CN113382464B - Directional ad hoc network power control method based on minimum spanning tree - Google Patents
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
- H04W52/248—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters where transmission power control commands are generated based on a path parameter
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/28—TPC being performed according to specific parameters using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
- H04W52/283—Power depending on the position of the mobile
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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Abstract
The invention discloses a directional ad hoc network power control method based on a minimum spanning tree, and belongs to the field of wireless network communication. The invention adopts the link constructed by the minimum spanning tree as the basis of the link, thereby ensuring the connectivity of the network; links are properly added for the nodes, the hop count between the nodes in the network is shortened, the number of the links in one sector is limited by considering the characteristics of the directional antenna, the communication interference is reduced, and the performance of the network is improved; the unidirectional links are deleted, the last constructed links are all bidirectional links, and the problem that the network performance is influenced due to the fact that the network topology is complicated due to the existence of the unidirectional links is solved. The method can reduce the power of the transmitting antenna, ensure the connectivity and relatively high performance of the network, can be applied to the fields of military battlefields, disaster area emergency communication and the like, and solves the problem of network performance reduction caused by reducing the power of the node antenna.
Description
Technical Field
The invention belongs to the field of wireless network communication, and particularly relates to a node antenna power control method of a directional ad hoc network.
Background
The directional ad hoc network is a wireless ad hoc network using a directional antenna, and has the advantages of high gain, spatial multiplexing, interference resistance, interception resistance and the like. Nodes in a directional ad hoc network cannot transmit signals at maximum power because the nodes have limited energy and can cause frequent data collisions resulting in reduced network performance. The main purpose of the power control algorithm is to reduce the power of the transmitting antenna as much as possible, while ensuring the connectivity of the network and improving the performance of the network.
Current power control algorithms can be divided into algorithms based on angular direction information, on node location information and on neighbor number information. The LMST algorithm is a power control algorithm based on node location information, but the characteristics of a directional antenna are not considered, and the network performance is reduced due to the fact that the number of hops between nodes is large.
Disclosure of Invention
The invention discloses a method for controlling the power of a directional ad hoc network based on a minimum spanning tree, and provides a method for controlling the power of nodes in the directional ad hoc network, which can reduce the power of transmitting antennas and ensure the connectivity and relatively high performance of the network. The method can be applied to the fields of military battlefields, disaster area emergency communication and the like, and solves the problem of network performance reduction caused by reducing the power of the node antenna.
The purpose of the invention is realized by the following technical scheme: firstly, a distance matrix and a sector number matrix are calculated by using node coordinates, and then a minimum spanning tree is constructed by adopting Prim or Kruskal algorithm. And setting the upper limit of the number of the node neighbors and the upper limit of the number of the sector neighbors on the basis of the link constructed by the minimum spanning tree. Then, the neighbors are sequenced from near to far according to the distance, links between the neighbors are added to each node until the upper limit of the number of the neighbors is reached, and the unidirectional links are deleted. And finally, calculating the communication radius of each sector according to the link in each sector, thereby controlling the power of the antenna.
The invention discloses a directional ad hoc network power control method based on a minimum spanning tree, which comprises the following steps:
the method comprises the following steps: calculating to obtain a distance matrix
And calculating the distances between all the node pairs according to the coordinate information of the nodes of the whole network to obtain a distance matrix D. Where D (i, j) is the distance between node i and neighbor node j, if node j is not a neighbor node of node i, then D (i, j) = ∞.
Step two: calculating to obtain sector number matrix
For node i and node j in the network, the following operations are performed:
(1) Judging whether the node pair is a neighbor or not
If the distance D (i, j) = ∞ between the nodes i and j is not a neighbor, the sector number is set to 0, i.e. S (i, j) =0. If the distance between node i and node j is not infinite, they are neighbors, continue (2).
(2) Calculating the angle of the direction of the neighbor
As shown in fig. 2, a ray extending rightward from the node i is taken as a direction with an angle of 0, and counterclockwise is taken as a direction with an increasing angle. And (4) solving by using an arc tangent function, and correcting the node i and the node j into a real angle according to the relative position between the node i and the node j, wherein the result is a radian system.
