N;
1.3) for N service station W group network coordinate is set at random, N<W<2N, based on the value of each group network coordinate Calculation objective function F, select to make objective function F to reach the initial network coordinate of that group network coordinate of minimum as N service station:
F = Σ i = 1 N Σ j = 1 N ( l i , j - d i , j l i , j ) 2
d i , j = Σ k = 1 D ( s i k - s j k ) 2
s iThe coordinate of expression service station i, s jThe coordinate of expression service station j, s i kThe k dimension coordinate of expression service station i, s j kThe k dimension coordinate of expression service station j; l I, jReal network between expression service station i and the j postpones, d I, jBe the coordinate distance between service station i and the j;
1.4) utilize the network detection method to obtain service station i and any service station j, the real network between j ≠ i postpones latency, according to the coordinate distance d between service station i and the service station j I, jPostpone the coordinate mistake diff that latency is provided with service station i with real network i, the coordinate mistake refers to the deviation between knot-net coordinate and the node actual physical location,
diff i = | d i , j - latency | min ( d i , j , latency )
1.5) by initial network coordinate and the coordinate mistake of root node after N service station transmission determined;
Second step, determine the new initial network coordinate that adds node, method is:
1) new node is P adding the fashionable probability that becomes service station, and the P value is 50%, and P should dynamically adjust according to the autgmentability and the maintenance costs of system;
2) determine the initial network coordinate of initiate user's node:
I) suppose that A is initiate user's node, node A adopts the mode of broadcasting arbitrarily to send the definite request of network coordinate;
II) each node in the forward-path all carries out following processing to the definite request of network coordinate that node A sends:
A) each node is all preserved the set of service station, and the contact details that are used to write down the related service node are node IP, node ID and node coordinate, and wherein, the service station far away apart from this node is called the remote service node;
B) each node from the set of the service station of its buffer memory at random selection percentage be the remote service node of Q, Q gets 50%;
C) if the service station number of selecting is less than the service station number K that coordinate is determined needs, then continue to transmit this network coordinate and determine request, the K value is the dimension D of knot-net coordinate;
D), then the contact details of the service station selected are issued the node A that submits request to, and the service station selected of notice is determined the network coordinate of request node A if the service station number of selecting is determined the service station number K that needs more than or equal to coordinate;
III) the service station S that has notice utilizes two point coordinates to determine that method Coordinate_T determines the network coordinate of request node A, and the network coordinate that obtains is returned request node A; The idiographic flow that described two point coordinates are determined method Coordinate_T is as follows:
2.1) obtain the current coordinate and the current coordinate mistake of asking node A, if do not have, then current coordinate (a is set at random for request node A 1, a 2..., a D), current coordinate mistake diff is set A=1;
2.2) coordinate of establishing the service station S that has notice is (s 1, s 2..., s D), obtain S and the coordinate distance CoordinateDis that asks node A,
CoordinateDis = Σ i = 1 D ( a i - s i ) 2 ;
2.3) on each dimension, obtain the relative movement distance x of request node A with respect to S i, i=1,2 ..., D
x i=s i-a i,i=1,2,......,D;
2.4) real network of utilizing the network detection method to obtain between S and the request node A postpones latency;
2.5) definite new coordinate (n that asks node A 1, n 2..., n D)
n i=a i+δ×x i×(CoordinateDis-latency),i=1,2,......,D
Wherein, δ = diff A diff S + diff A , Diff AThe current coordinate mistake of expression request node, diff SThe current coordinate mistake of expression S;
2.6) postpone the coordinate mistake diff that latency adjusts request node A according to new coordinate distance NewCoordinateDis between request node A and the S and real network A,
NewCoordinateDis = Σ i = 1 D ( n i - s i ) 2 diff A = | NewCoordinateDis - latency | min ( NewCoordinateDis , latency ) ;
IV) behind the network coordinate that the service station of asking node A to select in receiving the second step step d) is determined, utilize position fusion method Coordinate_Fuse to determine final network coordinate; Described position fusion method Coordinate_Fuse comprises three kinds of minimum deflection degree position fusion methods, median location fusion method, arithmetic average position fusion method:
