CN101835234B - Industrial wireless sensor network communication method based on relay nodes - Google Patents

Abstract

The invention relates to an industrial wireless sensor network communication method based on relay nodes, belonging to the field of sensor network communication. A network management center distributes a preferred communication path resource according to the request of a source node and current network state information, selects a relay node and a relay path according to constraint conditions, and distributes the communication resources of the relay path. In the communication process, when the relay node receives the negative response from the node of the last hop, the probability that the transmission delay exceeds a threshold is reduced, the frequency of retransmission initiated by the source node is reduced, and the energy consumption for retransmitting data is reduced. Meanwhile, the relay node also dynamically changes the priority of data packets, avoids delaying transmission of the data packets again, and ensures that the data packets reach a destination node in delay requirements. By adopting collaboration among the relay node, the destination node and the network management center, the packet loss rate is reduced, the frequency of retransmission initiated by the source node is reduced, and the energy consumption for retransmitting data is reduced.

Description

A kind of industrial wireless sensor network communication method based on relay nodes

Technical field

The present invention relates to industrial wireless sensor network, relate in particular to the communication for coordination technology in the industrial wireless sensor network communication field.

Technical background

Industrial wireless sensor network is the more recent application field of wireless sensor network technology, compares with sensor network to have outstanding feature.The industrial wireless sensor network standard of at first formulating, demand from the industry spot application, adopt centralized (such as ISA100), perhaps concentrate the hybrid network management (WIA-PA) of decentralized photo combination, strict management is carried out in internodal communication.Secondly the operational environment of industrial wireless sensor network is complicated, and except various Communication Jamming, the restriction of working space and various external factor such as vehicle, Big Gold metal elements, plant equipment etc. are covered the inter-node communication interruption that causes in addition.The interstitial content of industrial wireless sensor network is less in addition.

Industry spot is that the application of industrial wireless sensor network has proposed hard real time and reliability requirement.Wherein space diversity (Spatial Diversity) is wherein important technical field.In current research, the methods such as multi-path transmission, Mesh net, redundant path, communication for coordination have been proposed mainly.Each node in the multi-path transmission technology on the communication path can both select mulitpath to carry out the transmission of packet, and each node is selected fastest transmission path according to the time delay of packet.Although this mode can greatly improve real-time and the reliability of communication, can consume a large amount of communication resources and energy, reduce the throughput of network.Although the Mesh net can guarantee internodal K connection degree, usually need to take a large amount of communication resources.Limited at the communication resource, especially in the limited situation of number of nodes, just can not guarantee the performance of Mesh net can not satisfy the requirement of industry wireless network.

The path redundancy technology is the most used also the simplest technology in the industry wireless network, and in the situation that internodal prefered path lost efficacy, node is selected to be provided with alternative path in the routing table.But can not finish at alternative path in the situation of communication, communicating by letter between source node and destination node just accused with failure.Above-mentioned technology has requirement to the quantity of the topological sum node of network.Such as there being many disjoint paths between multi-path transmission specification requirement source node and destination node.In the unappeasable situation of precondition, performance can descend greatly.And industry wireless network is compared with the sensor network of opening, all can be restricted on space and network size.

No matter adopt real-time and the reliability of which kind of technology raising industrial wireless sensor network communication, all can not avoid the situation of bust this fully.In case enter re-transmission, just need to adopt the mode of being initiated re-transmission by source node, this mode not only can consume larger energy, and in the situation that does not have to get rid of at network failure, simply retransmitting can not transmission success.In wireless sensor network technology, the network that adopts relay nodes to carry out communication for coordination adopts distributed algorithm usually, although can not need to carry out basis instrument, and can make real-time reaction to the variation of network environment.But in the situation of multi-hop, owing to affect the many factors (such as the transmission interference between multihop path selection, the multi-hop node, the number of retransmissions of multi-hop node etc.) of node transmission rate, reliability, real-time, be difficult to obtain the value of optimization.Therefore mostly be used in the occasion of single-hop relay.The relay nodes function singleness can only be carried out data cached re-transmission simultaneously.The use of relay nodes fails to solve relay nodes and source node is all received the conflict that repeat requests causes.And be that with conflicting of industrial wireless sensor network maximum distributed algorithm needs free initiating communication.Utilize merely the transmission speed of the message that node location estimation receives in [MMSPEED:Multipath Multi-SPEED Protocol for QoS Guarantee ofReliability and Timeliness in Wireless Sensor Networks], select accordingly the path forwarding data of different transmission speeds.This mode is carried out the judgement of speed to each single node, causes easily the load imbalance of node.Above-mentioned technology is applied to the needs that industrial wireless sensor network all can not adapt to industry spot, can not form perfect solution on the one hand, does not meet on the other hand the demand that the industrial wireless sensor network technology is used.

