CN100452742C - Method for multi-address switch-in for moving target detection wireless sensing unit network - Google Patents

Abstract

This invention discloses one motion aim detecting wireless sensor network interface method, which comprises the following steps: According geography position, processing group and sending group points; processing group point time; adopting group TDMA communication type to send data in time lag of each point; adopting TDMA plus random means to reduce group communication data collision; if several points time achieves Tilde into sleep status as Sleep; when remaining energy of points less than gate values, then sending selection frame to other point for new group point.

Description

Method for multi-address switch-in for moving target detection wireless sensing unit network

Technical field

The invention belongs to wireless communication technology field, relate to the multiple access method of sensor node in the moving target detection wireless sensing device network.In moving target detection wireless sensing device network, this method can be used for a plurality of sensor nodes sharing wireless channel efficiently.

Background technology

Wireless sensor network be by one group of transducer with the wired or wireless network that distributed network Ad Hoc network mode constitutes, its objective is the information of perceptive object in the geographic area of perception collaboratively, collection and the processing network coverage, and be distributed to the observer.In the network of all Channel Sharing, multiple access access control MAC protocol reasonable in design is to guarantee one of key technology that network can operate as normal.The MAC agreement that is applicable to sensor network of broad research can be divided into two classes at present: based on the MAC agreement of conflict with based on there not being the MAC agreement that the conflict time division multiple access inserts TDMA.The former typical case's representative has IEEE802.11, S-MAC.IEEE802.11 adopts the carrier sense type multiple access CSMA/CA agreement that collision avoidance function is arranged, and can effectively handle concealed terminal and exposed terminal problem, and avoids conflict by the method that sends the reservation grouping as far as possible.Therefore and be not suitable for sensor network but the IEEE802.11 agreement does not solve the free time to be intercepted and crosstalks, and the data that promptly do not belong to this node are received the energy dissipation problem that is caused, and the realization of carrier sense also needs extra hardware device.The S-MAC agreement has been improved the IEEE802.11 agreement, and the dormancy by envoy's property dot cycle reduces the energy loss that the node free time intercepts.But S-MAC still uses the MAC agreement based on conflict, still can not effectively avoid the collision of data transmission when the data volume burst is big, thereby can not effectively reduces the energy consumption of node.Having based on the MAC agreement of TDMA does not have conflict and the few characteristics of control grouping, but its disadvantage be need be accurately synchronously and autgmentability relatively poor.

In moving target detection wireless sensing device network, it is big that network has sensor node quantity, the characteristics that density is big, and data is sudden very strong, when target appears at the sensor network investigative range,, have the motion that numerous sensor nodes successively detect target along with the motion of target, these sensor nodes all will transmit mass data to aggregation node Sink, and this can effectively solve the problem that mass data is transmitted simultaneously with regard to requiring the multiple access access protocol.In addition, owing to require to know timely at Sink node place the movement locus of target, this just requires the multiple access access protocol can guarantee the real-time of data when effectively transmitting data.Therefore, existing multiple access method can't satisfy the needs of network.

Summary of the invention

The objective of the invention is in order to solve the problem that prior art exists, a kind of multiple access method of suitable moving target detection wireless sensing device network is proposed, with the consumption of energy between the energy consumption that is used for reducing idle node and the balanced node, the reasonably access delay of control channel.

Technical scheme of the present invention is: adopt the strategy that hives off, the mode that adopts TDMA to add random back between the communication mode of employing TDMA, group in the group reduces the collision of communication data, and save the energy of sensor node by periodic dormancy and the strategy of changing cluster, Here it is method for multi-address switch-in for moving target detection wireless sensing unit network of the present invention, the specific implementation step of this method is as follows:

(1) according to the geographical position of node, node is hived off.

(2) hive off after, time shaft is pressed the form of TDMA superframe and is divided, in each TDMA superframe zero hour, cluster-head send synchronization frame carry out group interior nodes time synchronously.Synchronously, whether node begins to intercept has upper layer data to arrive.

(3) when the upper strata has data to arrive, if the destination node of data is the nodes in this group, then sending node sends these data in this group with in its time slot corresponding.If the destination node of data is group exterior nodes, then carry out step (4).