Minimum deflection degree position fusion method: each service station not only returns the network coordinate of request node A, and return the coordinate mistake corresponding with network coordinate, the network coordinate of choosing coordinate mistake minimum in the all-network coordinate is as the network coordinate of finally choosing, promptly
FCoord = C oord i = ( Coord i 1 , . . . , Coord i j , . . . , Coord i N ) ,
diff i=min(diff 1,diff 2,......,diff SNum)
FCoord represents the network coordinate finally chosen;
Suppose to receive altogether SNum service station and return network coordinate,
Coord iAnd diff iRepresent network coordinate and corresponding coordinate mistake thereof that i service station returns, i=1,2 ..., SNum;
Coord i jThe j dimension of representing the network coordinate that i service station returns, j=1,2 ..., D;
The median location fusion method: on each dimension, choose the network coordinate that the corresponding median conduct of tieing up is finally chosen in all network coordinates that return, that is,
FCoord j = median ( Coord 1 j , Coord 2 j , . . . . . . , Coord SNum j ) , j=1,2,......,D;
FCoord jThe j dimension of the network coordinate that expression is finally chosen, j=1,2 ..., D;
Coord i jThe j dimension of representing the network coordinate that i service station returns, j=1,2 ..., D, SNum are the service station number;
Arithmetic average position fusion method: on each dimension, choose the network coordinate that the corresponding arithmetic mean conduct of tieing up is finally chosen in all network coordinates that return, that is,
FCoord j = Σ i = 1 SNum Coord i j SNum , j=1,2,......,D;
FCoord jThe j dimension of the network coordinate that expression is finally chosen, j=1,2 ..., D;
Coord i jThe j dimension of representing the network coordinate that i service station returns, j=1,2 ..., D, SNum are the service station number;
3) initiate service station B utilizes the minimum errors coordinate to determine that method Coordinate_D is provided with the initial network coordinate; Described minimum errors coordinate determines that the idiographic flow of method Coordinate_D is:
(1) initiate service station B sends the definite request of network coordinate to root node;
(2) root node is selected D service station to form from the service station of existing network coordinate arbitrarily to gather L, and will gather L and send to service station B;
(3) utilize the network detection method to obtain the real network delay between each service station among service station B and the set L;
(4) for service station B D network coordinate is set at random,, selects to make objective function F to reach the initial network coordinate of the network coordinate of minimum as service station B based on the value of each network coordinate calculating target function F:
F = Σ i = 1 D ( l i - d i l i ) 2
d i = Σ k = 1 D ( b k - s i k ) 2
s iThe coordinate of i service station among the expression set L, s i kThe k dimension coordinate of i service station among the expression set L, b kThe k dimension coordinate of expression service station B; l iBe the real network delay between i service station among service station B and the set L, i=1,2 ..., D, d iBe the coordinate distance between i service station among service station B and the set L, i=1,2 ..., D;
(5) utilize the network detection method to obtain the real network delay latency between any service station i among service station B and the set L, according to the coordinate distance d between service station B and the service station i iPostpone the coordinate mistake diff that latency is provided with service station B with real network B,
diff B = | d i - latency | min ( d i , latency )
(6) the initial network coordinate of service station B after the root node transmission is determined;
The 3rd step, upgrade the node coordinate, method is: when carrying out information interaction between the node, obtain the other side's current network coordinate, and further obtain the current network coordinate distance between the node; The real network of utilizing the network detection method to obtain between the node postpones; Judge that current network coordinate distance d and real network postpone the extent of deviation between the l, if satisfy | l - d l | ≥ β , β is taken as 0.2, then carries out network coordinate and upgrades; The flow process that the network coordinate of user's node and service station upgrades is identical, flow process the step 2 in i.e. second step definite with the initial network coordinate that newly adds the access customer node) identical.
CNB2007100355653A 2007-08-16 2007-08-16 The distributed collaborative network coordinate that a kind of position-based merges is determined method Expired - Fee Related CN100574223C (en)

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