Summary of the invention

Technical problem to be solved by this invention is, existing wireless sensor network use relay nodes technology is failed for the problem of industrial wireless sensor network technical characterstic, easily cause conflict, energy that node transmits simultaneously to consume method excessive, the distributed collaboration transmission when relay nodes and source node are all received repeat requests and cause the problems such as node load is unbalance, a kind of industrial wireless sensor network communication method based on relay nodes is provided, improves real-time and the reliability of industrial wireless sensor network.

The technical scheme that the present invention addresses the above problem is communicating by letter between relay nodes, network management center, destination node coordination assurance source node and destination node.Network management center plays the hard core control effect in the present invention, the communication process of initialization, optimization and management node indirect force node.Network management center NM selects prefered path according to the request of source node and current network state information with the method for source routing; Selection comprises relay nodes R, destination node D, the relay path of intermediate node set; NM docking power path and prefered path are carried out resource distribution; By relay Path Connection source node and destination node.And set up communication between source node and the destination node.Can select node on the prefered path as relay nodes, also can select with prefered path on the adjacent node of node.When relay nodes belongs to prefered path, from the intermediate node of prefered path, choose destination node D with the disjoint path of prefered path namely two paths do not have identical intermediate node; In above-mentioned disjoint path, select to satisfy condition delay _RD+ delay _SR＜deadline _SDIntermediate node as relay nodes, wherein, intermediate node postpones delay to the path transmission of destination node D _RD, source node postpones to be delay to the path transmission of intermediate node _SR, the out-of-service time of packet is deadline _SDSelect the arbitrary node i among the node set I, calculate LT effective time in relay path, the battery life in relay path satisfies the time requirement of source node institute initiating communication; Neighbor node set Nbr by arbitrary node i _iAnd concentrate the interstitial content that comprises to determine Communication Jamming and the resource limitation Inf that cause in the relay path; According to the internodal delay of the depth calculation of message priority formation delay _{I, i+1}, calculate thus relay nodes R to the time-delay of destination node D, determine the relay path according to These parameters.Resource distribution comprises, relay source address A _RsBe used for monitoring the data that this source address sends, relay source address relay destination address is used for receiving the data that relay nodes listens to; Configuration prefered path failure threshold L _Fm, relay path failure thresholding L _Fr, relay path testing failure threshold L _Tr, priority change thresholding L _Pc, be used for the decision relay nodes and report prefered path to NM, the thresholding of relay path and SR path communication fault; When node chosen by NM become relay nodes after, NM sends one to relay nodes message is set.

When communicating by letter between the auxiliary source node S of relay nodes R and the destination node D, relay nodes is transferred to the time delay of R use from S according to the Time Calculation of receive data bag _SR, work as delay _SR≤ D ₀, adopt prefered path to transmit, work as D ₀≤ delay _SR≤ D ₁, R is according to delay _SRPriority to message is adjusted, and sends and retransmits, if delay _SR＞D ₁, packet discard, when the node on the prefered path passed data failure, the upper hop node sent Negative Acknowledgment, after relay nodes is received the Negative Acknowledgment message, transmitted by the relay path through the message of prefered path bust this; Frequency of utilization is low when the relay path, initiatively initiates the detection in relay path.During with the communication of relay nodes, the destination node statistics receives the number of times of message from prefered path and relay path, and the number of times of losing message between by network management center management SD; Network management center is assessed the real-time in prefered path, relay path accordingly, upgrades in time and optimizes employed resource.