The correction formula of the angle alpha is
Wherein, let the coordinate of the node i be (x) 1 ,y 1 ) The coordinate of the node j is (x) 2 ,y 2 ) Let Δ y = y 2 -y 1 And Δ x = x 2 -x 1 。
(3) Converting angles to sector numbers
The angle α is first divided by the angle size of one sector and rounded up so that the sector number starts from 1, and the result is written into the sector number matrix S. The sector number of the node i where the node j is located is S (i, j), there is
Wherein n is s Is the number of sectors in a node.
(4) And if all the nodes are traversed, entering the next step, and if not, returning to the step (1) to continue.
Step three: building a minimum spanning tree
The minimal spanning tree is constructed using Prim algorithm or Kruskal algorithm, and the adjacency matrix M containing all links in the minimal spanning tree is obtained. Where, for the node i and the node j, M (i, j) =1 indicates that there is one edge between the node i and the node j, and M (i, j) =0 indicates that there is no edge between the node i and the node j.
Step four: adding links
(1) And initializing the adjacent matrix for storing the link set into the matrix M obtained in the last step.
For node i within the network:
(2) The list of reachable neighbors of node i is initialized, a reachable neighbor refers to a neighbor that can be covered using maximum transmit power.
(3) And traversing the reachable neighbors of the node i according to the sequence from near to far, and acquiring the number j of the nearest neighbor.
(4) Reading the adjacency matrix, judging whether the edge < i, j > formed by the neighbor j and the node i is added into the link set, if so, jumping to (8), otherwise, continuing (5).
(5) And acquiring the number S (i, j) of the sector where the neighbor j is positioned, judging whether the number of the neighbors in the sector reaches the upper limit, if so, jumping to (8), and if not, continuing to (6).
(6) And judging whether the number of the neighbors of the node i reaches the upper limit, if so, jumping to (9), and if not, continuing (7).
(7) An edge < i, j > is written into the adjacency matrix M, i.e. let M (i, j) =1, this edge is a unidirectional link, pointing from node i to node j.
(8) If all the neighbor nodes of the node i are traversed, continuing to (9), otherwise returning to (3) and continuing.
(9) And (4) if all the nodes are traversed, entering the next step, and if not, returning to the step (2) to continue.
Step five: traversing the link set, deleting the unidirectional links in the adjacency matrix, i.e. deleting the edge < i, j > and the edge < j, i > when M (i, j) ≠ M (j, i), i.e. let M (i, j) =0 and M (j, i) =0. The directed graph is converted into an undirected graph so that all links within the network are bidirectional links.
Step six: and traversing all sectors of all nodes, and selecting the distance of the longest link in each sector of each node as the communication radius of the sector.
Has the advantages that:
1. the invention discloses a directed ad hoc network power control method based on a minimum spanning tree, which adopts a link constructed by the minimum spanning tree as the basis of the link, thereby ensuring the connectivity of the network.
2. The invention discloses a directional ad hoc network power control method based on a minimum spanning tree, which properly adds links for nodes, shortens the hop count between nodes in a network, limits the number of links in a sector by considering the characteristics of a directional antenna, reduces communication interference and improves the performance of the network.
3. The invention discloses a method for controlling the power of a directional ad hoc network based on a minimum spanning tree, which deletes a unidirectional link, ensures that the links constructed finally are bidirectional links, and avoids the problem that the network performance is influenced because the network topology becomes complicated due to the existence of the unidirectional link.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a schematic illustration of node antenna sector numbering;
figure 3 is a graph comparing the average hop count of the method of the present invention and the LMST algorithm in this example.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and examples. The technical problems and the advantages solved by the technical solutions of the present invention are also described, and it should be noted that the described embodiments are only intended to facilitate the understanding of the present invention, and do not have any limiting effect.
The application background of the embodiment is an ad hoc network for emergency communication, the network transmits information through a directional antenna, and coordinates of all nodes are known, and the invention is used for controlling the power of the node antenna.
The simulation parameters of this example are as follows: the node coordinates are randomly generated, the number of the nodes is 100 to 1000, and the number of the nodes is 10, the communication radius of the node is 200m, the node is located in an area of 1000m × 1000m, and the antenna beam of the node is divided into 6 sectors. The upper limit of the node neighbor number of the method is 6, and the upper limit of the sector neighbor number is 1.
