Background technology
The special wireless network that wireless sensor network is comprised of great deal of nodes, it has realized the functions such as the data sensing under complex environment, collection and analysis.Node in wireless sensor network has the features such as volume is little, computing capability is limited, the communication of dependence radio wave, powered battery, these characteristics have determined that wireless sensor network will work in optimum mode in specific environment, also have many problems to be solved.It is optimization method important in wireless sensor network that topology is controlled.The sleep of knot modification signal transmission power and plan node is the main method during topology is controlled.
In wireless sensor network, the main purpose that topology is controlled is guaranteeing under the prerequisite of network connectivty, by improving topology of networks, reach optimized network performance, improve stability, fall low-energy-consumption, extend the objects such as network lifetime.In different research, emphasize particularly on different fields, now these targets be summarized as follows:
Connective: the basic demand that topology is controlled is the connectedness that guarantees network, otherwise the connective topology of having destroyed network is controlled and will be had influence on the more availability of upper layer application.This target can more clearly be expressed as, and topological control will guarantee that the node that can reach by some jumpings in maximum transmitted figure still can reach in the topological control chart generating.
Energy efficiency: when sending node transmits data to receiving node, require the expenditure of energy, energy expense ratio in the gross energy expense of node during this data transmit is very large, and, guarantee that the needed least energy expense of normal communication is along with the growth of distance is exponential growth.Therefore, reduce normally topology of energy expense as far as possible
Be controlled at the main target guaranteeing on connective basis.
Reduce and disturb: the sharing of propagation medium and opening between node, may bring communication to disturb, also may
The conflict that causes data to send, thus a large amount of re-transmission produced, and these all can cause extra energy expense.So controlling the schemes of research, many topologys is intended to reduce internodal communication and disturb by the signal transmission power of node is rationally set.
The sparse property of network: the computing capability of radio node is limited, so guarantee that the sparse property of network is most important for the extensibility that improves network.By guaranteeing the sparse property of network, i.e. the linear relationship of number of links and nodes, the complexity in the time of can reducing Routing Protocol and carry out Route Selection, improves the autgmentability of network.
In recent years, distributed wireless sensor network applied because of it attention that is subject to research field widely.Field in the common application such as environmental monitoring, Industry Control, Smart Home, distributed wireless sensor network is often higher than centralized efficiency.But along with going deep into of research, we are faced with and further raise the efficiency and cost-effective demand pressure.In research and application, introduce mobile node at present also more rare, but the application of mobile node becomes break-through point and the bright spot of solution wireless sensor network great number of issues gradually.The present invention combines distributed control and mobile node, based on asymmetric Energy distribution, has proposed the Topology control scheme of a kind of high efficiency, self-organizing, in research and practical application area, has higher reference value.
Summary of the invention
technical problem: the object of the invention is to apply mobile sensor node and realize a kind of efficient wireless sensor network topology control protocol.The present invention is based on clustering two-level network structure, in agreement running, introduce distributed thought, use asymmetric Energy distribution, realize connectedness, stability and low-energy-consumption that wireless sensor network is good, to extending network lifetime, play a key effect.This agreement provides a kind of new design philosophy for designing efficient wireless sensor network topology control, has solved the deficiency of conventional topology control method.
technical scheme:sub-clustering topology control method based on asymmetric Energy distribution and mobile node of the present invention adopts mobile node to improve the weak connection that packet loss is high based on geographical position, asymmetric Energy distribution is introduced to the competition of Distributed cluster head, the connectivity and the spreadability that have greatly improved network, postponed network lifetime.The present invention use two-stage time wheel sheet mode carry out bunch in static topology control, make two close ordinary nodes of position externally show as a node, further saved energy consumption.
one, architecture
Wireless sensor network clustering topology based on asymmetric Energy distribution and mobile node of the present invention
Control method has two-stage Cluster Networks structure.The node using in wireless sensor network is divided into mobile node and ordinary node.Two very near ordinary nodes of geographical position will match alternation, externally show as a node.In network, mobile node participates in the competition of bunch head based on dump energy, and relevant ordinary node maintains clustering architecture, the lifetime of prolonging wireless sensor network.In wireless sensor network running, idle mobile node carries out data retransmission by the junction that moves to high packet loss, improves the connectedness of network.