In the communication process, retransmit from the relay path receive the Negative Acknowledgment of upper hop node when relay nodes after, reduced the probability that transmission delay surpasses thresholding, reduce source node and initiate the number of times that retransmits, reduce the energy consumption of data retransmission.Relay nodes also dynamically changes the priority of packet simultaneously.When the node on prefered path and the relay path sent data failure at the down hop node, the upper hop node sent the Negative Acknowledgment message, after relay nodes is received the Negative Acknowledgment message, transmitted by the relay path through the message of prefered path bust this.Relay nodes changes the priority of incuring loss through delay packet, avoids being incured loss through delay by the packet of high priority in follow-up transmission course, guarantees that packet can arrive destination node in the time delay of regulation.In order to adapt to communication environment, especially operational environment changes the impact that causes.The frequency of failure in relay nodes statistical preference path, relay path, the address of unreliable node, source node is to the delay number of times of relay nodes, in order to grasp the whole network information.Can calculate simultaneously the prefered path frequency of failure, source node to the mean value of relay nodes delay number of times, if prefered path frequency of failure subaverage person illustrates that then relay path frequency of utilization is low.Relay nodes is in the low situation of relay path frequency of utilization, with the detection of initiatively initiating new relay path.The destination node statistics receives the number of times of message from prefered path and relay path, and the number of times of losing message.Relay nodes and destination node are reported above-mentioned information by the management path to network manager.Network management center is assessed the real-time in prefered path, relay path accordingly, upgrades in time and optimizes employed resource.

The present invention can the inter-node communication interruption occur, in the situation that message transmissions is incured loss through delay, by cooperating between relay nodes, destination node, network management center, reduces packet loss, reduces the number of times that source node is initiated re-transmission, reduces the energy consumption of data retransmission.The network management center real-time update is also optimized node and the resource that participates in communication, and adaptive ability is strong, realization is simple, not high to system requirements.The time division multiplexing, the message that have taken into full account the industrial wireless sensor network technology have the characteristics of priority, centralized network ma nagement, have good adaptability.

Description of drawings

Fig. 1 network management center workflow diagram

The communication resource exemplary plot that NM distributes among Fig. 2 the present invention

Fig. 3 time slot allocation figure

The flow chart of Fig. 4 relay nodes work

Embodiment

Be illustrated in figure 1 as workflow diagram of the present invention, the industrial wireless sensor network structure comprises network management center NM, source node S, destination node D, intermediate node and relay nodes R.All nodes in the network management center NM supervising the network, source node S is at first sent communication request to network management center, network management center NM utilizes existing resource, according to the request of source node and current network state information, determine to distribute to prefered path and the first-selected time slot of source node S and destination node D, network management center is selected relay nodes in prefered path, and foundation and the disjoint relay of prefered path path; Network management center distributes the communication resource that has relay nodes, comprises distributing time interval resource, destination node address, failure threshold value, relay nodes etc.; After Resources allocation was finished, network management center notification source node, destination node, relay nodes transmitted.In the transmission course, according to the relay nodes role, set up communication between source node and the destination node by the relay path, relay nodes R is by adjusting data message priority, initiating the methods such as re-transmissions and assist communicating by letter between source node S and the destination node D.

The rule of setting up the relay path comprises that the relay path that relay nodes consists of is non-intersect with the prefered path that comprises source node, source node will meet data message out-of-service time and wait time-delay, take into full account relay nodes annoyance level and data message priority and time-delay on every side to the time-delay of relay nodes.

Below for technique scheme to communication process specifically describe.

1. source node sends communication request to network management center

The resource of industrial wireless sensor network is by network management center NM unified management, the communication request message that source node S is sent to network management center comprises source node S, destination node D, time delay restriction, message priority, whether needs to arrange the information such as relay nodes.

2. network management center is determined first-selected communication path

Under normal circumstances, the transfer of data between S and D adopts the first-selected communication resource, and set of intermediate nodes is combined into I.NM utilizes the topology information TP of network, node load information OL, and node energy information PR, link information LS between node, adopting the centralized resource allocation algorithm is node S, D and intermediate node set I allocate communications resource.The communication resource comprises the information such as communication path, communication time slot, communication channel.The first-selected communication resource may be suboptimal solution, namely comprises insecure intermediate node or communication path and passes through the congested zone of easy generation.