The embodiment discloses a method for controlling the power of a directional ad hoc network based on a minimum spanning tree, which comprises the following steps:
the method comprises the following steps: calculating to obtain a distance matrix
And calculating the distances between all the node pairs according to the coordinate information of the nodes of the whole network to obtain a distance matrix D. Where D (i, j) is the distance between node i and neighbor node j, if node j is not a neighbor node of node i, then D (i, j) = ∞.
Step two: calculating to obtain sector number matrix
For node i and node j in the network, the following operations are performed:
(1) Judging whether the node pair is a neighbor or not
If the distance D (i, j) = ∞ between node i and node j is not a neighbor, the sector number is set to 0, i.e., S (i, j) =0. If the distance between node i and node j is not infinite, they are neighbors, continue (2).
(2) Calculating the angle of the direction of the neighbor
As shown in fig. 2, a ray extending rightward from the node i is taken as a direction with an angle of 0, and counterclockwise is taken as a direction with an increasing angle. And (4) solving by using an arc tangent function, and correcting the node i and the node j into a real angle according to the relative position between the node i and the node j, wherein the result is a radian system.
The correction formula of the angle alpha is
Wherein, let the coordinate of the node i be (x) 1 ,y 1 ) The coordinate of the node j is (x) 2 ,y 2 ) Let Δ y = y 2 -y 1 And Δ x = x 2 -x 1 。
(3) Converting angles to sector numbers
The angle α is first divided by the angle size of one sector and rounded up so that the sector number starts from 1, and the result is written into the sector number matrix S. The sector number of node i where node j is located is S (i, j), has
Wherein n is s Is the number of sectors in a node.
(4) And if all the nodes are traversed, entering the next step, and if not, returning to the step (1) to continue.
Step three: building a minimum spanning tree
The minimal spanning tree is constructed using Prim algorithm or Kruskal algorithm, and the adjacency matrix M containing all links in the minimal spanning tree is obtained. Where, for the node i and the node j, M (i, j) =1 indicates that there is one edge between the node i and the node j, and M (i, j) =0 indicates that there is no edge between the node i and the node j.
Step four: adding links
(1) And initializing the adjacent matrix for storing the link set into the matrix M obtained in the last step.
For node i within the network:
(2) The list of reachable neighbors of node i is initialized, a reachable neighbor refers to a neighbor that can be covered using maximum transmit power.
(3) And traversing the reachable neighbors of the node i according to the sequence from near to far, and acquiring the number j of the nearest neighbor.
(4) Reading the adjacency matrix, judging whether the edge < i, j > formed by the neighbor j and the node i is added into the link set, if so, jumping to (8), otherwise, continuing (5).
(5) And acquiring the number S (i, j) of the sector where the neighbor j is positioned, judging whether the number of the neighbors in the sector reaches the upper limit, if so, jumping to (8), and if not, continuing to (6).
(6) And judging whether the number of the neighbors of the node i reaches the upper limit, if so, jumping to (9), and if not, continuing (7).
(7) An edge < i, j > is written into the adjacency matrix M, i.e. let M (i, j) =1, this edge is a unidirectional link, pointing from node i to node j.
(8) If all the neighbor nodes of the node i are traversed, continuing to (9), otherwise returning to (3) and continuing.
(9) And (4) if all the nodes are traversed, entering the next step, and if not, returning to the step (2) to continue.
Step five: traversing the link set, deleting the unidirectional links in the adjacency matrix, i.e. deleting the edge < i, j > and the edge < j, i > when M (i, j) ≠ M (j, i), i.e. let M (i, j) =0 and M (j, i) =0. The directed graph is converted into an undirected graph so that all links within the network are bidirectional links.
Step six: and traversing all sectors of all nodes, and selecting the distance of the longest link in each sector of each node as the communication radius of the sector.
As shown in fig. 3, the comparison graph of the average hop count of the LMST algorithm and the method of the present invention is obtained under 10 conditions with the number of nodes from 100 to 1000, wherein an asterisk indicates the LMST algorithm, a circle indicates the method of the present invention, the average hop count is defined as the average of the minimum hop counts among all node pairs, and the upper limit of the number of node neighbors of the LMST algorithm is 6. In this example, the average hop count of the inventive method is reduced by an average of 48.42% in 10 cases compared to the LMST algorithm. Therefore, the link generated by the method of the invention has the advantages of lower hop count between network nodes, smaller delay and higher network performance.