Node in described topology control method is divided into mobile node and ordinary node, and node possesses the ability in perception oneself and neighbor node geographical position.The fixing signal covering radius of employing of ordinary node, the signal of mobile node can cover all nodes.
Described asymmetric Energy distribution refers to that mobile node has the energy far above ordinary node, and the probability that mobile node becomes bunch head in a bunch competition process is greater than ordinary node.
In described topology control method, each mobile node is safeguarded idle mobile node table, idle mobile node table
In inundation mode, dynamically update.
two, method flow
1, netinit
(1) ordinary node pairing
After the random placement node of target area, two ordinary nodes that geographical position distance is less than specific threshold match, and form two a pair of node alternations, externally show as a node.
In described topology control method, any one ordinary node can only participate at most in a pairing process, node form to and between there is no common node.
(2) select bunch head
Start aggregation node, aggregation node oneself is aggregation node to whole Web broadcast.Ordinary node is according to connecing own geographical position, neighbor node number and oneself whether becoming a bunch head apart from the actual range decision of aggregation node.
In described topology control method, mobile node does not participate in the competition and becomes a bunch head in netinit process.
(3) formation bunch
After bunch head produces, each bunch of head oneself becomes " bunch head " in inundation mode to whole network notifications, bunch head that mobile node and ordinary node are nearest according to energy and distance relation chosen distance oneself, formation clustering architecture.Mobile node statistics in bunch obtains each mobile node information, forms idle mobile node Table I dleTable.
Described idle mobile node Table I dleTable has comprised idle mobile node and the geographical location information thereof in network.
2, bunch maintenance
bunch (1) in, static topology is controlled
In bunch, ordinary node is according to the work of time wheel sheet mode, if bunch in there is mobile node, mobile node is in running order all the time.
(2) mobile node topology is controlled
After clustering architecture forms, network starts transmission information.Nodes calculates the packet loss of weak junction interdependent node with triggering mode, until this junction obtains packet loss, drop to tolerable degree and just stop calculating packet loss.In this process, if packet loss is greater than set threshold value, bunch head of this node to its place bunch submitted service request to.
1., after a bunch head receives service request, bunch head judges the mobile node number Count in this bunch:
If mobile node number Count is more than or equal to specific threshold in this bunch, bunch head only sends to the idle mobile node in this bunch by service request.If there is no idle mobile node in this bunch, ignore service request.
If mobile node number Count is greater than 0 and be less than specific threshold in this bunch, bunch head sends to the mobile node in this bunch by service request information.
If mobile node number Count equals 0 in this bunch, bunch head sends to adjacent clusters head by service request in multi-hop mode, until send to bunch head that its bunch contains mobile node.This bunch of head judges whether oneself is mobile node: if fruit is not that mobile node just sends to service request a mobile node in this bunch at random; If this bunch of head is that mobile node does not just forward.
2. the mobile node that receives service request judges whether oneself is busy condition:
If this mobile node is in idle condition Idle, this mobile node drives and oneself to the middle geographical position of weak connection, carries out data retransmission, strengthen connecting, the operating state that oneself is set is simultaneously busy Busy, and inundation notifies each mobile node to upgrade idle mobile node Table I dleTable.
If the idle mobile node table that this mobile node, in busy condition Busy, maintains according to it is transmitted to a nearest idle mobile node of distance objective position by service request, and start the idle mobile node Table I dleTable of renewal.
In described topology control method, the geographical location information of two nodes that service request information has comprised lost data packets.
The idle mobile node table maintaining in mobile node of the present invention does not comprise this mobile node self.
3, bunch reconstruct
(1) triggering of restructuring procedure
Bunch head notice bunch interior nodes is carried out a bunch reconstruct.When prevariety head according to bunch in the dump energy of each node and neighbor node number select new bunch of head.Dump energy is higher, bunch interior nodes that neighbor node number is more, and the probability that becomes new bunch of head is higher.Described method adopts asymmetric Energy distribution, and mobile node has higher than ordinary node energy, and the likelihood ratio ordinary node that the mobile node in bunch becomes new bunch of head is large.