(4) sending node is inquired about its purpose group's who safeguards temporal information earlier, and last time slot of traffic frame sends upper layer data with random chance p in this group then; This random chance p satisfies: 0＜p＜1.

(5) after the above-mentioned time synchronized, if node is intercepted channel at T _IdleWithin, the upper strata does not have data to arrive, and this node sends sleep frame to other node in the group, shows that it enters resting state, and dormancy time is T _SleepAfter dormancy finished, node carried out again by the synchronization frame that receives cluster-head synchronously.Not dormancy of cluster-head.

(6) after cluster-head work a period of time, when its dump energy is lower than threshold value E _RThe time, this cluster-head sends election frame and elects new cluster-head to other node in the group, after other node is received the election frame that cluster-head sends in the group, replys the election frame and shows the dump energy of oneself.Cluster-head according to the dump energy information received select the dump energy maximum and be new cluster-head greater than the node of own dump energy, and upgrade E _RValue, otherwise do not change cluster-head.

Above-mentioned method for multi-address switch-in for moving target detection wireless sensing unit network, said node is hived off, the method of hiving off is: when initialization, whether the information of hiving off around intercepting earlier, a node is arranged, if do not have, then it can be used as cluster-head and begins to divide a group, and selects in the group number and the whole network is unique group number.According to the geographical position of cluster-head, the node in being in the cluster-head communication radius can add this group and select same group number and different groups in number, after the node number in the group reached the number of setting, hiving off finished; If the node number in group is more than the number of setting, then the back node that adds the group only has group number and does not have in the group number.

Above-mentioned method for multi-address switch-in for moving target detection wireless sensing unit network, said renewal E _RValue, its method is: the election frame that the node in the group sends by other node upgrades the own group node table of being safeguarded.By inquiry group node table, node can know whether this election is successful.After once successful election, E _RValue be updated to:

E _R＝E _{Vote_Remain}

E wherein _{Vote_Remain}When representing that this elects successfully, the dump energy of cluster-head is not if the election failure then changes cluster-head, E _RValue do not upgrade.

The advantage that the present invention compared with prior art has:

1, the present invention is based on the TDMA agreement, and when node had data to send, node at first sent in the group with in its time slot corresponding, has therefore effectively reduced the access delay that group's interior nodes sends.For communicating by letter between the group, owing to taked TDMA to add the method for random back, thus effectively reduced the transmission collision of group's intermediate node, need not any extra hardware spending.After adopting the present invention, the access delay of the channel access delay of group's interior nodes and group's intermediate node is much smaller than the channel access delay that adopts IEEE802.11 agreement posterior nodal point.

2, the present invention adopts periodic dormancy and in time changes the strategy of cluster-head.The periodicity dormancy has reduced node effectively and has intercepted the energy that is consumed because of the free time, and the strategy of in time changing cluster-head has been avoided in some groups, the situation that energy is exhausted in advance because cluster-head need send extra information, even thereby guarantee that in the network environment of high load capacity, high burst the present invention and S-MAC and IEEE802.11 specific energy mutually effectively prolong life-span of sensor node.

Description of drawings

Fig. 1 is the flow chart that the present invention realizes

Fig. 2 is the sensor node schematic diagram that does not hive off as yet among the present invention

Fig. 3 is a sensor node schematic diagram of having divided first group among the present invention

Fig. 4 is a sensor node schematic diagram of having divided two groups among the present invention

Fig. 5 is the schematic diagram of sensor node afterwards that finishes that hives off among the present invention

Fig. 6 is the structural representation of a TDMA superframe among the present invention

Fig. 7 is that the sensor node state changes schematic diagram among the present invention

Fig. 8 is under the same load situation, different MAC agreements to one jump delay performance influence simulation curve figure

What Fig. 9 was different p value to the double bounce delay performance influences simulation curve figure

Figure 10 is under identical free time situation, and different MAC agreements influences simulation curve figure to residue energy of node

Figure 11 is under identical dormancy time situation, and different MAC agreements influences simulation curve figure to residue energy of node