The above detailed description is intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above detailed description is only exemplary of the present invention and is not intended to limit the scope of the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (1)
1. A method for controlling the power of a directional ad hoc network based on a minimum spanning tree is characterized by comprising the following steps:
the method comprises the following steps: calculating to obtain a distance matrix;
the implementation method of the first step comprises the following steps:
calculating the distances between all node pairs according to the coordinate information of the nodes of the whole network to obtain a distance matrix D; where D (i, j) is the distance between node i and neighbor node j, if node j is not a neighbor node of node i, then D (i, j) = ∞;
step two: calculating to obtain a sector number matrix;
the implementation method of the second step is as follows:
for node i and node j in the network, the following operations are performed:
(1) Judging whether the node pair is a neighbor or not
If the distance D (i, j) = ∞ between the node i and the node j is not a neighbor, the sector number is set to 0, i.e. S (i, j) =0; if the distance between the node i and the node j is not infinite, the nodes are neighbors, and the step (2) is continued;
(2) Calculating the angle of the direction of the neighbor
Taking a ray extending out of the node i to the right as a direction with an angle of 0, and taking the anticlockwise direction as a direction with an angle increasing; solving by using an arc tangent function, correcting the node i to be a real angle according to the relative position between the nodes j, and obtaining a radian system;
the correction formula of the angle alpha is
Wherein, let the coordinate of the node i be (x) 1 ,y 1 ) The coordinates of the node j are (x) 2 ,y 2 ) Let Δ y = y 2 -y 1 And Δ x = x 2 -x 1 ;
(3) Converting angles to sector numbers
Firstly, dividing the angle alpha by the angle of a sector, rounding up to enable the sector number to start from 1, and writing the obtained result into a sector number matrix S; the sector number of the node i where the node j is located is S (i, j), there is
Wherein n is s Is the number of sectors in a node;
if all the nodes are traversed, entering the next step, otherwise, returning to the step (1) and continuing;
step three: constructing a minimum spanning tree;
the third step is realized by the following steps:
constructing a minimum spanning tree by using a Prim algorithm or a Kruskal algorithm to obtain an adjacent matrix M containing all links in the minimum spanning tree; wherein, for the node i and the node j, M (i, j) =1 indicates that an edge exists between the node i and the node j, and M (i, j) =0 indicates that an edge does not exist between the node i and the node j;
step four: adding a link;
the implementation method of the fourth step is as follows:
(1) Initializing an adjacent matrix for storing a link set as a matrix M obtained in the previous step;
for node i within the network:
(2) Initializing an reachable neighbor list of the node i, wherein the reachable neighbor refers to a neighbor which can be covered by using maximum transmitting power;
(3) Traversing the reachable neighbors of the node i according to the sequence from near to far, and acquiring the number j of the nearest neighbor;
(4) Reading the adjacency matrix, judging whether an edge (i, j) formed by the neighbor j and the node i is added into the link set, if so, jumping to (8), otherwise, continuing (5);
(5) Acquiring the number S (i, j) of the sector where the neighbor j is located, judging whether the number of the neighbors in the sector reaches the upper limit, if so, jumping to (8), otherwise, continuing (6);
(6) Judging whether the number of neighbors of the node i reaches the upper limit, if so, jumping to (9), otherwise, continuing (7);
(7) Writing an edge < i, j > into an adjacent matrix M, namely enabling M (i, j) =1, wherein the edge is a unidirectional link and points to a node j from a node i;
(8) If all the neighbor nodes of the node i are traversed, continuing to the step (9), otherwise, returning to the step (3) to continue;
(9) If all the nodes are traversed, entering the next step, otherwise, returning to the step (2) and continuing;
step five: traversing the link set, deleting the unidirectional link in the adjacency matrix, namely deleting the edge < i, j > and the edge < j, i > when M (i, j) ≠ M (j, i), namely, making M (i, j) =0 and M (j, i) =0; converting the directed graph into an undirected graph, so that all links in the network are bidirectional links;
step six: and traversing all sectors of all nodes, and selecting the distance of the longest link in each sector of each node as the communication radius of the sector.
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