(2) generation of new bunch of head
During restructuring procedure that each bunch restarted bunch, whether first judgement has mobile node in giving bunch.If there is mobile node, mobile node is with the leader cluster node that participates in the competition of the probability higher than ordinary node.Mobile node in this bunch carries out bunch head while selecting receiving, and the state of self is set to idle Idle, and upgrades idle mobile node Table I dleTable.In the selection course of new bunch of head, if there is mobile node to become a bunch head, the operating state of this mobile node is set to busy Busy, and upgrades idle mobile node Table I dleTable.
Restructuring procedure in agreement of the present invention bunch completes and in this bunch, reselects a bunch head.
Sub-clustering topology control method based on asymmetric Energy distribution and mobile node of the present invention, in clustering two-stage topology control procedure, introduce distributed thought, use the mobile node of asymmetric Energy distribution, realize the prolonging wireless sensor network lifetime, to playing a key effect, the step that described method comprises is:
First stage, netinit, completes and selects for the first time bunch head and form clustering architecture:
Step 1). the pairing of ordinary node: the geographical position of node perceived neighbor node, two close ordinary node self-organizings of distance match, alternation in the lifetime afterwards;
Step 1). select bunch head: start aggregation node, aggregation node, according to the dump energy of ordinary node and geographical location information, produces equally distributed leader cluster node in ordinary node;
Step 2). bunch formation: each wireless sensor node is according to bunch head that chosen distance oneself is nearest that is related to of energy and distance, forms bunch;
Second stage, bunch maintenance: after clustering architecture forms, network starts according to relevant Routing Protocol transmission information, and concrete topology control method is as follows:
Step 3). in bunch, static topology is controlled: in bunch ordinary node according to time wheel sheet mode work, if bunch in there is mobile node, mobile node is in running order all the time;
Step 4). mobile node topology is controlled: the node of link place that packet loss is large, to bunch head that bunch contains mobile node, submit service request to, the relevant mobile node of request moves to the place that packet loss is large and carries out data retransmission;
Phase III, bunch reconstruct:
Step 5). the triggering of restructuring procedure: the reconstruct that under bunch head counting and particular case, service request unsuccessfully triggers bunch;
Step 6). the generation of new bunch of head: bunch reconstruction task start after, when prevariety head according to bunch in dump energy and the neighbor node number of each node select new bunch of head; After new bunch of head produces, new bunch of head will be taken over the connectivity of old bunch of head maintenance with other bunch of head or aggregation node;
In sum, in aggregation node directs network, complete after initialization, network has just started complete self-organizing operation, bunch restructuring procedure in, bunch head that completes node motion and asymmetric energy is selected.
Ordinary node in described bunch, according to the work of time wheel sheet mode: ordinary node sensing neighbor node geographical position in bunch, completes not cross match; Two nodes of pairing are by cycle alternation, and cooperation is finished the work; Each node of pairing to other unpaired bunch in ordinary node in the mode of equality, carry out time wheel sheet, alternately to bunch head, submit a packet to.
The node of link place that packet loss is large, to bunch head that bunch contains mobile node, submit service request to, this bunch of head bunch in mobile node outnumber threshold value and during all in busy condition, ignore service request, otherwise the mobile node of bunch head in service request is sent to bunch; This mobile node judges own operating state: if in idle condition, mobile node moves to the middle geographical position of two nodes that packet loss is large, carries out data retransmission; If in busy condition, in the idle mobile node table that mobile node is safeguarded at oneself, select a mobile node that distance objective geographical position is nearest, and send service request to it, move it target geographic position, the middle geographical position of two nodes that packet loss is large.