3. select the relay path

The relay path comprises relay nodes R, destination node D, intermediate node set I, i.e. R → I → D.Transmission delay delay _ABThe transmission delay of expression from A to B.The relay nodes number that adopts from the different of position so that employing relay path and multi-path transmission, redundant path technology have very large similitude.Consider the complexity of industrial environment, present embodiment minimizes the angle Selection single relay path implement mode feasible with scheme from resource occupation.The following specifically describes the selection of relay nodes R.

Relay nodes can be selected the point on the prefered path, also can select adjacent with it node.Belong to the point in the intermediate node of prefered path such as relay nodes R, namely require R ∈ I, relay nodes belongs to prefered path, according to following rules selection relay nodes.

From the intermediate node of prefered path, choose destination node D with the disjoint path of prefered path; Such as the path transmission delay delay of above-mentioned intermediate node to destination node D _RD, source node postpones to be delay to the path transmission of above-mentioned intermediate node I _SR, the out-of-service time of packet is deadline _SD, in above-mentioned and the disjoint path of prefered path, select to satisfy delay _RD+ delay _SR＜deadline _SDIntermediate node as relay nodes.

Determined after the node node, needed to determine the relay path.Relay nodes R, destination node D, intermediate node set I determines the relay path.Following requirement need be satisfied in the relay path:

The battery life in relay path satisfies the time requirement of source node institute initiating communication.Relay path P ' belong to the optional set of the first-selected communication resource obtains by the intermediate object program that keeps first-selected communication resource distribution process.Select the arbitrary node i among the node set I, wherein node i ∈ I.Node i is reported this node battery dump energy and node power consumption at network operation period to NM, calculates LT effective time in relay path according to formula (1),

NM keeps the optimality of Path selection according to the real time information of in time understanding node effective time in relay path, guarantees that simultaneously the battery dump energy in relay path satisfies the time requirement of source node institute initiating communication.

Calculate Communication Jamming and the resource limitation that cause in the relay path.The interstitial content that the neighbor node union comprises reflects issuable interference and resource use restriction to a certain extent.Neighbor node set Nbr by arbitrary node i _iAnd concentrate the interstitial content comprise to determine Communication Jamming and the resource limitation Inf that cause in the relay path, according to following formula:

$\mathrm{Inf}=\left|\right|\underset{i\∈I^{\′}}{U}\mathrm{Nb}{r}_i\left|\right|---\left(2\right)$

Calculate Communication Jamming and the resource limitation that cause in the relay path.Delay delay between computing node _{I, i+1}, relay nodes R is to the time-delay of destination node D.In the industrial wireless sensor network of short haul connection, transmission delay is mainly by processing delay, queue delay and congested causing.Processing delay t _HandleBe that node receives packet to the time interval that can transmit this packet, minimum value is a time slot.The formation time delay is born the cycle of communicating by letter by the load of node with node to determine that the cycle is shorter, and assignable time slot is just fewer in each superframe, and the formation on each time slot is just longer.Node i, the delay delay between i+1 ∈ I _{I, i+1}Calculated by formula (3):

${\mathrm{delay}}_{i,i+1}=t_{\mathrm{handle}}+(\stackrel{\‾}{Q}\left(t_i\right)+Q\left(t_i\right))\×\mathrm{SF}---\left(3\right)$

T wherein _iSend the time slot of message for distributing to i to i+1,

For priority is higher than the degree of depth of the formation union of message priority, Q (t _i) be the degree of depth of the formation that equates with message priority of priority, SF is superframe length (millisecond).

Calculate relay nodes R to the time-delay of destination node D by formula (4),

${\mathrm{delay}}_{R,D}={\mathrm{delay}}_{R,1}+\underset{i=2}{\overset{\left|\right|I^{\′}\left|\right|-1}{\mathrm{\Σ}}}{\mathrm{delay}}_{i,i+1}---\left(4\right)$

The optimization aim in relay path is

P is the relay path, and concrete restriction comprises: LT, Inf, delay _{I, i+1}, delay _RDWherein LT represents the effective time in relay path, and Inf represents Communication Jamming and the resource limitation that cause in the relay path, delay _{I, i+1}Represent internodal delay, delay _RDExpression relay nodes R is to the time-delay of destination node D.Above optimization aim is exactly a multiple target combined optimization model, non-linear (NP) problem.According to formula:

Obtain

The value maximum becomes optimized value, is the preference value in relay path.α in the formula, β, ε, the η value is according to the concrete condition in the network and require definite.