Figure 12 is α=0.5 o'clock, and the strategy of changing cluster influences simulation curve figure to residue energy of node

Figure 13 is α=0.25 o'clock, and the strategy of changing cluster influences simulation curve figure to residue energy of node

Embodiment

With reference to Fig. 1, it is the flow chart that the present invention realizes, can clearly be seen that the concrete steps of this method from flow chart.Now its course of work is described referring to Fig. 1～Fig. 7:

1. according to the geographical position of node, node is hived off.Divide group time in initialization, whether node has the information of hiving off around intercepting earlier, if do not have, then it can be used as cluster-head and begins to divide a group, and selects in the group number and the whole network is unique group number.Node in being in the cluster-head communication radius can add this group and select same group number and different groups in number.If node is received the information of other group again after adding certain group, then this node will ownly be demarcated and be group intermediate node, and write down the synchronizing information of other group, when being convenient to communicate by letter between the group and the time synchronized of other group.Because communication protocol and its application of sensor network are closely related, and the difference of node density will influence the energy consumption situation of node, and in actual applications, the number of group interior nodes can be set as required.Embodiments of the invention are set each group and are comprised 7 nodes, and consider that the communication radius when node is 15m, and node density is 0.01/m ²Application scenarios.When the node number in the group did not reach 7, node was selected in 0～6 in the group number at random, and the node in the same group is selected in the different groups number.When group's interior nodes number reaches after 7, the node that the back adds only obtains the group number of this group, and does not have in the group number, and these nodes will no longer add other group, but as the secondary node of this group, will enter dormancy then.After all nodes all obtained a group number, initialization was hived off and is finished.

2. after hiving off, time shaft is pressed the form of TDMA superframe and is divided, in each TDMA superframe zero hour, cluster-head send synchronization frame carry out group interior nodes time synchronously.The TDMA superframe is meant the base unit of tdma communication in the present invention, and each TDMA superframe all is made up of three parts: synchronization frame, traffic frame and election frame.Synchronization frame is used for the time synchronized of group interior nodes, is sent by cluster-head.In order to combine with hiving off of setting of embodiment, traffic frame is divided into 8 time slots again, and wherein preceding 7 time slots are used for communication in the group, and last time slot is as communication between the group.In a group, only have group in number node just obtain communication time slot in the group, node with it the correspondence communication time slot in send data; The election frame is used to elect new cluster-head, wherein comprises the dump energy information of node.

In each TDMA superframe zero hour, cluster-head all send synchronization frame carry out group interior nodes time synchronously.Receive the time of the node of synchronization frame, thereby guarantee the time synchronized between group's interior nodes according to the temporal information adjustment of receiving oneself.If the time step-out of certain node, then it can utilize the time of synchronization frame adjusting oneself next time.Synchronously, whether node begins to intercept has upper layer data to arrive.

3. in order to obtain group information of interior other node, the present invention designs each interior node of group and safeguards a group node table, and the group of interior other node of collection of record is interior number in the table, the state information of node etc.Because the node in group is a full-mesh, the group node table that therefore can utilize the existence of crosstalking to come new node more to safeguard.

When the upper strata had data to arrive, the behavior of node was: 1. inquire about the group node table and come whether the destination node of specified data is this group interior nodes, if then send data in the group with in its time slot corresponding.2. if the destination node of data is group exterior nodes, then carry out step 4.

4. if the destination node of data is group exterior nodes, the purpose group's that safeguards of query node temporal information then, this information is along with the synchronization frame of receiving other group upgrades, and last time slot of traffic frame sends data with random chance p in this group then.Because the step of the asynchronism(-nization) between each group, therefore the collision of communication is difficult to avoid between the group, and the task of MAC agreement is exactly as much as possible to reduce packet collisions, therefore sends with random chance p, can reduce to send between the group collision that produces to a certain extent.In addition, in order to guarantee the reliable communication between the group,, then send ACK information and confirm if destination node receives is correct data from group's exterior node, otherwise, send NAK information and denied.