The reconstruct that under bunch head counting and particular case, service request unsuccessfully triggers bunch: the number of data packets of current leader cluster node record oneself transmission, bunch number of data packets that hair send reaches after specific threshold, start a bunch reconstruction task and pack task waiting list into, bunch head after completing current data transformation task, the reconstruction task of dispatching in task waiting list and starting bunch; When the packet loss being connected between prevariety head and other bunch of head surpasses threshold value and produces service request, when the movable joint of prevariety head in its bunch, count while being more than or equal to set threshold value and each mobile node all in busy condition, ignore service request and trigger the reconstruct that this bunch carries out bunch.
beneficial effect:the present invention is based on mobile sensor node and realize a kind of efficient wireless sensor network topology control protocol, mobile sensor node moves to the local Strengthens network that packet loss is high and connects.The present invention is based on clustering two-level network structure, in agreement running, introduce distributed thought, use asymmetric Energy distribution, save to greatest extent ordinary node energy, extend network lifetime, improved network connectivty.Specifically, Routing Protocol of the present invention has following beneficial effect:
(1) sub-clustering topology control method of the present invention is introduced mobile node in the network configuration of sub-clustering, utilize the mobility of node, drive mobile node to there being the place of demand to carry out package forward, strengthened connection, reduce the loss of packet, safeguarded the coverage of network.
(2) described topology control method has limited the maximum mobile node number that can have in each bunch, under the mode of self-organizing, has realized being uniformly distributed of mobile node, has greatly ensured possibly the lifetime of each bunch and the coverage of network.
(3) described topology control method calculates packet loss and stops calculating packet loss in the mode triggering, directly effective, is conducive to save energy consumption.
(4) in described topology control method, each mobile node is safeguarded an idle mobile node table, and is responsible for dynamically updating by mobile node, has alleviated the work load of ordinary node, is beneficial to the lifetime that extends network.
The use of idle mobile node table, has realized the nearest idle mobile node in fast searching distance objective position.
(5) in the method for the invention, ordinary node is used fixing signal covering radius, and mobile node letter
Number can cover global network, reduce power and controlled computing relay and the energy consumption bringing.
(6) the present invention uses bunch head competition under asymmetric Energy distribution condition, the probability that the node that dump energy is more becomes bunch head is larger, so mobile node becomes may increasing of bunch head, realized and saved to greatest extent ordinary node energy, extend network lifetime.
(7) in described its bunch of sub-clustering topology control method, ordinary node is used two-stage time wheel sheet working method, has further saved ordinary node energy consumption.
Embodiment
For a more detailed description to accompanying drawing some embodiment of the present invention below.
1, netinit
(1) ordinary node pairing
Each ordinary node calculates respectively oneself to the distance of each common neighbor node based on geographical location information.As shown in Figure 1, if the distance d of two ordinary nodes is less than specific threshold value, two nodes match, otherwise unpaired.Any one ordinary node can only participate at most a centering, and what node formed does not intersect to having.
Form two right nodes according to the mode alternation of time wheel sheet, as shown in Figure 2.Two right nodes are configured to use identical No. ID and identical geographical location information automatically, externally show as a node.
(2) select bunch head
Start aggregation node, aggregation node oneself is aggregation node to whole Web broadcast.Ordinary node is according to connecing own geographical position, neighbor node number and oneself whether becoming a bunch head apart from the actual range decision of aggregation node.As shown in Figure 2, bunch head producing in initialization procedure is all ordinary node.
(3) formation bunch
After bunch head produces, each bunch of head oneself becomes " bunch head " in inundation mode to whole network notifications, bunch head that mobile node and ordinary node are nearest according to energy and distance relation chosen distance oneself, formation clustering architecture.Bunch head is added up the mobile node number Count in this bunch.
Mobile node statistics in bunch obtains idle mobile node and the geographical location information thereof in network, forms idle mobile node Table I dleTable.
2, bunch maintenance
After clustering architecture forms, network starts according to relevant Routing Protocol transmission information, and concrete topology control method is as follows:
bunch (1) in, static topology is controlled
In bunch, ordinary node is according to the work of time wheel sheet mode, if bunch in there is mobile node, mobile node is in running order all the time.Wherein embrace two right ordinary nodes externally to show as the mode of a node, receive the timeslice that bunch head distributes.