Said process is the system of selection in single relay path.Can consider also that with many relays path method is come subsidiary communications with single relay path by at mulitpath relay nodes being set respectively.

4.NM allocate communications resource

NM docking power path and prefered path are carried out resource distribution, comprise prefered path is distributed time slot, from the source node S Resources allocation.The allocate communications resource need be followed following principle, can not allow node mutually produce conflict in transmission, on this basis, selects as much as possible and use the distribution method of optimum, take into full account the possibility that relay nodes retransmits, for re-transmission reserves corresponding time slot.

In order to support to adopt the communication of relay nodes, need to carry out corresponding resource distribution, comprise the resource distribution of relay path, prefered path resource distribution, concrete collocation method can adopt the method for salary distribution of conventional TDMA.Time division is become periodic frame, and each frame is divided into several time slots again, and to the NM transmitted signal, under regularly satisfied and synchronous condition, NM can receive the signal of each node respectively and not produce conflict in each time slot according to time slot.The signal that NM is sent to a plurality of nodes all is arranged in order in the time slot that special algorithm calculates and transmits, and each node just can receive at the signal that accurately other nodes is sent as long as receive in the time slot of appointment.

Be the communication resource that NM distributes in the present embodiment such as Fig. 2.Prefered path is S → n1 → R → m1 → D among Fig. 2, and the relay path is S → i1 → i2 → D.Getting superframe length is 10, and each node adopts single superframe mode.

NM at first is that node distributes time slot on prefered path and the relay path.Know that by Fig. 2 the timeslot number that the node on the prefered path need to distribute is [12532], the timeslot number that the node on the relay path need to distribute is [43].NM at first accesses the Time Slot Occupancy information of interdependent node from management information bank, judge the remaining time slots number, if the remaining time slots number is less than required time slot, then need redistribute.Begin Resources allocation from the S node.For distributing time slot t2, S is used for sending message to the n1 node; The t2 time slot of corresponding n1 node is used to receive the message that S sends; The n1 node needs another time slot to transmit the message of source node to R; In order to shorten time delay, directly choose t3 and send message to R; R needs 3 receiving slots and 2 sending time slots.3 receiving slots are used for respectively receiving E-Packeting and m1 of n1, and the next-hop node that the Negative Acknowledgment message of i1,2 sending time slots are used for respectively on prefered path and the relay path sends data.The t3 time slot is assigned with the message that the reception sources node sends, and t4 is used to receive the Negative Acknowledgment message of node i 1 on the relay path, and the t5 time slot is not is not received and dispatched, and relay nodes R processes local operation.At time slot t6, R sends message to the m1 on the prefered path; Time slot t7 is idle, distributes t8 to be used for receiving the Negative Acknowledgment that m1 sends; T9 is used for sending failed message at m1 and sends to the node i 1 on the relay path.Then the message that the t6 time slot receiving node R of m1 sends sends to destination node D at t7, utilizes t8 to send unsuccessfully to the R report when sending unsuccessfully.Node i 1 on the relay path utilizes t2, t9 to receive message, t4, t10 transmission Negative Acknowledgment and the message that is retransmitted by relay nodes of Negative Acknowledgment and R.Node i 2 utilizes t1 to send data to destination node, and t2 constantly upper hop node sends Negative Acknowledgment, and the t10 time slot receives the message of i1.Destination node t1 and t7 receive respectively the message that sends on relay path and the prefered path.

5. dispose the R inner parameter and notify S can begin communication

NM is relay nodes R configuration relevant parameter.

(1) NM comprises configuration relay source address A at first to the most basic information of relay nodes configuration _Rs, relay destination address A _RdThe relay source address is used for monitoring the data that this source address sends, and the relay destination address is used for receiving the data that relay nodes listens to.