5. after the cluster-head time synchronized, if node is intercepted channel at T _IdleWithin, the upper strata does not have data to arrive, and this node sends sleep frame to other node in the group, shows that it enters resting state, and dormancy time is T _SleepSleep frame comprises the node dormancy time, is used for notifying group time that interior this node of other node will enter resting state and want dormancy.Receive the information of the group node table that the node updates oneself of sleep frame is safeguarded.After dormancy finished, node carried out again by the synchronization frame that receives cluster-head synchronously.Because cluster-head need be safeguarded the synchronous of group interior time, so cluster-head can not enter dormancy.

6. after cluster-head work certain hour, when its residual energy value is lower than threshold value E _RThe time, E _RBe the dump energy of the successful node of last election, this cluster-head sends the election frame to other node in the group, comprises the dump energy information of cluster-head in the election frame.After other node is received the election frame that cluster-head sends in the group, reply the election frame and show the dump energy of oneself.If have such node in the group, its dump energy is greater than the dump energy of cluster-head, and then this is elected successfully, otherwise this election failure.If cluster-head is elected successfully, this cluster-head will become ordinary node so, and the node of dump energy maximum will be managed the synchronous of whole group as new cluster-head.

Because the existence of crosstalking, the node in the group can be received the election frame that other node sends, thereby upgrades the own group node table of being safeguarded.By inquiry group node table, node can know whether this election is successful.After once successful election, E _RValue be updated to:

E _R＝E _{Vote_Remain}

E wherein _{Vote_Remain}When representing that this elects successfully, the dump energy of cluster-head is not if the election failure then changes cluster-head, E _RValue do not upgrade.

In election next time, have only the dump energy of cluster-head to satisfy:

E _{R_new}＜E _{R_old}

Could carry out the election of a new round once more.E wherein _{R_new}Be the dump energy of cluster-head, E _{R_old}The dump energy of the cluster-head that the last election of expression is successful.

Fig. 2～Fig. 5 is the schematic diagram that node hives off among the present invention, therefrom can clearly be seen that above-mentioned concrete steps of hiving off.

Fig. 6 is the schematic diagram of a TDMA superframe among the present invention, each TDMA superframe is all by synchronization frame, and traffic frame and election frame three parts are formed, and wherein traffic frame is divided into 8 time slots again, S0～S6 time slot is used for communication in the group, and last time slot S7 is as communication between the group.

Fig. 7 is that the sensor node state changes schematic diagram among the present invention, and the state of node is constantly in dormancy with intercept middle switching as can be seen.

With reference to Fig. 8～Figure 13, in order to check performance of the present invention, the present invention and existing sensor network protocol IEEE802.11 and S-MAC have been carried out emulation, this emulation has mainly been studied under the high data burst network environment, when the value of random chance p and node dormancy time and two parameters of ratio α of free time not simultaneously, use behind the present invention influence to network performance and residue energy of node.

The simulating scenes of embodiments of the invention is: 100 groups of nodes are evenly distributed in 100 * 100m with the network that the mode of Ad Hoc distributes ²The zone in, whole network is communicated with.The communication radius of node is 15m, and node density is 0.01/m ²Simulation software is OPNET10.5, and emulation experiment is by finishing on the dominant frequency desktop computer that is 2.4G.Characteristic for the burst of analog sensor network data in Fig. 8～Figure 13, adopts simulation parameters as shown in table 1.Data packet length is obeyed the negative exponent distribution in the table.For quantitative description performance of the present invention, adopt a jumper connection to go into time delay, double bounce access delay in the present invention, these three indexs of residue energy of node are assessed its performance.

Table 1 performance simulation parameter

Simulation parameter	Numerical value	Simulation parameter	Numerical value
				The information source traffic intensity	100 packets/second	MAC layer bag is long	1088 bits
The Frame size	1024 bytes	The node primary power	10 joules
				Channel speed
	1×10 6Bps	Node sends consumed energy	80 milliwatts
				Information source has between the data generation	1 second	Node receives consumed energy	30 milliwatts
Between the information source free of data produces	99 seconds	The idle consumed energy of node	0.003 milliwatt