(2) mobile node topology is controlled
1. in message transmitting procedure, the node (comprising ordinary node and mobile node) that sends packet is found data-bag lost for the first time, while not receiving ACK information, trigger the packet loss that this node starts periodically to calculate this link place.This process until the continuous certain number cycle of packet loss just with triggering mode, finish during lower than threshold value.
2. in this process, if packet loss is greater than set threshold value, bunch head of this node to its place bunch submitted service request (if this node is submitted to oneself for bunch head) to.
3., after a bunch head receives service request, bunch head judges the mobile node number Count in this bunch:
If mobile node number Count is more than or equal to specific threshold in this bunch, bunch head only sends to the idle mobile node in this bunch by service request, as shown in Figure 3.If there is no idle mobile node in this bunch, ignore service request, as shown in Figure 4.
If mobile node number Count is greater than 0 and be less than specific threshold in this bunch, bunch head sends to the mobile node in this bunch by service request information, as shown in Figure 5.
If mobile node number Count equals 0 in this bunch, as shown in Figure 6, bunch head sends to adjacent clusters head by service request in multi-hop mode, until send to bunch head that its bunch contains mobile node.This bunch of head judges whether oneself is mobile node: if fruit is not mobile node, just service request is sent at random to a mobile node in this bunch; If this bunch of head is that mobile node is not just transmitted to other nodes in this bunch.
4. the mobile node that receives service request judges whether oneself is busy condition:
If this mobile node is in idle condition Idle, this mobile node drives and oneself to the middle geographical position of weak connection, carries out data retransmission, strengthens connecting, and as shown in Figure 3, Figure 5 and Figure 6, the work of oneself is set simultaneously
As state, be busy Busy, inundation notifies each mobile node to upgrade idle mobile node Table I dleTable.
If the idle mobile node table that this mobile node, in busy condition Busy, maintains according to it is transmitted to a nearest idle mobile node of distance objective position by service request, and start the idle mobile node Table I dleTable of renewal.
3, bunch reconstruct
Bunch reconstruct concrete steps as follows:
(1) triggering of restructuring procedure
Bunch restructuring procedure can be triggered by two kinds of modes:
The triggering mode one of bunch restructuring procedure:
1. the node of elected bunch head records the number of data packets that oneself sends in the register Reg of oneself.
If 2. bunch head is mobile node, bunch head packs a startup bunch reconstruction task into task waiting list after sending M packet, as shown in A in Fig. 7 bunch;
If 3. bunch head is ordinary node, bunch head packs a startup bunch reconstruction task into task waiting list after sending N packet, as shown in B in Fig. 7 bunch.Bunch head after completing current data transformation task, the reconstruction task of dispatching in task waiting list and starting bunch.
Described Packet Generation number is set to M according to the energy relationship of mobile node and ordinary node and is greater than N.
The triggering mode two of bunch restructuring procedure:
Bunch head in the own process data packet sending of counting, occur bunch head to the packet loss connecting between bunch head over threshold value and produce service request.If be responsible for to calculate this link packet loss bunch, the movable joint in its bunch is counted and is more than or equal to set threshold value and each mobile node all when busy condition Busy, bunch head is ignored service request and is triggered the reconstruct that this bunch carries out bunch, as shown in Figure 8.
(2) generation of new bunch of head
1. bunch head sends and starts a reconstructed message to bunch interior nodes, the reconstruct that notice bunch interior nodes is carried out bunch.
Bunch 2. the mobile node in carries out bunch head while selecting receiving, and the state of self is set to idle Idle, and upgrades with mobile node in inundation mode informing network the idle mobile node Table I dleTable safeguarding separately.
3. a bunch head judge to bunch in whether have mobile node.If there is mobile node in this bunch, mobile node is with the leader cluster node that participates in the competition of the probability higher than ordinary node.
4. when prevariety head, with dump energy, many and neighbor node number mostly is principle, selects new bunch of head.
If 5. there is mobile node to become new bunch head, the operating state of this mobile node is set to busy
Busy, and in informing network, mobile node upgrades idle mobile node Table I dleTable.
6., after new bunch of head produces, new bunch of head taken over old bunch of head and kept the connectivity with other bunch of head or aggregation node.