(2) configuration prefered path failure threshold L _Fm, relay path failure thresholding L _Fr, relay path testing failure threshold L _Tr, priority change thresholding L _Pc, be used for the decision relay nodes and report prefered path to NM, the thresholding of relay path and SR path communication fault.Relay nodes all is to send message to carry out the information transmission to the form of NM.

(3) node is set as relay nodes.When node chosen by NM become relay nodes after, NM sends one to relay nodes message is set, and after relay nodes is received, flag bit is set, node gathers out effective information from message, formally become relay nodes.

6. communicate by letter between the auxiliary source node S of relay nodes R and the destination node D

Relay nodes is transferred to the time delay that R uses according to the Time Calculation of receive data bag from S _SR, judge time delay _SR, work as delay _SR≤ D ₀, adopt prefered path to transmit, work as D ₀≤ delay _SR≤ D ₁, R is according to delay _SRPriority to message is adjusted, and sends and retransmits.If delay _SR＞D ₁, relay nodes judges that this packet can not arrive destination node, packet discard on time.

As Fig. 4 be relay nodes auxiliary source node with destination node between the flow chart of communicating by letter.After R receives the packet that S sends, record time of reception T _A, the calculated data bag is transferred to the time delay that R uses from S _SRIf delay _SR≤ D ₀(D ₀Be the theoretical shortest time of data packet transmission), the next-hop node forwarding data bag of R on the prefered path.And unlatching timer T _r, the initial value of timer equals the life cycle of message, abandons the message of buffer memory behind the timer expiry.When the node forward data on the prefered path was failed, the upper hop node sent Negative Acknowledgment, arrived relay nodes R through multi-hop transmission.Relay nodes utilizes the relay path to send the message of buffer memory to destination node.

As from R to D, only having double bounce on the prefered path among Fig. 2, when m1 at t7 after constantly m1 (t7) sends unsuccessfully to destination node D, m1 (t8) sends Negative Acknowledgment to R, be forwarded to i1 through R (t9), i1 (t10) is forwarded to i2, and i2 (t1+FR) arrives destination address the most finally.In the present embodiment, through the forwarding in relay path, the time delay of message arrival destination node is 3 time slots among Fig. 2.

If D ₀≤ delay _SR≤ D ₁(D ₁Be the out-of-service time of packet) change the priority of the packet that receives into higher priority p ' and forward.Superframe length is 10 in the present embodiment, and each time slot is 10ms, D ₀=20ms.Do not retransmit time slot owing to directly distribute in the time slot allocation of Fig. 3, therefore will cause the length (100ms) that postpones at least one superframe in case missed the sending time slots that distributes.If S or n1 delay time, delay _SR=120ms, the time delay from S to D is 160ms.If the propagation delay time threshold value of SD is 200ms, the transmission that can only once incur loss through delay in transmission course so.So D ₁=120ms.Present embodiment is divided into 0,1 with message priority, and 2,3 are total to level Four, and 0 grade the highest, and 3 grades minimum.Node is stored in corresponding formation with the message that receives according to priority.When in two formations the message that sends to same node being arranged, the message of low priority sends and is delayed.In order to guarantee that message can send according to the time of distributing, R is according to delay _SRPriority to message is adjusted.For example be that 3 message is promoted to 1 or 2 with priority, priority is that 2 message is promoted to 1.The priority adjustment is avoided message priority is adjusted into 0, in order to avoid disturb the transmission of crucial message.The R node is directly rewritten the priority territory of buffer memory message.If delay _SR＞D ₁, relay nodes judges that this packet can not arrive destination node, packet discard on time.

7. communicating by letter between the auxiliary NM management of relay nodes R S and D

The industrial wireless sensor network work under bad environment, the NM managerial flexibility is relatively poor.Break down when environmental change causes communicating by letter between S and D, during hydraulic performance decline, need self adaptation to adjust the communication resource.Relay nodes management protocol stack inner parameter, R initiatively initiates to dock the detection of power path, periodically detects the relay path.According to the various parameters of relay nodes internal control, such as prefered path unit interval Failure count C _Fm, relay path unit interval Failure count C _FrDeng, R sends corresponding warning message according to the variation of each parameter to NM, and NM can in time understand and adjust path parameter.