With reference to Fig. 8 and Fig. 9, Fig. 8 is under the same load situation, different MAC agreements to one jump delay performance influence simulation curve figure, wherein embodiments of the invention can be described as TBEA.What Fig. 9 was different p value to the double bounce delay performance influences simulation curve figure.As can be seen from Figure 8: be under the high bursty data situation of heavy load at network, i.e. λ=0.8192 o'clock, the jumper connection that TBEA of the present invention introduced is gone into time delay and one is jumped time delay much smaller than what the IEEE802.11 agreement introduced.This is because the IEEE802.11 agreement is based on the MAC agreement of CSMA/CA, each node is before the transmission data, all to intercept the busy not busy situation of channel, to determine whether and in next time slot, to send, if listen to the channel spare time, then continue to intercept a period of time, if channel still sends for the free time again; If find channel busy, then intercept channel always, become the free time up to channel.Be under the situation of high load capacity data burst and work as network, each node all wants access channel to send data in a short period of time, therefore, has introduced long time of intercept.And because TBEA of the present invention is based on the TDMA agreement of hiving off, each node sends data in the time slot corresponding with it this group, and therefore, the channel access delay is smaller.

For communicating by letter in the group, can obtain each user's wait time delay in the tdma system by present general M/G/1 type queuing system

Be:

$W_{\mathrm{TDM}}=\frac{m}{2(1-\mathrm{\λ})}$

Wherein, m is a number of time slots among the TDMA, time slot of each CU; λ is the packet arrival rate of whole system, and the value of λ satisfies: 0≤λ≤1.

As can be seen from Figure 9, under the different situation of random chance p, the value of double bounce access delay also has very big variation.For communicating by letter between the group, because a business time-slot comprises 8 time slots, communication takies preceding 7 time slots in the group, and communication takies last time slot between the group.If the data that have node mail to outside the group, must wait until that then last time slot of purpose group business frame sends with random chance p again, then the access delay T of node is:

$T=\frac{1}{8}\left(\underset{i=0}{\overset{7}{\mathrm{\Σ}}}i\right)(p+2(1-p)p+3{(1-p)}^{2}p+...)$

Wherein i is the timeslot number that node need be waited for, does not consider that here node is in the remaining time of this time slot.Because sending node may be waited in 0～7 time slot any one, so probability is

(p+2 (1-p) p+3 (1-p) ²P+ ...) expression once sends successfully, twice transmission success ... probability, therefore can obtain double bounce access delay W _TotalCalculating formula be:

W _Total＝W _TDM+T

Access delay is the intrinsic access delay W by TDMA in the group of node _TDMDecision, the difference because of the p value does not change.But different p has determined the time delay T of transmission between the group, if the p value is less, then under the light situation of network load, node need wait for that the long period could send data; If the p value is bigger, then when node sends data with big probability, may increase the transmission collision.

With reference to Figure 10, it is under identical free time situation, and different MAC agreements is to the simulation curve that influences of residue energy of node, wherein fixing T _IdleValue, T _Idle=10 seconds.Among the figure, PS refers to adopt the algorithm of dormancy strategy; WS refers to not adopt the algorithm of dormancy strategy.As can be seen from the figure: the present invention compares with S-MAC with IEEE802.11, has effectively saved the energy of node.Because the IEEE802.11 agreement is based on the MAC agreement of CSMA/CA, the big energy of node consumption is used for Channel Detection, and the present invention is based on the TDMA agreement, therefore the energy loss of effectively having avoided Channel Detection to bring.The slightly inferior properties of WS strategy is in S-MAC, and this is because node is intercepted most energy charges in the free time.And after taking the PS strategy,, thereby slowed down the consumption of dump energy because periodic dormancy has reduced the idle time of intercepting, its performance is better than S-MAC.When node dormancy time and node free time than α value not simultaneously, the performance of agreement is also had Different Effects, the node dormancy time of the big more correspondence of α is long more.