Relay nodes R management protocol stack inner parameter specifically has: prefered path unit interval Failure count C _Fm, relay path unit interval Failure count C _Fr, relay path testing unit interval Failure count C _Tr, prefered path fail address A _Fm, relay path failure address A _Fr, change priority number of times C _CpParameters C _Fm, C _Fr, A _Fm, A _FrSafeguarded in running by R.R is at time slot m1 (t8) C when receiving Negative Acknowledgment among the embodiment _FmAdd 1, at m1 (t4) C when receiving Negative Acknowledgment _FrAdd 1.To send simultaneously the address A of Negative Acknowledgment _Fm, A _FrBe kept in the corresponding formation.Same every change message priority 1 time, C _CpIncrease by 1.

If C _Fm〉=L _FmPerhaps C _Fr〉=L _Fr, C _Cp〉=L _Cp, R utilizes the management path to comprise C to the NM transmission _Fm, A _Fm, C _FrA _Fr, C _CpWarning message, and zero clearing.Notice NM breaks down or the node of Quality Down.

In the stable situation of the network operation, relay path frequency of utilization is lower.In order to safeguard the relay path, in time find the hidden danger on the relay path, R initiatively initiates to dock the detection of power path.Owing to when initiating to detect, still have message transmissions on the possible prefered path, the detection of therefore docking power path will avoid conflict.In the present embodiment, in the relay path detection cycle, respectively from R (t6), R (t9) time slot sends R with the message that receives.Node D is finally from D (t1), and D (t7) time slot receives detection messages and original message.If R has received Negative Acknowledgment from the relay path, equally to C _TrOperate.

Between network management center NM management SD with the communication of relay nodes

NM judges according to the relay nodes information that receives the resource in the first-selected communication resource, relay path distributes whether need renewal.Communication with relay nodes between the SD node can be initiated by S, distributes during the SD resource bid.At the establishment stage of communication, select suitable relay path, the allocate communications resource.Also can determine it is directly with the redistribute resources of relay nodes according to the success rate of communicating by letter between SD and time delay by NM, or with existing communication path as prefered path, add the relay path.Although NM can operation optimization algorithm, the variation of network environment, operational environment, often so that the resource of distributing, the relay path of selection changes.Therefore NM need to carry out real-time oversight, management, optimization to the communication between SD.The management function of NM comprises the correspondence of setting up between SD, optimizes the correspondence between SD, ends the correspondence between SD, optimizes correspondence between SD based on R, D to the statistical information of NM report.The optimization of communicating by letter between SD is based on R, the D statistical information to the NM report.The information of R report represents respectively the degree of reliability on prefered path, the relay path, unreliable node address, the time delay of SR.Destination node D maintain internal parameters C _Rm, be used for record setting-up time interval T _rThe message amount that interior D successfully receives from prefered path, C _RrBe used for record T _rIn, the message amount that D successfully receives from the relay path, C _fBe used for the number of times that record D fails to receive message.After the setting statistics time interval arrived, above-mentioned parameter stopped counting.D utilizes the management path to send above-mentioned parameter to NM, it is set to 0 after sending successfully.NM receives the A that node R is reported up _Fm, A _FrAfter the information, corresponding address in the management information bank is set as unreliable node, then calls corresponding routing algorithm, resource allocation algorithm, redistribute prefered path or relay path, the switching in the walking along the street footpath of going forward side by side.When the cut-off of the time limit in cycle of data message, perhaps NM receives the warning message that R sends, and judges to draw the correspondence that need to stop between SD.NM just need to end the communication of SD timely, and the path is adjusted.

At first end the sending function of source node S, the relay function of R node, the receiving management function of D node.NM accesses in the management information bank relative recording of the communication resource between SD, sends to comprise to interdependent node and ceases and desist order and dwell time, needs the message of the resource that discharges.After dwell time arrived, S, R, D be hold function simultaneously, and the time slot that distributes in the release graphics 2.NM sends the message release communication resources to all the other nodes subsequently, if resource does not discharge fully, disturbs possibly other nodes to send, and produces communication failure.After the node communication resource discharged and finishes, NM discharged the relative recording of the communication resource between SD.