With reference to Figure 11, it is under identical dormancy time situation, and different MAC agreements influences simulation curve figure to residue energy of node, wherein fixing T _SleepValue, T _Sleep=5 seconds.Among the figure, PS refers to adopt the algorithm of dormancy strategy: WS to refer to not adopt the algorithm of dormancy strategy.As can be seen from the figure: the present invention compares with S-MAC with IEEE802.11, can effectively save the energy of node, and different α values is also influential to the consumption of node energy.In the case, if α hour, promptly free time long, then node is in idle condition for a long time, effectively conserve energy; And the α value is when big, and what node was frequent switches to resting state from state of activation, and handoff procedure also will consume lot of energy.

With reference to Figure 12 and Figure 13, they be the α value not simultaneously, the strategy of changing cluster influences simulation curve figure to residue energy of node, wherein, WVS refers to not change the algorithm of cluster strategy; VS refers to change the algorithm of cluster strategy.From figure we as can be seen, the α value not simultaneously, the VS strategy is compared with the WVS strategy, the energy consumption between can effective balanced node.In the algorithm of WVS strategy, as the cluster-head that initialization is hived off, consumed the energy of Duoing than other node in the group, this is that therefore, its energy is easier to be exhausted because cluster-head need send extra control information.If this node is the task that a key node in the network or this node are being born group interior convergence, then because the exhausting fast of this node energy, will cause the obstruction of whole network data or overlying roaduay by failure.And after adopting the VS strategy, after the certain energy of cluster-head consumption, can re-elect new cluster-head.Like this, by continuous replacing cluster-head, the consumption of the node energy in the feasible group is tending towards evenly, thereby has reduced the probability of happening of the depleted incident of energy elder generation of certain node in the group.

Claims (3)

1. method for multi-address switch-in for moving target detection wireless sensing unit network, the specific implementation step of this method is as follows:

(1) according to the geographical position of node, node is hived off;

(2) hive off after, time shaft is pressed the form of TDMA superframe and is divided, in each TDMA superframe zero hour, cluster-head send synchronization frame carry out group interior nodes time synchronously, synchronously after, whether node begins to intercept has upper layer data to arrive;

(3) when upper layer data arrives, if the destination node of data is the nodes in this group, then sending node sends these data in this group with in its time slot corresponding; If the destination node of data is group exterior nodes, then carry out step (4);

(4) sending node is inquired about its purpose group's who safeguards temporal information earlier, and last time slot of traffic frame sends upper layer data with random chance p in this group then, and this random chance p satisfies: 0＜p＜1;

(5) after the above-mentioned time synchronized, if node is intercepted channel at T _IdleWithin, the upper strata does not have data to arrive, and this node sends sleep frame to other node in the group, shows that it enters resting state, and dormancy time is T _Sleep, after dormancy finished, node carried out synchronously not dormancy of cluster-head again by the synchronization frame that receives cluster-head;

(6) after cluster-head work a period of time, when its dump energy is lower than threshold value E _RThe time, this cluster-head sends election frame and elects new cluster-head to other node in the group, after other node is received the election frame that cluster-head sends in the group, replys the election frame and shows the dump energy of oneself

Cluster-head according to the dump energy information received select the dump energy maximum and be new cluster-head greater than the node of own dump energy, and upgrade E _RValue, otherwise do not change cluster-head.

2. method for multi-address switch-in for moving target detection wireless sensing unit network according to claim 1, it is characterized in that said node being hived off, the method of hiving off is: when initialization, whether the information of hiving off around intercepting earlier, a node is arranged, if do not have, begin to divide a group by it as cluster-head, and select in the group number and the whole network is unique group number, geographical position according to cluster-head, node in being in the cluster-head communication radius can add this group and select same group number and different groups in number, after the node number in the group reached the number of setting, hiving off finished; If the node number in group is more than the number of setting, then the back node that adds the group only has group number and does not have in the group number.

3. method for multi-address switch-in for moving target detection wireless sensing unit network according to claim 1 is characterized in that said renewal E _RThe method of value be: the election frame that the node in the group sends by other node upgrades the own group node table of being safeguarded, by inquiry group node table, node can be known whether success of this election, after once successful election, E _RValue be updated to:

E _R＝E _{Vote_Remain}

E wherein _{Vote_Remain}When representing that this elects successfully, the dump energy of cluster-head is not if the election failure then changes cluster-head, E _RValue do not upgrade.

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