Above-mentioned instantiation has only been told about implementation method how to utilize relay nodes to carry out industrial wireless sensor network communication; and be not used in limitation the present invention; all any modifications of making within method of the present invention and principle, being equal to replacement, improvement etc. all should be included within protection scope of the present invention.

Claims (5)

1. the industrial wireless sensor network communication method based on relay nodes is characterized in that, network management center NM selects prefered path according to the request of source node and current network state information; Select on the prefered path node or with it adjacent node select to comprise relay nodes R destination node D, the relay path of intermediate node set as relay nodes; When communicating by letter between the auxiliary source node S of relay nodes R and the destination node D, relay nodes calculates the time delay that is transferred to the R use from S according to the time of receive data bag _SR, work as delay _SR＜D ₀, adopt prefered path to transmit, work as D ₀≤ delay _SR≤ D ₁, R is according to delay _SRPriority to message is adjusted, and sends and retransmits, if delay _SR＞D ₁, packet discard, the upper hop node sends Negative Acknowledgment, after relay nodes is received the Negative Acknowledgment message, transmits by the relay path through the message of prefered path bust this; During with the communication of relay nodes, the destination node statistics receives the message number of times from prefered path and relay path, and loses the message number of times between by network management center management SD; Network management center is assessed the real-time in prefered path, relay path accordingly, upgrades in time and optimizes employed resource.

2. described industrial wireless sensor network communication method according to claim 1, it is characterized in that, when relay nodes belongs to prefered path, from the intermediate node of prefered path, choose destination node D with the disjoint path of prefered path, namely do not have identical intermediate node on two paths; In above-mentioned disjoint path, select to satisfy delay _RD+ delay _SR＜deadline _SDIntermediate node as relay nodes, wherein, intermediate node postpones to be delay to the path transmission of destination node D _RD, source node postpones to be delay to the path transmission of intermediate node _SR, the out-of-service time of packet is deadline _SD

3. described industrial wireless sensor network communication method according to claim 1, it is characterized in that, select the step in relay path to be specially, select the arbitrary node i among the node set I, calculate LT effective time in relay path, the battery life in relay path satisfies the time requirement of source node institute initiating communication; Neighbor node set Nbr by arbitrary node i _iAnd concentrate the interstitial content that comprises to determine Communication Jamming and the resource limitation Inf that cause in the relay path; According to the internodal delay of the depth calculation of message priority formation delay _{I, i+1}, calculate thus relay nodes R to the time-delay delay of destination node D _RD, the optimization aim in relay path is

According to formula: $\max \underset{i=1}{\overset{L}{\mathrm{\Σ}}}P=\frac{\mathrm{\αLT}}{\mathrm{\βInf}+{\mathrm{\ϵ}}_{{\mathrm{delay}}_{i,i+1}}+{\mathrm{\η}}_{{\mathrm{delay}}_{\mathrm{RD}}}},$ Obtain

Be the preference value in relay path, wherein, P is the relay path, and L is the nodes of intermediate node set I, α, and β, ε, the η value is according to concrete condition in the network and require definite.

4. described industrial wireless sensor network communication method according to claim 1 is characterized in that resource distribution comprises, relay source address A _RsBe used for monitoring the data that this source address sends, the relay destination address is used for receiving the data that relay nodes listens to; Configuration prefered path failure threshold L _Fm, relay path failure thresholding L _Fr, relay path testing failure threshold L _Tr, priority change thresholding L _Pc, be used for the decision relay nodes and report prefered path to NM, the thresholding of relay path and SR path communication fault; When node chosen by NM become relay nodes after, NM sends one to relay nodes message is set.

5. described industrial wireless sensor network communication method according to claim 1, it is characterized in that, the frequency of failure in relay nodes statistical preference path, relay path, the address of unreliable node, source node is to the delay number of times of relay nodes, calculate the prefered path frequency of failure, source node and incur loss through delay the mean value of number of times to relay nodes, subaverage person, then relay nodes is low in relay path frequency of utilization.

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